Cam bearing cap question

[Slow old poop]

We broke one of the cam bearing covers the other day when reassembling the head after P&P machine work. Just snapped it in two.
Mitusibshi won't sell me one -- they want to sell me an entire head!
So I got one off a junker turbo and one off a spare head lying around the shop.
Problem is, the numbers don't match.

The one I broke says E3 with a big arrow pointing to upper left.
The rest of the cam bearing covers on that side are numbered E1, E3 and E4.

The closest I can match this is one that says 3-2 E3.
The other says 2L3

I also have about 16 other cam caps from assorted heads, but none have the number 3.

How critical is this bearing cap? The Mitsu parts guy says the different numbers probably relate to who stamped them and when.

Another problem is that I don't know where the head came from. I bought the car built, and it came with two spare junk heads and a bag of parts (including the bearing caps).
This is an engine that can rev tyo 8500 rpm, so I thought I'd ask the wizards.

How critical is the bearing cap?
Advice, please.

Rich

 

[project_tsi]

I'd think that it woun't be too critical, as long as its installed correctly.

BUT, this is a big but here. I'd think some sort of a line hone would need to be done to ensure proper clearances, etc. Just like when adding ARP main studs a line hone needs to be done. Or when changing main caps, a line hone needs to be done. So some sort cam line hone would probly need to be done, however I wonder if anyone would have a hone that would go that small.

Call up Mitch at Engintecs, he's very nice, and see what he says.

 

[ECLIPSE4x4]

First off I never heard them called cam bearing caps. Just cam caps.

Second they are matched to the head that is why mitsu is trying to sell you a whole head.

I doubt you will find someone just selling one cap. If you do, you may or may not have issues with clearances.

I have always been told that you should never swap cam caps.

maybe someone else has other knowledge.

 

[gsxtacy]

I have swapped them from one head to another and haven't had any problems.....yet. I would just make sure its the same location cap from a different head.

Thats my opinion though.

gsxtacy

 

[ECLIPSE4x4]

Personally since he is in a bind, I don't think one cap is going to hurt myself. but that is me.

 

[pneumo]

I got a used head without caps and nothing fit it, it was junk. You might want to do some checking before you commit to running that head. Simply install the cam and one spare cap, and spin the cam by hand to see if it turns smoothly. If not, try another cap. The number 3 is used to identify it's location- 3rd back from the cam gear. 2 through 5 share the same dimensions, so you can try others. I'd also pop off the valvecover after the engine has about 500 miles on it and check that cap's bearing surface just to make sure it's holding up to regular use. Good Luck!

 

[Slow old poop]

Thanks for all the advice. I am definitely NOT going to buy a new head just to get one crummy cam cover cap, especially since I have at least 8 same-side caps from two different heads in my parts bin and access to probably dozens more at a local DSM shop.

If "2 through 5 share the same dimensions," then how would I match up one? Remove another 2-5 cap from the cam in my engine and compare it to all the spares? What is the critical measurement? A Plastigage reading of bearing clearance?

Rich

 

[pneumo]

If "2 through 5 share the same dimensions," then how would I match up one? Remove another 2-5 cap from the cam in my engine and compare it to all the spares? What is the critical measurement? A Plastigage reading of bearing clearance?

Rich

I should clarify that statement a bit; 2-5 have the same external dimension, but the bearing surface may differ slightly. That's what determines if it will work or not. It's also why each cap is numbered- so you can put it back in it's original location. Since you don't have the original cap, you'll have to settle for 'good enough'.

To check the caps install one without the cam and run your fingernail over the bearing surface junction between the upper cap and head and feel for any edges. Hopefully you'll be able to find one that makes a smooth transition. If not try another one.

Once you find one that's close, install it with the cam and check for smooth operation. Plastigage would be a good idea too, clearance should be 0.003" max.

 

[90turbotsi]

I agree with the above response. Try a few caps out and find the one which fits and has the smoothest transition between surfaces. From my personaly experience id never buy or run a head that was missing cam caps as they are specific to the head they came off of. Im sure with enough attempts to find one that fits you will have some success. However I guess the question is, is it one of the outer caps or inner caps which are more interchangable and such...?

I had a head on my bench, it was a damn perfect core at the least... came back the next day and the thing was on the floor. Somehow it fell off the work bench (how id love to know) and dented the hell out of the last cam cap by the cas. I am still to this day searching for an exact fit cap (with no success).

Oh well good luck

 

[steve]

The caps are the bearings for the cams that's why they are not interchangable. The set is bored during assembly. You might come close with a replacement but on anything you really expect to spin at 8500 RPM again that side should be line bored or honed.

At the very least you should find the best match and then check the clearances on that cam.

