engine camshaft bearings
- Thread starter tudoor
- Start date
Patrick L.
Well-known member
The good engine rebuilders can install cam bearings or bore for an oversize camshaft.
James Rogers
Well-known member
There are no commercially available camshaft bearings. Even if there were, you would have to have the cam bores align bored to open them up enough to fit them then, the bearings would have to be align bored to fit the cam. 100% of the original used or reground cams have some wear on the center bearing. The most economical way to solve this problem is to get a new performance cam from Bill Stipe to remove the wear in the cam bearing. This won't take out the wear in the block but it will solve half the problem. The other resolution would be to get a cam from Bill with .003 oversize bearings and have the bores honed to the new size plus the suggested clearance of .001.
If you go with a cam with oversize bearings, you can have it ground with more lift for better performance. I believe Bill has these available off the shelf.
If you go with a cam with oversize bearings, you can have it ground with more lift for better performance. I believe Bill has these available off the shelf.
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MikeK
Well-known member
I have two engines that have bronze bushings in the cam bores, bringing the size back to standard. I did them as James explained above. The cam center bearing is actually two bronze bushings, one on each side of the helical gear. I turned the bronze stock 0.003 larger than the overbore and I shrunk them with liquid N2 to install them before final align-bore. You need to drill the oil feed holes in them and pin the bushings to prevent them from drifting. A LOT of work, but I wanted very tight clearance, 0.0005, for OHV builds with a lot of spring pressure.
Going this route permitted me to get the crank/cam bore center spacing dead-on and permits easy swap to different cams of stock diameter. If you go with oversize cam bores you are stuck with the necessity to always use a custom made cam.
I'm not saying this is the best option, it is just what worked for two builds I did. If you have no intention of trying a half-dozen different cams in the same engine, just go with an oversize cam from Bill Stipe.
Going this route permitted me to get the crank/cam bore center spacing dead-on and permits easy swap to different cams of stock diameter. If you go with oversize cam bores you are stuck with the necessity to always use a custom made cam.
I'm not saying this is the best option, it is just what worked for two builds I did. If you have no intention of trying a half-dozen different cams in the same engine, just go with an oversize cam from Bill Stipe.
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As noted there are no cam bearings. I assume you have measured the existing bores and the cam and that there is more clearance than you want. The stock bores were 1.560. Acceptable, but not good, diameter for the cam bearings is 1.557. Is your problem the cam, if so, first search for a better cam. If it is the block, it can be align bored out to whatever size you want for an oversize cam, or, bored out to any size, install bushings, and then as James says align bore the bushing to the size you want. That is what is possible.
What is practical is something else. Finding someone who would do the work for me was tough and when I found someone it was expensive for what I thought was a fairly simple job. The rebuilders of modern engines around here told me they did not have the equipment to handle an A block. Maybe they just did not want the job, don't know. The guy who finally did it explained all the problems he had getting the block in his machines and the time it took. He did a good job, things are fine, but Wow. First measure, then call around.
What is practical is something else. Finding someone who would do the work for me was tough and when I found someone it was expensive for what I thought was a fairly simple job. The rebuilders of modern engines around here told me they did not have the equipment to handle an A block. Maybe they just did not want the job, don't know. The guy who finally did it explained all the problems he had getting the block in his machines and the time it took. He did a good job, things are fine, but Wow. First measure, then call around.
Mike V. Florida
Well-known member
Did you measure your block? Do you really need to have the work done of are you just being careful? Is this for a stock engine or something else?
Patrick L.
Well-known member
You're on the east coast. I think J & M can do it and I know Schwalm's can.
Mikeinnj
Well-known member
Most eighty+ year old Model A blocks have worn center cam bores, thus causing a whipping action to the cam and throwing off valve clearances. I had my block's cam bearing surfaces bored and bronze bushings installed by Schwalm's Babbited Bearings in Pennsylvania. I also installed a set of modern valves/guides and a new Stipe 340 cam.
Cam Bearings Installation - $495.00
Includes boring block for bronze cam bearings, cam bearings, grinding cam bearings to .010 undersize, and installation of cam bearings
Cam Bearings Installation - $495.00
Includes boring block for bronze cam bearings, cam bearings, grinding cam bearings to .010 undersize, and installation of cam bearings
J and M Machine
Senior Member
Tudoor: We handle this with ease since Stipe machine has oversize camshaft's available we can machine the block oversize to accept the camshaft. No need for oversize bearings.
http://www.jandm-machine.com/lineBoring.html
MikeK
Well-known member
I've heard of this being done by Schwalms and it puzzles me. If one goes to all the work of installing cam bearings why would you make them 0.010 under, requiring any cam you use to have the bearing surfaces reground?
I suppose you could then salvage a worn cam, but you have ruled out drop-in use of any standard dia. new or excellent used cams.
The thought of taking a new Stipe 340 and grinding it 0.010 under is a pretty permanent step. If the block goes south, you can't re-use the cam. At least a new cam ordered oversize can, at some point, be ground back to std.