fed up with this stupid car

[TIMS-98Vette]

Quadrajunk

i am sick of tired of trying to tune this car.

i thought i had everything fixed with the exhaust popping but the damn thing just wont run right.

i am on my second quadrajet now both bought new from jet performance.
both run so rich that even with the mixture screws all the way in the car still runs.

idle screw has the spring completely compressed just to get about 700 rpms.

choke is all the way open
fast idle screw is completely removed
timing is 12 degrees with the vacumm unplugged.

i should have bought the square bore and holley when i had the chance

Back in the late sixtys/ early seventys thats what we called them. It seemed like if you got a hold of a good one you could not beat it, but the chance of that were slim. good luck.

 

[GerryLP]

... it is a stock 454
the mark on the balancer lines up with the 0 mark on the tab when the cylinder is up and both valves are closed. i checked with the valve cover off.

Baxsom, Do you happen to know if the #1 electrode in the cap is aligned with the rotor inside the cap when the above is like you said? If so, then you are running your engine at zero degrees before top dead center, and if so, the it would be normal to get after-fire (popping from the tail pipe). Back fire (from the carburetor) is almost always caused by a lean condition (a vacuum leak would cause a lean condition, for it is diluting the mixture that gets to the cylinder with air.

.. i cant find a vacuum leak anywhere. i even took the intake off and resealed it to no avail.

leaks can be anywhere to include the base of the carb, a vacuum port not capped, a torn gasket, etc.

pcv inlet is blocked.

brake booster inlet is blocked.

hose to headlights and wiper door as well as tranny is blocked.

no noticable air leaks around the base gasket.

The best way to search for vacuum leaks is to spray WD-40 around suspected areas slowly (for example, spray around the left side head intake side before moving to the other suspected areas). Idle the engine to do this. If the rpm picks up, then that area you just sprayed is leaking. You could have more than one area leaking.

timing is 12 degrees without the advance hooked up.

choke is all the way open.

fast idle screw is taken completely out to make sure that the fast idle cam doesnt get in the way

I guess here you mean that the choke plate is open all the way...right? With the engine off, and the choke spring cold, check that the throttle plates at the base of the carburetor (not the air flaps on top and behind the primary side) are closed. There is a lock-out feature that prevents the secondary plates from opening if the choke is not completely open. Make sure that the plates closed all the way and did not hang open by the lock-out feature.

Good luck.

 

[baxsom]

on the distributer question.
i am a little stumped.
when i installed the distributer with the #1 cylinder at TDC i installed the distributer with the rotor pointing to the #1 plug wire.

then cranked, then set timing. the engine smoothed out at 14 degrees.

thats how i understood it was always done. did i do it wrong. from what i was told the exhaust popping on decell was normal and the only reason i was noticing it was the holes in the exhaust pipe so close to the manifold.


no leaks that i can detect with an electronic rpm meter.
first thing i did was get the engine warm and then squirt a little wd40 straight into the air horn to get a baseline on what it should do.

then i started spraying around the carb, around all the vacuum lines, etc.
no change in rpm

choke plate is straight up and down but the lock out thing on the secondaries is something that i did not think about. i need to check those.
is there an adjustment to verify the secondary plates are all the way closed at idle?

 

[muddywaters]

A 1979 coupe I had once would not stay running when I adjusted the timing to the correct setting. Came to find out that the harmonic balancer must have seperated and was knocked together out of sync. I noticed hammer marks on it so I replaced it, timing problem solved. I'm lucky the balancer did not come apart and cause me more grief...........Most guys don't like Q-Jets but I never had any problems with them even after I modified them a bit

 

[fine69]

on the distributer question.
i am a little stumped.
when i installed the distributer with the #1 cylinder at TDC i installed the distributer with the rotor pointing to the #1 plug wire...

The problem I had was that I always seemed to run out of turning room (advance can hitting the manifold).

Here's the process I utilized before I switched to an electronic ignition...

I tap the engine until the mark on the damper is approx 6 degrees BTDC. I then re-check the dwell to ensure that it is right on at 30 degrees.

Next I remove the cap and put a rubber band around the distributor weights, recap it, remove the vacuum advance hose from the advance can and plug it. I then loosen the distributor hold-down clamp, leaving it slightly snug.

I hook up my timing light, and dial-in 36 degrees. I start the engine, and rev it 3,000 RPMs and turn the distributor until the timing mark is pegged at 36 degrees/3,000 RPMs.

I shut off the engine, remove the rubber bands, but leave the advance hose plugged; recheck it after starting it up to ensure the advance is good at 36 degrees when revving.

I had replaced my stock advance can with a NAPA VC-1810. The vacuum is okay at 15-16" Hg - lights work, but sluggishly.

If you don't have it, I can send you a copy of JohnZ's paper on timing... it's a valuable resource.

Ralph

 

[baxsom]

interesting thing today.

i finally got the 2.5 inch exhaust system from corvette central installed today.

first thing that happened is that the idle was higher than it was before the install.

before the install choked idle was 1500 rpms.
first start up it went to 2500 rpms
after warm up and tapping the pedal to release the fast idle the curb idle was 1100 rpms in park where before it was 800.

once i dialed the idle back again the car idled smoothly and very quiet with the new system. no popping or backfiring period.

i took it out for a drive and it may not be tuned perfectly but man those magnaflows sound great.

 

[GerryLP]

on the distributer question.
i am a little stumped.
when i installed the distributer with the #1 cylinder at TDC i installed the distributer with the rotor pointing to the #1 plug wire.

then cranked, then set timing. the engine smoothed out at 14 degrees.

....

Many different ways to solve a problem. It looks like that should have worked fine.

So you're saying that the new exhaust fixed it? Perhaps you had a partially blocked exhaust? Did you find out what what was blocking it?

GerryLP:cool

 

[baxsom]

i know that the factory exhaust valve was stuck about half way closed due to rust.
i replaced it with a 2.5 inch spacer from ccentral.

there is still a slight popping noise coming from the passenger exhaust. from what i have been reading that is a common issue. but yeah, as soon as i tried to crank it the rpms were a lot higher than normal.
something was blocking something somewhere.
now i get to go back into tuning all over again.

 

[GerryLP]

Good! A fix is a fix! And that new tuning should deliver more feel-of-the-seat too.