Pushrod length measuring and zero lash? What lifter preload?

[Clarkstar]

All that work to come up with what the mfg recommends... 7.400. I guess it's good to check, but I doubt there's enough variance in manufacturing components that someone would have disastrous results by installing a cam and using the "recommended" length push rods... my 2 cents...

[1Camaro2SS]

Originally Posted by Clarkstar

All that work to come up with what the mfg recommends... 7.400. I guess it's good to check, but I doubt there's enough variance in manufacturing components that someone would have disastrous results by installing a cam and using the "recommended" length push rods... my 2 cents...

What length did you come up with?

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[Clarkstar]

Originally Posted by 1Camaro2SS

What length did you come up with?

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I did not measure, bought what tsp recommended...

[sdynak]

Originally Posted by christianchevell

Since I am the old man On here I have kept many old threads this one showing what was the go too Robert Way; and his thread installing his own cam was the one many used installing theirs as he did a big DIY which was nice but he was confused in his own ways during the process. I put this out there what I have learned over the years on here, .070 is the preload for the ls7 which uses a higher preload with a higher rev limit and this is all in my opinion from reading so much over the years.

The lower preload amount he referred too is .060 the ls3 preload average which actually can be noisier and some do go lower to .040 range as the more preload makes more noise in typewriter sound, and different varied lifters such as Johnsons or Morels will have different varied preloads recommended.

I bring this zombie thread back from the dead so some may learn if only it is alive, to get the correct lash you go to zero which for most being that they have a new base circle for the cam being smaller stock pushrods that 7.375 area and 7.4 its I think different ls3 to l99 IMO...... and can vary and most have to add some length for the loss of base circle to be added to the stock pushrod length for the correct geometry ideally.

IMO Robert got lost with not knowing that yes the Threads are .047 thread pitch on the bolt for the rocker but when you tighten the bolt down from zero lash you are tightening on a fulcrum that the rocker is, thus one turn on the bolt/(nut on stud for those with studs and that thread pitch), is .077; as 1.7 rocker ratio x .047 = .077 thus why most tighten in the 2/3 to 3/4 turn area from zero lash to get into " the Range" as .060 the average lash being on the ls3 from people tearing it down to lows of .045 area....

As you can read if you read this thread is that Robert over tightened his preload which would make the engine a little more noisy and well also bottom out the pushrods into the lifters internals as he was way over the preload needed and would of course still run being roller lifters and a strong engine.....

The problem with over tight preload is it grenades the engine eating the roller and cam with to much pressure so it basically trashes the top and it takes time being that its a roller cam.....Pushrods do bend and do cause cups to go into the lifters too far making things really hard on the engine to just stay alive. Just a thought I have had for a long time and seeing this old thread I thought I would share, maybe BO has a opinion on this also he's done more cams than anyone else here...LOL ' he's as addicted to change as I wish I could be.....and used to be with a fleet of old chevys.

ANYWAY IT SOUNDS LIKE TO ME ROBERT WAY HAD THE RIGHT LENGTH OF PUSHRODS BUT OVERTIGHTENED HIS PRELOAD WITH 1.5 TURNS TWICE THE NEEDED TO GET TO A PRELOAD RANGE HE AIMED FOR WHICH WAS HIGHER THAN EVEN THE LS7 AT .070 SO THE PLUNGER ON ALL HISE LIFTERS WAS GOING INTO THE BOTTOM OF HIS LIFTERS AND THUS MAYBE WHY HE DISAPPEARED OVER TIME...... AS 1.5 TURNS = .385+.077= .1155 PRELOAD NOT A HAPPY RANGE.....

JUST THROWING IT OUT THERE STUFF IMO THAT A LS ENGINE WOULD SURVIVE FOR WHILE BEING THAT ITS SO STRONG BUT THEN IT WOULD EAT THE TOP END MAYBE EVEN BREAK A SPRING/ PUSHROD. AND OF COURSE LIFTERS....ANYWAY THATS MY RAMBLE FOR THE DAY FROM THE OLD FART..

Think of it from this angle... The pr side is only moving here not the valve where the 1.7 applies from full motion. Seems factoring the full 1.7 here should not apply? Some of it maybe? It is simply pushing the plunger side. The best way regardless is with a checker from 0 eliminating the ratio and thread variables for a true plunger preload. The only way the thread technique could prove viable is with a dial indicator on the pr side of the rocker and measure the travel while torquing.