'86 350

Allright, this afternoon I figured I'd tackle my carburetor and mess around with the jetting, etc. Well I changed the primary metering jets from .098 to .101. I left the secondaries the same at .095. On the metering rods I went from .075 x .047 to .073 x .047. I then changed from the stock step-up springs (4" yellows) to 5" step-up springs. All this is almost the exact same calibration that Edelbrock runs on their 1405 carb, which is set-up more for performance from the factory as opposed to the 1406 carb (the one I run) which is set-up to be leaner and more towards fuel economy.

Also, on the accelerator pump, I have the rod in the middle hole on the arm, I believe this is right but if anyone wants to conform that'd be great.

Now the idle on the car seems to wander badly by a few 100 rpm and it bogs pretty badly at part throttle or WOT in the lower RPM range. Anyone know what the cause of this could be? Is it an airleak or something else?

-Thanks, Brandon

camaronewbie

Have you checked for a vacuum leak? Spray carb cleaner (NOT STARTING FLUID) all around the base, the vacuum lines, and see if idle smooths out and/or increases.

Have you checked the float level as per instructions? Maybe a float needs adjusted - I just bought a brand new one off the shelf, and the floats were way out on it.

What's fuel pressure at? timing set to? Make sure vacuum line plugged and not connected to dizzy when checking base timing.

Have you adjusted the carb (two screws on front) for the highest vacuum on the driver side vacuum port? Put vacuum guage on drivers side port on front, start car, screw one screw all the way in until it wants to die, then back it out slowly and watch for highest vacuum level. Then, do the other screw same way. Then back to first screw - do this 3-4 times each screw until you achieve the highest vacuum level. You may have to adjust the idle downwards during this process, to mainati nthe idle level you desire (I was shooting for 800rpms). When you get it, screw each screw back in 1/2 turn - and your adjusted.

That's all the things a newbie can think of.

'86 350

There isn't a vacuum leak, there was none prior to this and I didn't pull off any vacuum lines or anything even vacuum oriented. I'll try the carb cleaner trick if I can't resolve this.

This carburetor is about 7-8 months old, it's not brand new out of the box, the float has always been fine before, and I didn't touch it today.

The fuel pressure is at 5.5 psi. The timing is basically wherever the car started to ping and then I backed it off roughly 2 degrees. None of these things were touched though before or after I changed the calibration.

This I haven't done yet. I'll have to rent a vacuum gauge from pepboys on Monday and do that. I've been meaning to for a while, but I never have. The thing is though, I never really touched any of these things. They're all the same as they were before the calibration. The only thing I changed was my fuel pressure I previously had it at about 6.5 psi, but that was too much so I backed it back down to 5.5.

Also, the searching at idle seems to have gone away, I notived it only 1 or 2 more times today, but Monday I'm gonna pick up some carb cleaner just to make sure I don't have any air leaks. Stock the carb came with the accelerator pump rod (that what it's called?) in the middle hole on the lever. When I put it to the top hole (pump opening later) it seemed to bog even worse. However when I put it in the bottom hole (pump is pushed down almost as soon as I'm on the throttle) it seemed to have less bogging, virtually none. Does anyone know why this is? Was the car not getting enough fuel in the lower RPM ranges and bogging out?

-Brandon

camaronewbie

Did you remove the top of the carb for these replacements? If so, you touched the floats, if not (I see where you can change rods and such on the edelbrock without removing the top), then assuming they were fine before, next...

Get a timing light and check it - no telling where it is - no good can come from guessing timing by sound. Timing lights are cheap, like $25 - check harborfreight.com, or northerntools.com - if you have one close by, they should be open tomorrow - autozone/advance will be open for sure, and their lights aren't much higher priced - it's a great investment if your going to do your own tinkering.

don't rent - buy! A vacuum guage might be $10 at most - you don't need anything fancy - any parts place open tomorrow will have one.

Recalibrating means EVERYTHING changed, and your carb settings will need to change too for the new calibrations!

Start with timing - buy, beg, borrow, steal a light and check it, so we know - make sure to disconnect the vacuum line to the dizzy, and cap the line at the carb so no vacuum leak there. Mine is about 11* BTDC on my 350 carb'd motor - set yours somewhere between 8 - 12 - I had mine at 8, but had to up it a tad to get more vacuum for my brakes (increasing timing and decreasing idle makes a tad more vacuum sometimes). Then adjust idle to where you'd like (mine is about 800rpms). Then spray the carb cleaner around base and vacuum lines just for giggles and make sure no vacuum leaks. Then, try the adjustment screw settings with the vacuum guage and see what happens.

I'd leave the accel pump in the middle hole for now, until we are more sure of the other settings and such - then, after we get a decent run, we can try the accel pump in a different hole and see what happens - but I'm assuming a different hole would mean changing the settings on the front again with the vacuum guage.

