So I took my car on my second run today cruising around. About 15 minutes in it backfired a couple times through the exhaust. I fouled a set 3 days ago as well. I think I'm running pretty rich. Also, the car ran great 2 days ago on manifold vacuum and about 24 degrees initial advance. I switch it to ported for some reason.

Also, I hooked up my timing light tonight when I got home to plug wire #1 and it didn't even flash, I'm sure it was hooked up to the battery. I have a 650 Holley DP with 71/76 jetting in it now, stock specs. Can anyone shed some light on to what I do next? This is getting expensive.

 

ha, get used to it. That cam will foul up your plugs faster to some degree.

It sounds like you're misfiring though, the backfire, the no flashing on that plug wire.
Tonight after it gets darker, take 'er for a spin around the neighborhood. Bring your timing light and a flashlight.
If it starts to run funny or backfire, pull over. Look around the plug wires real quick to see if any are arcing.
If not, hook up the timing light. If you see 24* at idle, great, swap to different wires (at the distributor, don't want to burn your hands on the headers). Each wire should get the light flickering, but anything besides 1 won't show any meaningful timing marks. Just make sure they all flicker. If any don't, wiggle the clamp over the wire a bit.
If still nothing, shut it off, pull the plug wire off for that cylinder, and remove the plug. Yea, bring gloves, this is gonna burn a bit.
Then put the plug back into the wire, start it up, hold the ground strap against something metal there, you should be able to watch the plug arc. Check to make sure the center electrode to ground strap isn't completely joined in carbon.

If no carbon bridge, no spark - Your dist or wires are bad.
If a carbon bridge - I'd look at the heat range of the plugs, etc etc.

 

Could you elaborate on this a bit? I think the plugs are just extremly fouled that it won't run right.

I'm going to post a pic an a few minutes.

 

If the center electrode and ground strap are joined electrically via crud/soot/carbon/etc then it'll misfire. If it's just dirty then it's probably firing, but not ideally.
It shouldn't be loading up that fast. Cures:

-run more timing (I think you're ok here)
-get the combustion chamber hotter (not always a good thing)
-get your plugs hotter (use a hotter heat range plug, depending on where your heat line is on your ground strap this might be your solution, i'll check the pics you upload)
-lean out the idle/cruise mixture

 

Just pulled all the plugs... Some extremely white (lean) some pretty black (rich) what the hell is going on here?
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Still looking for my digital camera. Some are reallllllly white, some are realllly black.

 

Ahh, dual plane intake eh? Same performer RPM as me.
I was talking to supervisor42 about this thing last summer. But that would make the front 2 and back 2 lean/rich, and the center 4 something else. (Know what I mean?) So it's probably not a dual plane issue...

Since you have the BACKS lean, and the fronts RICH -

Your rear barrels are lean and the fronts are rich. You're idling off both right? Perhaps you're not pulling fuel out of the back barrels, only air?

I'm not sure how/if you can control idle mixture on the rear barrels, I'm not a holley guy myself.
What power valve are you running?
Vacuum at idle?

 

12-13 inches vacuum at idle. 4.5 P.V. but that is with ported vacuum, I am going to try running manifold vacuum. What can this be? Im as confused as a baby in a strip club.

 

I'm running NGK V-Power 6574-7 Plugs

Cylinders 1,2,3,4 Rich
Cylinders 5,6,7,8 Lean

 

Hold up here, 12-13 INCHES of vacuum at idle.

4.5 power valve should open up at 9" of vacuum, and make the thing pig rich. I'd probably want to go smaller I think, but don't trust me on holley stuff. One way to find out is to drive around with a vacuum gauge hooked up. I duct tape mine to the front windshield. Driving around slowly it should never drop below the vacuum level when the power system kicks in.

Ported or manifold vacuum is for the distributors advance, and shouldn't make any difference in the power valve. Manifold vacuum will raise your vacuum level at idle, but it'll also jump up your idle speed.

I couldn't find those plugs on a cross reference, but here is some info

http://www.dragstuff.com/techarticle...reference.html

I'll wait for someone with some holley tuning experience.

 

I also kept some spark plug cross reference sheets here;

On the second page I put a star next to the ones that come up as stock replacements for the '85 LG4 type of engine - Ie. reach, thread, etc, that is right for a typical SBC.

 

the 4.5 power valve will open at 4.5IN of vacuum might be okay but i was pulling 13-12 and 6.5 PV wasnt enough went to 9.5 and is better but not perfect
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how much have you opened your secondarys at idle? i have been told to open both primary and secondary blades to expose .015-.030 of the idle transfer slot

 

woooah. hold on sonix.


