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Tech Area => General Buick Tech => Topic started by: larrym on February 12 2015, 02:08:07 PM

Title: Red Neck wrenching lifter preload
Post by: larrym on February 12 2015, 02:08:07 PM: So I had some noise in my new motor that is covered in another thread.....
Before I pulled it I wanted to check my lifter preload, I have an adjustable push rod set it to zero lash brought it to my machinist with the pushrod I was using he measured and said it looks like .045 to me that's pretty much perfect from my understanding.

I wanted to double check a few more I had read on the other board were someone was trying to figure out their preload without an adjustable pushrod, figured I would try it.

Here is what I did install 1 pushrod start all the bolts holding the rocker shaft get them finger tight with a little movement on the pushrod, slowly tighten the nut closest to the pushrod with your fingers until you get zerolash next tighten the nut fully and note how many turns, in my case 3/4 of a turn.
Now for the math the bolt is 18 threads per inch so 1 full turn 1/18=.0555555 next 3/4 of that so .055555*.75= .04166

Its not exact but it will give an idea of where you are at I was lucky to have the adjustable pushrod but I did not have the the tools to measure it.
Title: Re: Red Neck wrenching lifter preload
Post by: Just a Six? on February 12 2015, 02:48:22 PM: Sounds close enuf to me since the pre load can vary an easy 20+ thousand from build to build. Wasn't stock close to 45ish yet many aim for 30ish depending on the parts used.
Title: Red Neck wrenching lifter preload
Post by: Steve Wood on February 12 2015, 03:21:40 PM: 0.025 is what I would aim for on built engine for maximum rpm without pump up but some of the stock factory engines were probably over 0.050.
Title: Red Neck wrenching lifter preload
Post by: Steve Wood on February 12 2015, 03:23:25 PM: duplicate
Title: Re: Red Neck wrenching lifter preload
Post by: earlbrown on February 13 2015, 03:55:09 AM: Quote from: Steve Wood on February 12 2015, 03:23:25 PM

duplicate

Attention whore.
Title: Re: Red Neck wrenching lifter preload
Post by: Steve Wood on February 13 2015, 09:58:18 AM: I just wanta be in one of your movies
Title: Re: Red Neck wrenching lifter preload
Post by: larrym on February 13 2015, 03:38:30 PM: hmmm The spec I found for the Morels I use was no less than .030 no more than .050 but the interweb has lead me astray before......
Title: Re: Red Neck wrenching lifter preload
Post by: Steve Wood on February 13 2015, 05:25:16 PM: I was thinking stock rockers...soun ds like you are in the range for that specific lifter
Title: Re: Red Neck wrenching lifter preload
Post by: ULYCYC on February 15 2015, 10:35:03 AM: Quote from: larrym on February 13 2015, 03:38:30 PM
hmmm The spec I found for the Morels I use was no less than .030 no more than .050 but the interweb has lead me astray before......

That spec is to cover all applications. For iron block and iron heads keep it close to .030. If you beat the piss out of it .025-.030 would work best.