TOPIC:

BOM.... Oh hell no , Absolutely not.... lol!

I think what Street Fighter has in mind is BODY of the Month, with pics of OMR in a speedo scrolling across the homepage!!!

Cool, I hope it works.
Steve

Thanks guys. I picked up a cap from Bob's Used Motorcycle yesterday before I watch the Diamond Backs loose to the Dodgers. I will put it on today after work and see how it fits. I will most likely have the original cap welded as a back up. I will have to make something to bolt it to so it doesn't twist after being welded.

If you replace a broken cap with a random one from another head, there is two things you should check for compatibility.

1. if that cap is the end thrust bearing one, bolt it on with both knock pins and torque it down without the cam in place and check that the thrust bearing surfaces align / match very close top and bottom at both ends. You can also check by installing the cam and checking to be sure you have the minimum specified cam end play.

2. Get some plasti-gauge and check the cam bearing clearances in the new bearing cap at the top and at about 45 degrees from top - make sure you have adequate clearance at both locations.

If you are within limits for both 1 and 2, you should be o.k.

I've done this a few times, and usually had to chose from a few doner cam caps before I got ones that fit well enough to use.

Thanks I will do some double checks before it goes back together.

kaw-a-holic wrote: Thanks I will do some double checks before it goes back together.

Hey, I forgot to think that through - you can't plasti-gauge the caps with the valves in the head....the springs will compress the plastic and give a false indication. The head has to be disassembled before you can test the bearing clearances that way.

You might be able to use the plasti-gauge if you place the strips at the bottom (head) side of the bearings, but even then you might get an inaccurate reading.

There is another way to check without pulling the head, though:

Remove the cam and bearing shells for both of the exhaust cam caps. Install and torque the original (#2) and replacement (#1) caps without the bearing shells, and compare the bore size between the two with a bore gauge or snap gauge and micrometer at the 6 - 12 o'clock, 1:30 - 7:30, and 4:30 - 10:30 positions. The bores should be within 0.0015" (AT MOST) of each other on all measurements...the new cap can not be any smaller diameter than 0.001" smaller than the original (#2) one.

I don't recall if the head's machined bearing bore size is given in the service manual; if it is, check against those.

Jon I'd use the new one as a jig bolted together to the broken one flat to flat and have the old one welded. Grind a V in the crack and the welder should have it done in a few minutes.
Steve

phoenix.craigslist.org/evl/mpo/5779126844.html -probably a J motor but might be worth checking out.

TexasKZ wrote: I think what Street Fighter has in mind is BODY of the Month, with pics of OMR in a speedo scrolling across the homepage!!!

OMG not OMR

Im going to have nightmares over this

Dave

PS Getter Done Jon !!!!!!!!!

I suppose we could start a therapy fund............

swest wrote: Jon I'd use the new one as a jig bolted together to the broken one flat to flat and have the old one welded. Grind a V in the crack and the welder should have it done in a few minutes.
Steve

Welding will distort the cap and change the way it fits onto the head....no getting around it. Thermal expansion is a powerful - no, let me phrase that better - unstoppable force.