budget builder

iTrader: (3)

ok here goes I have a 350 bored 40 over flat top pistons (appx. 400miles after rebuild)

vortec heads

performer rpm 7116 intake

xe268h cam from comp cam.

stock tbi puel pump running

mallory 4309 reg. I got pressure at 6.5psi.

going to a edelbrock 1411 which is a 750cfm four barrel.

I have no emissions,

headers 1 5/8 primaries to 3in. collector to 2.5in ypipe straight thru exhaust noooo CAT. to dual outlet v-force muffler with 2.5 in pipes. and serp assembly.

ac delco plugs gapped properly,

mallory 8mm wires,

hei dizzy,

flamethrower 50kv coil,

stock cap,

gutted thermostat. temp is cheked with infared gun on goosed neck and doesnot go over 230 the fan comes on about 180. single large fan.

I have to press the gas pedal down to set choke when firing up for the first time in the day. I allow to warm up to operating temp. drop it in drive and it idles down just fine sounds beautiful. i give very light acceleration and the car takes off just fine but just past (foot laying on pedal) type pressure and the the motor stumbles all over the place. only after pressing about 1/4in down or farther does the motor catch up and the power is back. I don't know how much power the motor has but it doesn't take half or even 1/4 throttle to get the car up and going (i mean when cruising around town 25-35mph) sometimes I just want to putt around and show off the car but can't because it sounds like it is about to shut off. I jumped on I-95 and got it up to about 65mph and hit it and it did stumble a little trying to get to 80mph (just a little) I will say the more I drove it the better it seemed to do. and when I drive it for awhile and shut it off it takes alot longer to fire up. like rrrrrrr rrrrrrr rrrvroom instead of when I set the choke r-vroom (almost instantly). My so-called mechanic told me that in the summer that I would have to retune the carb when the temp came up. (he socalled tuned it during avg. temps of 45degrees and did this twice and told me this is the best he could get it and charged me $600. price included (tuning carb, rechecking timing, connecting vaccume lines, brake booster and pcv, and connecting shift cable, and wiring choke)
Please help me and sorryfor the long post. Is it possible it is flooding?

pancherj

The first thing I would want to know is what does the timing curve look like (initial, total mechanical, vacuum advance hooked up?, etc.). After I got that sorted out, I would work on the carb. What is the idle vacuum and speed?

Why would you gut the thermostat? No reason a non-emissions V8 should be running 230F. Put a 180 degree thermostat in there. I don't like mine to go over 190F when I am cruising around.

I only ever owned one Edelbrock carb and I hated every day it was on my car. It sounds like the secondary may be opening too quickly and that is causing the "pause and catch up" that you are describing. As I recall, there is a way to adjust that. You can find the owner's manuals on line.

bestracing

First off you should be using the vacuum advance on the distributor and it should be hooked up to your manifold vacuum. You set your base timing around 6 to 8 degrees BTDC and when you hook up you vacuum line it should jump up in idle speed. Now adjust your idle speed back to 600-800 RPMs.

A lot of times people set their distributors up with ported vacuum and with the idle timing at 6 to 8 degrees they have to open up the throttles too much and cause problems with the idle transfer circuit of the carb which leads to a stumble.

An old school fix for Holley carbs was to drill a small hole in each primary to allow more air in while closing the throttle blades enough to cover the transition slot correctly which improved the part throttle and off idle response. I do not recommend you do this.

Also, have you played with the accelerator pump arm to either add or lessen the shot of fuel when you move the throttle lever?

budget builder

iTrader: (3)

thx fellas,

I prolly will have to wait till next week to play with it. please keep in mind that I know nothing about a carb. as a matter of fact I found out that not many ppl around know about a carb which might be why it went to the mechanic twice and still came back in this condition. But based on thirdgen and as many books as I can get my hands on i will be learning quickly. I have no idea what any of those answers are but i WILL find out. there is alot of things that this mechanic did not tell me and info that i should have been told but hey, you live and you learn to be honest he might not know. so now i have to find out how to test these parts and get all the info i need and then use that info to determine what the problem is. oh and temp is appx i can't remember what the top number was exactly.

initial timing
total timing first mechanical then vaccume
then try to pull a vaccume and see what numbers I come up with
then check the carb floats and see how they are set
learn about primaries and secondaries and
uuuugggghhhhhh!!!!!!!!!!!!!!
there is a ton of info this is why I got away from fuel injection/

bestracing

Find a book like this one and read up!