Here we go, that cam is large enough that timing should be locked out, or 24-26 initial, 36-ish total with no vacuum advance hooked up. Sounds like your transition slots are not open the same amount, both should look close to a square shape when the carb is flipped over. 4.5 power valve should be close, it will open at below 4.5" of vacuum not 9. I think you need to check first to see that all 8 wires are firing, by hooking up the timing light to each one and check for it to flicker on/off like every other wire. Next set floats, and adjust the mixture screws for highest vacuum. On my car the 4 corner idle screws are just over 1/2 turn out. If it is running rich on idle then you need more timing first for more complete combustion then work on setting up your mixture screws. That cam is far too large for such little initial. Honestly, locking it out would be the best thing you could do.

 

x2 on the locked timing. I just installed a Mallory HEI that came with locked advance, with 36 degrees of advance the car runs better than ever.

 

I'm running 24 degrees initial timing 36 all in. Although, the transition slots are noth the same. the primaries are square or a little over and the secondaries are slightly open, like a hair open. Could this be why the lean/rich idle? Battyice or others, what part number for a pretty cheap distributor will give me locked advance and a revlimiter for my manual trans?

 

I run a Mallory "race prepped" HEI, Part #MAA-8548201RC. It is $180 through summit racing. Most of the "billet" distributors sold by MSD allow you to lock the advance, some of them come with the rotor hooked directly to the shaft.

If you want a revlimiter, I would consider a performance ignition box like a MSD 6AL or Mallory Hyfire VI-6AL.

Depending on which distributor you are running, you may be able to lock the advance by either tack welding the advance mechanism or using cable ties. If you post some pictures of your advance mechanism setup I'm sure some members can offer advice.

 

Oops, there we go, another reason I shouldn't comment on holleys 4.5" PV means 4.5" now I know.
Yea, he is running good timing, that's why I corrected him that he got 12-13inches of vacuum at idle, not to be confused with degrees of timing.

And yea, you can try locking out your advance with zip ties, it's pretty easy, F-bird'88 has posted how to a number of times. I don't really think it'll change your rich/lean situation though.

Check for misfires first. Based on your timing light comment, I think you really need to hammer that down first.

 

I hope this isn't an ignition issue. The instructions weren't quite clear on my Crane Cams XR-i ignition conversion if I had to run a ballast resistor or not... I am currently running that for ignition and a Crane Cams round coil. I believe the PN is 7300020. I am not running the ballast resistor. Could this cause my problem? If so, how can I tell if I toasted it already?

Also do any of you guys know if I can buy an after market HEI distributor w/ a rev limiter inside of it already so I don't have to by a separate box? I know they sell aftermarket ignition modules with the revlimiter, but most stock hei's give wayyy to much mechanical advance for how much initial I run.

Also, the transfer slots on the primaries and secondaries are not equal right now. The primaries are open so it looks like a square and the secondaries are open just so the transfer slot is barely exposed.

 

Also, for adjusting the mixture screws at idle, I am running manifold vacuum on the lower port at the front of the carb. How do I check vacuum then, the back port is used for power brakes and my pcv valve?

 

no resistor is used on HEI type ignitions, only points. No HEI has a rev limiter inside of it, it's usually controlled in the box, I prefer the digital 6 box and have had several mallory components fail on various friends over the year, so we all stick to MSD now exclusively. Are you considering your idle timing to include manifold vacuum? With that cam you can toss the vacuum can away and just run off mechanical advance exclusively. Try turning in the mixture screws 1/8 turn and drive it around. I have my idle so lean that without a choke the first 30 seconds of the motor running I have to rev it a bit to keep it from dying out. This is where a quality wideband would make all the difference in the world. Otherwise turn them in 1/8 turn or even 1/16th of a turn and drive the vehicle around, as long as it doesn't have a tip-in stumble under light acceleration, you can keep doing this.

Now for vacuum guage tuning:
You keep leaning the mixture until you get highest vacuum # off the manifold vacuum port, with the vehicle hot and in gear for auto and out of gear for manuals. I'd put in fresh plugs afterwards and check again if you're fouling them out. Make sure that you also are firing on all 8, which you didn't post back on checking yet either.

