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Old 06-08-2007, 10:38 AM
BogiesAnnex1 BogiesAnnex1 is offline
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Originally Posted by ljjjrome
SBC question for you guys.
will run holley 750 HP no choke on the street, will be driven in winter in pacific NW
have performer RPM intake with exhaust crossover
have AFR 195 heads, and exhaust crossover hole is about 3/8" (much smaller than rectangular hole in intake)

I was told that on cold days it would help alot to run the exhaust through the crossover by having a valve on the passenger collector close, all exhaust would run through the crossover, to drivers side and out. That seems like an awful lot of air to squeeze through a small hole. When the engine got up to operating temp, the valve would close and exhaust wouldnt heat up the crossover anymore

this valve is called a heat riser valve, hedman sells one.

My question is, with the tiny size of my exhaust crossover, will the valve do any good? seems like it would kill the engine if it could seal.

Also, will much exhaust be flowing through the hole with the valve open? and will that decrease performance much?

Forget the heat riser valve, SeaTac doesn't get cold enough to warrant their use, Fairbanks would. They rust and carbon up inside of a few months to a year and quit working anyway.

A bigger help on cold rainy mornings is heated air going into the intake. Keep a factory type aircleaner housing with a hot air riser and control valve off one side of your headers and the engine will be happy all winter long.

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