My first car was a 72rs with a 2bbl 350. To time it I HAD to remove the vacuum line from the advanced canister to set the correct timing or it would be too high. Later when I switched over to a Holley 600 (in 1985) they advised using ported vacuum and then there wasn't any vacuum at idle. Little did I know then that this was due to emission systems and my car originally used manifold vacuum.

Back then I had to deal with setting the points too.....look that one up

bestracing

Oops DP

bwiencek

I'm going to take a guess and say that your accelerator pump circuit needs tuning - probably a lean condition when you're pressing the accelerator - the higher the RPM it is when you 'tip in' the less noticeable it is...

Do yourself a favor and pick up a wide band O2 sensor or borrow one and use it for tuning - it'll make your life a LOT easier than the old fashioned trial and error. Once installed you'll likely see that when accelerating the AFR dips then picks up as the car stumbles then picks back up. You can also monitor the idle mixture, the cruise mixture and the 'power' mixture (when WOT accelerating) and tune each one for best driveability, gas mileage or performance...

budget builder

iTrader: (3)

RRRRIIIIIIIIIGGGHHTTTTT! ok what i'll do is look up a wide band o2 sensor and learn how to use it.

budget builder

iTrader: (3)

dang! close to 200 does advance auto lend these things out ?

bwiencek

All it's doing is measuring your exhaust's Oxygen content to determine your air fuel ratio. Most wideband O2's measure stoichemetric ratio at about 14.7:1 and you tune with that in mind... Generally the leaner the cruise ratio the better the economy (up to the point where it starts to do a lean misfire), under hard acceleration you'll want to be on the rich side (how rich depends a lot on intake/head designs, cylinder distrobution, etc. - somewhere around the mid12.x:1 is a good spot to start with), Idle mixture - I like to set it the old way of max vacuum but then try and lean it out a little more. As for what you're expierencing - you'll probably step up 4-6 sizes in squirter nozzles to eliminate the 'dead' feeling and then you can tune the accelerator pump cam from there to fine tune the delivery.

I don't know of anyone renting or loaning them out - you can rig a 'meter' up with a bare sensor (about $80 online) and a regular old voltmeter - it requires 2 of the leads go to power and the other 2 go to the voltmeter to read the output - you'll need to get the chart for the O2 sensor's voltage vs mixture (AFR) curve and use that to interpret the readings (which most 'kits' do that for you and display the AFR on the display.

There is more to tuning a carb than setting the idle speed... It's just like tuning EFI but without the digital control to just plug in a number and magic changes happen - everything EFI does emulates what a carb did (or tried to do) with it's various circuits...

bestracing

Yes that can help as well and can overcome the dead spot.




To the OP, The best advice I can give is get a book like I posted. Not directed to anyone on here but advice/opinions on message boards is like butts, everyone has one and they're all different. Speed shops and local racers are good sources also.

Make sure your timing and idle settings are correct. Adjust the accelerator pump linkage to deliver more fuel (I believe that would be the top hole) If you still are having a bog then increase the squirter nozzle size by 3 to 4 numbers (ex. from 61 to 64). Then try that and see if the bog is less or gone. If it is still there but better then increase the squirter again by 3 to 4 numbers.

Get a tuning kit which has the multiple metering rods and springs. in Edelbrock's tuning manual they have a 2D chart on how the car preforms and what changes you need to make to correct them. Very easy to follow.

I haven't worked much on Carter/AFB/Edelbrock carbs but the basic concepts are the same as on other carbs.

budget builder

iTrader: (3)

[/QUOTE]I knew a little about that but honestly not alot and I thought I was going the easy way out when I took it to the mechanic but now i know better.

budget builder

iTrader: (3)

thank you very much everyone and I'm buying that book if i keep this up my house is going to look like a library for just one car

bestracing

I got a lot of books like that as well.

What I have collected through the years. ( that I can recall now but I know there's a lot more)

How to build a small block chevy
82-92 Camaro Chiltons manual
82-92 Camaro Haynes manual
62-79 Nova Chilton manual
67-81 Camaro Chilton manual
1970 Camaro Service Manual
1986 Trans Am Service Manual
82-91 S-10 Chiltons manual
How to build a Powerglide (J.W. Performance)
ATSG TH700R4 service manual
ATSG TH700R4 service upgrades
Modifying Small Block Chevy Engines - John Lingenfelter.
TPIS Insiders hints
How to run 11 sec ET's on a budget book. Got it quite some time ago because it had some useful info and a GM part number on manual steering box for 3rd gens.

budget builder

iTrader: (3)

ive got how to rebuild your chevy small block
and a haynes manual 82-93 camaro
hayens manual for 87 dodge d150
haynes manual for 92 lincoln towncar
andhaynes for 98-2008 lincoln towncar

I need how to rebuild your 700r4 for dummies
and of course edelbrock carbs for dummies
step by step brake upgrades for dummies
and "how to make your 355vortec run like a 455 monster"
thx for all the advice I ordered the book a little while ago and will not touch the carb until then.

bwiencek

Since you say you're going with an Edelbrock carb - I know they had a tuning guide that came with the carbs and if you bought it used there should be one on their website - as I recall it had a diagnostic chart and recomendations (i.e. go up/down on part xxx) and then they had part numbers for jets, metering rods, etc.

