Replacing the VX head gaskets -job almost done

[Lex]

Well a bit of an update: Today is my first day off in a while, so having bought the gaskets and new head bolts, I figured to have a really close look at the heads.... I need glasses most days... and I discovered two cracks in one head. Bugger. The other head seemed fine.

So, I have a donor car with 330,00kms on the motor, although I could not get the car running due to having the car go into theft mode etc. The motor may have two good heads. So, I am pretty sure these heads are interchangeable from left or right, all I can notice is the spark plugs will point either forwards or backwards, not an issue. And I dont see a stamp RH or LH.

So, I reckon the best option is yank the heads off the donor car, examine them, use a good one to put on mine. I'm thinking as the donor car has not overheated, the heads will not need re-surfacing.

Any thoughts out there?


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Just swap motors?

 

[Mr Blackstock]

I have no way of checking the donor car motor. All I know is how many kms are on it, and that there is no evidence of the motor being stuffed. The donor car's motor may have other issues.

 

[Grimes]

Well a bit of an update: Today is my first day off in a while, so having bought the gaskets and new head bolts, I figured to have a really close look at the heads.... I need glasses most days... and I discovered two cracks in one head. Bugger. The other head seemed fine.

So, I have a donor car with 330,00kms on the motor, although I could not get the car running due to having the car go into theft mode etc. The motor may have two good heads. So, I am pretty sure these heads are interchangeable from left or right, all I can notice is the spark plugs will point either forwards or backwards, not an issue. And I dont see a stamp RH or LH.

So, I reckon the best option is yank the heads off the donor car, examine them, use a good one to put on mine. I'm thinking as the donor car has not overheated, the heads will not need re-surfacing.

Any thoughts out there?


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View attachment 222757

Left and right heads are interchangeable. Rip them off and have a look. If not cracked it’s unlikely you’ll need a skim but that’s a cheap job anyway.

 

[Mr Blackstock]

Thanks for the info, I was hoping they were interchangeable... I just figured knowing my luck.... