1745cc bulld

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[Pruneman99]

It's not really the thrust faces. After I used a hammer and drift they seemed to seat fine, and the cam spun in the case halves. When I bolted it together, at 10lbs on the main studs it started to bind. There are witness marks on the inside of the thrust brearings near the edges. I think Brian was right that the inside chamfer wasn't letting the bearings sit down tight enough, and pinching the cam when it started to snug down.

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[Pruneman99]

Yes double thrust cam bearings. The case has been notched to accept the second thrust bearing without filing off the tang.

[Pruneman99]

So after messing with the Silverline cam bearings for another 3 hours I've thrown in the towel. These things are JUNK. I dug out a used Clemex bearing for comparison. It's like night and day on the quality. Too bad it's ruined from debris or I would have just used it.

I found some NOS Clemex bearings on VWNOS.com and ordered them up. I've done business with him before and have always been happy with the parts and customer service.

They are single thrust, but since I'm only running a CB2239 I'm sure it will be fine. Can't be any worse than the JUNK Silverline ones.

[Pruneman99]

I mocked up my new crank with the Silverline main bearings without measuring just to see if they were going to be obviously bad like the cam bearings. Happy to say the crank spins free and smooth. I'll take measurements later.

Since I had to order new cam bearings, I'd thought I'd go ahead and start cleaning up the cam. The mold must be getting old because there is some flash on the parting line. Worse is this:

The flash is so thick, it got ground into the lobe. Lifter chewer for sure. I'll hand flie this back, and take the edge off the others and touch up where necessary.

[Pruneman99]

I think I'm mostly talking to myself, but I got a bit of garage time.

I dropped the oil relief plundger into it's bore to make sure there was no problems there, and problem..

I didn't really want the machine shop to pull the plug at the top of the oil plunger bore but I forgot to tell them that. So it got pulled and tapped. Not necessarily a bad thing but it did leave a ridge preventing the piston from seating. An hour or so with some micro-files and a strong flashlight to clean it up and get the piston to seat and travel smooth.

Just something that needs checked and corrected if others have the same case plug pulled and tapped.

[Alstrup]

your issue with the silverlines is not recognizeable (for me at least) I have used maybe 25 sets of Clemex bearing in my life. At least 5 of the sets had issues. Soooo (!)
The casting inaccuracies on the cam is just about normal today. The higher priced cams do have less, but they all need chamfering on the edges. I do not see this as a problem. Its just something that needs to be done.

[Pruneman99]

I think the problem with the cam bearings is that the double thrust bearings were a bit too big. I think if I sanded the parting line, they may have fit but I.was done messing with them. The cam would spin nice in each case half, but when torqued, the bearing would crush too much and distort the bearing.

Anyway, after I cleaned up the oil plunger slot, I figured I'd clean up all the new threaded gallerys. After I checked each one and filed down any burrs, I stupidly decided to run some EMPI aluminum plugs in each.. well the #4 main bearing gallery plug got stuck, and stripped out. I swear these are made of butter. I barely put them in snug. Anyway the rest came out ok. I'll need.tk drill out the one that stripped and use an easy.out. serves me right for using thoes stupid aluminum ones instead of just waiting until I had steel ones.

Two steps forward, one back. Eh, that's how it goes normally.

[Brian_e]

You should wait to install your plugs until the very end. I do mine first thing during final assembly when the case is fresh out of the wash cabinet and dry. Then you know nothing got left in them during the mock-up.

And throw all the aluminum plugs in the trash. Mcmaster Carr has super cheap steel plugs in all the sizes.

I still think you should be using double thrust cam bearings. If not, make double extra sure your thrust surfaces on the cam are super polished and perfectly smooth. I lost a Mahle single cam thrust surface with a CB cheater cam and HD single springs. Never again will I use single thrust on any engine. I have had the best luck with Mahle double thrust cam bearings lately.

Brian

[Pruneman99]

Got the NOS Clemex bearings in the mail (Thanks again VWNOS.com!)