'86 350

Well I was gonna get a vacuum gauge, but I was about 15 minutes away and my parts store was closing in 10 minutes, so I'll have to get one tomorrow. On the timing, I'm not going by the timing marks because we are not sure how accurate they are, they've always seemed to read completely wrong and I'm not sure the previous owner actually has the marks in the right spot, so I'm not going by that right now, I'm basically just running it where I always have. There really isn't much I can do. I do have a timing light, but that isn't gonna help, due to what I said earlier.

Hopefully I can at least get the vacuum gauge tomorrow and get the mixture screws all striaghtened out.

'86 350

What would the changes be if I were to go from the 5" orange spring to the 7" pink one? I believe it'd provide me with mroe vacuum, but are there any drawbacks to it? I still haven't had a chance to get a vacuum gauge, none of the parts stores around here have one that's cheaper than $23, so I'm just waiting till my friend gets home today and then I'll borrow his for a while.

'86 350

Anyone know about the spring changes? Edelbrock reccomends running a larger springs on a car with a big cam, so I tried that, and it actually seemed to run pretty poorly, I went back to the 5" orange spring and it seems pretty good, is that where I should keep it?

Also, the car, although I'm sure it's producing more power then the lean calibration it had before, seems to be less snappy on the low-end. In first at 10mph I used to be able to light up the tires like nothing, now they barely spin at all, although it seems to pull harder up top, is there any happy median for this? I went from .095 to .098 on the secondaries as well in hope to gain a little more power up top, but I haven't tested that yet. On the low rpm issue though, would that be caused by the secondary jetting, primary jetting, metering rods, or springs? What should I change and experimaent with to try to get a little bit of the low-end back that I had before?

'86 350

Anyone at all?

'86 350

Night rider327

iTrader: (13)

You got the carb dailed too rich for your engine.

I can say that cause of your comment on the pump rod.. The top hole gives the biggest pump shot, bottom hole gives the smallest pump shot.

So it made it worse in the top hole (more fuel at tip in) and got better in the lower hole (less fuel at tip in)

Start with the basic tune 1st.. Make sure the floats are set to 7/16" at rest and 15/16" to 1" drop ( I don't care what the book says the above is the right specs that works best)

Set idle mixture screws with vac gauge to give highest vac reading.

Make sure fuel psi is 5 to 5.5 max (no more than 5.5 ever)

Your probbly going have to go leaner on jet and rod sizes..

You went WAY too big on the jets and way too small on the rods unless you got close to 500 HP.

Just to give you an idea.. I run a 1405 edelbrock on my car.. I run 11.59@ 118 mph, with a 1.77 60' and heres the cal I'm running.. .104" main jets, .101 sec. jets, 068 x 042 rods, pink 7" spring.. Now remember thats on a mid 11 second car.

For yours I would start with just a rod and spring change and a sec. jet change..

Here's what I recommend for you to put in..
.098 main jets
.101 sec. jets
073 x 037 rods
orange 5" springs

Set the pump rod to the top hole

Oh yeah to answer your question.. The step up springs in the enrichment point for the smaller step of the rods.

As you go WOT the vac drops.. Steady drop all the way to 0. As the vac reachs the springs set vac rate it will let the metering rod lift up out of the jet so more fuel can get through.

The higher inchs of HG on the spring the faster it will enrich.

Remember too much fuel too fast aint good.. Causes a rich bog

'86 350

Wow, thanks for the help, that is very, very helpful. I'll go and change the jetting now, I can basically just switch my primary and secondary jets (the secodaries are the one's farthest towards the back of the carb right?) and I should be fine. I'm running the .073 x .047 rods, is that okay or not? My calibration kit didn't come with the size .073 x .037. Or could I pick these up for cheap at a parts store or something? As for the springs I should be good, those are the 5" orange ones I'm running now.
- , Brandon

Night rider327

iTrader: (13)

86 350... Your welcome.. I been playing with, and useing the edelbrock/carter AFB carbs for about 7 years so I pretty well have tuning them down pat.

What rods and jets did your cal kit come with? I keep forgeting edelbrock don't give all the same things in the 1405 and 1406 carb's kits, and that most people don't keep 20 diff rod pairs and jet pairs around like I do lol

And yeah the sec. jets are the ones in the rear most part of the carb, almost right under the float baffle plates that slides in and out of carb.

'86 350

I have options of:

.070 x .037-What I run now
.073 x .042
.073 x .047
.075 x .047- What was stock in the car.

Night rider327

iTrader: (13)

Ok Out of that I would go with the .073 x .042 to start with along with the jetting I said before.

You probbly know this already.. The 1st size of the rods (.073) is your cruz stage.. Like when your tooling around town, not pushing the car hard, etc. I like to keep the cruz stage as lean as I can w/o detonation or overheating.. That helps with fuel mileage alot.

The the second size of the rods is your "power" stage. That comes in during sprinted driving, pulling harder up a hill, etc (when ever your vac. reachs the metering rod specs)

Going too lean there could cause bad probs, with worse being a busted piston due to detonation. On the other hand too rich there could cause a bog, less overall power, etc.

