Reconditioned 37 rods

[Mark's 37]

A couple of the reconditioned rods in the set of 8 have some pitting near the joint that meets the cap. They have been resized and honed to 2.221" and they are round per micrometer readings. Are they usable? The now-deceased machinist obviously thought so. Thanks.

[GOSFAST]

Hi Mark, you should be fine with those rods.

Thanks, Gary in N.Y.

P.S. They are +.001" over the high limit (2.2195"/2.2200"), but won't be an issue!

[GB SISSON]

Talked about that subject many years ago with an experienced machinist but it was about pits in a cylinder bore. He said when they used to race volkswagens they would machine dimples or 'pits' in the bore because they held a bit of extra oil for lubrication. He said not to worry a bit....

[Mark's 37]

Thanks. I measured the rods again tonight and got 2.2200". Onward.

[flatheadmurre]

The force at the surface where the cap and rod meet is low so wouldnt be an issue.
Im more concearned about the hone finish looks corse to me for a floater bearing ?

[Mark's 37]

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Originally Posted by flatheadmurre

The force at the surface where the cap and rod meet is low so wouldnt be an issue.
Im more concearned about the hone finish looks corse to me for a floater bearing ?

I am concerned about that too. Looking into doing some finishing for the surface. Got some fine steel wool 800, scotch brites, fine grit polishing compound to experiment with. Got any suggestions?

[dumb person]

If it does chew up the bearing you could probably plate it in nickle and hone to size.

[Lawrie]

There are oversize bearings avail,Hard to get but availible
Take it from me the finish IS important,Walt or ol Ron will chime in,the surface needs to be as smooth as the finish on the crank.
Just remember the rods are more readily available than the floaters.
Lawrie

[JWL]

Rub the rod bores with some 400 grit and they will be good. There is a cushion of oil between rod housing and bearing surface. The rod surface should never be in solid contact with the bearing surface. If the oil is not present something else is wrong.

[JM 35 Sedan]

Originally Posted by JWL

Rub the rod bores with some 400 grit and they will be good. There is a cushion of oil between rod housing and bearing surface. The rod surface should never be in solid contact with the bearing surface. If the oil is not present something else is wrong.

I would highly respect JWL's opinion and do exactly what he said. JMHO

PS...not meaning any disrespect for the other's who replied.

[JSeery]

As JWL stated, there should not be any metal to metal contact!

[Ol' Ron]

I also run more clearance in the rod. 2.221/1.222 and 1.997 for the crank. I made my own 4 1/8 strolers back then and one of them is still running, and considering the mileage and driving it does, I'm surprised.

[Mark's 37]

Originally Posted by JWL

Rub the rod bores with some 400 grit and they will be good. There is a cushion of oil between rod housing and bearing surface. The rod surface should never be in solid contact with the bearing surface. If the oil is not present something else is wrong.

I have been looking at as much info on fitting and bearing surfaces as I can find. Have the flywheel for a flat surface, a soft head plastic hammer and micrometers along with a second set of rod bearings if needed. I bought 400 grit wet/dry paper with the other stuff yesterday. This is going to take some time and patience. Also trying to get as accurate rod dimensions with the dial bore indicator I have.

[Fordors]

Although I have never fitted floaters I might approach it this way- mic the diameter across one bearing shell, then mic the radius using a ground, precision parallel held on the bearing. Subtract thickness of parallel to establish radius dimension. Compare diameter and radius readings and adjust with soft hammer until correct. Most accurate way, or overkill?

[Mark's 37]

Originally Posted by Fordors

Although I have never fitted floaters I might approach it this way- mic the diameter across one bearing shell, then mic the radius using a ground, precision parallel held on the bearing. Subtract thickness of parallel to establish radius dimension. Compare diameter and radius readings and adjust with soft hammer until correct. Most accurate way, or overkill?

That's kind of what I have been practicing. I measure the bearing OD across the tips of the four corners and near the middle oil groove. Then put the two halves together and measure the OD across the center of the bearings using a outside mic and compare to the rod bore measurement. Hope that makes sense.

[flatheadmurre]

Originally Posted by JSeery

As JWL stated, there should not be any metal to metal contact!

You have some kind of an electric oilpump
If the hone is to corse the leftover oilfilm isnt enough at startup

[Mark's 37]

I worked sizing the first floating rod bearing this morning. Here are the measurements so far.

Rod bore ID is 2.220"
Bearing OD is now 2.219" across the ends of each half after massaging with the plastic hammer. .

Putting the two halves together the diameter across the centers is 2.224" and doesn't move freely in the rod bore.

Can I use some 200 grit or so on a flat (flywheel) surface to sand the butting ends of the bearing halves to get that measurement down from 2.224" to match 2.219"? Thus freeing up the bearings in the rod bore?

The crank OD measures 1.969". Bearing thickness is .125".

Well into the learning curve on this stuff, thanks.

[Ol' Ron]

Ya gota work with the math, The diameter of the crank subtracted from the bore of the rod and tne thickness of the bearing times two, If the numbers add up and the clearance is right. THEN start fitting them. Also you must check for width , especially in the filit radius of the crank. You don;t want to hang up there. I like .015 on the width of the bearing, this lets the oil out of the bearing. Next the rod side clearance should be .008-.010" on a street engine and .015-.020 on a track engine. This allowa plenty of oil flow through the bearing to cool it. But the added clearance makes the rings work harder, but the excess oil on the bottom of the pistons keeps them cool.

[Mark's 37]

Originally Posted by Ol' Ron

Ya gota work with the math, The diameter of the crank subtracted from the bore of the rod and tne thickness of the bearing times two, If the numbers add up and the clearance is right. THEN start fitting them. Also you must check for width , especially in the filit radius of the crank. You don;t want to hang up there. I like .015 on the width of the bearing, this lets the oil out of the bearing. Next the rod side clearance should be .008-.010" on a street engine and .015-.020 on a track engine. This allowa plenty of oil flow through the bearing to cool it. But the added clearance makes the rings work harder, but the excess oil on the bottom of the pistons keeps them cool.

Ron,

Edited and corrected the measurements:

My numbers are rod bore = 2.220" minus 2 x .125" bearing thickness(.250") = 1.970" minus crank journal 1.969" = .001" clearance.

Isn't this clearance too much?

[GOSFAST]

What "undersize" brgs are you working with, that shaft size is .030" under!

Thanks, Gary in N.Y.

P.S. I may be missing something with all your numbers but you cannot run .011" (rod brg) clearance??