octane
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Freshman User
Joined: Aug 2004
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From: Saybrook,Ill
octane
I have changed cams from a comp cam 292 mag to a much smaller one.I have read some of the posts talking about cams,compression and pinging.My old cam was measured at .006 40 BTC,80 BBC,72 ABC,32 ATC.Old cam is 560 lift, 292 dur and 244@ .050.The new cam is measured at .050 3 BTC,41 ABC,47 BBC,-3 ATC.New cam lift is 506,315 dur and 224 @ .050.I changed from C8AE-H heads to D2TE heads.Same pistons flat top TRW w/valve relief.I had no trouble with the old cam running on 87 octane.What I'd like to know is if I will have any trouble with fuel with this new combo?The reason I am asking is I still have the engine out of the car and it would be easier to change cams now if I made a radical mistake than to wait and try it out later.
Post Fiend
Joined: Jan 2003
Posts: 8,600
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From: Iowa
There's a few variables we dont have here. What's your compression ratio? You compare seat-to-seat timing to .050" timing, we cant directly compare the cams that way. Also, your new cam is actually bigger than your old cam. It has more duration, but lower lift. So if I had to venture a guess, this new cam will be a higher RPM cam than your old one. If you're looking for something smaller than your old cam, I'd send it back.
Edit: I see your new cam has less .050" duration than your old one, but a lot more advertised duration, along with less lift. This means that this cam will suck at everything. The big advertised duration will make it idle rough and kill low end torque. The low lift and .050" duration will kill your top end power. I'd send it back and look for something different, like the Crane 343941.
Edit: I see your new cam has less .050" duration than your old one, but a lot more advertised duration, along with less lift. This means that this cam will suck at everything. The big advertised duration will make it idle rough and kill low end torque. The low lift and .050" duration will kill your top end power. I'd send it back and look for something different, like the Crane 343941.
Last edited by rusty70f100; May 19, 2005 at 09:56 AM.
Thread Starter
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Freshman User
Joined: Aug 2004
Posts: 44
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From: Saybrook,Ill
When this engine was first built the builder said it would come in at about 10 to 1 compression with the C8AE-H heads and I noticed that the D2 heads were the same cc so I figured the compression would be close to the same.I understand that overlap has a lot to do with the compression.I just wish that comp cams would have listed their figures the sqame as most other cam builders at .050.