Installed, set the seat with a hit of a rubber mallet and bolted the case halves together with the cam. Whatdoyaknow- the cam spins like glass. The Silverline bearings where definitely the issue.

.004 on the thrust. Can't find my book right now to verify that's in range.

So a question-

Do you guys think I'd be ok running the CB 2239 with a single thrust bearing? HD singles for springs, helicoil gears.

[modok]

Sorry didn't catch that you had silverline cam bearings.

yeah they are junk. Silverline main bearings are the best, but the cam bearings are the worst I spent an hour messing with them to get the crush right and the thrust faces flat. Two sets were like that. Next set I got, I just threw them out.

Make sure the thrust faces on the cam are smooth and polished. If you have any old cam bearings....check the thickness with a ball end micometer (or whatever you can rig up). less than .0005 wear, use em again!! Turn the unworn thrust side is towards cam gear.

[Pruneman99]

I only had a used Clemex bearing in my stash for comparison, that's how I noticed the difference, and why I ordered the NOS Clemex bearings. Unfortunately the one I had was debirs runied, or I would have used it.

Interesting thing was the NOS Clemex bearing had a paint mark on the thicker (by my eye) side. I placed it to the gear side. Compared to the Silverline bearings, these are WAY better, and the cam spins like glass.

My only concern is that it's a single thrust bearing. My cam is only a CB 2239, but I'm still concerned that I'd be running a single thrust.

[Brian_e]

I won't do it, but you can go ahead and try it.

Like I said, make sure the thrust surface on the cam is mirror smooth or it might chew into your already limited bearing thrust surface.

For what a set of good bearings cost, why not just order another set and use just the thrust? You will always be wondering once it's together and running. Not worth saving $20 over.

Brian

[Pruneman99]

That's a good idea. Now that I know the Clemex bearings fit well I can see if he has another set.

There is no tang on the thrust bearing though. If I use two thrusts there would be no tang in the case. Think the crush would be good enough to keep them in place?

Crazy tthe stupid cam bearings have been such a headache. I'm going to spend more cash on the bearings than the cam

[okubricko]

Hey all, I have a quick question but don't want to hijack this thread. I like this build and during this winter I will be doing a new build myself. Would it be possible to use 87mm pistons with the 76mm crank? Just a thought that came to mind.. it would be even more different than Pruneman's build Thanks and back to your regularly scheduled thread.

[Brian_e]

[Pruneman99]

[Pruneman99]

Got my cam all cleaned up, flashing filed down, and the sharp edges knocked off the lobes.

Played with the cam gears next. I was going to use a OG used gear I had on hand, but one of the teeth is bent slightly, making a sticky spot when rotating the gears together in my hands.

Picked up a crank gear. The CB timing gear needed to be touched with a file as some of the teeth had a high ridge on the edge. A dry erase marker works good for checking for high spots

Also finally weighed all my pistons. Heaviest was 349.2 grams, lightest was 348.45. So .75 grams out of the box. The pin bosses are very stout and have plenty of material that can be filled to balance them up.

Piston pins are within .1 gram as well.

The build marches slowly forward.

[Pruneman99]

Sorry I haven't updated this thread in awhile. I don't get much time in the garage, and really I've just been "fixing" new parts mostly. The AA rods needed a bunch of attention. They had nasty burrs on the parting halves, and needed the threads chased. The bolts would not thread through by hand at all. Got them all cleaned up, and installed on the crank.

Since this is a 76mm crank I wanted to see how much I was going to need to clearance the case and just mocked it up. With the radiused rods, there isn't going to be much at all. In fact, I can spin it over by hand if the crank isn't pulled all the way forward. Surprised, because without the Pistons installed, it looked like there would need some serious clearancing to the case at the cylinder openings. Once I put the cylinders and pistons on to hold the rods in the right place, it didn't hit anywhere.

I'm sure I'll have to clearance a bit here and there to make sure I'm not too close, but it's going to be very, very minimal.