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Discussion Starter · #1 ·
Hello, everybody.

I have a few questions regarding a 496 I've built for boost. I've changed my mind about the boost application, and until I decide, I'm curious how the motor will run with a blower cam and pistons gapped for boost until the supercharger is installed. I'd rather not tear apart the engine to swap out pistons/rings/cam down the road when I slap on the blower.

It's a freshly machined 496 forged internals and stock rebuilt 781 heads. I have Malhle pistons (#929869510) and I gapped the top at .026 and second at .028. These pistons and Eagle stroker kit yield about 8.5:1 compression.

Will I have any issues running these pistons with these ring gaps until boosted? Will I have excessive blow-by? Will the engine be a complete dog at 8.5:1 comp? I have a turbo 400 and will be going with a 2200 stall converter, 3.55 gears, and a Gear Vendors overdrive.

Thanks.
 

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Boldly procrastrinating
66 El Camino 57 Chevy pickup 2004 Tahoe
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29,262 Posts
What Bill said. just do it.
 

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13,074 Posts
Pyro,
I was mainly replying to the blowby part of your question. Obviously the engine is not going to be that great at 8.5 to 1 compression with the wrong cam but with 496 cu in you might not notice it that much :)
 

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11,789 Posts
Its going to be a slug, but rebuilder rings have bigger gaps then that and run fine.
 
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78 Posts
Send it. Those ring gaps arent that big. Also, Ive seen machine shops accidentally take rings out to .030-.034 shooting for the gap you have and no one ever knows.
 

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4,659 Posts
Blower cam?

What is a blower cam? There ought to be lift and duration specs, and I'd bet they're really quite tame.
 

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1969 El Camino SS396
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915 Posts
You shouldn't have any problem. I ran my car for several years with a "blower cam". I ran it with 14:1 compression and a small shot of nitrous. The rings were gapped for nitrous. Nitrous and blower cams are very similar. When I finally went to the blower I changed the rotating assembly because the crank needed a BBC snout and double keyways to drive the blower. Plus the compression was reduced to 10:1.
 

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2,299 Posts
Hello, everybody.

I have a few questions regarding a 496 I've built for boost. I've changed my mind about the boost application, and until I decide, I'm curious how the motor will run with a blower cam and pistons gapped for boost until the supercharger is installed. I'd rather not tear apart the engine to swap out pistons/rings/cam down the road when I slap on the blower.

It's a freshly machined 496 forged internals and stock rebuilt 781 heads. I have Malhle pistons (#929869510) and I gapped the top at .026 and second at .028. These pistons and Eagle stroker kit yield about 8.5:1 compression.

Will I have any issues running these pistons with these ring gaps until boosted? Will I have excessive blow-by? Will the engine be a complete dog at 8.5:1 comp? I have a turbo 400 and will be going with a 2200 stall converter, 3.55 gears, and a Gear Vendors overdrive.

Thanks.
8:1 being a dog?, better tell that to my BBC that run some great numbers, but the cam you have for a boosted application could make the power in the higher RPM range not what you want with a low compression BBC.
 
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