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502 valve clearence

G

ged

Contributing Member
"hi all, i,m rebuilding my 502

"hi all, i,m rebuilding my 502 gen iv motor,on setting the valve clearences followed the manual,set engine to #1 tdc set the valves it said by taking up all back lash on the pushrod then going 3/4 of a turn more. then # 6 tdc and same again. turned the motor over a couple of times,set it to # 1 tdc again and can still turn the pushrods, is this normal or do i go through the job again until they won,t turn,
thanks Ged"
 
"That happened to me,it took b

"That happened to me,it took best part of an hour and we went around to # 1 several times till the push rods would not turn anymore."
 
"You have to realize that the

"You have to realize that the inner lifter plunger rides on oil within the outer lifter body. When running, just enough oil is pumped into the lifter to create zero lash at the valve stem.

Not running, without oil supply, the force on the pushrod is minimal, as the oil within the lifter "leaks down". So being able to turn the pushrod at rest is not unusual IMO.

In the dynamic setting in the other thread Bondo referenced, the valves are tightened at idle to just remove any clatter, and cause a minor hesitation. This is the point where the valve lash is just eliminated. The extra 3/4 turn compresses the inner lifter plunger down a little so it can do its job of maintaining zero lash through varying engine temps, by varying its position within the lifter body, riding on oil.

The way you first set it sounds right to me. You will know if they need further setting when you start it up. There should be no clatter.

Rod"
 
Personally I am not very comfo

Personally I am not very comfortable with "presetting" lifters that way.

I like to rotate the engine over and get each pushrod to lifter so there is some friction and leave them to complete the assembly of the engine with the exception of the valve covers.

Once I am ready to fire it up I do that and do a quick carb adjustment and timing or if efi do what is reccomended.

Once the engine is running and idle is ~ 800 rpms I then adjust each rocker arm individually. I tighten each one at a time till the clacking just goes away and tighten 1/2 turn more. That is it

I like to leave them at 1/2 turn vs 3/4 to 1 full turn as a personal preference from experience. If I were running a high rpm motor I would probably preload them to almost 1 full turn.

I have had much success with this method and there is virtually never any issues. You cant make a mistake adjusting while running.

Just my opinion.
 
"thank,s everyone. have gone w

"thank,s everyone. have gone with the manual on this one. took out free play and 3/4 turn more. which just pre-loads the lifter. thanks. Ged keep up the good work.!!!!"
 
Kghost...why would you preload

Kghost...why would you preload them more with a high performance engine? I was thinking less to keep them from pumping up if valve float occurs???
 
"Not High performance, High re

"Not High performance, High revving.

I feel when going beyond 6000 rpms the amount of preload become more critical. If the preload is to little the push rod is more likely to bounce around between the lifter and rocker arm.

When below the norm 5500 red line a little less preload works well and puts a bit less strain on the lifter.

Just my reasoning......."
 
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