Remember to read your plugs.. The engine will tell you want it needs, you just have to 'listen' to it and the spark plugs is how you do it.

Jetting for max power though is best done when you can measure your results like a dyno or drag strip. I dailed in my carb at the dragstrip. I ended up changine jets, rods, springs about 20-22 times to get the combo that worked the best for me at WOT but still lean enough at cruz to keep good mileage.

On a track your looking for the jetting that gives you the highest MPH trap speed (forget ET, dont even think about ET, trap speed shows power, ET shows power and traction)

'86 350

Well honestly, before I made the rod change (to what you reccomended, .075 x .042) the plugs were black. I haven't checked them since, maybe I'l pull a few tonight.

Thanks for all the help, I'll report back on how it is.

Night rider327

iTrader: (13)

Your welcome...

Was the plugs black with the stock out of box settings or was they black with your re caled BIG jetting tune?

If it was with your re caled tune I figured they would probbly be black. Like I said before that's way too rich.. You want to see a nice even tan coloring to the plugs.

Make the changes, drive it, read the plugs then get back with me with the results of how it feels, whats it doing, and how the plugs look, and if the tune still aint right I'll help you figure out what you need to change

'86 350

Out of the box they were a tad white, hence the reason I richened it up a little. I'm gonna try driving it tonight for about 10-20 miles and I'll get back to you on how the plugs look and how the car performs. Last night before the rod change from .070 x .037 to .075 x .042, but witht he jets changed, the car pulled very hard up top and felt strong, and I didn't have a real noticable rich bog, in fact it only happened right off idle, and even then it wasn't bad at all.

'86 350

Allright, just got back from driving. Compared to the .070 x .037 rods, I had to retard the timing a good amount to prevent pinging, I'm guessing this is normal though. I also have a fairly bad low-end bog now too. Any reason for this?

By the looks of it, it seems like a .075 x .037 or .073 x .037 would be perfect for my application, but I don't have one in my calibration kit (damn you edelbrock!). Think I could just pick a set of these up at a local speedshop? I'd give 'em a call but they're closed. I'll have to call tomorrow and ask.

As for plug color, I'll have to check tomorrow. I'm heading to bed soon, and I can't even think about going near the headers for at least an hour after drving the car, and I don't wanna wait that long, so I'll have to get back to you on color tomorrow...... I need header wrap......

-Brandon

Night rider327

iTrader: (13)

Brandon... What's your timing set at? Most SBC's like 34-36* total in by 2800-3200 rpm.

With 34-36* of total timing if your pinning then it's too lean. Check timing 1st and make sure you wouldnt at anything like 38, 40, 42 degress etc. If your timing is with in specs then I would say that rod combo was too lean in the power mode.

Time to go to a smaller rod and try that.. You said with the jet change and the .070 x .037 the car felt good.. So lets work from there. Was the plugs plug with that combo?

You said you had a light off idle bog that sounds like the common pump linkage and or float level probs. You got the arm in the top hole?

Also have you checked and made sure your floats are at 7/16" rest and 15/16" to 1" drop?

'86 350

I honestly don't know what the timing is at. I got the car when the previous owner had put the engine most of the way in and I had to finish it up. He never marked the crank with tape or anything, so I have no way of knowing where it is exactly. I've always just set it to the point where it starts to ping, and then I backed it off a couple degrees or so. After switching from the 7073 rods, I left everything else the same. I had to retard the timing a good amount beforeit would stop pinging.

Unfortunately I didn't have a chance to look at the plugs with the 7073 rods. I have a pic of plug #1 and plug # 3 with the 7542 rods.

Here is Plug #1:





And Plug #3:





The tips of them are a tad gray/white with the 7542 jets. I'm guessing I should richen it up on the rods?

These pictures make my hands look fat....

-Brandon

Night rider327

iTrader: (13)

Ok, those plugs are showing a good bit too rich. You want a real light tan color not brown, black, etc.. You know the look of the off white almond color used on home frezzers, tosters, etc.. That's the color your wanting.

To set total timing, and really any person that works with high performance cars any then you need a good dail back or advance timing light. The guns that has the **** on the rear of it, or the digital display and the advance buttons on the gun.

All dampers will have a "hash" mark on them which is just a line cut into the damper.

You'll then need a taming tab or pointer made on to timing chain cover or bolted on.

If you a tab it will read left to right from like 18* downward to 0 or TDC, then maybe 4* ATDC.

With that and a dail back light. You just have a buddy to rev and hold RPM to say 3200 RPM.. Then you shoot the light at the damper and tab.. Turn the **** (or push button) till the hash mark on damper lines up with the )/TDC mark on tab.. Now look at you gun's dail or display and see what number it's on.. That's your total timing.

If you can't get a dail back light and have a reg. light you can buy timing tape for under $5 and use that. Wrap it around your damper putting the ) on tape right over the hash mark on damper.. Then just shoot it with your light at 3200 rpm.. What ever the TDC point of tab lines up with on tape is your amount of total timing.

