429 Cr
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429 Cr
Any ideas on how I can reduce the CR on a 429 thunderjet. I think going with 460 heads will put me bellow a 9:1 and the 72cc heads are around a 11+:1. I'd like to lower it just enough to run safe on 93 octaine. Can I double up on head gaskets or will that cause other problems? Still, that may not even be enough. Don't have much cash to spend and the truck needs to be reliable. Any thoughts are appreciated.
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Joined: Aug 2006
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From: Elma, Wa.
I dont think you need to worry about the CR of your engine, its only 10.5:1 for the Thunderjet 429. I'm running 93 octane in mine with no problems...
As for stacking head gaskests... I wouldnt advise it. Though I have seen people who have done it, they have had more problems than not. If you feel the need to drop compression, you could go with a copper head gasket. A few companies out there do offer different thickness gaskets for this aplication. one company is www.headgasket.com . Give them a call to help find the best set for what you want.
Prost!
Ron
As for stacking head gaskests... I wouldnt advise it. Though I have seen people who have done it, they have had more problems than not. If you feel the need to drop compression, you could go with a copper head gasket. A few companies out there do offer different thickness gaskets for this aplication. one company is www.headgasket.com . Give them a call to help find the best set for what you want.
Prost!
Ron
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Joined: Aug 2006
Posts: 8
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From: Elma, Wa.
While you are at it, you might want to go with a hardened oil pump drive shaft. Moroso makes one, and its cheep insurance. I had a new Ford oem shaft let go on me after only 30 miles... I think it may be the only weak point in these engines.
Prost!
Ron
Prost!
Ron
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Good info guys. Much appreciated. I may even install a summit cam a lifter kit while I'm at, it if can manage it. The engine still runs good with the exception of the oil pressure prob and a ton of blow-by. I can imagine what she'll do with some fresh rings. Hope to have time to start on it this weekend.
