Rebuild on hold

C-Gazer · Postby **C-Gazer** » Sun Jan 25, 2015 3:32 pm

Following up on my post on the NB8B engine rebuild from last week I am searching for the #1 exhaust bearing cap. I have tried Automotive Plus, overseas sites and the wanted post. The local Mazda dealer cannot supply the bearing cap on its own. I think the cap must only be available with a new head. Has anyone run into this problem before? The strange thing is that all other parts of the head are readily available eg valves,valve guides,valve seals, springs and cam shaft. My reconditioner can repair the head but not the damaged cap. Any ideas ?

project.r.racing · Postby **project.r.racing** » Mon Jan 26, 2015 8:22 am

what is an exhaust bearing cap?

whatever the part may be, the exhaust is the same as all the not vvt mocels, to steal the part from another car second hand.

tbro · Postby **tbro** » Mon Jan 26, 2015 2:37 pm

C-Gazer wrote:Following up on my post on the NB8B engine rebuild from last week I am searching for the #1 exhaust bearing cap. I have tried Automotive Plus, overseas sites and the wanted post. The local Mazda dealer cannot supply the bearing cap on its own. I think the cap must only be available with a new head. Has anyone run into this problem before? The strange thing is that all other parts of the head are readily available eg valves,valve guides,valve seals, springs and cam shaft. My reconditioner can repair the head but not the damaged cap. Any ideas ?

c,
The caps are line bored on the head at the factory, so you will need to get a cap, then have all the exhaust caps resurfaced on the mating surface and then line bore the cam
tunnel, I'm suprised that the machinist didn't tell you this, basically your gunna need to spend some serious money and would probably be cheaper to get another head.

What exactly is wrong with the original cap, I hope your going to tell me it has pin holes in the cam surface, if so, find another machine shop as this is quite common
in alloy heads and poses no problems in anyway, even in a race motor.

Terry

C-Gazer · Postby **C-Gazer** » Mon Jan 26, 2015 8:03 pm

My apologies I should have described the #1 exhaust bearing cap as the exhaust cam shaft #1 bearing cap. The lower bearings for the intake and exhaust cam shafts are part of the head . The caps are the upper bearings which bolt the cam shafts into place. My engine seized at the #1 exhaust cam shaft bearing due to no oil supply tearing off metal from the exhaust cam shaft. I have located another cam shaft . The reconditioner can repair the the lower bearing by welding / machining but not the cap. The cap is most likely the same on NB8A and NB8B.

Caffeine · Postby **Caffeine** » Tue Jan 27, 2015 1:53 pm

I'm picking up my engine tomorrow from being rebuilt (including a new head) so I'll check the condition of the part on my old head, and if it's OK I'll sell it to you

Caffeine · Postby **Caffeine** » Wed Jan 28, 2015 4:34 pm

Got my engine back, and picked up the old head too. The bearing cap is in good condition, but you will probably have to machine it to match your head.

Let me know if you want it.

C-Gazer · Postby **C-Gazer** » Tue Feb 03, 2015 9:55 pm

The rebuild is happening. I managed to get the No1 exhaust bearing cap from MX5 Mania in Sydney.
Thanks Mania.
I have looked at their website often but never realised they sell second hand parts.