i said they probly did this on OEM lifters seeing as people (like yourself) have bottomed out aftermarket ones....and yes they tested it on a dyno and it (350 tpi vette heads mild cam) was still gaining power with 3 full turns after 0 lash....its in there insider hints book i beleive....The factory set them at 1 full turn, if your using oem lifters 1 turn is the way to go...http://www.walmart.com/catalog/produ...00000000040820

this is the book that i have...everything you need to know about the LT1 motor...i HIGHLY recommend it

 

Come on jonaddis84, I have been waiting for your reply
to the last few posts. Please continue to justify your 1/2
turn theory. Nothing like data to flavor a good discussion.
Please convince me why the data generated by TPIS in
their "Insider Hints" book is bogus and why I am crazy to
run my lash at 1.25 turns.

If you have some proof that 1/2 turn is the setting to make
the most power, please share your data. I want nothing
more that to generate the most HP possible and I'm all
ears.

 

For umpteen years, I have always heard that "looser is faster" for hydraulics and have seen dyno run graphs (can't remember where) that showed it. All you are doing by turning it down more is reducing the lift at the valve. So should everyone be buying <1.5 ratio rockers to add power? Why does no one make any as power adders? Hmmm...

I find it hard to believe that even a stock lifter has 3 turns of adjustability without getting dangerously close to bottoming out.

 

Sounds like a good topic for an experiment. I wish that
unlimited $$$ were available to play around with this.
I would think that the cam mfgs would have done tons
of this type of stuff. Why would the recommendation
from Crane (yesterday) tech support be to set the lash
to 1 full turn? I don't have the answers either but it
would be nice to have some real data to carry on a
decent conversation.

I would set mine back to 1/2 turn before the next dyno
run but I don't want to change two things at the same
time. If anyone is volunteering to pay for the run I would
be glad to make two runs. I would even be happy to eat
some crow for the sake of a few ponies.

 

Probably because that is the normal recommendation. Even the factory manual says 1 turn ± ¼. It's the standard used for quiet operation and reduced maintenance for the most cars. Is this the best performance setting? Apparently, that is up for debate.

The original question was about Comp R's and they are not the same as every other lifter.

 

I never said I had proof of this...All I was saying is that there is a 97% chance if you talk to any experienced engine builder that they would never tell you to preload them any more than 3/4 turn, that that is the absolute most I could ever see someone preloading for performance.

It would only make sense that the looser you can run it, the more performance you will see...we all obviously know a valve even slightly open is a very bad thing (leaking compression out)...so whether you have proof or not of whether you are gaining or losing HP...why even take the risk when it is proven that you can run them at less than 1/2 turn on any oem replacement lifter (not GM)

Not saying you are for sure losing power...but why take the chance?

Likely the reason they are giving you those #'s (Crane)...is because it would be safer to tell you that...since there would be no chance at all of losing a pushrod if it is in there that tight.

 

So what went KABOOM?

 

Somebody's compression was way more than it was supposed to be. Those crappy Speed Pro hypereutectics are only good for 10.5:1...mine was well beyond that. I'm surprised they held up for as long as they did. We didn't pull the head, but the #7 spark plug was flattened...I'm guessing it scattered a piston again. The rest of the rotating assembly seems to be fine...it will still start and run fine other than smoking like a **** (eating coolant from a hole in the head).

New forged goodies going in soon...lower compression too. We'll see how she does after all of that.

 

Damn Jeff I was hoping it wouln't be that bad Oh well on to bigger and better things

 

It's not awful...anything that's broke inside there (basically, the head) can be repaired easily. Jimmy can weld that up in no time. The rods and the pistons blew nuts from day one, so I guess it just wanted to tell me that it wanted good internals. The crank is fine...no strange noises while it's running. I'd bet $20 that all I'll find is a busted piston, just like last time.

After A&M is done with the machining, it should be good as new. My engine should win a gold medal for surviving the most internal part failures.

 

Youre lucky..I only had one and all I was left with reusable was the pushrods!

 

I run my Comp R's at 1/8th turn past zero. That's about what Comp calls for these lifters...and after hanging a valve when at 1/2 turn...I believe them. I run a sick amount of lift for a Hyd setup, and it may have something to do with it....but do NOT treat them as OEM lifters...they ain't!