PLEASE HELP 86 454 distributor problem

[roempty]

engine seems to have a miss like it is starving for gas or air when you accelerate.I noticed when it's idling a pop comes from distributor it like a puff of air every few minutes.got me never seen this before.any help would be great

[Grim Reaper]

Somewhere is a knock sensor on that engine. unplug the wire from it and see what it does. Listen for spark knock and be easy on it. If the problem changes then try a new knock sensor. If that doesn't fix it then the ECM might be bad. I have one you can have for $10 and shipping but ppersonally if you can't fix it with a knoc sensor I would scrap it and switch ot HEI if your not going to have a smog nazi problem.

You also need to make sure this is not a carb problem. That carb you have has a mixture control solonoide on it. It can cause simular symptoms.

[swervin ervin]

I doubt a Holley DP has a mixture control solenoid on it.

Also, I very seriously doubt it came with a computer at all, or even an ESC distributor. I don't think 454's has that mess, only 305's.

If I were guessing, and it would be, I would say the coil might be causing the puff of air or pop. I know HEI's will heat up pretty quick inside the cap if some part is not performing right.

99% of the time a miss is electrical. I say give it a good tuneup if it hasn't had one in awhile. Oh, check all your grounds too.

[roempty]

has no computer-all vacuums are plugged of no smog I can't figure it out any what is a knock sensor

[8t5Silverado]

the knock sensor (if it has one) would be on the side of the block, probably just above the oil pan.

[NeCrOmAnCeR]

Since you stated that you hear a "POP" from the distridutor at idle, this made me think of a distributor problem i had roughly 15 years ago. Back when the truck had a points distributor, in the mornings when I started it, the distributor cap would be blown off of the dizzy. Turned out to be a leaky vacuume advance. Over night fuel vapors would leak into the dizzy and the first spark from the rotor to the terminal would light it off. Since a vacuume advance is (or should be) hooked to a ported air source where their is no vacuume at idle, it's possible that fuel vapors could accumulate in you're dist. This could be the sorce of the "pop" you are hearing. And the faulty advance could be to blame for the lack of performance. Just a little advice on a problem which is very rare. Good luck.

[Lester]

454's in 85 and 86 C/K 30's had an ECM. The ECM ONLY controlled the AIR system, and the ducted air for the carb. Input for the ECM included the water temp, vacuum and engine speed.

In the C30 the ECM does not control either the carb or the HEI.

The C30 did not have O2 sensors or cat's from GM. They did have two AIR pumps and associated hardware to manage air quality at the exhaust at the mainfold and the EGR.

There are two types of emissions systems on the 454, and HE4 or HE5 (i think thats the rpo's). You can tell which one you have by the exhaust manifold. The HE4 has cast exhaust manifold. The HE5 has a tubular stainless exhaust manifold, both have true duals with stainless steel header pipes.

I agree with Mike you have something lose in your HEI and complete tuneup will go along way to fixing this problem.

Lester

[roempty]

I have fumes getting into cap.making it pop.when I open cap it is moist,like exhsust fumes it's like they are coming up distrib shaft getting in cap than it pops

[Lester]

Moist, an oil residue. Exhaust fumes, what it smells like after you heard the pop and pulled the cap. There are two likely issues, a clogged fresh air and PCV combo not allowing blowby gasses to be purged or two an internal gas leak. Check the PCV valve its hose and fresh air hose and filter, making sure these are functional. Replace parts as needed. Once you are sure these should be functional you will need to check the system. I do this by removing the fresh air tube from the valver cover and start the engine and let it warm up a little. Now take a tissue like Kleenex or Puffs and hold it slightly above the opening in the valve cover where the fresh air tube would be inserted. If the fresh air system that pulls blowby gasses from the engine is working the tissue be held in place over that hole it should not get sucked in. If it doesn't get sucked against the rubber grommet then the system is being affected by either sludge in the heads blocking the oil return holes which also act as fresh air holes or the blowby in the bottom end is too strong. While you have been doing the engine has been warming up. You can get and idea of the internal condition of your engine by revving the engine up quickly and letting it drop back to idle while you watch the open fresh air hole. Blowby and hot oil smoke may come out of this hole. A little is not an issue, but if its coming out all the time or alot comes out when you rev the engine this may need some further investigation. If the fresh air system is working reasonably like it should the problem is likely a gas leak and you are likey to have three problems.

Other than a block fesh air system about the only way you get gas fumes in your distibutor is the shaft bearing is worn out of service tolerance allowing some oil residue into the bottom of the upper part of the distributor and it smells like gas.

You can check this easily by pulling the distributor then hold the housing with one hand and apply side pressure with your other hand to the top of the shaft where the rotor attaches. There should be no side to side play and it should spin easily. If there's side to side play you will need a rebuilt distributor.

The gas/oil mix accelerated the bearing wear in the distributor. Depending on how long this has been the case your mains, rods and rings have not benefited from this either. Does your exhaust smell rich or are ther any signs of smoke?

The likely cause is the Qjet on top of the intake. These carbs have pronounced tendency to leak, either the needle and seat floods the bowl or the two plugs in the bottm of the fuel bowl are loose and leaking. Either way the carb will drip gas right into the intake which eventually bypasses the rings and contaminates the crankcase oil and with enough driving finds its way into your distributor.

If you are lucky you have caught this early enough to minimize serious damage.

Check the distributor and the Qjet and change the oil and filter immediately. I'd not dirve this until you have solved the problem.

Good luck.

[roempty]

I change the distrib all is well.Must have been bad o rings.THANKS TO EVERYONE

[roempty]

Also used seafoam in engine, carb and oil.GREAT STUFF cleaned it out no more smoke and running better than ever

[rage'nrat638]

STOCK CHEVY DIZZY'S DON'T USE O-RINGS...
ONLY AFTER MARKET ONES