Herbie
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« on: September 13, 2010, 02:48:48 am » |
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I have an idea for an engine combo using some bits out of some old motors. I have a set of 1640 barrels and pistons and out of another motor a 78m crank. My question is can I use these together or will the crank push the piston too far out into the head.
Also would a 78mm crank fit into a stock case or will clearancing be required? I know its going to be close. I might ever put the crank in the case to test it later tonight if I have time.
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2165cc 106hp Herbie
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Clinton DdK
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« Reply #1 on: September 13, 2010, 01:21:48 pm » |
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I built a 85.5 X 74mm engine and had to clear the case some, not much.
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KAFUR1
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« Reply #2 on: September 13, 2010, 02:55:47 pm » |
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I used this combo and did not have to clear the case at all 94 x 74 you do have to use scat rods thoe
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Ohio Tom (DdK)
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« Reply #3 on: September 13, 2010, 03:48:20 pm » |
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The style rod will determine the amount of clearanceing.
No matter what, it's an easy task with a die grinder or Dremel.
You will have to use quite a stack of barrel shims to get the deck height where you want it, but it will work fine.
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Ohio Tom Simpson. Home of the Killa' Bee.
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Herbie
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« Reply #4 on: September 14, 2010, 08:31:13 am » |
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Thanks for the replies guys. Very keen to build this motor. Will go for as41 case, 78mm crank, 87mm pistons, engle 125 cam, 1:1.25 rockers and 40x35.5 ported heads. Should be a good combo I think. Works out to be an 1855cc motor.
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2165cc 106hp Herbie
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maui
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« Reply #5 on: September 17, 2010, 03:50:44 pm » |
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In the 70s plenty people out here had that combo and 48s and gearing and we would have some fast bugs and major fun action. Mine had a Norris 408s cam.
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Kehau
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rockerarm
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« Reply #6 on: September 18, 2010, 09:48:40 pm » |
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If the pistons are cast, won't the skirts,which are longer on cast vs forged, hit the counterweight when each piston is at BDC ?
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junkyard racen
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« Reply #7 on: September 18, 2010, 09:59:49 pm » |
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I think that would depend on you rods.
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dreamcatcher 4189
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rockerarm
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« Reply #8 on: September 19, 2010, 01:36:42 pm » |
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I assumed this is a budget buildup and was gonna use 311B rods.
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Herbie
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« Reply #9 on: September 20, 2010, 06:42:10 am » |
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It is a budget build. I was hoping to use the rods that are connected to the 78 crank right now. The rods are CBs Chromoly H Beam 5.4" race rods
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2165cc 106hp Herbie
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Kevin Alexander
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« Reply #10 on: September 22, 2010, 09:20:37 am » |
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I tried to do an 87x76 one time with cast 87s and the skirts hit the counterweights. I was using a 5.4" rod. Only way to make it work would've been to trim skirts and rebalance pistons, use a 5.5" rod or buy forged pistons.
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165 RWHP pumpgas 2332
12.72 @ 104
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Herbie
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« Reply #11 on: September 24, 2010, 04:35:53 am » |
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Thats good info to know. I would have never thought of that. Im going to try a mock up so see how all these parts will get a long. Hopefully the crank won't hit it but machining the pistons shouldn't be too hard.
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2165cc 106hp Herbie
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