Burnishing in?

[Jalopy Tin]

I have read all that i found on the mtfca forum about this matter but still i look like a nesting box in my face..
First. I had to replace my rear main cap due to to large crankshaft end play. Ok.
Second. I measured my crankshaft and it had standard diameter. Ordered a rebabbited standard diameter main cap.
Third. Cap Too long.. Spent two hours to grind it to the right measurment, now my end play is 0,006". I'm happy
Tightened the nuts a bit, have three shims, still 1/8" gap between cap and block surface AND I NEED A TURNINGBAR PROBABLY ONE YARD to turn my crankshaft over... I'm mad
Earlier i could hardly turn the crankshaft with my bare hands using the crankshaft flange and pulley, so the play must have been tight. Remember this car was restored and then put in a car collection, not much driven.
Can i scrape the babbit? No, wrong.. Should i scrape the babbit?
It seems that that my new cap is a bit tight, on the surface nearest the edge of the cap.
I feel that i can't assemble the engine now and discover that my little 6volt starter just....burned up, trying to turn the engine over.
Please.. i know You guys have some good, easy, bullitproof ideas to solve
my problem. And NO.. ebay is not a solution.. I love my car.. still..
/Tom

[Doug Money]

I would start by getting an undamaged main cap since that one is junk now. There should be no reason that out of 15 million engines, yours needs the cap ground down. We use time saver to "burnish" the bearings.

[J Franklin]

In the old shops they used to scrape in the babbit for fit. the "time saver" compound sounds like a modern way to do it. Google it and maybe there is some information for you. Don't toss the cap out till you are certain it is not usable. Was it just babbit you had to grind?

[redmodelt]

More shims and use bluing to check contact surface. You should have .0015 to .002 clearance on your crank when you have it set up. Are you sure you got a "STD" re-babetted cap? Yes the end play must be set before use. They are made that way for wear.

[Ernie Clerihew]

How about getting a Plastigage to check clearance between the crank and the cap? You can check clearance on your other bearings while you're at it.

Ernie Clerihew

[redmodelt]

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Plastigage will work after he finds out why he has a gap between the cap and block that is larger then what one would expect with a standard size cap and crank. Check the parts number, there should be one written on the cap or bag it came in.

[Jalopy Tin]

I have only adjusted the front and rear sides of the cap to get the accurat end play. In my engine the front, main and rear cap has their triangle marking pointing toward the water pump. When i recieved the new cap from the Lang's and i should have the thickest part of babbit pointing toward the crankshaft flange, the triangle marking pointed to the other side.. turned 180 deg. Are MY original main caps turned the wrong side?
In the second picture it looks like the line bore on the new cap is obliqued drilled. What do You think?
When i lay the cap on the crankshaft, it wiggles side to side and when i tighten the nuts as much as i can still turning the crankshaft, i will still have the 1/8" gap on both sides where the shims are supposed to be AND i will get a wear marking inside the cap. (pics three) Btw my crankshaft is 1,248" in diameter and the new cap is 1,249" on one side and 1,251" on the other. Maybe i got an oversized by misstake? I asked if i could use a standard cap for my 1,248" crank and was answered yes.
/Tom

[Doug Money]

How are you measuring the cap to get two different sizes?

[Jalopy Tin]

I'm measuring each sides half moon opening with a digital calipers.

[Kohnke Rebabbitting]

Originally Posted by Jalopy Tin

I have only adjusted the front and rear sides of the cap to get the accurat end play. In my engine the front, main and rear cap has their triangle marking pointing toward the water pump. When i recieved the new cap from the Lang's and i should have the thickest part of babbit pointing toward the crankshaft flange, the triangle marking pointed to the other side.. turned 180 deg. Are MY original main caps turned the wrong side?
In the second picture it looks like the line bore on the new cap is obliqued drilled. What do You think?
When i lay the cap on the crankshaft, it wiggles side to side and when i tighten the nuts as much as i can still turning the crankshaft, i will still have the 1/8" gap on both sides where the shims are supposed to be AND i will get a wear marking inside the cap. (pics three) Btw my crankshaft is 1,248" in diameter and the new cap is 1,249" on one side and 1,251" on the other. Maybe i got an oversized by misstake? I asked if i could use a standard cap for my 1,248" crank and was answered yes.
/Tom

