I want to change the rod bolts on a small journal 327 and need to know if the rods "must" be resized. I know the corporate response but would like to hear from someone who has machine shop experience. Do they really distort or can I just press 'em in and go?
I guess my response is "it depends". I have swapped out rod bolts and the journals were still round afterwards, but they came out and went back in real easy with just a tap of a plastic hammer. OTOH, I have swapped some that needed a pretty good push to replace and the journals were not as round when I was done, so they had to be resized. In any case, having the journals resized is a low-buck job and if you have any doubt, just do it.
I'd like to do them today and not have to farm it out to the machine shop, so I was hoping for a "warm fuzzy" feeling that I could just get 'er done in the shop.
I've seen plenty of times when it worked, and a few times when it didn't. I guess the question you've got to ask yourself is.....do I feel lucky? Well, do ya, punk?
odds are if you torqued the nuts down and measured the bores in the rods, they'd be out of spec now, even before you change the bolts. So no matter what, the rods need to be resized to get the bores round again. Would they be worse with new bolts? maybe, maybe not.
I had this same question too on the same engine. I have one bolt with bad threads in the whole set of set of rods and was going to try to just tap it out and tap the new one in, Just got the crankshaft out of the machine shop too, guess that means another trip How is the resizing done anyway?
The resizing proceedure goes like this: press out bolts vat and glass bead blast rods and caps grind mating surfaces on a rod grinder deburr press in new or used bolts assemble and torque resize bore with a rod hone If the pistons are still on the rods, skip the bead blasting!
This is how bad engs get built, then the machine shop gets the bad mouthing blame. If you want to be a eng builder, then change the bolts and let the machine shop re size them.
OK, so it sounds like you can't swap 'em at home. That was just one of those "mystery" procedures in the machine shops that we common-folks don't know about and wasn't sure if it "had" to be done.
Yup-resize them. The odds of the bearing bore coming out EXACTLY the same are low, and when you're talking about oil film thicknesses measured in ten thousandths of an inch, you need "exactly". It's cheap insurance when you're talking about the possibility of ruining the bottom end of your motor when you smoke a rod bearing.
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