Board logo

Head gaskets
teegray19 - 5/4/13 at 07:39 PM

Valve clearance problems are meaning machining pistons. Don't really want to do this, has anyone fitted two head gaskets to a crossflow, or anything for that matter?

Problems please, cheers


steve m - 5/4/13 at 07:49 PM

Thats a real bodge, and will end in tears , so dont do it

Steve


teegray19 - 5/4/13 at 07:55 PM

Not as much as trying to machine pistons in the bores, what problems can occur?


richardm6994 - 5/4/13 at 07:56 PM

Burton power can supply upto 120tho thick mls cometic head gaskets. That thickness isn't held in stock and they will have to get it from USA so takes about 6weeks. Cost is about £130.

I really wouldn't use two head gaskets!


Canada EH! - 5/4/13 at 07:57 PM

This happened to my racing Datsun in the 70's. I ordered pistons from a California company which had a raised deck, unknown to me Nissan had changed the combustion chamber in their competition head and these piston were for that head.

The pistons we had been using were for the old head with a Mini shaped combustion chamber.

After oil ring failure in two races we milled the pistons to flat tops and solved the problem.

The car had won two championships the year before and was now a DNF.

The wins came back after the piston were fixed.


teegray19 - 5/4/13 at 08:11 PM

I need a 1mm more valve to piston clearance, I did get them pocketed but mr machinist didn't pocket them enough.

0.5 clearance at TDC really worries me and don't want to scrap the engine after a full rebuild.

Two head gaskets give that clearance? what are the main problems, leaks very low compression ratios?


teegray19 - 5/4/13 at 08:22 PM

How will it end in tears though, I have seen the cometic head gaskets but its crazy money for one gasket.

If it gets me rocking for the summer il happily buy one, but if I can get away with two gaskets with the good we'll seal?

Worth a try cause its not hard to pull a crossflow head off either in the car or out?


snapper - 5/4/13 at 09:41 PM

The only thing that may happen with 2 gaskets is a leak
So try it
IMHO the right way is to take the pistons out and machine properly


Canada EH! - 5/4/13 at 11:24 PM

Remember rods lengthen at high rpm, I was always taught than 60 thou was the minimum clearence for valve to piston, otherwise the positive valve closers will do their job with disasterous results.


skodaman - 6/4/13 at 12:38 AM

Yeh it's a bodge. I've done it on a motorbike and I'd be lucky to get 100miles without it blowing a chunk out of the gasket. If the gaskets were all metal it might work. Come to think of it MZs used extra metal gaskets to lower compression for poor quality petrol.


silky16v - 6/4/13 at 06:52 AM

Try Ferriday