 

I know HEI does not require a ballast resistor, I'm running a points style dizzy right now w/ the crane cams conversion. The directions don't really specify if one is needed or not. It talks about one for certain coils and replacing certain coils but I am not. I am not running one. I was wondering if this may be causing a problem. #1 cylinder is not firing according to the timing light. The plug was extremely fouled. Like I said the front 4 are rich, back 4 are lean. My transfer slots aren't exactly equal.

 

Yea, I think this might be more ignition than fueling right now. If it's not firing, the plug will read as if it's pig rich.

Pull #1 plug and hold it against the block and start the car, see if you can see a spark. Try putting a new plug into the boot and hold it against something metal and see if it gets a spark then.
If still no, check #2. Try swapping wires, etc etc. I'd want to SEE a good spark before I want further and checked fueling.

 

It's running very poorly right now. I already pulled all the plugs and I'm going to replace them with hotter plugs. Apparently the plugs I was running were very cold and battyice recommended a hotter plug by ACdelco that he runs. He is also running the same cylinder heads as me. I'm also going to order new wires right now from summit. I have 2 different kinds of old wires right now. I just hope its not my ignition module or the distributor, that would be a waste of money for me.

 

See that's why two threads is annoying.
Your plugs are pretty hot, I was going to recommend going colder. 10:1 will keep things pretty hot in there anyway.

I'd be leery about doing the shotgun effect without clearly finding the problem first. You might be out $100 and have the same problem, and less money. Now THAT'S annoying.

You can always pick up an HEI distributor from the JY for about $20. I'm using one from an '84 Cutlass, with a pertronix coil and module now.
But even fresh from the JY it would "work", and not foul out plugs in 30 miles sorta thing.

FYI I run a Delco R42T in my iron headed 10:1 motor. It does load up from all the idling and driving like Ms Daisy that I do. I'm going to be using a WB02 next summer to tune my engine.

 

Well, I'm not going to run the plugs in there, a couple of them are sooo carbon fouled its rediculous, and 2 of my spark plug wire boots are somewhat melted at the boot of the plug from the header. So I don't think I'm wasting money. I also have my wires sorta laying on the valve cover, bad idea? When I find my digital camera I will post pics of the plugs.

Sonix, I haven't been to the other thread for a while I PM'ed battyice about the spark plugs.

Zach

 

do the decent tune up then do all the things i listed previously, and you should be alright. Fresh plugs and wires aren't that expensive, in fact i'm running 8mm AC delco 8mm plugs off a 91 suburban 5.7L tbi engine from the catalog. Has all 90' boots and are cheap. Fresh non-platinum plugs and report back. Make sure to gap them .040 or so for now and see how they do. Turn in mixture screws and even out the transition slots while waiting. Without a choke it should take 30 seconds of revving to keep the motor running cold on initial tune, that should be lean enough.

 

Bought the plugs today ACDelco R44TS. Ordered summit 8mm wires for 40 bucks w/ shipping, also ordered the wire looms that bolt the the side of the valve cover so I don't have any arching wires. I will even out the transition slots. How can i check for vacuum while using the manifold vacuum for the distributor at the same time? I am using the rear port for power brakes and PCV, the front port if for the dist. I think it running rough had something to do with me tuning the idle mixture screws with the motor running off ported vacuum, then switching back to manifold without readjustment. Maybe with the higher idle I will pull more vacuum and have to bump up my PV to a 6.5 which I have laying around. Let me know your thoughts. I hope my ignition will be alright...

 

Are you sure that is the number? 6574-7 doesn't show up in my book, but a 5674-7 does.

A 5674-7 is listed as an NGK Racing plug, 14mm, .460" reach, 5/8" hex, tapered seat, non-resistor, with a projected tip. It crosses to an Autolite AR12, which is a racing plug.

What plug you run should be based on how you plan to drive the car. If it is track-only with minimal idle time, a cold plug would work great. However, as Sonix stated, if you drive Miss Daisy around town, a hotter plug is required. If the car is for street and strip, you'll have to use something with a moderate heat range unless you like changing plugs weekly.

 

I'm sorry, the plugs I had in there were 5674-7. This is a street/strip car, I will be putting around town a little with it. About half street half strip. Do you still suggest the ACDelco R44TS plugs?

