I am currently rebuilding my 305tpi and am building it for low end torque with out requiring a tune to my brain box. I am putting a 95 LT1 stock camshaft (203/208@.450/.460 116LSA) in to give it that edge but those specs are for a 1.5RR and I know that in order to increase flow I wanna upgrade to 1.6RR Rockers so Im looking into them however I have stock rebuilt heads and know that they can only handle around .480" of lift right?

so If I install the 1.6RR rocker arms it takes the cam to .480/.491 and I also heard it might require a tune afterwards so would it still be safe to install 1.6RR rocker arms? Or should I just buy 1.5s? (im replacing them no matter what cuz im getting rollers and have mechanical now) I mean I can handle a tune I just need to be sure I know about it first =P but I cant handle buying new heads =/

Thanks for your help =P

 

Stick with the 1.5s

You're near the limit already and there is very limited power to be gained from that upgrade alone. Your cam is already hotter than stock and that will make a bigger difference than the rocker ratio ever will.

You mention that the heads are "stock." Does that mean stock springs as well? If so, an upgrade to better springs would certainly be further up the list than higher ratio rockers. Nothing fancy for a stock LT1 cam (a set of drop-in Comp 981 springs will do just fine with a mild factory roller), it's just that the factory springs were barely adequate for the stock cams of their day (that had less lift) and don't do a very good job of controlling the valves over about 5000-5500 RPMs. Add even a slightly more aggressive cam to the mix and the situation only gets worse.

 

Thanks for the tip but I thought of that already replaced the valve springs =P I just didnt know if the 1.6RR was worth it...

Thanks for your help =P

but you say im near the limit does that mean it could cause a problem? because for the same price as the 1.5s even a small increase would be nice but if its dangerous i dont wanna risk it...

what risks would i be running? sorry for questioning it I just found a good deal but I dont wanna cause problems

 

i too am curious im looking at a set of pro com 1.6 full roller rockers and the big question i have is 1.5 or 1.6? stock l98 but i wanna throw i zz9 cam in it before i ship in late july

 

On most stock head the retainers will hit the guides/guide seals at about .470" lift, give or take. You don't want to be flirting with that. Could result in bent/broken valvetrain parts.

Watson- you have to be very careful using 1.6 rockers with the ZZ4 cam. Even with stock 1.5s it's already got .525" lift on the exhaust side. That's already way too much for most factory heads.

 

sorry man not trying to steal your thread but i had alot of the same questions that you had so i thought i'd jump on hope thats alright but so for right now i should just stick with full roller 1.5's? lets say i dont get a zz9 cam this summer and just wanna keep what i have till i do a total rebuild on the motor. with stock heads with stock cam 1.5 or 1.6?

 

Stock heads, stock cam you can usually go with 1.6s for a small bump in power. Just watch the lift. Even the stock LT1 cam, above, is on the edge of what a stock 80s vintage heads can take without modification. Earlier cams, like a stock TPI cam, it should be no problem.

 

Thanks for the help =D
but now my build just changed cuz I was talked into a 350 (shortblock only $150 with forged pistons H rods and new crank) and throw my 305 heads on it for a higher compression so my new question is since its still the 305 heads i cant go any bigger in lift i am guessing but what about duration? would i get any more power outta the 350 with a longer duration? I heard no more than 240 duration on the 350 will be fine for my brainbox but I am goin for low end torque and was wondering what the best cam specs would be? as far as duration, lift, and lsa

Thanks =D