Steve

 

[jetdriven]

the max the cam sees is half the engine speed, so 3750 rpm is the limit on the cams with stock rev limits. Try plastigauging the new cam cap and try a few out perhaps you'll find one that is close enough. Or buy another 1G stock head and swap it on.

 

[Slow old poop]

the max the cam sees is half the engine speed, so 3750 rpm is the limit on the cams with stock rev limits. Try plastigauging the new cam cap and try a few out perhaps you'll find one that is close enough. Or buy another 1G stock head and swap it on.

Buy a new head? Crikies, I just spent a fortune getting that head ported and polished.
What's the worst that can happen with the current situation? Wear out the cam bearing?
It won't fail catstrophically, will it?

Rich

 

[NOSNUSE]

The letter indicate which side of the head they go on I=intake and E=exhaust. The number is the place in which they go in order from the CAS(i believe) to the other side. The arrow points in the direction as to which way it is placed on the head so you don't put in on backwards. I would not use a cap off of another head I would just get another head and go that route. You could get an aline-hone done and that might work, but then the spacing between the caps and the cams has increased.

 

[jetdriven]

Buy a new head? Crikies, I just spent a fortune getting that head ported and polished.
What's the worst that can happen with the current situation? Wear out the cam bearing?
It won't fail catstrophically, will it?

Rich

what I would do is put the dry cam in the head and plastigauge 3 or 4 of the other caps and torque them all down. then remove the caps and measure the clearance. Say for instance it is 2 thousandths.

then take your bag of cam caps and keep plastigauging and torquing them down and removing them until you get one that is really close. slightly loose is better than too tight. If its too tight the steel cam will gall and pick up metal from the cap and tear up the head. If you have one that is slightly loose you can wet sand it with 400 grit until the clearance comes in.

 

[steve]

What's the worst that can happen with the current situation? Wear out the cam bearing? It won't fail catstrophically, will it?

Wosrt case is a catstrophic failure where the cam seizes, strips the timing belt, all the valves on the other cam hit the pistons and some on the seized cam. If your lucky you only bend the valves, if your unlucky you break one or more and trash the engine.

Steve

 

[90turbotsi]

Or metal fragments will end up down in the pan, get to the bearings and then you'll eat the bearings up... trashing the crank

 

[Suparata]

Buy a new head? Crikies, I just spent a fortune getting that head ported and polished...

That was nothing compared to what you will throw out the window if use the wrong cap there.

I should clarify that statement a bit; 2-5 have the same external dimension, but the bearing surface may differ slightly. That's what determines if it will work or not. It's also why each cap is numbered- so you can put it back in it's original location. Since you don't have the original cap, you'll have to settle for 'good enough'.

To check the caps install one without the cam and run your fingernail over the bearing surface junction between the upper cap and head and feel for any edges. Hopefully you'll be able to find one that makes a smooth transition. If not try another one.

Once you find one that's close, install it with the cam and check for smooth operation. Plastigage would be a good idea too, clearance should be 0.003" max.

That is the best you can probably do at this point and you might be lucky.
On another note you should be tortured because you ruin additional heads that might be good cores trying to fix a mistake .
One way or another it will only be a “fix” and not perfect. Pray that nothing will happen because any kind of a warranty that you might get on the shortblock will be completely void if you use that head.

 

[jetdriven]

you guys are reading too much into this. Just find a cam cap that meets the oil clearance and be done with it. You can use a brake cylinder hone to enlarge it.

 

[Slow old poop]

Wosrt case is a catstrophic failure where the cam seizes, strips the timing belt, all the valves on the other cam hit the pistons and some on the seized cam. If your lucky you only bend the valves, if your unlucky you break one or more and trash the engine.
Steve

OUCH!!! OK, already. You guys have scared the crap out of me. I don't want to risk blowing up my brand new 2.3 stroker and stage 4 race head. So I hunted around and found a machine shop in Davenport, Iowa, that will line bore the camshaft bearings. I'll pull the head and take it over there this weekend. They will match up all my spare cam covers, find the best fit, and then hone it or line bore it and make everything cool. I'll post the results after the work is done.

By the bye, thanks to everyone for all the advice. I'll print this whole discussion out and take it to the machine shop. They do a lot of DSM work, so they seem to know what they are doing.

Rich

 

[blue1]

Good move! And when you are reassebling after getting it line honed tighten them down EVENLY half a turn on each bolt in the same sequence as if you were tensioning a head, work from the centre out.

 

[Slow old poop]

Good move! And when you are reassebling after getting it line honed tighten them down EVENLY half a turn on each bolt in the same sequence as if you were tensioning a head, work from the centre out.

As it turned out, we stuck a replacement cap on there, and it felt perfectly smooth at the junctures. We plastigaged it all the way around, and it measured 0.003 everywhere, just like the other caps. So, the collective opinion was to go with the replacement cap and not linebore it.

Here's hoping...

Rich