undersized cam bearings

[skabrock5]

this seems to be a common issue with aftermarket cam bearings. My machinist is planning on machining the bearings to fit the cam journals. is this safe?

[baldo]

Well they do have to measure the fit before they put them on. Thats the other main problem some dont do. As far as I know and keep hearing the same stories from everybody, you should keep the last stock bearing even if you put new ones on. Now thats with your own stock reground cam. Now if you buy a cam, then yes you have to "press your luck"............ (who is old enough to remember that?) and get bearings and make sure they fit. If he already told you he will machine it to make sure it fits then you should be ok. Machine shops can do ANYTHING! Some are good, some are not. I just make sure I tell them exactly what I want. They go by the manufacturers book specs. So tell them you want it to be in the middle as close as possible.
Let me explain a bit for you. So if they are going to grind something to factory specs they have a "too low" and "too much" number. So lets say for a cam the minimum is .0025 and the max is .0035. You want it to be at .0030. Metal shrinks when cold and expands when hot. So if you are in the middle, then you dont have a problem.

[73GTV]

Toyota does sell Undersize bearing for example on a 18RC they were sold in sizes 0.125 Undersize to 0.25 Undersize.

For the T-series engine: sold for a TA22 Celica: in sizes 0.125 Undersize: (11803-25010) 0.25 Undersize (11804-25010)

[skabrock5]

I couldn't find undersized bearings for the 3tc, maybe I didn't look hard enough. I'm already on my 2nd set of bearings trying to get over this hurdle. YES Baldo, I told him to keep it at the nominal dimensions. I told him as an option that he could slot the journals on the old cam and use it as a reamer to open up the bearing I.D.'s.

[skabrock5]

my machinist did a terrible job with the cam bearings. they look like total crap. I bought a third set of cam bearings and installed them myself with ease and it took less than an hour. when I went to test fit the cam, BAM, still doesn't fit. So I decided to hit it with 1200 grit paper and WD40 to remove some material for fitment...NO LUCK. Theres gotta be a better way. I'm just going to put some used original bearings from the one of my other blocks. FYI: I removed #4 first toward the back of engine, then pulled it out from the little opening between bearing 4 and 5. Then I removed #3 toward the back and out the same opening. then #5, #2, and finally #1 (toward the front of engine). To put them back in: first #3 toward front. then #4 toward front, then #5 toward rear, then #2 towards rear, and finally #1 towards rear.

[Estebot]

Where do you live? My machinist here in reno no built a tool to cut in the 2t/3t cams correctly. He has done mine before and no hassles. Basically it looks like a cam tapered with grooves and he works it in. Not a fun process but works perfectly.

[skabrock5]

Thanks Estebot but I'm in Houston. I ended up using some decent old bearings (#2 thru #5) from a spare block. I used the new Clevite #1 bearing but hit it with 500 grit for clearance and 3hours later it worked. Halleluya! It took a while because I was test fitting it frequently in between sand paperings. Now I have to clean block again and gap the rings for assembly. All down hill from here. woo hoo.