XU5 M lockdown project.

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GRAHAM WALLIS

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Well this filled in the lockdown time nicely but I had a setback yesterday in that the copper head gasket didn't seal and combustions gases were getting into the cooling system. See photo. A standard head gasket will lower the compression so I think I will just fit the original stock head and cam to get it running again. It will have the GTi intake system and aftermarket ECU so should still be a worthwhile modification. Looks like it is a good idea to fit o rings, something I didn't do. I have ordered a 1.6 mm Cometic MLS gasket for the spare XU9J4, which will replace the copper one that I fitted.
 

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Hi Graham,

I had a similar experience to you with a copper head gasket on that setup - I didn’t know about the threebond trick then. Mine even seeped/bubbled down the back of the block.

I changed to a standard headgasket and it ran strong and happy on 98ron.

Hope you get a good outcome,

Dave
 
I used the 3 bond, it was leakage from the fire ring area. Your head and cam will no doubt be used at some later time, just taking the easy way out for the time being. I don't have any real use for the car, it was a chance to experiment.
 
That's unlucky, like Peter said, as the liners protrude the cylinder seal is usually okay. My experience was the opposite, good compression but leaky at the back of the block. Never had a problem with a standard gasket. What is your experience with the cometic MLS Gaskets? I'm thinking of using one of those on an XU10J4 block.

Dave
 
No experience with the MLS gaskets but I like the idea better than copper. Over twice the price though, Cometic Australia didn't have an 84 mm 1.6 thick gasket. Triumph Heralds had a piece of mild steel although there was a crease around the bore area.
 
Gasket was a used one from Jeff R, the cut outs are to prevent valve shrouding. It was annealed and is nice and soft. The liners are all protruding, I had no way of adjusting the protrusion whilst in lock down so didn't go very far in checking the exact amount. Gasket is .9 mm, the reason I used it was to get more compression.
The XU9J4 has a 1.6 mm gasket to reduce the compression, has high comp Wiseco pistons with standard cams, new gasket from Ridgeway. I had the head off and on again on this one and there were noticeable impressions of the liners so maybe I should give this a try? If I fix the coolant chucking problem with the one in the 309 I may never need to use this one anyway.
 
Yes, but you can't do anything to change it if it was wrong. At least in the 504 you can adjust the height by means of changing the seal thickness.
 
Graham, I can't remember what liner protrusion I had but It was enough to seal. Even removed & refitted the head a couple of times by re-annealing. With a new gasket from Ridgecrest using ThreeBond both sides you should be getting a good seal. I used 25, 50 70 lbs/ft on the bolts.
 
Yes, I planed the block to get the protrusion to what it is.
 
Thanks but I do like the XU5Mz cam, comes on at 3000 and gives great performance from there on. The engine I got the 1.6 GTi pistons from never went any good, whether it was with Megasquirt, L Jetronic or the Marelli mono point system. All were tried and probably the monopoint went the best. Even the official figures for the 115 hp 1.6 GTi motor show it is slower than the original 105 Hp version except mainly for top speed. Thinking the big valves and big cam of the 115 version are too much for 1.6 litres. I drove the original 1.6 GTi that JRA imported for evaluation purposes and it flew, was a 105 hp model.
 
Was the JRA car red? I had a red 1.6 import and it was a rocket.
 
pgti6 said:
Yes, I planed the block to get the protrusion to what it is.
Click to expand...
That is now my spare XU9J4 engine. I have fitted a new copper gasket to this. Did remove and replace the head while assembling, forgotten why now, would this cause any problem?
 
Without knowing the details if it was fully torqued down I’d have reannealed the gasket and used new bolts.
 
Didn't do the stretch thing on the bolts, never do. Maybe should now do the full angle tighten bit and give it a try. Not that hard to change a head gasket in situ if it all turns to crap. Not sure about suitability of compression ratio etc anyway, bit like the 1.6 in that it is an experiment.
The 1.6 gasket didn't go hard after it was torqued down and run.
 
Well you’ve go nothing to lose by giving it a go I suppose.
 
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