Cam selection help please

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I ran some numbers on the United Engine site and got 8.2:1. So, he's probably cammed about right.
 
moper said:
A couple things here - That 268 is an excellent cam for a street 383. I run them too and they are hard to beat.
I dont think a bigger cam will get you more power than that xe268. I run them with 9.8:1 in 383s and they make past 400hp. You may want to look into heads with smaller chambers to get you more compression rather than cam. Cam without compression is more detrimental than helpful when compared to compression without cam. I really would advise against this until you have a better understanding of what you have, and can manage the weak points first.
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I posted in one of his earlier threads that i thought his original combo was pretty good as is. I also said that to really step up alot he would have to go into the engine and probably step up the converter. I think we're pretty much thinking the same.

I understand his wanting to step up as his previous car was a 690hp brand "C". Wonder if a cranking compression test would confirm if a cam change was warrented with the current long block. Say 160 lbs. or higher maybe and less would be a no go. Just thinking aloud.
 
Sage advice,from all three of you. Hard to make any torque with a short stroke/no comp.Was associated with a similar build,but heavier car.Gears (3.23 to 3.91) netted the biggest change.(7/10ths).
 
Now....if you can get comp in the 9:1 range, then that cam I suggested might be worth it......but as you stand now, I think you're about right. Is there something maybe you left out that would put you at a true 9:1?
 
Here is what I know about this motor. Previous owner states 9.0-1. I know factory 452 heads were approx. 88 cc chamber volume. These heads were milled 0.060" which from what I have read puts chamber volume now at around 74-75cc. Pistons are stock and have no valve reliefs. Steel shim head gaskets were used, not "thick" gaskets. Pistons are in the hole .090". I've read info in several articles regarding similar builds with same milled heads and stock pistons, and they all claim around 9.0-1 compression, but all I can go by are what I've read and what you guys are telling me on here, since I didn't build the motor myself. I do run 4.10 gears and currently have 2400 Stall, which I fully expect to and can easily replace if I have to. Also I've found several companies that make a single spring that will match the Comp XE 275 HL, so I would not have to machine the guides. Hope this helps. And again, this is all in a '74 Dart, no rear seat, battery in trunk.
 
Using all the info you just provided, I got 8.867 on the United Engine calculator. But I also used .020 for a compressed thickness. I THINK those steel shims go a little thinner than that, but I am not sure. That would probably put it right on top of 9:1. If it's got at least the 8.8, I am still thinkin the xtreme high lift will help.....you said you wanted a little more rumble, and it will provide that. It will also produce some more power......provided the compression is there.
 
I ran my motor specs thru a few engine compression calculators too and with the steel shims at .020", 75-76 cc chambers with milled heads 0.60", flat tops .090 in the hole, stock bore and stroke I get 8.7-8.8-1. Will .2 of compression be a deal breaker with the 275 XE HL cam?
 
That's cool. But remember, without the heads off, you're guessin. I'd still think you'd be ok though.
 
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