Really man if your pinging that much you have other probs to look into. Do you know any of the specs on the engine you can tell me.

I'm running 10.18:1 compression with 1965 GM iron heads, a smaller cam than most people to build high cyl pressure, pump 93 octane fuel.. Timing at 34* total all in at 3200 rpm, and 2 steps colder spark plugs. No ping what so ever.

With out knowing info like compression ratio, cam size, etc or atleast a compression test result and timing it's hard to say for sure whats the cause of the pinging on yours or what to do to stop it. It could be caused by too much vac advance being added if it pings at part throttle., temp running too high, plugs too hot, way too much timing, timing thats coming too fast, cam thats too small for the compression (I will not say too much compression like alot of people cause if you cam it right and dail in the carb, and timing right you can run 13:1 compression on pump 93)

Guessing on timing is a real no no really. 35* total on mine and a ping, 34* I dont, 33* and I'm .08 second slower in the 1/4 mile, 32* and I'm .21 seconds slower... That shows you how much just a degree or two can change things

'86 350

The camera seems to have discolored those pics a little, the tip of the elcectrode was a tanish color (maybe I was mistaking it for white). Although you are right, they look a little rich still. What do you think my next step with the rods is? Stay with the 7542's or maybe go with the 7547's? After we got rid of the pinging it was fine, car ran pretty good, and I put the 7542 rods back in today and the bog I was experianceing before seems to be gone.

When I first got the new distribuotor a few days ago, I changed the stock springs where full advnace was in by 1,600 to where it was all the way in by about 2,600. Was this a smart choice, or should I go up or down more?

I have a tab and I see the notch in the balancer, tomorrow I'll try to pick up some timing tape and measure it, I just have a normal timing gun.

Specs on the engine, well unfortunately it's hard to say, the previous owner had built the motor and put it in the car most of the way, I just had to finish it up. The heads are 2.02 cast iron chevy heads, nothing too special. I'm also running Accel 576s plugs. I had a part # written down for the pistons when I tore the engine down to the short block, but I can't find it. For some reason I remember the compression being right around 9.5 and 10 to 1 with the 64cc heads I was running. Cam I'm not sure on, it's pretty lopey on idle, but other then that I have no specs.

I wish I had cash for a dyno session and then I could really see what the changes do, instead of just feel.

I'll get the timing tomorrow, gotta pick up some of that tape.

Night rider327

iTrader: (13)

Ok, now we're getting some of the info I need..

Your ping is your timing curve. 2600 rpm is too fast to bring the timing in on any 9.0:1 and up engine running pump fuel. Most cars are going to like 3000-3200 rpm better.

But don't trust the paper that came with the recuvre kit. When recurving the dist. its best to always check your self..

I write out on paper....

RPM Timing
Idel
800
900
1000
1100
1500
2000
2500
2800
3000
3200
3400

Now check your timing at each of those RPMs and write the # down next to each RPM.

Your looking for a curve that starts advancing about 300 rpm past your idel speed, and is fully advanced at 3000-3200 rpm. Change springs to get that.. Re test, change again if needed and re test.

For the timing tape remember you have to buy it for the size damper you have. The 3 common sizes are 6", 6.75" and 8" measure across yours 1st to see what you have so you can buy the right tape.

Ok now on your carb.. Keep going bigger (leaner) on the rods till you get the tan color and no bog. Try the 75 x 47's again and see what the plugs look like then, and how it feels. You are not going to need or want the 75 x 42's based on your plugs.. Bigger # means leaner and your too rich now so. Your probbly going to have to go bigger than just that little small step but try the 75 x 47s just to see.

But get that timing right 1st man.. Timing is a very big thing

I never had much luck with accel plugs. I have had best luck with AC delco's and NGK v power. I like the NGK's for my race plugs cause of the gold color makes reading them easier. The NGK's do wear faster so I use AC's for street use.

I don't have my plug cross ref in front of me so I aint sure what heat range your accel is.. I'll use AC as a quick point.. an AC delco R45 is the std. If your running around 130-140 psi cyl pressure you might could go up one heat range to a R46. If you have 150-170 psi cyl pressure the std. heat range R45 would be right. 180-200 psi you need to drop one heat range cooler to a R44. Above 200 psi to 220 psi drop two heat ranges to R43's

Was your pinning before at part throttle, or only WOT or what?

If you can find the piston PN's for me and maybe tell me what head gaskets you used when you put the heads on it would be a BIG help. Also if you knew the head cc or get the casting #'s off of the head (under valve cover and bettwen rocker studs) that would be great

All of your tuning is based on your compression and cam size really. Low compression small cam, low compression big cam, high compression small cam, high compression big cam are all going to need major changes in the tune from each other.

It's hard to know cam specs on an already installed one and no paper work for it...

