When are roller rockers really necesary?

I bet this has been covered a million times already but I'll ask again anyway.

At what lift/duration/lbs spring rate is it totally necesary to switch from stock rockers to rollers?

I'm betting there are a few motors running really big cams with good condition(new)stockers with adjustable pushrods out there.

I have rollers with the prerequisite alum/tall valve covers on my current motor but I'm thinking on my next build to go for the stock look. Allthough a painted SP1 probably will not pass for stocko No: . JK

Generally I've been told that it's the lift and higher spring rates that are the culprit here. The rockers don't see as high of stresses from being opened longer as much as the angularity involved with being opened farther.

Now if someone would just make a roller tipped stock replacement(Hi Comp Cams)out of chromoly or uh, Titanium? Yeah theat would be cheaper?:eek2:

:3gears:

 

While were at it anybody know how long adjustable push rods will last

 

I do a bit of error / failure analysis at work (not car related) and I just dont understand the logic of ADDING 16 additional, independant points of possible failure to a system when you really get nothing in return.

If you motor is set up properly and all your valve stem heights are the same or very close, then I personally think the only time an adjustable pushrod should be used is to find out what length pushrod you need for your combo ... and then order the correct length solid rod from TA or elsewhere.

I've seen them break more than once ... seen them come undone ... and I just dont understand why o No:

 

They used to run NASCAR races on stock-type rockers. Of course, they threw 'em away after each race. So, "totally necesary" is a matter of opinion; and includes your expectation for service life.

Absolutely right.

 

I've seen them break more than once ... seen them come undone ... and I just dont understand why o No:[/quote]

I've had 2 failures with adjustables, and everything was dialed in just right
Both times, 1 tip let go....:af:

 

I had very good luck with adjustable pushrods, but they were the solid design (no oil hole) so the tips were probably a bit stronger than the later design.

Devon

 

I appreciate the info and recomendations on the pushrods but I'd still like some solid answers regarding the stock style rockers. Just for general knowledge.

thx

 

Honestly, I would tell you that roller rockers are needed for solid lifter cams, or real big hydraulics. And of course the solid lifter roller cam stuff. You have to have them to set valve lash.

Generally..

Over .550 lift and or valve springs with 320 lbs or more on the nose of the lobe, or with any solid flat tappet or roller valvetrain should have a roller rocker.

Probably 80% of truely streetable BBB builds don't require roller rockers. While they are an excellent durablity item, and make fine tuning adustments possible, I have told more than 1 customer to sell the rollers, and spend the money on head porting..

And I never recommend 1.65 rollers on a hydraulic cam. TA does make a nice 1.55 roller rocker that I use on the bigger hydraulic cam motors. That's the TA cams, 290H and bigger..

JW

 

Thank you Jim, As always an informative and honest answer. Shame you are so far from here. I'd be a pest at your shop if you were closer till my motor was done. :grin:

 

The reason there in my motor is because I didn't do my homework.

I agree, and they come out this season.

Cam is under a 490 lift. How long will they last?
Anybody need a tool to check length?