Looking for advice on some aspects of engine build.

[Chewpapa]

Test fit the cam today, double thrust bearings were too wide for the cam. After massaging the bearings I got the cam to fit but I have 0 end play. SO what it a target spec to set it to?

BUT I also have a clearance issue on the cam journals. My measurements were telling me I should have started with .0004 ( But I am closer to 0 than .0002. ( bad math on prior posts) I ordered in a set of Mahle cam bearings and they are actually thicker than the Silverline.

Mahles .0500
Silverline .0494

The camline is measuring a consistent 1.0834 and the cam journals are consistent. .9844.

The only info I have found on journal size is a max of .9840. Can someone verify this?

[bedlamite]

https://www.thesamba.com/vw/archives/manuals/1971withoutguesswork/8_9.jpg

[Chewpapa]

[modok]

Those booklets were never re-printed. Some of them have year specific into not found elsewhere, but 90% of that info is in the common bently manual. Half the cars I bought cam with one of those manuals in them already so I never had to buy one.
Google "without guesswork samba" it should come up. hard to navigate but free.

[chrisflstf]

Looking at crank bearing clearances, I wonder why the spec for #2 bearing, the split one is
.001 to .003", when the others are .002 to .004"

Why tighter on that bearing? Is that relevant still today, or is .0025" a better overall clearance?

[modok]

Because magnesium expands 2.5 times faster than steel as it heats up, the main bearing clearances could increase by as much as .003" when hot.
The other mains are made of a tin and aluminum alloy, no layers just solid.

Being a flat engine the crank slapping back and forth with .005" clearance caused excessive noise.

I think VW found making the center main extra tight clearance was the easiest way to fix that "problem".
Subaru did the same thing with their EA engine, probably for the same reason.
The center main has a thick steel shell, and a tri-metal facing, so that allows it to run tighter clearance, and since the steel shell does not expand as much it stays tighter clearance when hot.
But in order for the bearing itself not to be loose in the case when hot they put .003-.005 crush fit on it. And that's so much interference fit that it holds the case halves apart a few thou, and it has about .002" eccentricity in the wall thickness to accommodate the fact that..... in that condition it is residing in an oval hole. And it also seems to change shape as it heats up, it gets looser vertically and tighter horizontally as it heats up and the case halves come together.
It's a very strange bearing, but if it fits half right it does work fine, tho I would not have believed it if I didn't already know.

[Shane Tuttle]

Not sure if you ordered your oil pump yet or not: I bought Berg's 26mm. CB's Maxi 2 is supposed to be a good quality, as well.

Rick Wright built my transaxle. You did good going with him.

If you still have issues with your bearings, Marcel at VWNOS hooked me up with old KB main bearings. I have Silverline double-thrust cam and rod bearings that I bought from DPR as a backup. I'll be in your boat looking for those if they fit as bad as everyone else is saying when I build my engine.

[Chewpapa]

[quote="modok"]Because magnesium expands 2.5 times faster than steel as it heats up, the main bearing clearances could increase by as much as .003" when hot.
The other mains are made of a tin and aluminum alloy, no layers just solid.

Being a flat engine the crank slapping back and forth with .005" clearance caused excessive noise.

I think VW found making the center main extra tight clearance was the easiest way to fix that "problem".
Subaru did the same thing with their EA engine, probably for the same reason.
The center main has a thick steel shell, and a tri-metal facing, so that allows it to run tighter clearance, and since the steel shell does not expand as much it stays tighter clearance when hot.
But in order for the bearing itself not to be loose in the case when hot they put .003-.005 crush fit on it. And that's so much interference fit that it holds the case halves apart a few thou, and it has about .002" eccentricity in the wall thickness to accommodate the fact that..... in that condition it is residing in an oval hole. And it also seems to change shape as it heats up, it gets looser vertically and tighter horizontally as it heats up and the case halves come together.
It's a very strange bearing, but if it fits half right it does work fine, tho I would not have believed it




This is the issue that I ran into while doing some math the other day. My split bearing puts me at -.001 clearance. Ordered a set of Mahles to measure

[chrisflstf]

Main bearings are all over the place on clearance. I went thru 5 sets before I could have decent clearance on #2. Three sets of Silverlines, 1 old set of Kolbenschmidt and a new Clevite I just bought

With the case fully torqued and using crank OD of 2.165” I had these for number 2 bearing

1st Silverline - .0009”
2nd Silverline - .0015"
KS - .004” also had almost no crush. Inner grooved, but not steelbacked
Clevite - .0042”, #3 was way over also, but very nice #1. Steelbacked
3rd Silverline - .0022”

All 3 brands had different oil hole sizes, KS was biggest, then Silverline, then the new Clevite. Diff by .060”

First 2 sets of Sliverline came from Gary Berg and had Empi stickers on them. 3rd set did not and came on a more orange box, not yellow, Probably an older batch

[modok]

IF the case bore is on the small size of spec, and that is causing the center main to be too loose in the horizontal direction (it's basically holding the case halves apart more than needed), then I think you can sand the parting surfaces of the bearing and tighten up the ID maybe .0015" or so with that, but that's about all you can do to that bearing.

[Chewpapa]

[modok]

Yep not the right fix for you but maybe would help the other guy.

Same thickness as the other bearings... so it's not a steel shell bearing then.
I might use it anyway.