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-   -   Rocker Clarification is up!!! (https://classracer.com/classforum/showthread.php?t=38396)

Tom keedle 01-22-2012 11:14 AM
Re: Rocker Clarification is up!!!
 
Quote:
Originally Posted by Alan Roehrich (Post 305116)
Unless the rule has changed, a 1.6:1 rocker arm on an engine that came with a 1.5:1 rocker arm is illegal in Stock Eliminator.
what about vice-versa?

X-TECH MAN 01-22-2012 11:16 AM
Re: Rocker Clarification is up!!!
 
Quote:
Originally Posted by Alan Roehrich (Post 305116)
Unless the rule has changed, a 1.6:1 rocker arm on an engine that came with a 1.5:1 rocker arm is illegal in Stock Eliminator.
Correct-A-Mondo............Alan is 1000% correct......brush up on your stocker racing history. Remember the Crane stamped steel rocker that came in 1.6 for the small block chevys. Several big name stocker racers were DQ'ed many years ago by NHRA for using these even though the lift checked correct at the retainer. It changes the rate of lift and produces more flow as the valve rises off the seat. Its DUMB to even think you could use rocker ratios greater than what the engine spec. book calls for. Stop trying to reinvent the wheel.

X-TECH MAN 01-22-2012 11:22 AM
Re: Rocker Clarification is up!!!
 
Quote:
Originally Posted by Tom keedle (Post 305161)
what about vice-versa?
Less would gain you nothing unless you had some major piston to valve clearence or geometry problems with some odd ball engine. The OEM stock steel stamped rockers are way less to begin with.

novassdude 01-22-2012 11:38 AM
Re: Rocker Clarification is up!!!
 
If the stock stamped rockers were less and all the cam makers know this. What are the odds that just switching to a aftermarket roller rocker will bump the lift at the retainer over the allowed limit?

Tom keedle 01-22-2012 11:38 AM
Re: Rocker Clarification is up!!!
 
Quote:
Originally Posted by X-TECH MAN (Post 305164)
Less would gain you nothing unless you had some major piston to valve clearence or geometry problems with some odd ball engine. The OEM stock steel stamped rockers are way less to begin with.
exactly my issue....
and while we're at it, is it legal to run less lift than spec?

X-TECH MAN 01-22-2012 11:41 AM
Re: Rocker Clarification is up!!!
 
Quote:
Originally Posted by Tom keedle (Post 305170)
exactly my issue....
and while we're at it, is it legal to run less lift than spec?
Yes.....some do to gain piston to valve clearence and use more duration. Duration and overlap is more important than valve lift. Maybe not so much with the bogus aftermarket pistons of today which give you more piston to valve clearence than the OEM unit.

Rick Leininger Jr. 01-22-2012 11:48 AM
Re: Rocker Clarification is up!!!
 
[QUOTE=X-TECH MAN;305163 Remember the Crane stamped steel rocker that came in 1.6 for the small block chevys. Several big name stocker racers were DQ'ed many years ago by NHRA for using these even though the lift checked correct at the retainer.[/QUOTE]

How does NHRA check rocker ratio at teardown?

69Cobra 01-22-2012 12:05 PM
Re: Rocker Clarification is up!!!
 
I don't know how NHRA does it but I would think the easiest and most accurate way would be cam lift divided by valve lift.

Stocker 2 01-22-2012 12:12 PM
Re: Rocker Clarification is up!!!
 
Quote:
Originally Posted by novassdude (Post 305169)
If the stock stamped rockers were less and all the cam makers know this. What are the odds that just switching to a aftermarket roller rocker will bump the lift at the retainer over the allowed limit?
That's right! Anyone making the switch to roller rockers will need a new cam ground. Sounds like the cam manufacturers were all for allowing aftermarker roller rockers.

Alan Roehrich 01-22-2012 12:17 PM
Re: Rocker Clarification is up!!!
 
Quote:
Originally Posted by ss wannabee (Post 305120)
Don't see why ratio would matter as long as valve lift spec wasn't exceeded...Again, the spring pressure deal "opened" up this can of worms...

Would think though...that MOST stocker cam lobe profiles were created with the STOCK rocker arm ratio in mind....notice that I said MOST...but not ALL...

It's called "area under the curve". Making the rocker move the valve faster than the lobe can with the stock rocker ratio gives you more area under the lift curve.


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