Rocker Clarification is up!!!

[Tom keedle]

Originally Posted by Alan Roehrich

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]

Originally Posted by Tom keedle

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]

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?

[Stocker 2]

Originally Posted by novassdude

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.

[X-TECH MAN]

Originally Posted by novassdude

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?

Thats for the racer to check to make sure this dosent happen. Not the cam company or rocker makers.

[novassdude]

Originally Posted by X-TECH MAN

Thats for the racer to check to make sure this dosent happen. Not the cam company or rocker makers.

I am well aware that it is the racers job to check I was just curios what the odds are that it is going to come up with a little extra lift. With the old set up knowing the ratio was generally a little short I assume that the cam company's add a little lift to compensate at the request of the racer. Not blaming them for any thing,
I was just wanting to know what the odds are you are going to have to change cams when switching to roller rockers that have a true 1.5 ratio.

[X-TECH MAN]

Originally Posted by novassdude

I am well aware that it is the racers job to check I was just curios what the odds are that it is going to come up with a little extra lift. With the old set up knowing the ratio was generally a little short I assume that the cam company's add a little lift to compensate at the request of the racer. Not blaming them for any thing,
I was just wanting to know what the odds are you are going to have to change cams when switching to roller rockers that have a true 1.5 ratio.

Probably a 50/50 chance or better. Id be talking to the cam grinder and find out what was done.

[Grant Eldridge]

We've just been through this upgrade with rockers, pushrod length etc. What we saw was changes in lift at the valve due to the rocker change, but also as we varied the pushrod length and went from break in to full racing valve spring pressure. After sorting out the rest, we had to order a cam with .006" less lobe lift to get back under our allowed lift of .398" on the 325hp 396. You get rid of a lot of deflection going to the new rockers, so if you'd used a cam ground with extra lift originally to get close to the spec, it would be important to check it after installing the roller rockers. Just my 2 cents.......

[X-TECH MAN]

Originally Posted by Grant Eldridge

We've just been through this upgrade with rockers, pushrod length etc. What we saw was changes in lift at the valve due to the rocker change, but also as we varied the pushrod length and went from break in to full racing valve spring pressure. After sorting out the rest, we had to order a cam with .006" less lobe lift to get back under our allowed lift of .398" on the 325hp 396. You get rid of a lot of deflection going to the new rockers, so if you'd used a cam ground with extra lift originally to get close to the spec, it would be important to check it after installing the roller rockers. Just my 2 cents.......

BINGO ! A smart racer right there. Less deflection but more so in more accurate Rocker Ratio. But check what you order. Not all rocker arms are made equal. Some out there are as bad as OEM or worse. Some of the best are the ones you stocker guys are not allowed to use.

[Tom keedle]

Originally Posted by X-TECH MAN

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?