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CAL(KS) 
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Joined: 18 Sep 2009
Location: Chapman, KS
Points: 3786
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 Topic: 45 crank and wc flat tops
Posted: 09 Jun 2024 at 2:45pm |
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Working on my sons 37 wc concurrently with the UC project. It had a fresh overhaul and has very little runtime since. We are checking things over as I've found a few shortcuts were taken. I had a 45 crank laying around so figured we would slap it in with the 4 1/8 flat tops. Measuring at 2.382 ch. Will stay oem with cam and everything else. Need a new cam gear as I dont like the backlash. Can we safely run 91 octane with this config? I dont know the deck height or rod length or could look into it. Going to run this for my boy, if he really wants to stick with we can build something bigger down the line. Thanks.
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Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20
Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15
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DrAllis
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Joined: 12 Sep 2009
Points: 20534
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Posted: 09 Jun 2024 at 6:05pm |
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Get it running and run a good compression test on it and I'll tell you.
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CAL(KS)
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Joined: 18 Sep 2009
Location: Chapman, KS
Points: 3786
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Posted: 10 Jun 2024 at 7:07am |
man i would prefer to know before putting it back together in case i need to take a little off the top of the pistons.  this would be using stock wc camshaft. does a guy assume higher dynamic compression with the oem cam vs performance grind because of less duration?
edit. did some math after talking to a friend.
12.656 deck height and 7.5 rod with 2.382 comp height give a deck clearance of .524 and according to my friend. thats 8.7 to 1 static. so comparing to knowledge base stats on the 175 (minus power crater). with 240 CI and roughly the same compression, it should yield a few more ponies over 175. taller piston yielding 10 to 1 static can run on 91 octane and give a little more, says friend who ran that combo.
sounds like either way a good combination for my son to get started without me going broke.
Edited by CAL(KS) - 10 Jun 2024 at 7:51am
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Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20
Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15
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DrAllis
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Joined: 12 Sep 2009
Points: 20534
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Posted: 11 Jun 2024 at 6:24am |
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You should be fine. Be sure to have your ignition timing set at LESS than 25 degrees BTDC, probably closer to 22-23 degrees, but the Dyno is the best adjustment. Flywheel is marked 30 degrees BTDC.
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CAL(KS)
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Joined: 18 Sep 2009
Location: Chapman, KS
Points: 3786
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Posted: 11 Jun 2024 at 7:12am |
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thank you for the input. will do
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Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20
Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15
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