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TR4/4A Cam Bearing Install - TR4

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M

MoHealey

Senior Member
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Pressing new cam bearings into my TR4 block. Equipped with a bearing tool. Can someone give me a tip on how to best ensure the oilways/set screw hole are properly aligned as I press the bearing into place? Just trusting this to "eye" seems like it will result in multiple attempts to get it right.
Thanks,
Bill
 
I did mine by eye, and only had to redo two of them. A small mark on the block to indicate where the hole has to go may help.

There is some leeway (the pins are smaller than the holes), but do check to be sure the pin clears instead of catching the insert and bending it.
 
I did this a month or so ago - if you haven't seen this yet, this thread shows some pictures that might help: cam bearing install

I used a small marker pen as Randall mentions to help mark the block relative to the bearing, then slightly rotated until I got it right. And yes, I think it easily can take multiple steps - I tried to put a reference line in to the oil drain hole and that still didn't help make it foolproof.
 
Great thread.
Thanks for sharing. I've got one bearing installed, and the screw head alignment looks good.
I'm going to use the mirror tip to be certain of the other holes before I proceed any further.
Thanks again
Bill
 
Would someone be able to advise me how to connect to the "cam bearing install" thread that TR4nut mentions in this old BCF forum thread? I'd appreciate being able to see the pictures. I'm trying to ensure that my machinist installed the cam bearings with all the right holes matched up, both the locator holes as well as the oil feed holes. This is for the TR4 engine that is in my TR3. Thanks!
Regards,
Bob
 
Randy, thank you very much for the pictures. That is very helpful. Based on your pictures and comments in that thread, I believe my cam bearings were installed incorrectly. Here are how mine were installed:
1) Back bearing: Oval hole over retaining bolt hole. Small round hole up to hole that goes up to main bearing. Large round hole goes up toward top of block.
2) Middle bearing (near middle main bearing): Oval hole over retaining bolt hole. Large round hole is not over a hole, i.e. is blocked by head
3) Small narrow bearing: Oval hole over retaining bolt hole. Small round hole toward bottom of block to what looks like a small hole in the block.

Are these installed incorrectly? Can you tell me where each type hole should be placed? (for example I would guess that the small round hole should go over the hole for the retaining bolt.)

Thank you!!!
Regards,
Bob
 
Very interesting topic. I have never installed cam bearings, mostly because I assumed they had to be reamed all at the same time (like line boring) to make sure the cam is aligned with all the bearings. Do you guys have a reamer that does that or do you ream just one at a time?

Jerry
 
This afternoon I called Dave at TRF Tech Support, He is EXTREMELY helpful!! He told me some information that he had written down quite a long time ago concerning how the cam bearings are to be located in the block housings. As a result, we concluded that my cam bearings are installed in the correct orientation with the right holes in the right places, except that the hole alignment could have been a bit better.

Here is the information that Dave told me:
1) The oval hole is the one used for the locating/retaining bolts and as you look at the front of the block with head at the top, the hole should be oriented at 3:00 o'clock.
2) The small round hole is the main bearing feed and as you look at the front of the block with head at the top, the hole should be oriented at 8:00 o'clock. (Note: we could not determine a use for the small hole in the narrow cam bearing.)
3) For the middle cam bearing (by the middle main bearing) the large round hole has no purpose and is probably blocked. Although Dave did not have it written down, we concluded that for the back cam bearing the large round hole is the rocker assembly feed hole from the head, and the orientation of that hole is 10:00 o'clock. We assumed that the large hole is put into both of the wider cam bearings to allow the installer to place them in either the middle or to the back so no worry about which one to use.

Jerry, the new cam bearings get pushed in using the special tool and it also pushes out the old cam bearings. No need to ream anything. Although my machinist did verify that the new cam bearings correctly fit on the new cam before he installed the cam bearings.

Hopes this helps!
Regards,
Bob
 
Bob-

Sorry I missed your question but looks like you have things sorted. I wouldn't have been able to answer with much authority anyway, as its been a couple years since I last did this. My way of thinking there are really only 2 critical items to sort out with the bearings - get them installed so that the locating bolt cleanly threads in and doesn't interfere with the bearing, and ensure all oil holes are open to the bearing which you can check with some kind of probe. Other than that its just a slightly tricky and tedious job to pull them in place to get the alignment satisfactory.

Randy
 
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