Lapping plate for cleaning a cylinder block face in situ.

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Fergus OMore:
Personally, I think that you are wrong on several counts.
Frankly, buggering your head gasket from a thermostat fault is questionable. I've done quite a number of heads in the past and the first question that I would raise is whether you removed and replaced the repair with new bolts etc. The next question is whether you 'blued in' the top of your cast iron block 15000 miles ago and whether you have checked the block yet again- on this, the second blow up. As you inform us that you do not possess anything, I would assume to be correct.

You can- or I could- blue in the block and scrape it- assuming that nothing really serious exists but the cheapest and most reliable repair is to have BOTH the block and the head checked and flattened.
Again, at the end of the day- when all is well again, you will need to torque down the head.

Having said all this, the cylinder head might not be strong enough now to stand the weaknesses already created. I've had to be aware of oil ways which are hidden just below the face of the head- and if it is a cast iron block- porosity.
I once skimmed a 12G295 Mini Cooper 998cc block, opened up the ports, reworked and rebalanced the combustion chambers etc for larger valves- and the lot wouldn't turn over. I pulled the plugs, and got an eyeful of glycol from a unseen hole :bang:

Read Pete's comments about 'blowing the block' His views are worth digesting.

Norman

chipenter:
Why not use the head remove any locating dowels , use a figure of eight motion was standard pratice for racing 50 years ago .

dawesy:
Should probably give you more info on the engine.
It's a Toyota 3S-GTE but bored and stroked to 2.2 Ltrs from 2.0. It's running over 500hp.
The thermostat failed just before Christmas temps hit a max of 115deg c. Before this it ran absolutely fine. After the stat replacement the temps would rise significantly only on boost. Cruising round they were fine. I expected it to be a cracked block as this is common on this engine and I have had two go in the past.
On removing the head I found the cylinders in perfect condition but a small dark spot on the headgasket suggesting the gasket had been passing combustion.
Head studs are uprated items from ARP.
This engine was fully built 15000 miles ago. Both block
and head were decked and faced at that time.
All I want to do is ensure that the block face hasn't been marred by the escaping gas.
Pete thanks for the suggestions on protecting the bores. It was something I was thinking of ;)

Pete.:
I expect that what happened was the gasket let by, shooting up the temperatures making you think the thermostat was to blame. Did you use the ultra-torque grease that ARP supplies for torquing the bolts? If not they might have fallen short of torquing spec.

dawesy:
Yeah I did. It may have been a bit of both to be fair. I tested the stat and it was goosed. I've built countless of these engines ( including this one ) and to be fair the head nuts didn't seem as tight as normal. They were defiantly torqued up to spec so have either stretched or the headgasket has settled causing torque drop off.
I originally built the engine for a friend who after losing his job sold it to me. It had never been in the car. He used a cometic gasket which I had never used. I normally use a HKS one in big power builds. So not sure if it's a gasket issue or not I'll be using a HKS one this time though.
I'll also retorque the head studs after 500 miles or so even though not specified by arp.

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