Also - the other day I just ran across the Holley technical videos on youtube when I was looking for pictures to show someone how to adjust their accelerator pump cam and they have quite a few videos on tuning their carbs - the general methods and concepts are applicable to the Edelbrock - it's just the edelbrock accomplishes them in slightly different ways.

As for your pump shot - I believe on the Edelbrock carb the first thing to try is to move the pivot point on the pump arm to gain more motion per throttle travel (it should make sense once you look at it) I think the rod that comes from the throttle linkage gets moved to a hole closer to the pivot point of the lever

Clemson327

iTrader: (4)

You can do the same with a one-wire sensor for cheap. See the link below for a lot more information. The O2 sensor info is about 2/3 of the way down the page.
http://www.bob2000.com/carb.htm

plasmeh

iTrader: (10)

I can't believe that float levels were only mentioned once in this thread. It takes all of 2 minutes to adjust both floats and can potentially solve the problem altogether.

EvelBist

iTrader: (1)

so you have an electric choke now? you mentioned someone hired to wire it.

at tip in, the accelerator pump shoots extra fuel into the venturies. Have you verified that happening? Its easy, engine off, look into the primary venturies and move the throttle. Make sure youre getting a stream of fuel into the venturies.

Lets say that you are. Maybe your vacuum isnt really enough to atomize the extra fuel when coming off idle. Have you measured your vacuum? Put a gauge on one of the manifold vacuum ports (the ones in the base plate of the carb) at idle. It should be somewhere around 14 give or take a few for a healthy engine.

Finally, thats a quadrajet clone. Theres an adjustment for the rear butterfly valves thats hard to see but if you do a search, a lot of helpful pix are available online to see how that thing is adjusted. If the adjustment is too soft, the secondary butterfly valve will lean things out because they will open too soon. That could be the cause of the problem your having.

budget builder

iTrader: (3)

[quote=bestracing;5544828]First off you should be using the vacuum advance on the distributor and it should be hooked up to your manifold vacuum. You set your base timing around 6 to 8 degrees BTDC and when you hook up you vacuum line it should jump up in idle speed. Now adjust your idle speed back to 600-800 RPMs.

A lot of times people set their distributors up with ported vacuum and with the idle timing at 6 to 8 degrees they have to open up the throttles too much and cause problems with the idle transfer circuit of the carb which leads to a stumble.

An old school fix for Holley carbs was to drill a small hole in each primary to allow more air in while closing the throttle blades enough to cover the transition slot correctly which improved the part throttle and off idle response. I do not recommend you do this.

quote]ok I finally had a little time to get a little brave and curious and moved the accl pump arm and man what a diff. it was in the top hole so I just moved to the middle hole. and man what a diff. now, pleez hear me the car under very light (almost feather light accl. still wanted to bog but it was like it would power thru it. I now can lay my foot on the pedal and it will go ahead accl. to 35-40 mph with only slight stumble. very slight!

I also discovered that my choke was loose. {some mechanic} #smh#
and in moving it I have changed the way it fires up soooo now I have to go back and figure that out. I mean unless there is always some kind of looseness to it.

I also have to buy a timing light, a new tach (my oem is not working anymore), and a carb tuninig kit if I am going to try to fix this myself.

the pump arm moving made the car FEEL like it had more umph on take off with very little accl. now I don't know If going to the middle hole added more gas or not but it def. takes off with a bit more head snapping. I also have to adjust valves again and check fuel filter. OH I checked fuel pressure. when I got it from the mech. it was at 6.5psi and now for some reason it is sitting at what looks like 5.75psi all on its on. I will be keeping an eye on that. and I will be getting a vaccume pressure gauge.

bestracing

Sounds like you are on the right track getting the right tools and tuning kit.

