ok Q-Jet air valves are running and working fine even tried a Q-Jet my neighbor had off a 77 350 in a olds. still bogged could this be a sign of a bad fuel line or fuel pump maybe not feeding the motor that it needs under a load. Or possibly a hose collapsing under the demand for more fuel. It does not do this at a idle or rev's while sitting just under a load when the motor has to work harder. As i stated before this started and this is why the vette got parked. It was a slowly developing issue that has slowly gotten worse then lead to it's parking.

 

Do you get a good shot from the accelerator pump? Is your vacuum advance working?

 

Read.

http://forums.corvetteforum.com/c3-t...t-quality.html

 

hey from both paul's

paul#1 yes get a good shot from the pump when done by hand.

Pual#2 i have read every bit of that post as my pump is working fine.


as i stated above is still doing this with a different Q-Jet 2 whats the chances of 2 carbs doing the exact same thing on the same car.

I have adjusted the air vavles as lars and others suggested and found out my air vavles where catching on the carb body by the rear air horn screws i filed that away till they where free moving no hanging up. My car ran fine for 2 days after doing that no issues this is just based on back road testing as my car is not fully together.

took it for a run yesterday to make sure all my gauges tach and speedo worked after putting my dash back together and blahhhhhhhhhhhhhhh at high RPM's

timing is dead nuts on. vacuum advance functional.

My neighbor had a Q-Jet of his 350 from a Olds. he let me borrow it to see if it was my carb. placed the Q-Jet from the Olds. took it out and blahhhhhhhhhhhhhhhhhhhh same exact spot at high RPM.

The car is doing the same thing with 2 different carbs.

But at sitting it revs with no issues just seems to be around the 3k mark when the motor is really starting to pull itself.

If i drive it like gramma it runs fine if i drive it like i stole it well i could only hope the cops car exploded cuz i aint getting away

 

Maybe it's trying to tell you something....

 

We all have different notions of what a bog is and yours could be entirely different from any of ours. In that regard, make sure you don't have a restriction in your exhaust. Make sure your fuel tank is venting (try making a run without the cap on). I'd tell you it would be a good idea to help diagnose this with a fuel pressure gauge but you'd have to be at the point of being driven to madness to install one.

 

The advice you get can only be as good as the quality of information you supply.
Does the "bla" part of blahhhhhhhhhhhhhhhhhhhh mean you have a momentary sag in accel. as the air valve opens? (the usual meaning of a bog, a momentary drop off in power).
It may seem wierd that it seemed to go away for 2 days, but if the air valve tension is 'right on the edge', the bog can appear under some circumstances and not others. I suspect you need to tighten the air valve spring a tenth of a turn tighter - bog is variable if you are on the edge.
Why do 2 carbs demonstrate the same symptom? I will guess that the brass tubes that feed the transition holes for the air valve's opening have fallen out into their wells. This is a very common problem and both carbs may have it. So why would the Olds carb owner not have the problem? I speculate there is a substantial difference in weight and gearing between the cars (and rates of accel.) and it just didn't manifest on the Olds.
my 2c. Pull the air horn off and check that the tubes are still attached to it. Also check that there is some light weight grease on tthe spring.

 

Try a different ignition coil.

 

ok let's see if i can explain this better as it's a bog to me maybe more of a dead spot. when accelerating the car does fine till it starts to hit it's power curve at 3 grand or so. i guess it would be more of a lose of power and becomes lurchy as of late. if you got your foot in it it will run like a bat out of hell then hit this spot and it's like you stepped on the brakes the front end will dip then become very lurchy if you keep your foot in it. i guess best example would be like being in the car with a teen new drive gas,stop,gas,stop. adjusted the timing all threw the range no matter where timing is set still does it.

i took it for a run with the secondaries locked out and still had the issue

took the fuel line off cranked the motor the fuel pump seems to be pumping fine. but could it be losing its edge at higher RPM's or maybe a section of rubber hose getting sucked closed.

as for the olds. Q-jet it was a fresh rebuild with a kit from cliff's and that was its first time it saw fuel was on my car. had to do the air/fuel mixture and all to get it to run on the car.

 

Sounds like your HEI module has crapped the bed. A fuel issue, like inadequate delivery, will just lay down and die. No real sputtering or anything, just die and not come back until you have sufficient fuel in the bowl and that is not a rapid intermittent display.

 

i didn't even think to give the HEI module a thought i believe i got a spare in a box somewhere around here. i will switch that out and give it a go. Thanks gerry. and all others we shall see what happens


I'll try this anyway but in most case if the module goes they just done run period right. or get to hot then just crap out completely or am i wrong on this.

 

with gerry72......as soon as I read in your post it happens at higher RPM I thought "HEI module". Stock modules are well known to not deliver the best quality of spark at higher RPM's

 

cool stoker i will be switching them out if i can ever find it lol i know i got one around somewhere just the matter of where lol. as i said never even gave that a thought. and this has been a growing issues not something that started overnight and has steady gotten worse. will be given it a try since there's not real way to test a module that i know of.

 

I'll jump in here with something off the wall. Do you have an EGR valve? If so, have you checked to make sure it's functioning properly. A bad EGR valve can cause all kinds of mixture problems. It may not be your carb at all. Just a thought and my $.02.

 

thanks vettefixr well i can elminate that suggestion as the egr went the ways of the emissions stuff. i am thinking it's in the dizzy now gonna check coil pick-up and change the module give it the full run around if that don't clear it up then i am back to the fuel issue as my dizzy will be basiclly rebuilt lol

 

After reading more, I am inclined to agree with the posters who say change out the module. Don't forget the dielectric grease that goes under it to help dissipate heat.
Good luck and please let us know if that works.

 

ok update this is totally weird iso i changed the module today and when i started the car it wouldn't start. but i did get it started. when it started sounded horrilbe grabbed my timing light and hooked it up my timing chaged when i changed the module 15 degreees i went from a idle at 18 no vacuum connected to 3. so redid the timing back to 18 at idle. does this sound like i normal issue with the module. ugh should go get a old points dizzy and stuff it in there

haven't got to drive it yet its raining but it changed alot of things

 

Nope, ive had an HEI module fail to where it runs but once hot it doesnt like to run or restart until its cool. Try replaceing your module, coil, cap and rotor, this is what we replaced on my friends car and that fixed his running and starting problems!

Will

 

ok update got to take it out for a test drive while it was still cold it ran fine no issues but when it got to temp it once again started crapping out even after changing the module. gonna try a new coil when i can get one and see if that don't fix it. if it don't well then i am just plumb outta ideas and guess back to fuel delivery.

there's no cracks in the dizzy cover i changed the module, tested the coil with a ohm meter but that could change due to heat i guess so gonna change that after coil change i will basiclly have a new dizzy.

Open to more suggestions!

This is really starting to be a thorn in my side.


Why am i gettign that sinking feeling i would of been better of just buying a cheapo blueprinted from summit.