I decided to get roller rockers, but am confused about ratio, someone please explain, I have GT 40 P Heads with a 3 angle valve job, I will at the same time be putting in a Trickflow TFS51402000 cam, someone please let me know what ratio to pick and why.

 

1.7 ratio get a big cam more lift!

 

Stock size is a 1.6. Cobras run 1.7 stock, and I have a 1.7 on mine. It will give you about .030 of lift more by going with the 1.7. I just moves the folcrum down the rocker so it opens the valve more.

 

be sure to find out how much lift you can have without any problems too

 

How can you find out?

 

Which cam is that? ...the stage 1? If so, it's similar to the E cam which I'll be running w/ 1.72's for about .535 lift (from .498 on 1.6's). On the stage 1, I think the duration is different than the E cam and the lift on the exhaust side is .510.

You'll probably need to get a valve spring upgrade kit. I got a Crane kit from summit for $130. You need to make sure your cam is duration below 230 on (unless your pistons have valve reliefs or are flycut) and try to keep your lift below .550--that should keep you from breaking anything.

 

im going to tell you this from experience. P heads dont like over .500 lift!!!!!!!! they dont flow well unless heavily ported above 5k with more then .500 lift so you adding that extra lift is going to hurt you more then you think it will help. with P heads the stage 1 cam is all you need. anything more then that will make your car slower. you can listen to me and have a solid running car or not listen to me and post in a few weeks asking why your car isnt performing the way you think it should