I read the recent Hot Rod article about cams and am not sure about my cylinder pressure. Before I first started my car, we got a pressure of 240ish psi on a compression test. The impression I got from that article is that anything over 200psi is not good for pump gas.

My cam specs are 216/216 @.050 with .454/.454 lift. Lobe seperation is 110*. Advertised duration is 272

According to the GM book, my springs max lift is .480. I was almost considering getting a different cam. The Crane Energizer 278 looks pretty good but I don't know about the lift.

Its specs are 222/222 @.050 with .467/.467 max lift. Lobe seperation is also 110*. Advertised duration is 278

If I swapped the cam/lifters with the bigger one, would it be better for my engine (ie lower pressure)? Also, would I see a power increase? a decrease perhaps? Is .467 too close to the max .480? I just don't know. I thought it would be nice to get other opinions. Thanks guys

oh yeah, it starts easy. i can start it reaching in the window

------------------
Andy
aim: Andyman350
1970 Camaro - Its running and is tons of fun
pics of me and stuff

[This message has been edited by 70 Cam Guy (edited August 25, 2002).]

 

what's your compression ratio?
if it's not pinging right now though, why change anything?

 

I'm not real sure what the ratio is. The info I've found about my pistons say 9.7:1 with 64cc heads. I have 58cc chambers. They also decked the block and I used normal head gaskets. I am guessing compression is in the 10.5-6:1 but aren't sure

I know this is gonna sound silly but what exactly does pinging/detonation sound like. My friend said its obvious, like someone hitting metal with a hammer thats really loud. I haven't heard anything like that and it sounds like a v8 revving when I'm on it

[This message has been edited by 70 Cam Guy (edited August 26, 2002).]

 

With the longer duration and same LSA you should lose a little cylinder pressure at low RPM, so the new cam will probably work better for you. You'll also pick up some power in the mid-range, although the car will idle slightly rougher.

With that much cylinder pressure I would expect it to probably have some detonation problems on pump gas at low RPM under load.

-Dave C. '97 Z28

 

You would need to make a MUCH bigger change in cams than that to bleed off 40 PSI of cranking pressure (if that's your goal). It's not like a few degrees makes much difference. I'd recommend getting a cam with about 230-235* of duration @ .050, same LSA if you want to make any kind of real dent in cranking compression. Otherside, stay put with the current cam and save up for heads with the chamber size you really need.