If you can get the head CC, piston PN, head gasketed used, and a compression gauge reading in PSI I can pretty much tell you for sure what compression ratio you have, and get very close to the cam size.

Then that info well tell me what I need to know to pretty much give you dead on timing specs, plug heat range and carb dail in.

Oh yeah truthfully IMO the dyno is not the best place to tune a car. We don't drive or race on dynos. I like doing all my tuning at the local drag strip.. $5-20 to run your car as much as you can.. That time slip can tell you HP just as good as a dyno can.. Most tracks has weight scales there too, get a weight of your car with you in it, and look at the Trap speed MPH and that can tell you HP. When I'm dailing in my car I go to the track and really I don't even look at the 60' time, ET's just the final trap speed.. Tune and trap speed goes up you just make more HP, tune and trap speed goes down you just killed off some HP.

Sorry for the book type reply man, but just trying to share what I have found out over the years with you.

'86 350

Well, I can't get the car to idle correctly right now, so at the moment I can't get you all the different timings for the rpms. At full advance however, I'm running about 37*-38* of timing. Seems about normal.

I went back to the 7547 rods, and I got no pinging on about 37*-38* of timing, so I should be set there.

No for my BIG problem. First of all, the car bogs, horribly till about 2,500 rpm. It sputters and bogs and finally striaghtens itself out after that. The idle is also very inconsistant. The other day when I changed the jets too what you reccomended, I tryed playing with the floats. One of them was right around 7/16, while the other was a little below that. I tryed fixing the one below (driver's side float) and I think I may have messed it up. It turns out I was bending it in the wrong place from where your supposed too. I eventually ended up having the little needle thing under the float come out and I striaghtened out the float, put the needle back in and then set it to 7/16". I don't know if it did something or not, but I don't think it really did because I just noticed this terrible bog today, even though the jets were changed and I messed with the floats about 3-4 days ago.

Like I mentioned, it very strange, sometime the car will idle high (around 1100 when warm). This is usually after it comes off a rev, then after about 3-5 seconds, it'll drop down to about 700 rpms, and sometimes farther causing the car to sputter and die if I don't catch it in time. Plus, it seems now that after I let off the throttle the car taked a while to come off of full advance. Is this normal or what?

Also, about how much vacuum should I be pulling at idle? It seems I get aright around 7"-8" of vacuum, that sound okay?

Anyways, thanks for all the responses. I do appreciate them a lot, and it's been a BIG help to me. Hopefully very soon I can get this thing running like a champ.

-Brandon

'86 350

I started the car again today, I've been busy all weekend. Thing is really running horribly at low RPM's. There's still a horrible bog until after about 2,500 rpm. And it doesn't want to idle worth a damn.....

I'm almost positive it can't be the floats, this happened about 3 days AFTER I last messed with the floats.

Night rider327

iTrader: (13)

Sounds like a classic vac. leak now or your advance weights hanging/sticking in your dist.

Unless you got one MONSTER of a cam theres no way vac should be anywhere close to that low..

Then if you do have a cam big enough to lower the vac that much you won't get good under 3K rpm pull..

With my 272/284* cam I'm pulling 15" hg of vac at a 650 rpm idel

Are you sure you didn't leave a vac line off somewhere? Or did you may tear the gasket on the carb's air horn when you pulled the top off?

'86 350

It used to read about 15 hg of vacuum, about 2-3 days ago when I last measured it.... so something happened. The last time I pulled the carb off, there was a small tear, but it wasn't towards the end of the carb body, it was in the middle in just a little cross section, not anywhere that I'd think would cause a problem. Plus I think I'd know this right away anyways, not after a few days.....

I checked, no lines off anywhere. There's only 2 lines it could be anyways, PB line from intake and the line from distributor to carb. The distributor is a brand new (literally about 2 weeks old) Mallory unit.

The springs I'm using now are silver ones that begin advancing at 800 and are fully advanced by 2,600. I have 2 other options. Black ones that fully advance by about 1,500 and gold ones that advnace by a little after 4,000.

'86 350

Any ideas?

Night rider327

iTrader: (13)

Sorry bud for the long delay in time getting back to you. I been out of the state for a few days.

Ok you have a vac leak somewhere thats for sure. Maybe check the front and rear intake seals.. Get you a lenght of hose like rubber fuel line, an old garden water hose, etc.. Cut it to 2-3 feet long. Hold one end to your ear and move the other end around diff spots on engine (front and rear intake seals, carb base gasket, etc) If you run acorss a vac leak you'll know it. The sucking air sound or whistle from it will be real loud through the hose.

Now on your dist. springs you have alot more options than just the ones you listed. You don't have to keep two of the same color (tension) springs in there.. You can mix and match till you get the curve you need.

I use one light and 1 med. tension spring in mine.. I had some engines that needed 1 light and 1 heavy, or 1 med and 1 heavy

RLZ28

I am having similar problems, I have a 84 305, I replaced the intake manifold and put on an eldelbrock 1406 as well. I have one plug that will completly foul shut, the other seven look normal. I checked the compression and all cyclinders where within or under 20 psi of each other. My highest reading was 140 lowest was 120-125. I am going to try the suggestions you were given, and see if helps mine to run better.

