Rebuilding Cylinder Head on TB45 GU Patrol.

[raptorthumper]

For quite some time now i have been putting up with some rough running at idle due to partially burn't valves from running on LPG for 180,000 klms.
I know it's my valves as the thing ran really badly after a trip to fraser island and i checked the valve clearances once i got home and sure enough no clearance at all on 3 valves. I reset the clearances on the wide side and restarted and it was almost like n e w . Now 18mths later it's getting worse again and i think it's high time to rebuild the head. Priced some n e w exhaust valves from Nissan (out of curiosity) and about $600 a set.

Anyone got an idea of cost to get the head rebuilt.? (i will pull the head off myself) I know it depends on condition, but worse case; n e w stellite inserts and 6 n e w ex valves.?

I want the head rebuilt before the Garret GT35/40 Turbo goes on.


Grant
_______________________________________

[raptorthumper]

Deleted post.

[fatassgq]

Sorry for the hijack man but could you tell me how much of a job it was to set up ya clearances on the valves? And I spose what clearances you set em up to???

I know that 4.5's have a rep for bad idle I think mainly due to distributer? But the valve thing makes me curious.

would be a good idea to get the head done anyway I guess before the big turbo!

Have ya found out if one of those rb30 manifolds will go close to fitting up? I was thinking about going down to the local exhaust shop and comparing exhaust manifold gaskets for the rb30 and 4.5 and that should tell me.

Good luck anyway

[Brunsy]

Orger engines in Bawyswater know these heads back to front, They set mine up TB42 allthough it was a brand new casting and from memory it was about 1900 with gasket kit. Their work is amazing and their equipment shi*s all over what most machine shops have. I guess thats why they do heaps of the V8 supercar stuff.

[raptorthumper]

Thanks Brunsy. I might try to rip the head off it this weekend if i can. It all depends on whether i can borrow a car for a week or so to get around in. When the head is off i will check RB30 manifold for closeness.

It's pretty easy to set the valve clearances. Just remove the rocker cover and have your feeler gauges ready.

I find the best way is to pull off the distributor cap and turn the engine over until the rotor points to Cylinder 1 (Which means cyl 1 is near TDC on the compression stroke, valves closed) and set the gaps for Inlet and Exhaust to 0.35mm on this.

Then follow the firing order around. ie rotate the engine until the rotor points to the next cyl to fire and set the clearances for this cylinder.
This ensures each cylinder is on the compression stroke and hence valves are closed when you set them. I've found TB45's to run beautifully except when the valves are leaking. If you've got a miss at idle and it's not ignition related it will be the valves or head gasket or similar.

Also if your car is on LPG the gaps need checking regularly. I've found the gaps keep closing up after 12 months or so.



Grant.

[raptorthumper]

I decided to pull off the rocker cover again and check the valve clearances today as i haven't had time to rebuild the head. Sure enough all 6 exhaust valves had closed up with no gap at all. I had to back off the adjuster nut by at least 0.5mm.

The inlet valves were all OK. LPG is bloody harsh on the std exhaust valve seats. Anyway it's running perfect again, but that's 3 times in 3 years that i have had to back off the exhaust valves adjuster nut, so the exhaust valves are recessing.

Here's a few photo's, and i noticed i have a blown exhaust flange gasket but that will be replaced when i finally put the turbo on. Just need to finish getting all the bits and pieces together.