"B" engine questions.

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Does anyone know what sort of increase in HP an 6.5 to 7.5 compression ratio would produce in a "B" engine? 
Is it possble to acheive this by milling the head?
How much would you have to remove?

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SteveC(NS) Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Oct 2009 Location: Nova Scotia Points: 663	Post Options Post Reply Quote SteveC(NS) Report Post Thanks(0) Quote Reply Topic: "B" engine questions. Posted: 18 Jan 2012 at 7:40pm
	Does anyone know what sort of increase in HP an 6.5 to 7.5 compression ratio would produce in a "B" engine? Is it possble to acheive this by milling the head? How much would you have to remove?

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Dick L Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Edon Ohio Points: 5082	Post Options Post Reply Quote Dick L Report Post Thanks(0) Quote Reply Posted: 18 Jan 2012 at 8:40pm
	I have not worked it out because it is not as simple as just using the calculations. Read the information at the link. http://www.carcraft.com/techarticles/calculate_compression_ratio/index.html I don't put a head back on any of my B's or C's with out removing at least .150 . I have removed .200 off two heads without a problem. You might be able to take more off but I start to feel uneasy about removing more than .200. As I mill the heads I keep check the wall thickness in the water openings to the block. If someone had removed .150 and you decide to go for the .200 you might just strike water over a piston when she would get warm. After removing the .150 you can tell a difference in the sound of the engine.

dallasallis Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 09 Jan 2012 Location: NC Points: 11	Post Options Post Reply Quote dallasallis Report Post Thanks(0) Quote Reply Posted: 18 Jan 2012 at 8:42pm
	I have removed .100 without any issues

Steve in NJ Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Andover, NJ Points: 11560	Post Options Post Reply Quote Steve in NJ Report Post Thanks(0) Quote Reply Posted: 19 Jan 2012 at 9:03am
	When I did my B engine over bout' 10 years ago, I took Dicks advise and had .80 taken off the head. With the larger piston's, she does bark a little louder that's for sure! Had to put the muffler back on again. The straight pipe was a bit on the loud side. I think its my older age setting in now. And I used to pilot a Dragster years ago. Go figure... LOL! Steve@B&B

Dick L Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Edon Ohio Points: 5082	Post Options Post Reply Quote Dick L Report Post Thanks(0) Quote Reply Posted: 19 Jan 2012 at 11:25am
	Ten years ago, Huh? I didn't know that you, er we, were that old.

SteveC(NS) Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Oct 2009 Location: Nova Scotia Points: 663	Post Options Post Reply Quote SteveC(NS) Report Post Thanks(0) Quote Reply Posted: 19 Jan 2012 at 11:40am
	Dick, thanks for the info I shoulda asked about a CA not a B. It's also a 3.4375" bore. I CCed the head at 70cc (4.2716 cu.in.) and I sorta guesstimated the bore space above the piston including the gasket to be 4cc (.245 cu.in.) and the swept volume is 532.124cc (32.4722 cu.in.). I got 8.287 to 1 compression which sounds like what I wanted to shoot for so no wonder it had a "bark" to it when the governor called for juice. The only thing I can see is the 3.4375" pistons have more height than the stock 3.375 6.2-1 pistons have. The ones I have have an arrow facing the front of the block stamped into them. I measured about .032" from piston top to block surface, does that sound stock?