OK, so we just put the motor together (again!) for my Dad's '73 Camaro (in sig). The motor took on water and self-destructed. Anyways.....

.....the motor is a 355, ~11:1 compression, and the new camshaft we put in is the Comp Cams XE284H, with .507"/.510" lift, 240/246 duration (@ .050"). We had a set of roller rockers that we got off an old set of heads (cracked heads, but they had RR's and good valves) but they're a mixed set, 1.5 & 1.6 rockers.

We've currently put the 1.6's on the intake, 1.5's on the exhaust, thus making the lift .541"/.510". This was suggested to us by my Dad's friend who is an engine builder. He said that by giving the intake more lift, we'll get more low-end torque from the engine. However, looking at most cams that Comp builds, a lot of them have split #'s, where the exhaust lift is higher than the intake lift, and in some cases by as much as ~.020". SO, here's my question:

Have we done the right thing by putting more lift on the intake, and will this truly create more torque down low? ('cause it does feel better than with the old cam we had) or would switching the 1.5's & 1.6's be better, making the lift .507"/.544"??

My thoughts are that the motor would make more top-end power by putting the 1.6's on the exhaust, but we'd lose the torque down low, and with this cam, there really isn't a lot of power down low already?

OR, should we just bite the bullet and buy a full set of 1.6's and be done with?

Sorry for making such a long post, but I'd really like to hear your guys' opinions/experience with this..............thanks .

 

Swaping different ratio's has been done for years.It is a way to try to get the last ounce of power.Many different combo's have been tried--Different on 4 corner intakes,to make up for runner length,different I&E throught the engine,ect..It's just a way to see if the engine can be improved.It generally takes a lot of dyno time to get it right,or a lot of swaping from week to week to check the results.1.7I and 1.5E is common on the corners,with 1.6I&1.5E everywhere else.If you have the PTV clearance the combo's are endless and take a lot of time to prefect on YOUR engine.

 

Really?! Wow, that's a lot of mixing and matching isn't it?!

So what you're saying is that there is no single "rule of thumb" when it comes to using a combination of ratios?

I guess we're just going to have to see how the car works at the track then. 13.66 @ 103 was the car's best time last year, although that was spinning the whole way through 1st gear, feathering the throttle, and fish-tailing side-to-side. I honestly believe that it was capable of much quicker (if we had slicks, which we do now), but if we can hit a 12.something this year, I think we'll be doing OK.

 

You just have to see what works best on YOUR set up.It might improve and it might not.A lot of work though.