tight cam help please

zbug · Posted: Thu Jan 22, 2015 5:14 pm Post subject: tight cam help please

I'm starting a 2176 build with a brothers machined as41 case. While mocking up, everything in the roller assembly went like a breeze until I put the cam in the case by its self to do the thrust bearing. I closed the halves, tapped it back and forth. didn't do much. So I removed it to very lightly sand on the bearing until I achieved .002 clearance. It rolled fine in each case half, but when I close them and torqued the 6 case nuts down it would't hardly turn. had to use a little force with a big screw driver to turn it. undid the case and there was smoothed section on the plug side bearing and a little on the outside edges of the thrust bearing.

removed the end bearing, put it back together and it spun pretty good. put end bearing back in and crap. It seemed as if the bearing halves were sticking up out past the edge of the case halves and I wasn't getting a good crush. So, without asking anybody first, I started sanding the ends of the the bearing to attempt to fix it. Aaand I need a new set of bearings. There's no crush left and now it won't turn at all with 15 lbs of torque

Has anybody had this problem and what should I look for. The cam is an SLR, and it mics perfectly at 25.00mm on every journal
Thanks in advance, sorry for the long post

Max Welton · Posted: Thu Jan 22, 2015 5:20 pm Post subject:

Call Brothers. The case might have a problem.

Max
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modok · Posted: Thu Jan 22, 2015 5:34 pm Post subject:

yeah it happens and isn't a good sign. The case squeezes together over time and the cam bore gets too small, may have to ream it.
Some shops do that to every case that they line bore.

midtravelmidengine · Posted: Thu Jan 22, 2015 5:54 pm Post subject:

zbug · Posted: Thu Jan 22, 2015 6:08 pm Post subject:

Well thanks for the help. I'm not gonna build on this case if that's what it is. I'd rather send another case in to be done that I know is good, than blow all the money I've got in parts. thanks again

zbug · Posted: Thu Jan 22, 2015 6:34 pm Post subject:

one last question or two. is this case good anything? Maybe a small motor, or should I not trust for anything?

modok · Posted: Thu Jan 22, 2015 6:51 pm Post subject:

I'm sure there are lots of VWs going down the road with worse engine cases.
Might want to double check how warped it is at the case split, check size of front and rear seal areas, lifter bores. if it isn't terrible then it should still be useful for something.

raul arrese · Posted: Thu Jan 22, 2015 6:56 pm Post subject:

I think its common and I think allot of guys let it fly the way it is , I have a case right now that is tight in the center cam bearing , I might make my own cutter or reamer , havnt got around to it yet .
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Dale M. · Posted: Thu Jan 22, 2015 7:41 pm Post subject:

Try different brand of bearing.... I had similar situation and it was poor bearings causing all the grief....

Dale
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midtravelmidengine · Posted: Thu Jan 22, 2015 9:31 pm Post subject:

hooker · Posted: Fri Jan 23, 2015 11:01 am Post subject: Tight Cam bearings

I have found that about 1/2 the engine cases that come to me have a warped bearing boss mounting for the cam bearings and I run my reamer through them all at the same time I do the line bore on the case. That usually fixes the problem but lately I have found that now the new double thrust racing cam bearings need a lot of cleaning up to make them fit and let the cam spin freely. It appears the flanges on the thrust has been over bent during the mfg process and warps the bearing so the cam will not turn freely when cam is installed and everything torqued down properly. Another PITA for such a simple thing. I've had to cut the inside of the bearing flange where it fit's into the case because when you install the bearing half it spreads the bearing and makes the cam tight for the end play, not the crush.
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raul arrese · Posted: Fri Jan 23, 2015 1:41 pm Post subject: Re: Tight Cam bearings

[email protected] · Posted: Fri Jan 23, 2015 1:49 pm Post subject:

If you are using dual thrust cam bearings, that is most likely your problem. Just use standard cam bearings. Dual thrust are really unnecessary except for race engines.
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Brian_e · Posted: Fri Jan 23, 2015 2:02 pm Post subject: Re: Tight Cam bearings

mark tucker · Posted: Fri Jan 23, 2015 5:25 pm Post subject:

make sure there are no burrs, Ive seen some warped bearings, there pretty small so that bend can be wonkifying the bearing. I would think you could make a jig to put the bearings into and a shaft(biger then the cam) so there is no clearance and try to press the bearing straight.....or try another set of bearings.Ive seen the front cambearing that was not square when it was formed so it stuck up at one point&down at another, it was bad enought it was visable to the naked eye !! I had noticed some funkey wear patterns on some cambearings I figured it was the small bearing's not being exzactly right when the flange was formed. some are machined after they are plated some dont seem to be,I wonder just how good these things are done and whoo has the best ones.??. I hate these small cam bearings any way.the bearings on a cam should be bigger than the lobes base circle... a lot bigger.

raul arrese · Posted: Fri Jan 23, 2015 7:42 pm Post subject: Re: Tight Cam bearings

zbug · Posted: Sat Jan 24, 2015 11:09 am Post subject:

problem solved. I've tried some mahle bearing that just arrived. perfect fit. I tapped it back and forth and got perfect clearance, spun freely when it was torgued down. Thanks everybody for the input

mark tucker · Posted: Sat Jan 24, 2015 12:21 pm Post subject:

thats what i suspected.what brand did you have?

modok · Posted: Sat Jan 24, 2015 2:26 pm Post subject:

Mahle run on the looser side, as much as .004" clearance Shocked

Silverline have about .0005' more thickness.

blue77bay · Posted: Sat Jan 24, 2015 8:18 pm Post subject:

nothing but trouble here with those silverline cam brgs ,every set has required work mostly to get the thrust set but some are tight as well ,we now source a different brand (green writing on box) and had no problems since,funny enough the silverline mains and rods are ok just the cam brgs are a pain in the arse
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