So I acquired a 99 Head and IM recently. The only issue with the head is that it is missing the Cam Caps. Apparently somewhere down the line the cams were taken off this head and the caps were misplaced.

I do have the original cams.

My question:
1) Assuming replacement caps were within spec, is it stupid to use caps that are not the original set from this head? Is this a dealer available part? $$?

2) if question 1 is yes: Are 94-97 cam caps interchangeable with the non HLA 99 head/cams? are the Journals the same dimension, as well as the bolt hole location? I believe they physicality look like a different casting IIRC.

I would like to use my 96 HLA cam caps on my 99 head.

Chime in with your thoughts. I understand this wont be IDEAL, but i got the head for a good price, I know it is healthy, and yes i will be doing a valve job btw.

Thanks

 

You need the whole set for ex and in? I'd say buy new but that would be costly as hell probably.

There will be matching wear marks on the cams and head but if you can find a really nice used set and clean them up lightly with some fine emery cloth you will be fine. Just be sure to torque them to spec and measure with plastigauge before firing it up.

 

Yes I need all of them unfortunatly. I figure as long as there are no major wear marks on the replacements I should be OK.

So are the 94-97's interchangeable with the 99-00

 

I would think a used set would be fine, even if wear patterns aren't the same, so long as both the cams and journals/caps are within maximum wear specs. They will get to know one another after a while. I would think all of the caps would be the same, but I could be wrong, that's just a guess.

 

cam caps are drilled in the head. they only fit one head, in one place, in one orientation.

if you want NEW cam caps, you have to start with unmachined castings and line bore them for your motor.

 

+1

You'd have to be extremely lucky to find caps that fit from another head - highly doubtful.

Most likely you will have to skim some off the 'feet' of the caps, install them, and then line bore the assembly. You will need to re-do the valve clearances after the boring. Hopefully after all that, you still got a bargain, but most likely not .

--Ferdi

 

+2

At one point I assembled a head with a couple of caps on backwards(but in the correct sequence). The cam could not be turned with the caps torqued.

I would still try installing your 94 caps on at least 1 cam to see what the results are.

 

Is this a mazda thing? Sorry to point you in the wrong direction OP.

 

Same here. Look what I get for assuming. This isn't the case with some other engines I have dealt with. At least now I know what not to get when the time comes for a 99-00 head, one without caps.

 

If you had a high dollar head with tons of port work, it would probably be worth boring the cap holes slightly bigger. You will then need a cam with bigger journals.

It looks like that proceedure is in my future.

 

So what about aftermarket cams then? If every journal/cap is unique how can you throw some cams in without modification?

 

The head would be align bored with the caps in place. All the holes would be the same. You would then have a cam manufacturer build the cam to the specs. You would not be able to use an off the shelf cam.

The cam and head would then be a matched set. And if you wanted a different cam, you would then have to build a new one, and there would be very little market value once you decide to get rid of it.

It would be a viable option only if you had a big investment in head porting and development, and you had a failure at the cap, or you lost them. Otherwise, it is best to just buy a new head.

 

It sounds like the op is screwed. No cams or caps on the used head.

 

I have the cams just no cAps. I'll throw it on the classified section for cheap. No loss to me. It still has good cams along with a complete intake mani. Oh well

 

yeah basically a miata head without cam caps is not worth much of anything.

there may be one other option that I HAVE NOT VERIFIED TO WORK:

new caps (or used caps) plus an oversize bore plus journal bearings. basically you'd set up your cam bearings like the crank bearings--with a separate sleeve sized to fit the cams.

 

Yeah I am 100% sure a machinist could make this head work, but I'm already too broke to bother with it.