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Username Post: horsepower        (Topic#357028)
Posts: 1

Loc: rocklin ca
Reg: 05-26-17
06-29-19 06:40 PM - Post#2769546    

how much horsepower 55 chevy block with 56 head stock ??


Ultra Senior Member
Posts: 11434
Reg: 03-25-05
06-30-19 08:51 AM - Post#2769573    
    In response to Rtruckthom

I don't think the heads will make a difference. See chart under Carburetor:

66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)

Ultra Senior Member
Posts: 12288

Loc: Wisconsin..USA
Reg: 09-27-02
07-27-19 06:27 AM - Post#2771709    
    In response to acardon

Depends if the 1956 head is from a 2 barrel or power pac 4 barrel head.

ChevGene 1934 Master sedan 1939 Master DeLuxe Town Sedan 1950 Styline DeLuxe Power Glide 1957 Nomad 283 PG 1963 Corvair Convertible

Gold Supporting Member
Posts: 5838
Age: 69
Loc: Everett, Wa.
Reg: 02-26-08
07-27-19 08:04 AM - Post#2771716    
    In response to Rtruckthom

Stock, untouched 55, 265 short block? The reason I ask that is, stock would have had the true flat top pistons, without any valve reliefs. Start swapping parts and pieces around, and you risk valve to piston interference. A lot of warranty work was done the first few years of the 265 until they went with valve reliefs in the pistons. That had to drop the CR down a bit, and it's hard to really build much CR with these small bore, short stroke engines. With 56 PP heads, you may gain a little more power, but you have to watch out for the piston to valve contact issue. Not a problem with aftermarket or replacement pistons with valve reliefs. The #5306, 56 PP heads have 55.65 CC combustion chambers; good for a CR bump. If all you're looking for is a boost in CR/power, then go with #601, 305 heads having 53 CC chambers, and hardened valve seats for the lousy quality gas we have now. Don't even think of swapping to a performance camshaft unless/until the valve relief situation is addressed. I am Butch/56sedandelivery.


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