Phenolic spacer

fordman302 · 22-10-2012, 04:47 PM

Hi all, I'm just after some advice to help me with a problem I am having. I recently pulled my xr8 apart to give it some much needed love, stem seals, lifters and fix some oil leaks, all seemed to go well until I got to the upper manifold.

I have a phenolic spacer that was fitted by the previous owner, the first time I pulled the manifold down in sequence from middle out to 20nm I managed to crack off the lower back corner of the upper manifold, I then got that welded and had another go, didn't even get it to 20 this time and crack it went again through the welded repair.

After this I thought I wouldn't persist with that upper manifold so I purchased another one, made sure everything was right, started pulling down the bolts and this time the front lower part cracked, so now it's off getting welded again and I am going to order another spacer just incase this one is getting sad, I can't take it out because of my higher after market rocker covers which are there for my higher after market roller rockers.

Has anybody had this sort of experience before and can point me to what I am doing wrong and how to rectify the situation, I am at a stage of growing frustration, thanks

lotus · 22-10-2012, 05:30 PM

I had this problem when I got the 220 tuned in the EB. I had fitted a spacer to the motor before I fitted it to the car, got it tuned and they found the upper was cracked at the rear.
Was told this happens often if you fit a spacer. Had it repaired and refaced so it was level from front to rear. They checked the lower and found it was uneven, so had to remove it and get it refaced as well. Have not had a problem since.
So it may be that your lower manifold is not level and making the upper flex to suit it when tightened down. Could be worth checking before you go and refit the upper.

fordman302 · 23-10-2012, 06:42 AM

Did you still pull all your bolts down to 20nm after that or did you play it safe and just nip them up?

lotus · 23-10-2012, 07:39 PM

Since it was done when it was getting tuned at the workshop I have no idea, but I would suspect they would have tightened it down to the correct tension. Was done a while ago so I don't know if they would remember. But as I said I have had no trouble since.

blueoval · 25-10-2012, 08:27 PM

I had this problem years ago when I tried to fit a phenolic spacer to my EB XR8. tightened the back bolts down, started the car and it idled like crap. pulled the upper manifold off and the corner of it had broken off completely. Didnt reface it or repair it, rang Jim Mock and had a spare one I bought, got it sent over night and ditched the spacer and put it back to normal. Expensive lesson for zero gain.

fordman302 · 25-10-2012, 08:33 PM

Yeah I thought I would take the path of ditching the spacer to but I have after market rocker covers and I need the spacer so the upper manifold can clear them, doing everything I can to get all the edges perfect and hope for the best, the tip from lotus about having the bottom half refaced will hopefully save me