Night rider327

iTrader: (13)

RLz28... Is that a well used engine or one with a bigger cam in it. 120-140 psi is very low IMO. Sounds like you may have sealing probs or way over cammed.

Try a new plug in the place of the fouled one. I have seen bad plugs before. Also you might want to check that plug wire, and post on dist.. It could be a prob there and not letting the sprak make it to the plug.

If it's oil fouled then you could have a bad valve seal on that valve, or a worn valve guide thats letting oil slide down the valve stem and into the chamber

'86 350

Sorry I haven't gotten back on the problem. I'm in the middle of swapping in a new rear-end right now, and as soon as I finish then I'll start working on this again.

I'll get back to you on the problem......

'86 350

Well, I finally got the rear-end in, and I can tackle this problem now.

I checked for a vacuum leak. I didn't hear one. I used a 1.5' piece of rubber fuel hose, and I didn't hear anything that would indicate a vacuum leak. The car idles fine at about 1,300rpm (I know, ridicuously high), but if I just turn the idle screw 1/16th of a turn or anything past that point to back it off more, it just idles down real fast, stumbles, and dies. I'm not really sure what that's all about, but it's pretty much my biggest problem.

I'm guessing it's a float level problem, but I'm not too sure.

Night rider327

iTrader: (13)

The idle spped and float level don't really have much to do with each other..

Try your dist. vac advance on both ports (timed and full). I seen engines that liked ported better than full, and others that liked full better than ported.

Like on my engine if I use full time vac (port on driver's side) the engine will search for RPM at idle. About 200 rpm up and down the whole time. Now on my Dad's engine if he runs timed vac he just loses RPM at idle and engine feels alittle lacking at slower speeds.

I would get timing checked and set 1st thing.. I would think with that low of cyl. pressure the engine will want more lead at idle. I would try in the 18* range at idle with out vac advance hooked up,

Lower the Idle RPM down with idle screw to 900 RPM, use a vac gauge to tune the idle mixture screws.. Looking for highest vac reading, now turn Idle down to 700 RPM, and plug the dist. vac advance line into full time and see what it does, then try ported and which ever acts best and feels best leave it there.

'86 350

Allright, well I got everything sorted out. I haven't done much witht he car lately, been busy with SAT's and finals for school, but I can finally focus on the car now.

Anyways, I did switch vacuum ports and it seems to be better. I was running off of the driver's side previously, but it seemed to "search" for the idle like you described. Now I have it on the passenger's side port and it's idling much better.

My timing, like I mentioned is, at about 37* advanced. At about 38* it starts to ping. At idle I have about 14* of advance I believe. I can't remember exactly, if it's needed though I can go check it out and get an exact # for you.

I'm still getting a little bit of bogging off idle, and I've tried everything including going down to the 7547 rods. I've been having problems lately with idle, but I think I may have it now. However, even before when I tried switching ports the idle was still bad. Is it possible I had dirt or something in the needle to mess it up? Or is there a way to mess up the float needles (I had one of the floats actually off earlier)? I think something was messing it up before, but it seems pretty good now.

If I lower it too much though to around 450-500 rpm, instead of holding steady and just idling real rough, it just sputters for a sec and dies. It seems like there's sort of a "wall." It'll idle great before I drop below and exact RPM, and then it'll drop off dramaticall and won't idle worth a darn until I put the idle back up. You know what this could be?

-Brandon

'86 350

I've definitely got a vacuum leak somewhere. Measured vacuum again, and the highest I could get at about 800-900 rpm was only about 7-8 hg vacuum. I checked the line going from my distribuot to the carb and then from the intake to the brake booster.

I'm gonna try sealing up a few of the plugs in my intake, and if that doesn't work, my local parts store has a base/airhorn gasket set for only $6.

'86 350

Well this whole idea went to hell. Maybe I should just leave it alone next time eh?

Anyways, I went and bought the gasket, came home, and replaced it. I'm all excited to go start the car and see if my problem is gone..... and.... it won't start. I go to see what's going on and there is fuel ALL over the intake. I make sure I tightened everything, all my linkeages are correct, etc and after I cleaned up the fuel I went to try again. Well, same result. If you know where the 2 little screws for the metering rods are, and then there's an opening next to it towards the outside of the carb, the fuel comes out of there, among other places. If your not sure what I'm talking about can try to reprase it or do some editing in paint.

Well today, I took the gasket out again, after letting it dry out (there was some fuel on it), I matched it up to my old gasket. They both matched up just fine, except for one small part. It wasn't a part that would restrict fuel flow or anything, but I took out an exacto and got it to the same size hole as the other gasket had anyways, ust to be sure. Well I looked at everything else and saw it was fine, so I went to put the airhorn back on. I checked my float level, they were a little low so I adjusted them to about 7/16". I put everything back on, connected all the linkages and put the metering rods/springs in again.

