Chet1185

I have a tapping noise once warmed up. It will tap then go away and then just keep doing that. I have checked the rocker adjustment multiple times with no success. I bought a set of CC replacement lifters and some 7.2 thunder racing pushrods.

I am going to be installing longtubes so I thought this would be the perfect time to do the lifters/rods also. I just want to know the best way to go about it. Should it be TDC, or can i just tear it apart and install then do the "spin" method for setting the lash? Then adjust while its running? Thanks for any input.

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slick1hunting

I prefer doing one cylinder at a time method as I'm less apt to make a mistake. I dont spin the pushrod as its not as accurate as lifting up and down until the slack is just taken up. I can actually feel zero lash with the nut on my roller rockers and just go with it for the most part. Sometimes I will see if I get the same spot a couple times by verifying nut is in same location at zero lash. Its also helpful to mark the nut somehow to make setting the preload easier. Ive never adjusted with car running and feel I would struggle with that. If your going to have it open might be a good idea to look at the "valvetrain geometry" as perhaps your pushrods should be different length.

Chet1185

I have no idea how to check to see if the length Is right. The motor its completely stock inside except it's bored.030over.

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Chet1185

Anyone else mind sharing how they do the install? Any tips or tricks? Just want to gather as much info as possible.

I did build this motor but it was easier in my opinion to do this as i was building it.

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pizzi-man

This method is straight from GM
With the engine in the number 1 firing position, the following valves may be adjusted:

Exhaust - 1,3,4,8

Intake - 1,2,5,7
Crank the engine one turn until the damper mark and the "0" are again in alignment. This is the number 6 firing position. Adjust the following valves:

Exhaust - 2,5,6,7

Intake - 3,4,6,8

Chimera96

your intake manifold will need to come off to replace lifters so I would leave it off while adjusting the lash as you can see the PR on top of the lifter easily. you want to find zero lash which is when there is no more up/down movement of PR. using your fingers slowly tighten poly lock of RR until there is no more up/down movement. On stock motors you can then lash 1/2 to 1 1/2 turns past zero but most, including me, go 1/4-1/2 turn past zero lash but on motors with aftermarket cam.

I use the "do 1/2 the valves then rotate engine 360 and do the other half method". some like doing each valve by turning the motor for each one and others like doing it with motor running.

on PR aka valve train geometry check, use a sharpie type marking pen and cover the tip of a valve you want and put a RR on with zero lash. rotate engine by hand 2 turns and remove RR. witness mark should be centered BUT more important the sweep (width) wants to be as narrow as possible so if the pattern is slightly off center (more towards exhaust) but narrower, that is better. To far off center is not good and can side load the valve causing pre-mature valve guide wear. If the block and heads have not been decked most likely stock 7.200" length PR. "Generally" on motors with decked block & heads and high lift cams you need a slightly shorter PR (7.150 or 7.100). You need a PR check tool to confirm

pizzi-man

Bone stock motor uses bone stock push rods. You can go into any parts store and tell them what motor you have and they should be able to get you what you need. I think they are 7.2 while the older or latter models is 7.9.

Chet1185

How do I find tdc #1? I am no good at this stuff. Valvetrain intimidates me. Lol

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pizzi-man

with both valves closed on the #1 cylinder and the pointer in the center of the balancer facing up. This is on the compression stroke. You can turn the motor or bump the motor with #1 plug removed and stick your finger over the hole. When you feel pressure and a puff of air the piston will be coming up on the compression stroke.

Chimera96

op

go buy a Haynes service book for your car. It will have step by step instructions.

what it, and other, service books advise on finding "zero" lash, IMHO, is not right. Typically they say "spin PR with fingers as you tighten RR nut until you feel resistance"....you are way past zero lash doing it that way. You really want to just tighten the nut until there is no "up/down" movement. Then lash 1/2 turn past that.

Valve train work is both knowledge and experience based but if you are mechanically inclined you should be able to do it correctly. I had a qualified builder show me how to do it years ago and now "get it" and have no problems doing it myself.

pizza note on #1 is right. If your balancer hub has never been off the car, or if it was, as long as it was put back on right than the pointer will be pointed at 12 o'clock. It is also at 12 o'clock with #6 at TDC so confirm both valves are closed on #1 if starting on that cyl.

Once you do the associated 1/2 of the valves with #1 at TDC on compression stroke you rotate engine by hand 1 turn and do the other 1/2. At that time both #6 valves will be closed.

Chet1185

I have the manual. That's what I used to set them when i was building the motor. Ill try and do it the same way.

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slick1hunting

A rebuild isnt really a stock motor and several things could change from the stock 7.2 pushrods and since op stated he is having issues ruling out pushrod length while in there is a good idea because its simple to do. I still think doing the adjustments one at a time is easier and less chances of a mistake given motor is still in car but thats me

pizzi-man

The OP already has new 7.2 push rods and new lifters and also has the Haynes manual. If the OP wants to do one cylinder at a time then all he hes to do is turn the crank after doing #1 cylinder 1/4 turn then do #8, 1/4 turn on crank#4 and so on going by the firing order which is 1,8,4,3,6,5,7,2 each 1/4 turn on the crank brings the next cylinder in the firing order to top dead center on the compression stroke.

slick1hunting

Just because he has new 7.2 pushrods doesnt mean they are the proper length. His motor is rebuilt. Let me put it this way say the block was in tough shape so they removed a lot of material when decking it. Then to compound that the head was shaved to get flat, then say the head gasket was thinner, then if I'm not mistaken the "new" lifters may not have the same seat height. Any one or a combo of all could effect proper pushrod length and since checking it only involves a marker and a couple spins of motor I would check it.

As for the way you posted to do one at a time thats not how I do mine. Ill post shoebox link. I do method 3

slick1hunting

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