simple 350 with headers for exhaling and a 600 -650 cfm holley for inhaling. Issue is from a dead stop you put the hammer down it feels almost like the carb chokes out for about 2-4 seconds and then picks up and digs. Its tough that this issue causes me 2.583 seconds off the line in the 1/8 mile which leaves me with the time 9.589. I need this problem fixed with some advice from folks who might have had this issue before. Hoping to have thoughts before Thursday when i hit the track again.


MY thought, since its a stock motor with tiny mods...carb is not to drastic of a change it had the same issue with the rochester...could it be that maybe its demanding more fuel that my stock mechanical fuel pump cant deliver>?

 

From a stop, the carb is using gas that it had stored in the bowl, so it wouldnt be your fuel pump.

Sounds like a lean problem to me too. It's possible and likely that the holley and the quadrajet had completely different reasons for being lean, most commonly the secondary air flap opening too soon on the quadrajet, the holley of course doesnt have one so it's a different cause.

It might be your pump shot (the pump on the carb, not the one on the engine block). Look into the carb with the engine off, pull the throttle, make sure it's squirting gas out the nozzle into both primaries. If it's working, maybe you need a different size nozzle (bigger hole i think, lets the gas squirt faster), maybe you need a different pump cam. I never got that far into it so hopefully someone else can say which of these it needs.

Also make sure as many things are adjusted properly as you can first. Float level, gap for the pump shot lever, idle ratio, jets, power valve... I havent worked on a holley in a while, I liked the quad better so I'm sure I'm forgetting a lot.

 

What's timing set at?

 

Got done tinkering with the carb. today. All things check off from float to idles down to the valvetrain timing. Im so confused, even on a bad day I can figure out issues with the car but this is a stumper for me. Also had another "long term" thirdgen owner stop by and shot the **** with me and he said something about how the camaro's in the 80's had such small gaslines that sometimes even a ding in the line could nearly cut off all circulation to the carb..

Carb is getting nice pump shots of steady streams..

I dont wanna take just one guys opinion and start a project like replacing all lines from tank to carb.

Kinda sucks right now, I feel like my camaro has defeated me after many attemps of "breaking down" and is now mocking me saying " I run!!...just not the way you want me to"

 

A little more information about the engine would help. Is this mainly stock? What are you doing for a distributor? What is the timing curve set like? It sounds like a lean bog to me, but it could be timing related.

 

Its a vac. control Dis. (tested-works well) it self adjusts when its demanded if I'm not mistaken. Its all stock besides a holley 600-650 cfm carb and headers.....ALSO NEW ISSUE THAT HAS POPPED UP!! Dont know if it'll help but just imagine this like you were there.............


You're sitting there in your driveway in Park and you tap the gas quickly, the idle falls from 1000-900 down to 600-500 then returns to 1000-900. You continue to tap the gas in a feathering motion as the idle drops lower to the 400 range and then stalls out...you hit it like normal acceleration RPM raises but just a sudden quick tap drops my rpm? and then stalls?? (side story - ive had my 1987 camaro since i was 15 and im 21, love this car..but im tempted to just park in in the garage and take out in another camaro..but i dont wanna disrespect my faithful friend. SO I MUST FIX IT!)....

Also bogs under heavy loads obviously while from a dead stop or 50mph etc and then romping on it..it seems to be a very particular complication, hmm wheres sherlock when you need him most

 

Do you have a timing light? Check to see what the timing is, at idle, with the vacuum canister unhooked (plug it at the carb). Then, hook up the line and see where the timing goes to.

Also, with the car turned off, remove the air cleaner so you can see into the carb. Move the throttle lever (by hand) slightly and see if a stream of fuel shoots ouot of the squirters. You should get fuel even if you only move the throttle lever 1/16".

Check these two things and then we can go from there.

 

Check for lean condition, also check your powervalve....

 

Timing is as "0" degrees. was going to advance it to 6-12 degrees BTDC

 

Also, a bare minimal movement of the throttle with engine off, nice steady stream out of the left jet (driver side) and the right one has a "skimpy stream"

 

Get your base timing set no higher than 12*, If I were you I'd go to Holley's website and look uo how to tune your Holley carb to give you some basics on the process.... Should be under technical info, lookup a double pumper model....

 

0 degrees isn't going to cut it...not even close. Unhook the vacuum advance (after the car is warmed up) and then bring the idle down as low as possible (you want to make sure the mechanical advance isn't activating). Set it to 10 degrees advance. As you are doing this, the idle will try to creep up. Keep turning it back down. You want 10 degrees advance with the idle around 800RPM. Then, hook the vacuum advance back up and reset the idle to where it needs to be. With a stock HEI, that 10 degrees initial should give you around 35 total. You can fiddle with it from here to find what your car likes best. This should solve your carb issues.

 

Yep, like I said get your base timing set no higher than 12*....

 

This is what I would be doing!!! Also I would make sure to check for vacuum leaks anywhere on the carb. Make sure all the not used inlets are plugged, because this will also cause a delayed throttle response.

 

Awesome. In the process of trying the things you fellas suggested.....


..also while working on it i noticed how it has no issues of the "bog" situation up untill 120 degrees soooo.....got bored. Ended up wrapping the fuel lines with tin foil >.> dont judge or hate, cheap alternative to trying to reduce fuel line temp because i noticed how close the lines were to a 160 - 200 degree motor at times and maybe it was getting a bit of vapor lock

Probably going to fashion a "cool can"

 

Most "off the shelf" distributors are not going to get nywhere close to a total timing of 35 with a base of 10 - they don't have the springs/weights for that much advance.

To get timing set, loosen the distributor hold down just enough where dist won't turn on it's own, but you can twist it. Then set timing to 10BTDC, and take a drive with a WOT run - you (probably) will NOT hear any pinging (spark knock), so bump it up to 12, and WOT run again ... keep doing this until you get to a point where you hear the pinging (spark knock), then back it off 2 degrees.

So, say for instance that you get pinging at 16, but not at 14, then lock it down at 14.

Unless you have changes weights/springs inside the distributor, you'll never reach 35 total timing (without spark knock at WOT which is bad), but you'll get fairly close (maybe 30 total).

Of course, adjust your idle down each time you bump the timing up, so that your idle is at about 700 - 1000 rpms.

 

While we're talking about replacement distributors not being set up properly, you'll want to check on how much vacuum advance it's giving. As mentioned here http://www.73-87.com/7387garage/drivetrain/hei.htm and from my experiences, you'll probably get way too much advance. One I used for a while was giving me like 28 degrees. A piece of cheap sheet metal (like a soup can lid), some snips, and a drill and i put in a block to limit it to 12.

 

WHatdo you mean by distributors not being setup up properly?

 

I mean what I already said about the vacuum advance, and what camaronewb said about the springs and weights. A one-size-fits-all aftermarket distributor will never work as well as it could (and may even work like utter crap) until you get a recurve kit with new weights and multiple spring types, and an advance can with adjustable rate and amount, and then install and adjust it properly.

And "nice steady stream out of the left jet (driver side) and the right one has a "skimpy stream"" means you probably need a new nozzle whether your timing is good or not.

 

The timing curve you need will depend a great deal on the camshaft specs and your compression. At this point, I don't think we know either. The 10* advance I advised above is a good and safe start.

For example, my car likes 20* initial and 52* with the vacuum hooked up at idle. I have pretty light springs in, so my full mechanical (35*) is all in by 3000RPM. I have a Gm Performance HEI, and this is the curve it came with out of the box. Really nice distributor.