I believe the top hole gives the accelerator pump more throw which translates into more fuel being dumped. Try lowering it one more hole and see what happens.

budget builder

iTrader: (3)

will do!

budget builder

iTrader: (3)

And now we have black smoke on start up! And some deiseling when shutoff. Definitely too rich will get tuning kit next week and do what my 600 dollar mechanic couldn't seem to do

budget builder

iTrader: (3)

0-60mph in 13.28 seconds - am not an expert but this is ridiculous. No way it should be this slow. My carb and timing must be way off I will try to update by saturday.

budget builder

iTrader: (3)

I checked the carb fuel filter its ok. I haven't checked the under car filter. I also thought about I need to check the dizzy cap, rotor button, and spark plug wires. at night. I didn't have enuff for timing light, or vaccume gauge but will. I put about 5gals of 93 octane and about 8gals of 89 octane I don't think I should have done that. and the accl. pump rod did better in the middle hole (I think)

budget builder

iTrader: (3)

I found a huge chunk of the prob. I feel kinda stupid. I fired it up in the dark and below the headers it looked like the forth of july. It is eassy to see at idle and when holding the brake under a load its worse. I see the arching right where the wires meet the plugs. How in the heck to route them? Help? These cost $85 and now are appearantly no good! This might be y it appears to be running rich. - got to figure this out b4 I try to tune carb.

bestracing

What brand wires do you have? Just to be sure, you are getting a spark and not a glowing halo around the plug ceramic insulator

Is it arcing from under the boot where the plug is going in? Where the wire is going in? or through the boot?

budget builder

iTrader: (3)

I cant tell. all I know is that I seen blue in about 2-3 places on the drivers side and 2 places on pass. side . these are 8mm msd streetfire assembled. I found 2wires that were not (locked) into place they were loose and I ended up clicking them into place. I am trying to get summit racing to let me exchange b4 the warranty goes out in august. I really want to upgrade to 8.8mm accels and lots of wire looms. with some of these http://shop.advanceautoparts.com/web...923%7CL2*15034#

bestracing

A blue glow doesn't necessarily mean they are arcing. If they are arcing you will see a spark flash almost like once a second from that wire. A blue glow (corona) is an ion effect from the high voltage going through the plugs. Check out this article
http://aftermarket.federalmogul.com/...0Flashover.pdf

Having plug wires not fully snapped on can cause a miss-fire at higher RPM's and under load and still run fine at idle.

I've ran many sets of MSD 8mm wires for many years with no problems. We had 2 sets on our 67 race car, I had them on my 87 S-10, and have them on my 86 Trans Am, and my brother has them on his 65 Mustang, 86 IROC and 93 Z-28. We replaced the set on the race car after 6 years as a preventative measure because the resistance of the wires was getting a lot higher from when they were first installed. The only problem I've had with my wires was my fault. I had a boot come loose on #8 on my T/A and it got burnt. I had mistakenly got long plugs and the boot was a lot closer to the headers so when I thought I had snapped it on it must of been to the side and the boot slid back and hit the header.

budget builder

iTrader: (3)

I will try my best to double check 2nite I am still waiting for summit to give me an answer as to whether or not I can return these and exchange or what not. thx for the reply.

budget builder

iTrader: (3)

Yep pass. Side wires are actually arching. Not at boots but in middle of wires this was prolly the problem the entire time

bestracing

Yea that's not good.

I just installed a new set of MSD 8mm wires in my 86. I got the custom length set so I could route them using Moroso's wire looms along the side of the rocker covers and then straight to the distributor. No excess wire laying around and the wires are out of the way now.

budget builder

iTrader: (3)

I just found out several burnt wires everywhere.

bestracing

They have a loom similar to what I have for the center bolt rocker covers. Keeps the wire together and routes them down the side of the rocker cover.

This is the set I got http://www.summitracing.com/parts/MSD-5553 They are cut to length and then you crimp the ends on for the distributor. Hint, route the wires in the loom and leave some additional length. With HEI terminals trim the wire ~3/8" past the post (longer).

This is a nice loom kit for center bolt covers. http://www.summitracing.com/parts/mo...make/chevrolet That is very similar to mine for perimeter bolt covers.

budget builder

iTrader: (3)

Finally had a chance to fire car up: changed all plugs regardless of need,dizzy cap, wires, wire looms, and aluminized sheaths that aren't working (burning and will have to be removed). I checked for tdc on on number one checked position on rotor did firing order. Seen timing was at and this looks wierd but keep in mind that it did fire up even though it ran rough till I played with dizzy w/vaccume adv. Plugged. #1 up consistantly with balancer mark at. 14-12-8-6-4-0-4-6-8-12-16 its ahead of the timing tab on the left hand 12 which I think is atdc which is wrong I don't think it should ever be atdc. I try to get it to btdc and the car tries to die unless the carb a/f ***** needs adjusting. Or do I have it backwards the tab is a trd-4960 from summit. U know what as I am writing this I think I got it wrong I think that's really btdc. I know I should be timing for 3000rpm but I don't have timing tape yet. Somebody tell me any pointers. The tab has before on the passenger side and after on the drivres side. Thx please help

