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anyone out there able to tell me the length of a oem b17a rod? and the height of a oem b17a block? i'm hearing too much confusing info out there that isn't correct someone please help me thanks.
 

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Discussion Starter #6
thank you defiant.. thats the info i've been looking for!!!
 

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thanks to viprtwo for clearing that up. I had 2 reliable sources telling me the b17a rod was 137mm which is incorrect. Not as reliable as I thought I guess. The rod is actually only 132 mm in length.

This has broad implications when you drop in a b17a crank in a b18a/b block, since you need to deck the block in order to have the pistons sit at the correct height within the proper deck height.

However, b17a rod's small end still fits within the "non-R" family of cranks...b20a/b/z, b18a/b, and b16a...as well as the b17a crank obviously. They will not fit (too large) on the R-family of cranks (GSR, ITR, CTR) for the Bseries.

The block height (measured with steel ruler from deck to bottom of oil pan rail) is 10.354 in. or 263 mm according to Louis DeVirgilio at the g-speed.com website
 

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so a stock b17 has a rod ratio of 1.626? hee hee, Mike I will let you be the first to see the results. (if yaknowaddamean)
 

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Jacksont001 on Oct/04/02 said:
so a stock b17 has a rod ratio of 1.626? hee hee, Mike I will let you be the first to see the results. (if yaknowaddamean)
I was under the impression that a stock B17A1 has a rod ratio of 1.68.
 

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b17gsr on Oct/10/02 said:
I was under the impression that a stock B17A1 has a rod ratio of 1.68.
the rod length is 132 mm not 137 mm.

b17a r/s = 132 mm / 81.4 mm = 1.62

NOT 137 mm / 81.4 mm = 1.68 as you see in Joe Pettitt's book...it's a typo. The one error I did find in that book at the back. Actually, the credit goes to viprtwo for pointing that error out to me in that book.
 

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Ahh. What's the ideal rod ratio range for high rpm?
 

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hee hee. I'm still looking for a b17 crank. then I'll show you something very nice.
 

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anything over 1.65 is considered good for high revving. 1.75 is ideal according to some experts, since it compromises the best between dwell time at TDC & BDC, max. piston speed, and sideloading of the cylinder wall at high rpms.

Smokey Yunick used to think that 2:1 r/s was ideal. Look at the Accord C-series V6 engines...it's around 2:1 r/s.
However, for the most part, the piston speed suffers and with the added dwell time squeezing the mix you run into more of the negative sides of the high cylinder pressure/ high temp issues.
 
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