Reman rods

[wrench459]

While working on a non Opel set of rods today a question came up.
The rods are egg shaped ..shaved off a few thous on the rod caps..then removed the rods bolts and shaved even more from the rod..honed the crud out of it.
Question how much out of round could the rods be without problems.
When we checked it was out at the cap line around .0002

[Tru-Craft]

Are you saying .002" or .0002" ?
Not sure how you are measuring the ID?
But .0002" is about as close to perfect as your ever going to get with a hand held gage.
When I worked in Aerospace we had digital bore mics that could read within +-.0001". A bore mic not held in a fixture perpendicular to the bore won't check much better than +-.0002". Check to make sure the 2 bores run parallel to each other, and that the bores are not bell mouthed or tapered.
Sounds like you have them real close!

Remember when honing to always use a trueing sleeve to keep the stones from wearing unevenly. Also flip the rod around. This will keep the bore from bell mouthing.
I bore the rods to within .001" and then finish hone to size.
I also locate off the small end bore, so the 2 bores run parallel to each other and the rod lengths are perfect.
I have heard some NASCAR engine shops jig grind the rod bores.
Lyle

[wrench459]

When the shop is slow I'll move over into the machine shop.To help out where
I can. Normally I don't get to play with the big machines but it was slow again today. MAN did I ever get educated today on the rod machine.
After balancing two rotating assy. Steve said setup the machine up to recon some BBF rods.. if you have any questions just ask.
So old motor mouth me let then fly. And found out about splits and other cool
measurements. BTW BBF bigend spec is 2.6522-2.6530

[GTJIM]

When the tiny bit of metal is removed from the joint line it is just the up/down measurement that is closed up - the across the rod measurement is not altered very much and it depends upon how well the new big end bore is centred on the old one.

Fortunately rods seem to 'close-up' a bit on the across the rod measurement during use (may be detonation helps!!). Anyway that measurement is a little less important than the up/down one as rod bearings are made to 'bulge' there anyway by about 0.001" to 0.003" to prevent the oil film being scraped off the rod journal by the edges of the shell - particularly when detonation closes the ends in.

I guess 0.0002" variation is not too much to worry about!

[wrench459]

Originally Posted by Tru-Craft I also locate off the small end bore, so the 2 bores run parallel to each other and the rod lengths are perfect. I have heard some NASCAR engine shops jig grind the rod bores. Lyle

Thanks Lyle the light bulb just glowed in my tiny mind.
Slightly bent rods might be the problem with my math not working out .
Now I'll need to prove it at the shop next week.

[wrench459]

I'm still learning this stuff.
But lets say the specs are 2.2000-2.2014 on the mains.
From what I've found out is to take the center (splits) to 2.2007
Yes Lyle the setup is very critical shacky hands dont apply!
Then hope the crank grinder does the same split.

[jeff denton]

Dan, if you're looking for performance and perfection, throw away those forty year old rods and start over with new quality. The Crowers come with good bolts even. They come perfectly weight-matched. Other advantages are longer length, meaning then the pistons can be much lighter. The bearings are available in best quality at any parts store. The pins become very common and lighter, also. The rings are then available to your spec.
It's really simple. This combo just blows away the stock stuff. It's key to performance and so drastically eases the mind at 7000+ sustained rpm.