 

Skip the vacuum can altogether, I don't run one in my car at all and besides a little loss of mpg, it removed one more issue from my tuning. You hook a vacuum gauge to the manifold vacuum and adjust the mixture screws for highest vacuum reading. This may or may not be perfect to run lean, but it'll be close. less than 1/8turn from here either way will be perfect. If an off-idle stumble shows up then it needs to be a little richer, if not lean is better at idle. The more timing at idle the cleaner the engine will run, which is why I was pushing just locking out the timing at 32-38 and calling it good. A larger duration cam with lots of overlap will want more timing at idle. If you're dead set on keeping the can and the timing curve you have now, you still have adjust the mixture screws with a vacuum gauge or a 4 gas analyzer. The vacuum guage will have to be put on the manifold vacuum port for adjustment.

After you put the new plugs and wires in, you can turn in the screws 1/8turn at a time and keep checking plugs if you don't want to spend the 5 minutes to do it the right way with a gauge.

 

I have the gauge and thats how I was adjusting the screws. My dilema is that I want to run the vacuum advance and to check the vacuum and adust the idle mixture screws I need the vacuum gauge hooked up to manifold vacuum. The front port like I said is for the vacuum advance on the dist., the rear port is for my power brakes and pcv valve. Can I run the vacuum gauge without my pcv valve or power brakes at idle for checking vacuum with my distributer vacuum can hooked up in the front?

I guess thats what I was getting at before.

 

Another thing, I think I'm going to start back at square 1 for the carb. Re adjust the transfer slots to be equal (which they are not at the moment), back out my idle mixture screws to 2 turns out each side. Re install the carb. Replace fouled/leaned out plugs with new non platnium delco's, wait for my wires to arrive. Then fire her up. Last time I ran the car I was pretty dissappointed. I thought it would have more ***** then what it did. Granted I was only a little over half throttle and shifting at 4000 rpm's.

Which order would I go about timing, idle mixture screw tuning, or do I have to keep playing with both until it is right? Also, see my dilema about vacuum tuning and running manifold vacuum advance.

 

Buy a vacuum T. Hook it up and cap the T part. When you want to see the vacuum level remove the cap and check there. You want to see the vacuum while the vacuum is hooked up to manifold vacuum.
Manifold advance will give you ~40* at idle, it should kick up your idle speed A LOT. But once you give it moderate throttle it'll drop 20* or so. (depending on how much vac advance the can gives).


I'd set timing, then mixture. I'd stick with the 24* at idle, ported vacuum, and tune the mixture from there.

If you can't get it right, then try full vacuum. I'd just set the timing at 3500RPM to 36*, and not touch the base timing again - you don't want to change your timing at WOT while you're messing with idle settings/

 

why do you need the vacuum on the distributor hooked up while setting the mixture screws? Unplug the vacuum can, plug in the vacuum guage. 2 turns is too far out, on a 2 corner idle system you go 1.5 turns out, on a 4 corner idle system I use 3/4 turn out for starting point.

 

I thought you were supposed to set your idle mixture screws with the car set up how it's going to run? Me, I'm running manifold vacuum, the car runs best with it so wouldn't I check vacuum with it connected? Can I leave the timing alone all together? Last I set it was at 24 degrees initial and 36 all in. Would messing around with idle transfer slots and mixture screws affect my timing? Because when I hook up the manifold vacuum it's going to idle noticably faster, then when you turn the idle down to get it to idle right and plug the advance the car will probably stall. Thats why I'm wondering if the timing will stay the same.

 

24 initial with the vacuum can on or off? A typical HEI would be more like 12 initial 36 total unless you mod them. Then the vacuum can would add 12-15 degrees at idle which would bring it up to 24, I'm talking about strictly mechanical timing should be 24 then 36 fully advanced. You then could add vacuum can to make idle timing even higher at idle with vacuum + mechanical. In that case then just buy a T fitting from a local parts store in that hose diameter and call it good since you don't want to change it like I'm suggesting.

 

I am running 24 degrees initial w/o the vacuum canister. I only have 12 degrees of mechanical advance. Remember, I'm running a modified points style dist. w/ electronic conversion from Crane Cams.

 

alright then that is perfect. You can tee off the vacuum can line and check for vacuum, or just unhook it, it should not effect the mixture screws that much.

 

Well, I got it ironed out I think. My buddy and I took the carb off and apart. He's quite the Holley guru. He was checking idle feed restrictions and some other things. Then we removed the baseplate only to find out that this baseplate is not for my carb. It's missing the idle discharge holes on the secondaries, causing my lean/rich plug reading. I have it running lean at idle and the idle mixture screws are about 1 turn out each. It runs like a bat outa hell! I have to still break in the clutch and keep breaking in the motor and hopefully get this thing to the track this year yet.

Thanks for all your help.