How can I find out what my cam specs are?

edmonds007 · #1 (**permalink**) 04-08-2009, 04:49 PM

Hi All,

I bought a used SPF with a Roush 392 and my information states that the engine has a proprietary roush cam. The car came with Inglese 48IDA's on it but due to an engine failure the car was rebuilt and assembled with a Performer RPM intake and Holley carb. That was a couple of years ago and I've always wanted to put the Webers back on so I yanked off the intake manifold and am prepping the engine for the Webers. I have essentially no experience with engine building and I really don't know much about the specs of my engine or cam. I've read a lot of posts that discuss lift, duration, etc and I'm almost embarassed to say that this doesn't have much meaning to me. I do know that the car ran strong with immediate throttle response and insane power when the Webers were on it but there was definitely some popping when decelerating and my plugs were BLACK when I checked them. There was a lot of dark smoke from the exhaust pipes, too. This may not really matter anymore since I'm starting somewhat from scratch. So...on to my question. Does it matter that I don't really know much about my cam specs?

Thanks!
Bryan

RedBarchetta · #2 (**permalink**) 04-08-2009, 05:06 PM

From the Roush site for their 392 motor:

http://www.roushyatesparts.com/351_3...07-d392frt.htm

Hydraulic roller camshaft with .563" lift intake and 584" lift exhaust, duration at .050" is 232 degrees intake and 240 degrees exhaust

-Dean

edmonds007 · #3 (**permalink**) 04-08-2009, 05:47 PM

Thank you Dean!

RedBarchetta · #4 (**permalink**) 04-08-2009, 07:07 PM

FWIW, the specs on your cam are nearly identical to what another SPF owner (Terry Brown #930) is running with his Webers. Comp Cam Xtreme Energy Cam XE282HR-12. Same duration with int lift at .565" and exhaust at .574". That cam is ground on 112 degree lobe separation. I would suspect that yours is similar (a higher number promotes better engine vacuum). I've run cams with 110* and my power brakes worked fine.

I'm definitely not the source to help you with tuning, but I've kept a lot of notes on the subject in the event I ever decide to spend five grand on basic carburation.

I'm running a Comp grind with 540 lift, 240* int / 246 exh @ .050 duration (running way more duration than you) and on 110* lobe centers. Just too much cam to tune Webers with.

edmonds007 · #5 (**permalink**) 04-08-2009, 07:43 PM

Hmmm, now I have to wonder what the specs are on my webers. The original owner apparently had Inglese and Roush working together to get everything matched up properly. When my engine blew, the shop that was working on it played around with the tuning screw (can't recall the proper name but the one that is used for final adjustments) before digging deeper and discovering that the cam gear was wasted. We think the cam was never hardened properly and that's why the gear exploded, but that's another conversation. I guess I'll just have to install it and see what happens! Maybe I will look up Terry Brown to see if he has any advice.

bobcowan · #6 (**permalink**) 04-08-2009, 08:36 PM

Camp Cams has some new SBF cams with 114* LSA. More conducive to individual runner intakes.

ack fia · #7 (**permalink**) 04-15-2009, 05:56 AM

Remind me! What is the "rule of thumb" for cams in a sbf with webers? Is it more or less overlap (or is it lobe angle)? What is the rule for lift and duration? I am building a forged 347 that will be 80% track time.

bobcowan · #8 (**permalink**) 04-15-2009, 05:03 PM

Less overlap is good. If you want a "big" cam (more duration), you have to increase the LSA.