Cant drive 55 Literaly

[66CHEV]

Let me add when I changed the intake exhaust manifold gasket there was quite a bit of black carbon build up on the exhaust port walls of the head does that help with diagnosis

[66CHEV]

It is a Holley remanufactured one from autozone bought about 6 years ago

[66CHEV]

I think that is actually a remake of a old Rochester

[awbrown]

you can always try another carb and another ignition system , we all are running out of answers for ya...

[66CHEV]

It is a Rochester b found a diagram of it

[66CHEV]

Yea I'm running out of answers myself

[msaelens66]

Did it go faster previously? That's as fast as mine went with the original Eaton rear. Changed to a 80's rear with freeway gearing.

[62chevy302]

sprinkle water at night on wires and look for arcing? dig you check plugs for cracks after installing them?

[66CHEV]

yes it went faster just recently, and ran much smoother as well. the only thing i done prior to all of this issue was change the clutch/pressure plate and had the flywheel resurfaced. after that i have had this trouble.

[66Submarine]

Originally Posted by msaelens66

Did it go faster previously? That's as fast as mine went with the original Eaton rear. Changed to a 80's rear with freeway gearing.

Lol, I had my truck with a 4.10:1 Eaton up to about 80MPH the other day, and it still had some left in it. With a 5.14:1 that'd still be 65MPH.

Now, granted, that was wound out to about 3,500RPM, but I feel most engines should be capable of turning 3,500...

[awbrown]

The only thing that could have gotten hurt during a clutch change is wires ,try moving them around and tie them off in a new direction and give it a try...

[62chevy302]

your no confusing clutch slip with misfiring are you? the clutch could slip at the same time your describing

[66CHEV]

nah its definitely missfire,

[66CHEV]

Ok rebuilt carb with kit still not any better, did compression check 150 psi all six cylinders what am I missing here

[1966shortwide]

Did you ever remove exhaust from manifold, and drive it that way also check the heat riser for being open, if it has heat riser!!!!!!!!!!!!!

[Pinsco63]

I know you have good compression, but I would squirt some oil in each cylinder then do a compression test. If your numbers go up then your valves are sealing, if not well may start looking at valve issues. Another thing have you done a cylinder leak down test?

[TJ's Chevy]

My truck has a terrible misfire(Go to the link on my signature and see the video of my truck running in my build thread and let me know if that sounds like the same misfire) and it clears up under load and pops while cruising. My compression is at 95 pounds in all cylinders. If you valves were not sealing properly you would see uneven compression. If you have burnt valves you would see the same. Did you check the valve spring pressure? On the stock 1 barrel exhaust manifold there is a heat riser, when cold it is cold....as the engine warms up it slowly opens. It doesn't matter if it is open or closed when cold, but it needs to be open when warm.

[FetchMeAPepsi]

You should start posting all the things you've done up to this point in each reply (cut/paste) because the thread is getting big.


Did you soak the carb in carb cleaner overnight?
Did you put the little rolly ball bits in the right holes in the carb? There are two sizes, one larger and one small.
With the new carb kit installed, have you reconfigured your idle mixture screws and accelerator screw?
Did you bend your accelerator pump linkage before, and not bend it back now?
Did you re-check your timing with the vac advance off and plugged?

Have you changed your fuel filter (I dont remember at this point), there are two on some models.

[66Submarine]

Run a wire straight from the battery terminal to the coil and see if it runs like it should.

[66Submarine]

Also, I can't remember if you've already tried it, but put a new condenser in it. Some people say that the condenser just makes the points last longer, but it is required for the engine to run. The extra secondary condenser may have been for point life, but you need at least one good one for the truck to run at all. You can/will still have a visible spark, but the truck won't run. A condenser that's going bad will make the engine miss badly.

[TJ's Chevy]

You also need to make sure you accelerator pump is good. On the old 1 barrel I had on my 292 the accelerator pump's rubber was stripped, so it cause poor acceleration and it wouldn't go over 55.....On the exhaust manifold there is a butterfly that is spring loaded, when the motor is cold, see if it turns freely. Do a cold start and see if the butterfly slowly starts to turn, if it does that means it is open, it it doesn't that might explain one of your issues. Also check all your vacuum lines, might consider changing the pcv valve, and if the line that runs from your carb to the advance on the distributor is metal; I would take it off and flush if with WD-40 and see if it is clogged. You should get brand new plug wires and plugs, and a new distributor if it is all oem. The advance springs could be weak and that will cause poor performance. You can also take the exhaust pipe off and take it for a drive running straight pipes and see if it runs faster, that will automatically tell you if your exhaust is clogged. All I can say is that if you compression is even, then you won't have burnt valves or issues with the head.
Might try putting new valve springs on. I am out of ideas, next comes timing but it sound like you have that set. Also might just want to buy a BRAND new carb from Autozone and see if that helps. I rebuilt my rochestor 3 times and I finally relized it was scrap, so I did the performance mods and it runs better. minus the popping. I'm out of ideas now!

[cg285]

we're almost half way there!

[TJ's Chevy]

Originally Posted by cg285

we're almost half way there!

???????? Not sure what you mean....Is it meaning that we almost have the problem figured out, or we should have by now!

[cg285]

Originally Posted by T.J. MCCAULEY

???????? Not sure what you mean....Is it meaning that we almost have the problem figured out, or we should have by now!

earlier i predicted there would be 10 pages and the op would still be where he started.

[66CHEV]

well we are at 4 pages and yes the op is still where he started

but that just tells me obviously cg285 is not any smarter than i am because i have tried and tested everything that has been suggested except for the clogged muffler and still have the same problem.