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Low compression cam question

Posted By: gch

Low compression cam question - 05/01/16 03:38 AM

I have a stock smogger 440 that runs well and has good even compression numbers.I may play with it a little and swap some closed chamber 915 heads I have on it and of course a cam as well.
What would make a better running motor in a heavy c body with 3.21 gears and an 11" converter?

A comp 260 High Energy ground on a 113 lobe separation(have one here already) or some thing like a Hughes Whiplash design?

Which would you use and why?
Posted By: RapidRobert

Re: Low compression cam question - 05/01/16 05:11 AM

Quote:
A comp 260 High Energy ground on a 113 lobe separation(have one here already) or some thing like a Hughes Whiplash design?
Which would you use and why?
(1) this one (2) you have it & its mild I believe. after installation I would max out your dist subsystems in order to get the most out of it
Posted By: DARTH V8Я

Re: Low compression cam question - 05/01/16 05:58 AM

Ran a 509 cam on a 8.5:1 440 once, it wanted a lot of timing.. something around 40*.
Posted By: gregsdart

Re: Low compression cam question - 05/01/16 02:21 PM

A cam cut for your situation might be the best option hear. LSA requirements change with compression ratio and intake valve size to cubic inch. Basically the lower the compression and the smaller the intake valve per cube, the tighter you want the LSA. A 383 with 9.5 compression is going to want a wider lsa than a 440 with 7.8 compression, yet the catalogs all list the same cam for both.
David Vizzards book on how to build hp has a chart that predicts your combo would want a very narrow LSA due to low compression and 26 cubes per inch of intake valve. Total duration would be less than a wide LSA cam, and low compression needs to keep the exhaust valve closed longer to use the available cylinder pressure. Not having had a cam custom cut for a deal like yours, I can't say for sure how well it works, but trust his experience. I would be very tempted to get a 260h cam custom cut on as narrow as 104, and use a converter out of a 340 or 383 car for best results. If it works like he says, it ought to have a touch of thump to it yet hit hard at low rpm.
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