[chevyrestore]

i pulled off the driver side valve cover and ran the motor, all of the rocker arms move the same amount and didnt see anything physically wrong. I did notice however that all the pushrods had good oil coming out of them except for the #5 exhaust pushrod. what would cause this and how should I fix it?

[cdminter59]

Chevyrestore, Check the distributor. First make sure the spark plug wires are right. You will need an assistant. The #1 tower is the 2nd one from where all the wires plug in under the cap, going in a clockwise direction. An easy way to find #1 is to hook up your timing light to #1 spark plug wire. Pull #1 spark plug and bump the engine over until air is coming out around your finger. Turn the key switch to the on position. Look to see if the line on the balancer is near 0 on the timing scale. Take a socket and breaker bar and turn the crank bolt while holding the trigger on the timing light. Stop when the light flashes. You can rock the crank back and forth to get the light dead on. Turn the key off. Pop the cap to see where the rotor is pointing. If the rotor is not pointing to the #1 tower I said the distributor is in wrong. BTW check the cap make sure you don't see any carbon trails from the center button. You can rewire the cap starting where the rotor is pointing with #1 then in a clockwise direction 8-4-3-6-5-7-2. Fire the motor up and set the timing at 12*-16* BTDC. If you still hear the tapping noise adjust the valve lash again. Here's the article on how to install a distributor. http://www.crankshaftcoalition.com/w..._a_distributor

[chevyrestore]

I removed that one pushrod and blew threw it, felt somewhat free, after blowing through it it felt a little bit more free and looking through it I can see its totally clean inside, reinstalled, same thing, no oil from that one pushrod, I ran it with that lifter loose, no clatter, and 1/2 turn tighter after the clatter stopped. I dont think its the adjustment or pushrod itself, the pushrod also appeared unbent

[cdminter59]

Originally Posted by chevyrestore

i pulled off the driver side valve cover and ran the motor, all of the rocker arms move the same amount and didnt see anything physically wrong. I did notice however that all the pushrods had good oil coming out of them except for the #5 exhaust pushrod. what would cause this and how should I fix it?

With the engine off disassemble # 5 rocker arm. Check for burrs on the tipof the rocker where the pushrod sits. There is a little hole there, make sure it is not plugged. Clean the pushrod make sure it is not plugged. Reassemble the rocker arm. Start the engine and adjust all the valve lash again.

[1971BB427]

There's absolutely no problem replacing one lifter or anything less than a full set, but you need to do the same breakin on it that you'd do with a whole new cam/lifter set.
I'd also be looking at that ProComp distributor for the cause of your misfire. When they start to go the electronics will break down when warm or hot, and develope a misfire. It may be signaling you that it's failing. They don't have a great reputation.

[cdminter59]

Chevyrestore, I sent you a PM.

[cdminter59]

Chevyrestore, There is two ways to do this. You could pull the lifter and take it apart to clean it. You could also purchase the same brand lifter and swap the inside parts to your lifter. This way you don't have to go through the whole break-in process again.

[chevyrestore]

I took off the rocker arm on that valve and there was no damage to it preventing oil from getting all the way through, there was a very small ring of what looked like a burn mark.

[GMCTRUCKS]

Hey guys might it be a bad ground to the coil or ICM?

[1971BB427]

Originally Posted by cdminter59

You could also purchase the same brand lifter and swap the inside parts to your lifter. This way you don't have to go through the whole break-in process again.

Excellent idea! Never thought about rebuilding the bad lifter and saving breakin time!

[1971BB427]

Originally Posted by GMCTRUCKS

Hey guys might it be a bad ground to the coil or ICM?

Grounding is very important to electronic ignition systems, so it could be that if the engine and system isn't properly grounded, but it usually wont be heat related. It should happen all the time if it was a ground issue.

[chevyrestore]

when I get some time away from work im going to pull off the driver side valve cover this time and check out the travel on the rockers and readjust,

at this point based on your suggestions I may be leaning towards a distributor also if the driver side ends up checking out good.


Also on a side note, should I be running the vacuum advance on the driver side (manifold vacuum) or passenger side (ported vacuum)?

[cdminter59]

Do a search on this website for Distributor Vacuum Advance Control units
Specs and facts for GM Distributors

by Lars Grimsrud
SVE Automotive Restoration
Musclecar, Collector & Exotic Auto Repair & Restoration
Broomfield, CO Rev. B 8-19-02 It may be easier to type this in the search block and go to post #9.
Port or Full time vacuum - Hot Rod Forum : Hotrodders Bulletin It will be the second thread.

[chevyrestore]

From what I have learned and read in the past everyone said to use manifold vacuum since I dont have any emission requirements. I was also told though that with certain misfire problems many people ran with ported vacuum which is why I was asking.

When its hooked up to manifold vacuum it definitely has a deeper more throaty sound because of the lack of advanced timing at idle. Has anyone else on here experienced switching from ported to manifold advance help with misfires under load?

[cdminter59]

What is your timing curve? initial_____ mechanical_____. You want 36-38 total. This only leaves around 14*-16* for Vacuum advance. If your vacuum can is adding more you will have to buy an adjustable one. As for you not getting oil to the #5 rocker what we are saying is the lifter is not pumping oil up thru the push rod. Take the lifter apart to see if you have some trash in it or buy another lifter(same brand) and take the inside guts and install in your lifter body. This way you won't have to go thru a break-in process again. With your vacuum unhooked from your distributor is your idle high enough without using the curb idle screw on your carburetor? If it is okay you can use ported vacuum. If the idle is too low use manifold vacuum to raise the idle.