Broken Cam Bearing Cap?

[Ira B]

Got a lovely heap of parts that include two dead 1.6 diesel engines w 12mm head bolts.
The goal is/was to rebuild one to put in my Caddy when I restore it but there is a problem. Only one of the engines had a head. The head is in otherwise good shape but one of the cam bearing caps is broken. My guess is that someone torqued it on backwards and snapped it.
Any know of a reasonable way to fix this?

[82vdub]

Only possible way to fix it would be to have a machine shop weld the cap/seat in the head then line bore the cam journals when they're done. It's the same process when resizing connecting rods or when you get new (or different) main bearing caps for your motor. They remove a little amount from one of the "seats" of the cap, install and then bore out the openings to resize them back to spec. It may be just as much money as finding a rebuilt head. Call a machine shop and ask.

[rsxsr]

You could try a cap from a different head. In a perfect world, the cam should spin freely in the head when torqued in without a valve train. I would be inclined to use a cap from another head before I'd want to weld on. There is a company on the west coast called Rimco that can line bore the cam journals and machine it to accept bearings.

Another test is to lay the cam in the journals without caps or a valve train. If the cam rocks end to end, the head is warped and will need to be straightened or line bored. Maybe better to do the rock test first. If it rocks, you will not be able to spin it with the caps torqued.

If the cam does not rock and a cap from another head can be fitted and the cam spins, It would probably be fine for street use. I have seen much worse still running.

[82vdub]

You could try a cap from a different head.

If the seat and cap are what I think they are, they are a matched/machined pair, just like the main caps on the block. If you mix up the cap for the seat that it was machined for, it doesn't work. I would be willing to bet that the cam journals on the head are the same thing. The cap must be installed the same way on the same seat it came off of. By installing another cap, it's a mis-matched pair, and the setup should be line bored to get it fresh again. I also assumed from the original thread that the head was damaged (broken) where a new cap just doesn't bolt on.

[Ira B]

I know these caps are line bored "in situ" at the time of manufacture and are not in theory interchangeable. I also know that they are probably close enough from one head to another that if I had a mountain of them I could probably find one that would work. I just don't have a mountain of them.

Crying shame because the head is otherwise in excellent shape. I was hoping one of you brainiacs would have some magic fix for it.

I'll probably strip it and scrap it.

[Quantum-man]

I know these caps are line bored "in situ" at the time of manufacture and are not in theory interchangeable. I also know that they are probably close enough from one head to another that if I had a mountain of them I could probably find one that would work. I just don't have a mountain of them.

Crying shame because the head is otherwise in excellent shape. I was hoping one of you brainiacs would have some magic fix for it.

I'll probably strip it and scrap it.

Have you got a pic of the cap?
Which one?
Why not just glue it together.
Not a great deal of loading on any one cap until you get piston-valve clash.

Can it be moved into the middle?

[air-cooled or diesel]

welding is option, like said ^ another head will probably cost just about as much as all the work, and welding is not a guaranteed fix, sorry to say. if you go to all the trouble to weld and machine and it doesnt work its $$ out the window.
Gule? and you turning 2000 rpm and more (thats 1/2 the speed at cam), that wont work. you'd need to completely weld cap so its totally fused, tig welding only does outer part of 'groove', not the complete width of cap/break.

[Quantum-man]

OK if gule er glue is out then how about drill, and tap and stud. All depends on the place of bustation I think.

[air-cooled or diesel]

there you go good idea, but 1 problem you have the studs to contend with. if you join the 2 pieces just right and drill from 1 side and tap the length of the drilled hole, have a threaded screw thats threaded the length run it in tight and Then you can glue it too(first before running screw in w/ loctite/ or bearing mount). then drill out the screw where the cam stud goes, you may be able to make it work. drill all the way from one end to the stud opening on the other side.

the whole time of steup for this project the cam caps must be perfectly aligned.
oh yea put some loctite on the whole screw your running in too.

[air-cooled or diesel]

if you know to tig weld you can add some weld, if you have the right equiptment.

[air-cooled or diesel]

quantum man will know some better 'glue' to use.
if you can get it tig welded i have some advice for it, but you wont be welding on the bearing surface.

[Fatmobile]

I think you could find a cap from another head that would be close enough to fit,.. maybe have to be built up with weld before machining.
Or I wonder if it would be possible to install a couple bearing halves.
That would require the removal of alot of meat so how well the cap aligns wouldn't be so important.

[air-cooled or diesel]

what # cap is broken i have a couple of heads that i wont be using, i'd think of sending you a cap if i knew which one.(#1-5)