running 4.75 crank in aluminum block

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running 4.75 crank in aluminum block Empty running 4.75 crank in aluminum block

Post  hbstang on September 23rd 2019, 4:33 pm

i have an option to use a 4.750 crank im my c anc motorsorts block.it has a bore of 4.625,would this put to much load on cylinder walls/ rings ? N/A engine build with a-441 heads.standard 10.320 deck block.
also how would e-85 do at 14 to 1 comp on this?
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running 4.75 crank in aluminum block Empty Re: running 4.75 crank in aluminum block

Post  JBR-3 on September 23rd 2019, 7:45 pm

Hello Dan, just so happens I have an old SVO A/R block on the stand with my 4.75 crank in it.
Rod journals are BBM not BBC. The cylinder walls/liners are almost 6 1/2 inches long, longer
than any of the iron blocks. The crank easily fits. I have some steel aftermarket rods, I need
to bolt one in and rotate it. Have NOT done this yet, but eyeballing it looks like minimal if any
clearancing will be required. I can't comment about aluminum rods. Also can't comment on
cylinder wall loading.
JB

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Post  gt350hr on September 24th 2019, 1:49 pm

Dan with a 6.7 rod it makes a 1.225 C/H and that is still OK. Cylinder wall loading is subject to skirt profile and length plus top ring land diameter. I think E85 would be OK with the aluminum head @ 14-1. You know i'm only a mile away.
Randy

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running 4.75 crank in aluminum block Empty Re: running 4.75 crank in aluminum block

Post  JBR-3 on September 24th 2019, 6:03 pm

You can think of piston "side loading" as how hard it rubs on the cylinder wall. This depends on how large the skirt area is (more is better),

how much cylinder pressure there is (less is better), how short the rod ratio is (longer rod is better), how slick the oil is (more slick is better).

This is to minimize side loading, not to maximize horsepower. More HP generally means more side loading, more wear.

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running 4.75 crank in aluminum block Empty Re: running 4.75 crank in aluminum block

Post  BOSS 429 on September 24th 2019, 9:31 pm

In on 1
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