JaBoT

The top part of the tab is btdc (before) which is where you want to be. Since you don't have timing tape or a dial back light shoot for around 12 btdc at idle. Turning the dist counterclockwise will advance (before) the timing and clockwise will retard (after) the timing.
For reference:
advance = before = btdc
retard = after = atdc

budget builder

iTrader: (3)

so I was thinking wrong b4. the top is btdc and that is where I want to be. kool, thank u a bunch and I will be getting the timing tape today and a piston stop I just have to learn how to use it and then get that balancer super clean so it will stick. I was under the car and learned that thru a rookie rebuild that I have to put a new oil pan gasket on (used permatex) major no no. but that will come after I get the car running right. I thinik I got a valve cover leaking too b/c no.5 plug had oil on it. so the saga continues.

budget builder

iTrader: (3)

oh and another question do I check for the highest timing advance 32-34btdc at about 3000-3500 rpm with the vaccume adv. unplugged or connected? I got the timing at about 12 btdc with the vaccume adv plugged and disconnected from the dizzy. and right now manifold vaccume is connected to my fp regulator I have no kind of boost do I just plug it and leave the regulator to atmosphere pressure? its the common Mallory 4309.

JaBoT

Why do you need a piston stop? Do you not trust the motor to be close to where it should be?

JaBoT

No need to run vacuum to the regulator. That's for fuel injection or boost.
As far as total timing it depends on which springs are in the distributor. It could still be advancing after 4000 rpm. I would sugest buying an msd advance kit 88428 and install the light sprongs then set total timing anywhere from 32 - 34 deg @3000 rpm. It will really wake up the bottom end.

budget builder

iTrader: (3)

I got my timin light, vaccum gauge,and tach connected I fired the car up and it ran but not well. I give it more adv. It runs better less it runs crappier. When I put it to 12-14btdc and the further out the advance the better it ran. Of course. The car seemed to like almost 20 btdc but its not supposed to be that high so I put it back to about 12-15 and started trying to adjust the idle screws to get the vaccum gauge steady. I couldn't git it perfect but fairly steady. The most vaccume I could get was about 15 and I had to have the idle screw almost all the way in just to git to 800 rpm. Is setting the timing supposed to be this difficult or am I just a rookie? Please help. Advice? Tips?

t-top havoc

iTrader: (3)

Did you set the carb per instructions? Edelbrock has vids on their site.
IDK what the pressure should be. Might double check that too.
Tuning -- how fun--...

budget builder

iTrader: (3)

I found this tell me what u think http://forums.corvetteforum.com/c3-t...al-timing.html

t-top havoc

iTrader: (3)

Curious- what dizzy are you using?
MSD Street fire hazy had some issues

JaBoT

Disconnect the vacuum advance and plug the vacuum line. Set the timing to 12 - 14 base, then connect the vacuum advance to full vacuum. This will bump the timing at idle so it idles smoother.
Now lower the idle because it probably just went up higher due to the vacuum advance.
Now just set the air fuel screws to the highest vacuum or turn them in until the car starts to stumble then turn them back out a 1/4 to 1/2 turn.

budget builder

iTrader: (3)

Waht about ported vaccum?

JaBoT

ported vacuum will not help the idle quality.

budget builder

iTrader: (3)

Got it! Or at least it seems I do. I did just what u said the car didn't seem to lik 12 to good so I had to give it about 15 and tuned just like u said and voila! I haven't driven it yet but will I just have some other things to do first. Thm u all for all the help and don't worry if I have another question I will be askin. Oh and I just plgged the ported vacc. Once again thk u so much!!!!!!!

budget builder

iTrader: (3)

Its still dieseling some. I read some where that it could be caused by carbon deposits so feel its my duty to blow some cabon out! I will let u know the results. Oh it takes a couple tries to fire it up even when hot all though this might be a choke problem b/c it shorted out on a misplaced screwdriver. Let me kno

JaBoT

It shouldn't be running on at all. What speed is the idle at?
Also be careful with the timing at 15. It might be to high in the upper rpms. Until you get a dial back timing light to timing tape I wouldn't go over around 12. Plus once you put the vacuum can back on vacuum it will raise the timing up anyway.