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By LordMrFord - 16 Years Ago
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I am putting Chevy 2.100 rods to Y-block and machinist wants to know the tolerance for big end radius.
I want also know big end width and small end gap.
Thank you.
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By LordMrFord - 14 Years Ago
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2.1" +-0.001 or what?
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By mctim64 - 14 Years Ago
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I grind std. chebbie rod throws to 2.099" maybe 2.098" for racing. side clearance should be .004" but more is OK. This is how I cut the rods down. 
Cut equal amounts off each side to a width of .850 and run CB663HD rod bearings.
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By Highvoltage - 14 Years Ago
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What kind of rod are exactly using in your engines? You will put it on a 292? Thanks for your anwers!
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By John Mummert - 14 Years Ago
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If you have a crank offset ground check the bearing to radius clearance very carefully. Make sure that the bearing doesn't pinch the radius on the crankshaft. This will trap oil in the bearing and burn up the bearing, and / or the crankshaft. A safe number for bearing clearance is .001" per 1" of diameter. 2.100" journal=.0021" clearance ect. I like to see .014 to .018" side clearance between the rods. The only oil that lubricates the camshaft is what is thrown off the crank and rods. Y-Blocks had .012 to .016" from the factory. As for wrist pins .0004" seems too tight for any performance use and not much reason to go over .0008" so we try to hit .0006-.0007". Some aftermarket rods are .0008" off the shelf so you just have to live with it. Over .0010" is okay for drag race/circle track but too loose for street, IMO
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By miker - 14 Years Ago
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For what its worth, I've got 2 stroker motors with whole assembly's from John. They run very well. He also has a spec to the turn the fillet (?) if you are offset grinding the crank. Mine are about 320 and 340 with (I think) 2.1 and 2.0 bearings. Don't trust the memory so much any more.
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By yblockpinto312 - 14 Years Ago
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For what it`s worth this is what I did. My std. 292 crank, I offset ground it to a 3.48 in. stroke. I then used a set off $250 Eagle SIR Ibeam rods that I gound .010 off the inside and .060 off the outside to narrow them from .940 to .870 and center the beams. For bearings, I used King rod bearings, CR867HP std. These allow a 2.10 rod to be used with a 2.00 crankpin. The chamfer on the bearing worked perfectly with the crank throw. It was like these parts were made for the "Y". Just my 2 cents worth.
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By Don Woodruff - 14 Years Ago
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Greg, am I to understand the King rod bearing has a thicker section allowing you to use the rods normally configured for a 2.1 crank pin on the 2.0 journal? Is there an advantage to this?
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By scott5560 - 14 Years Ago
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Yblockpinto312 I sent you a private message. Wondering if you can give any more info on your stroking mods? Thanks
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By John Mummert - 14 Years Ago
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Don, there are limited choices in rods with 2.00 journal. A lot of the less expensive rods are only available up to 6.00" in 2.00" journal. With the 2.100 rods 6.125 6.200 and 6.250 are available in a wide price range. We use 6.200" rods with a combo like Greg's and that requires an H-Beam with 2.00" journal rods. The H-Beams are considerably more expensive.
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By yblockpinto312 - 14 Years Ago
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Don, John is exactly correct. I used these conversion bearings to free up my rod choice. The 5140 I beam rods will take all the power a "Y" will make. I used a 6.20 rod with a Probe piston that had a 1.82 C D. (I found them on Ebay) I`m very happy with the way it all turned out. I`m planning my next motor, 3.86 bore 3.62 stroke (an offset ground 312 crank) with a piston and rod combo like this one, only bigger. (338, I believe) O, and I really like the King bearings.
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By mr4speedford - 14 Years Ago
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Excellent info so far. For a 3.48 stroke on a 292, what is minimum diameter the rod journal has to be offset ground to?
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By yblockpinto312 - 14 Years Ago
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For a 3.48 in. stroke, the 292 crank has to have never been ground. The stock Dia. is 2.188. The offset grind will be taking .180 off the inside of the journal, therefor moving the center of the journal .090 out word. this is where the stroke increase comes from. I think Ted has used a Honda size of 1.88, but I dont know if he used a stock crank. Maybe he could shed some light on this?
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By Ted - 14 Years Ago
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yblockpinto312 (2/20/2011)
......I think Ted has used a Honda size of 1.88, but I dont know if he used a stock crank. Maybe he could shed some light on this?There is a problem with the crankshaft oiling holes when attempting to offset grind the cast and steel Y cranks using the Honda rod journal size while trying to hold the journal widths to 1.810”. When trying to grind the crankshaft that extra amount for the Honda rod journal, the oil hole going from the main to the rod journal ends up breaking through in the filet of the journal which pretty well ends the day for that particular crankshaft. It only takes breaking through on one journal to make the crankshaft unusable. Variances in the crankshafts in regards to the oil holes makes using the Honda rod journal scenario a difficult one without turning down several crankshafts in which to get ‘one’ that’s usable. Not very cost effective to say the least while also destroying what could have been some very usable crankshafts if offset ground for a slightly larger journal.
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By LordMrFord - 14 Years Ago
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Thanks for your answers.
I got set of 6.3" Carrillo K1 rods with Chevy journals and John's forged stroker pistons.
My machinist meant big end roundness tolerance, if you know what I mean, but I think that is odd question from pro, that I change the firm.
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By Ted - 14 Years Ago
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LordMrFord (2/23/2011)
My machinist meant big end roundness tolerance, if you know what I mean, but I think that is odd question from pro, that I change the firm.0.0003”
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