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IT's Friday!!!! OKay folks I have another question...I was thinking about changing my 1.7 ratio Summit stamped steel rockers for 1.8 Roller Rockers but haven't decided yet...My 396 has Edelbrock aluminum heads and the pistons have 20cc domes so I'm not worried about valve springs or valve to piston clearance...My cam lift would change from .540 to .572

I have read in Carcraft where they dyno tested a csb engine with stamped steel rockers, then 1.5 Rollers and 1.6 rollers...The hp gained with the 1.5 Rollers over the stamped steel was about 15 hp if I remember right...Then they tested the 1.6 Rollers and gained another 10 hp...

I can change the rockers out in about 30 minutes and it would only cost around $300.00...If I do decide to do this I was going to get the Scorpion Endurance series Roller Rockers...They fit under the factory valve covers with no mods...

Any opinions or advise would be greatly appreciated...

Thanks

Mike

I'll jump in and try to give some info on this, but I have little experience with big blocks without shaft rockers.
Here's my general experience with increased rocker ratios however.
The first issue I see is I would be concerned about valve to piston clearance personally, especially with a dome piston. Alsi it has more to do with duration and all aspects of your cam than just lift, so thats something to seriously consider.
The second thing is if you know the cam and manufacturer, give them a call and ask about an increased ratio, some lobe profiles don't like more ratio and you will kill springs etc. And then there are springs, if you don't know the spring spec you will want to REALLY watch for coil bind, roll the motor over assembled and see how close the valves are to bind right now.
Also, big chevy is not the best valve train geometry wise, so you really need to pay close attention to any change in that, or again you can kill parts.

The main issue I have with changing ratio is it seems like you can get a big increase in power for relatively cheap, and you may very well be able to. But magazines are notorious for taking a best case scenario and testing it, to get results. Bottom line if you are too small cam wise you will see an increase, 15 horse? I'd be surprised but maybe. The main issue is what seems like an easy swap can be much more involved, and with a cam that is a bit larger already, you are kind of rolling the dice.

Not to rain on you parade either, it may be a easy swap and you'll net some power, but it just rarely turns out that way. Good luck with your decision though!

Sean,
Thanks for your advise...I decided not to change the Rockers after all...Like you said to many variables to consider...It took me a long time and a lot of money to find this period correct 396 so I'm not going to chance it...

Mike

Many factors apply here..but one of the first things to mind..what part of the valvetrain will have to work harder to compensate for the ratio increase.To maintain a correct rocker sweep,the higher ratio rocker will move the pushrod cup closer to the rocker stud.Imagine just how much load is now transferred back down the pushrod and back to lifter/lobe interface.
Mike..its totally doable and safe with some effort and parts,but can not disagree with you not wanting to chance a failure with your period correct 396.
Sean steered you in the right direction.The minimal power gain comes at high cost if the geometry and clearances are not ideal.