OK Tom, to start with, the forging mark will fit ether way when you get a new 3 main babbitt job, just depends how the babbitter put them on there. The right way, should have the forging marks, or triangles on the cam side, so you can look at a glance as to how the cap goes on. First I see, that you have black rub marks on the radiuses, that in its self will keep the cap up off its seating. You have to fix that first, scrap the cap, and try again until they no longer rub. If you have a radius that is .001 to small, it will not let the cap set, if it is .005 to large, it won't hurt a thing. Fix that first, then we will go from there. Also take a picture of your crank main, with out the cap, I would like to look at the babbitt thickness. Thanks Herm.

[redmodelt]

First, I do not recall that there is a front or rear to any of the main caps. Once installed an run, they need to be put back in the the same place in the event of a tear down.
I would start by adding shims to the rear bearing to get the needed .0015 oil clearance. Then I would blue the cap and check for fit. You are looking to have around 85% usable surface on the cap. That means, when you put the bluing on the babbett in the cap and turn the crank in the cap mounted to the block with shims, what do you see? You are looking for as much contact between the crank and cap as you can get. If there are shinny spots on the cap, they need to be taken down.

[redmodelt]

I forgot about the rear radius for the crank to flange.

[Jalopy Tin]

First of all i would like to say that i appreciate it a lot all help i get from You.

Herm, here are the pictures You requested. My old cap and the crankshaft position in the bearing/babbit.
In the lathe today i also made a rod, exactly the same diameter as my crankshaft, and Voila!
The cap IS a standard cap and it should suit my crank perfect, but the bore is not straight, so it pinches. How about open up the bolt holes very, very little and regrind the ends without distroying the end play to much so it rides better on the crank?
Or even better.. order a new one..

[Jalopy Tin]

The gap in the last picture i assume fixes with the shims on each side.
/Tom

[Kohnke Rebabbitting]

Originally Posted by Jalopy Tin

First of all i would like to say that i appreciate it a lot all help i get from You.

Herm, here are the pictures You requested. My old cap and the crankshaft position in the bearing/babbit.
In the lathe today i also made a rod, exactly the same diameter as my crankshaft, and Voila!
The cap IS a standard cap and it should suit my crank perfect, but the bore is not straight, so it pinches. How about open up the bolt holes very, very little and regrind the ends without distroying the end play to much so it rides better on the crank?
Or even better.. order a new one..

It looks like you are doing a good job there Tom. I was going to suggest you open up the bolt holes, as that is about the only you have to fix it, as having the two bores match would be impossible, with out align boring. Are the ends at a right angle to the bore of the cap. If they are put the cap back on, and slide the cap on the bolts, and see where to remove only the metal where you need to to get the cap to align with the shaft. When you get that done, start snugging the cap, just so you can still turn it over,( pull the plugs, if you haven't) and leave black marks on the babbitt, so you then can scrap to fit. It is a long process. When you open up the cap holes, an end mill is the easiest, but a rattail file will also work, as it looks like your capable. thanks Herm.

[Jalopy Tin]

Done!! Fixed!! In place, with the right plays. It's a bit like domestic art...
A sharp knife, little imagination and nice knowledgeable guys at ford barn. Problem solved THANKS!!
/Tom

[Kohnke Rebabbitting]

Originally Posted by Jalopy Tin

Done!! Fixed!! In place, with the right plays. It's a bit like domestic art...
A sharp knife, little imagination and nice knowledgeable guys at ford barn. Problem solved THANKS!!
/Tom

Good Deal, Herm.