Shortest rods?
#2997670
12/22/21 07:41 PM
12/22/21 07:41 PM
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Joined: Jan 2003
Posts: 9,963 Frostbitefalls MN (Rocky&Bullw...
gregsdart
OP
master
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OP
master
Joined: Jan 2003
Posts: 9,963
Frostbitefalls MN (Rocky&Bullw...
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The only reason to consider this is to use some valuable parts in a new application. I am going to use the crank and intake from the 550 megablock motor in a new BMP Aluminum block. So what I want to do with the heads, valvetrain , pistons, rings and block left over from previous build is to put a stroker crank in it and lower the compression to a liveable level for the 440-1 heads. My Cp pistons have a pin height of 1.662. To get compression down to 11/1 with all this I would need to run a 6.700 rod on a 4.5 crank a friend has for sale. That ends up at 1.4888 rod ratio. Not too terrible, but there is also a 4.75 crank available which would need a 6.535 rod, which is 1.37. since this motor will be aimed at a power band of under 6500 rpm, maybe even below 6,000 rpm side loading will be somewhat less than a 7500 rpm race motor. So let's hear what you think. By being able to reuse the original heads, pistons, rings, and block the cost of this build would be pretty low. And the 4.75" crank would make good use of the fully ported -1 heads I have also, and at low rpm
Last edited by gregsdart; 12/22/21 07:43 PM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Shortest rods?
[Re: gregsdart]
#2997678
12/22/21 08:31 PM
12/22/21 08:31 PM
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Joined: Feb 2008
Posts: 711 Central TEXAS!!!!
sr4440
super stock
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super stock
Joined: Feb 2008
Posts: 711
Central TEXAS!!!!
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I think that you may have counter weight clearance issues with a 6.53 rod and a 4.75 crank.
Joe
Without Data, you’re just another guy with an opinion.
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Re: Shortest rods?
[Re: gregsdart]
#2997746
12/23/21 12:55 AM
12/23/21 12:55 AM
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Joined: Jan 2003
Posts: 30,947 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 30,947
Oregon
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I think that you may have counter weight clearance issues with a 6.53 rod and a 4.75 crank.
Joe Maybe, Not sure how to do the math. You can't do the math unless you know the size of the counterweights as well as the shape of the piston skirts. Most likely you'll need to mock it up. I'm pretty sure it won't work but if you have the parts sitting on the bench it will only take a couple of minutes to swing a piston and rod on the crank to see for sure.
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Re: Shortest rods?
[Re: AndyF]
#2997754
12/23/21 01:15 AM
12/23/21 01:15 AM
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Joined: Jan 2003
Posts: 9,963 Frostbitefalls MN (Rocky&Bullw...
gregsdart
OP
master
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OP
master
Joined: Jan 2003
Posts: 9,963
Frostbitefalls MN (Rocky&Bullw...
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Looks like the longest stroke I could use would be a 4.5 with those pistoñs. I figured longer might add value since the cranks would all cost the same. But after penciling it out adding stroke eats up clearance in a hurry.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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