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CAL(KS) 
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Joined: 18 Sep 2009
Location: Chapman, KS
Points: 3786
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 Topic: stroker clearences
Posted: 02 May 2017 at 12:52pm |
what should be the minimal clearance between connecting rods and cam/block etc. and what are acceptable rod/stroke ratios? I am between 1.58 and 1.47 with what i am wanting to do.
trying to get as much swing as possible without having to grind cam or inside of block.
currently what i have figured using a generous .4 over the rod journal even though the rod is .315 with the bearing on the thin side. (perpendicular of rod bolts) with this i still have .20 clearence. wondering if i could squeeze a little more out of her.
this isnt a 226 engine
Edited by CAL(KS) - 02 May 2017 at 1:15pm
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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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dawntreader74
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Joined: 28 Oct 2013
Location: Manteno
Points: 1770
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Posted: 02 May 2017 at 3:40pm |
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you can get more room in the old side plate block like a wd block or wc;
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CAL(KS)
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Joined: 18 Sep 2009
Location: Chapman, KS
Points: 3786
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Posted: 02 May 2017 at 4:25pm |
this is in a UM engine 
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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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dawntreader74
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Joined: 28 Oct 2013
Location: Manteno
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Posted: 02 May 2017 at 9:30pm |
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sorry about that' thought it was a 226'
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CAL(KS)
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Joined: 18 Sep 2009
Location: Chapman, KS
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Posted: 03 May 2017 at 7:51am |
This is my math and a diagram (about the 7th one) showing pretty accurately what im working with. I know there is pretty much no one messing with these but hoping you guys can give me some tips. The object on the right is a cardboard cutout i made to slip over the rod journal and measure the swing room i have to work with. The block just touches the round end of it. So working from that i came up with my current math. The journal will be 2.2 and the shaded area represents the space taken up by the connecting rod.
I only want to (and can afford to) do this once.  [/IMG]
Edited by CAL(KS) - 03 May 2017 at 10:27am
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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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wi50
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Joined: 24 Sep 2010
Location: weegieland
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Posted: 03 May 2017 at 11:37am |
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One thing that I made to help is a piece of round stock turned to fit the main bearing bore diameter with a 3/4" hole through the center. Another round stock to fit the rod bearing diameter or rod bore diameter with a 3/8-16 tpi hole tapped in it. A piece of 3/4" shaft with a 3/6-16 hole tapped in the end. Then I made a series of arms from some say 3/16X1" flat stock. I drilled 3/8" holes on center to the tune of the crankshaft stroke.... just say a 6" crankshaft has 3" of offset from center of the main bearing to center of the crankpin so my holes are 3" on center in the arm, or 3.25" for a 6.5" stroke, you get the picture.
I now have a jig I can assemble in the engine and swing the rod around and see how it travels in relationship to the other factors that may be in the way. All done before picking a rod profile or crankshaft stroke so we can change those things if needed before getting parts made.
I'll measure the crankshaft to camshaft centerlines... Lets just say for example that it is 6.000" in the engine in question. Now I can say the cam needs to be 1.25" in diameter so half of that is .625". So the crankpin is 2.2" you say and lets just say we want .400" for the rod and bearing. So, 6" minus the half cam diameter, minus half the crankpin diameter and subtract another .400 for rod and lets just say .100" for clearance would yeild 3.775" for your crankshaft offset, or that would be a 7.5" stroke length would fit in this example. But there may be something else in the way, the block side or oil pan rails. Maybe the rod cap needs to get rotated around to gain clearance.
You'll also need to take into account your rod length and piston depth, sleeve length to make sure you are not going to pull the pistons to far out of the bottom of the sleeve and that the sleeves will still clear the crankshaft and rods, etc.
Your rod ratios look fine. Just stay away from the super poor rod ratios, but anything in the 1.5 range is good. 1.3 and below I like to stay away from
I can't figure out how to post any pictures here but I could text you a pic of the tool so you get an idea and would be glad to help with anything needed
Edited by wi50 - 03 May 2017 at 11:40am
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"see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet"
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CAL(KS)
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Joined: 18 Sep 2009
Location: Chapman, KS
Points: 3786
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Posted: 03 May 2017 at 1:04pm |
thanks marty. I have most of this info in a file from posts you have made previously and that is how i arrived where im at.
center to center on cam/crank is 8 inches if i recall cant remember for sure. I have plenty of room on the camshaft for clearence, the problem is on a UM block its an /\ from the pan rails to the top, so it tightest about 10 o'clock and 2 if you see what i mean.
I will be using murphys M shelf rods at 10.3 inch. the bbc pistons im looking at are pretty short but i will be doing more measuring to verify crank/sleeve clearence. have a little room to notch sleeve if necessary but i dont think i will need it.
I think about the only thing i have left is to CC the head chamber so i can tailor the piston comp height for the compression im looking for and the deck height i have to work with. Just wanting to make sure i havnt overlooked something.
At 7" stroke im + a few thousanths over deck with the shortest piston i can find. past that would be custom rod but i dont think it would swing without a lot of grinding anyway and the ratio gets iffy.
so maby i have answered my own questions lol
Edited by CAL(KS) - 03 May 2017 at 4:14pm
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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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