I went to start the car. It started, but only ran for a second, and horribly at that. I gave it a few quick, short revs at start up (I always do) and then tried to let it idle.... no go. The car just died. I restarted it again, after turning up the idle slightly. This didn't work either as the car just died. I tried it one last time and kept it running for about 20 second. I would give it throttle and the car wouldn't repsond hardly at all. I pinned the throttle to the floor (this is still in my garage with no load on the engine) and it simply studdered a LOT, but didn't die. It reached about 3,000 rpms and then pretty much wouldn't climb any further. There was once again fuel on the intake and around the carb too.

It sounded like it was loading up with fuel, but I honestly have no idea. The gasket and everything is fine. From when it was running decent a few days ago (just the problems I mentioned before like low idle vacuum and the small idle problem) to when I replaced the gasket I made no changes. I pulled the old one off, put the new one on, tried to run it and this happened. Anyone got any ideas at all.... this is just pissing me off.

Night rider327

iTrader: (13)

Damn, that does sound strange.. The only thing I can think of is when you changed gaskets you shook the carb some and it had dirt in it or something and that got in the seats, holding the needles and not letting float move right.

Therefor acting like stuck floats and stuck floats will do just as you said. Spray fuel out the top.

Take the handle of a screwdriver and tap on the top and sides of carb around where floats are and see if that helps.

Or better yet, just pull the top off and take the floats off, needles out, seats out, etc and clean em'

'86 350

Wow.... I feel like a dumbass. When I took the floats off to pull off the airhorn gasket, I ended up taking the needles out and forgetting to put them back in.

Anyways, the car runs better now, seems to have more vacuum at idle. The brakes feel much firmer now, but I haven't actually put a vacuum gauge on it yet to measure. I'm guessing it's far better then the 7-8 hg I was getting before.

However, I'm still having a problem down low. The car idles okay right around 750rpm or so, but if I go down to like where 600 would be, then the motor just drops off and drops down to like 400 and barely runs. I know there really isn't a need to idle anywhere near 550-600, but shouldn't an engine be able to anyways, even if it wasn't a permanent thing, I'd think the engine should be able to hold that speed. I'm not sure where to go with this. Floats are set at 7/16", and I believe I set float drop a tad under an inch, around 15/16".

Night rider327

iTrader: (13)

Don't beat your self up too bad man.. We have all done ir before. Get in a rush and forget something. No needles sure would cause your prob.

Now as far as idle speed goes.... No, all engines shouldn't beable to hold a low RPM and keep running. It really depends on cam size, CID of engine, and compression. The bigger the cam is the higher the idle speed will have to be just to keep it running. There's alot of over cammed street engines out there along with some built right race engines that will die if idle is under 1,000, 1,200, etc RPM.

My own will die at 500 RPM idle speed.. I have mine adjusted to 650 rpm

On performance built engines I would say norm avg. idle speed is between 600 at lowest and 1400 at highest, 650-800 most common.

'86 350

Well I really got a chance to run the car today, and still no luck. I'm still only pulling about 7-8 hg of vacuum at idle. However I may have find the problem. I was talking to one of my friend's dad and he asked if I was running a spread bore intake. I told him I was and he asked if I was running an adaptor. I told him I just bolted the carb on. He told me that this could and probably is the source of my vacuum leak. I'm gonna call my local speed shop tomorrow and see if they've got the adaptors, hopefully they do. Will this work similiar to a spacer? Are spacers things that really make a difference or are they one of those things that don't really work?

Another question. The car has always run hot since I got it. Not coolant temp wise, that's always been around 170 or so. However underhood temps are simply ridiculous. I can't touch anything under the hood for at least probably 1.5 or 2 hours. The intake also gets EXTERMELY hot while the car's running. I know that it's not usually an area that real cold or anything, but mine you can't even touch for more then a 1/2 second or so even if the car has been off for about 30 minutes, forget about while it's running. Is there a reason for this? I always thought it was because my headers aren't ceramic coated or wrapped, they're just simply painted black. However I know a lot of other people who don't run wrapped or coated headers either, and they don't have everything as hot as I do. Even my air cleaner is incredibly hot after the car has been running/driving for about 20-30 minutes. The guy told me a few things to maybe help. He mentioned a spacer for one, aroud an inch or so. He then said that running too rich can cause problems too. I knew that running lean could, but could running too rich do it too?

-Thanks, Brandon

Night rider327

iTrader: (13)

Well alot of people will tell you need the adapter to work, I guess it depends on intake and carb. Diff brands on carbs/intake will match up diff. Like you would need the adapter to run a square bore holley carb on a eddy spread bore intake, but the eddy carb's base plate is alot diff than holleys even though both are square bore.

I have ran a performer spread bore intake with a eddy carb for over 8K miles on 2 diff engines with out an adapter plate and no leaks what so ever.

If you wanna try the adapter though your local auto zone, advance auto, pep boys, etc stocks the adapters


Carb spacers is nothing but a tuning tool. Yes they do work but at the same time no they don't. It just depends on what your engine likes and wants. The only way to know for sure is to get up a few diff types and go to the track and test them.. I tried no spacer, and 1" open, and 1" 4 hole, then combo of both the open and 4 hole put together on mine... I traped a higher speed with the open 1" spacer..

That was due to the fact I needed more intake for the engine I have.

A good gen guideline is... A carb spacer will move the peaks around 500 RPM or so, a 4 hole gives more low end while it hurts top end, and an open spacer gives more top end but hurts low rpm torque.


Under hood temps are a pain in these cars really. I think what your seeing is norm IMO. Very tight, sealed up engine bay with no place for the heat to exit


As far as rich/lean goes what I have always told people.. worse cases here you can run it pig rich for 100K miles, but dead lean only once for a few feet. Too rich is just gonna foul plugs, cause more carbon build up, power drops off some, etc..

Too lean and you get high EGTs, high water and oil temps, detonation, melted off plug ground straps, melted pistons, etc etc

'86 350

Well I ended up getting a Mr. Gasket 1" spacer to go from a square bore carb to a spread bore intake. The car seems to run even worse now and the leak is still there. Anyone have any suggestions? This car is just running like **** now. I was planning on bringing it to the New England Summer Nationals today, but had to go with my dad in his car instead since we couldn't get this running halfway decent.

The kit I got came with 3 missing bolts where they go up through the spacer and act as carb studs. This spacer is kinda odd, do most spacers do that or do most just go right over the carb studs? Maybe this one was different though because it was an adaptor as well. Anyways, after going through 2 or 3 cheap *** grade 2 bolts at the hardware store, I went and bought some Grade 5 ones from Napa. I bolted the thing on (again) and went to start it. Still no luck. Car doesn't wanna idle, and bogs a little at ful throttle from idle. The bog has alway been there, but the idle is worse then ever and I can't get it to even go below like 1100 rpm or it wants to die.

EDIT: Well, I got the idle under control now. It's so damn inconsistant, sometimes it'll idle perfect then a minute later it'll sputter and want to die unless I rev it up. It also drops down real low and wants to die if I come to a quick stop or make a hard turn. I'm guessing the majority of this points to the floats, but that still doesn't help my vacuum problem. I'm still only getting about 7 inches of vacuum. I teflon taped both connectors in my manifold and carb for plugs or brakes and still no luck, I have no idea where this leak is coming from.

'86 350

Still got this problem, think it could be the floats?

Night rider327

iTrader: (13)

ok... Sorry I aint replied back sooner. I don't really check thirdgen.org much. My "home" board is over at nastyz28.com


Your stalling during breaking and turns is float adjustment... No question about it your floats are set wrong.

The vac. probs well something is wrong for sure there.. You have a crimped test gauge hose, or a very bad vac leak somewhere.. 7" is around hald what you should have.

Your idle will not get right till you find and fix that vac prob.. I wouldnt even try to tune the car ANY untill I found out why it only has 7" of vac. Heck depending on step up springs you got in there, with only 7" of vac at idle your metering rods could be in the up (power/rich) postion.

On your carb adapter... It is NOT a spacer, its an adapter. Bigg diff in the two.

Most spread bore to square bore adapters I have seen has 4 larger counter sunk holes, and 4 threaded holes. You screw 4 carb studs into the threaded holes, then you have 4 short, big headed screws. You sit adapter on intake, drop the big headed screws in the larger holes and screw them into your intake's carb bolt holes. Then sit carb over the carb studs in adapter, put washers and nuts on and thighten them.


And you know install a carb gasket between intake and adpater, and a gasket between adapter and carb.

'86 350

I've been gone for a while too. I've still got the problem, I'm still trying to fix my ignition switch right now, I got the part, I just haven't been home for a while, basically the last 4 weeks I've been gone.

I've checked everywhere for that vacuum leak. Intake, all hoses (that's about 2), and all other things. The only one I haven't checked is the brake booster, I'm gonna try that and see if that fixes the problem. If not, then I guess I'll probably just try pulling off the intake/carb and trying to find the problem.

That adaptor I got I realize isn't a spacer, but in a way I'm sure it acts like one. It's about an inch tall, where as most adaptors I saw were very thin. Gaskets were installed between both the intake and adaptor and adaptor and carb.

x_wolf

I had a helluva vac leak on the back passenger side stud on my car, i mean you could hear the thing, and it almost sounded like a turbo yah it was that loud, and it turns out (even though it was a new carb AND mani) that the hole had stripped itself out. SO I helicoied it, tightened it back down with a new gasket, and it helped quite alot. No more high EGT (red hedders = BAD) and the car is more stable. I still have probs too, but the car is more stable.

I would check with carb cleaner, around the carb base, all the hoses etc etc to make absolutely SURE you have no leak! Good luck!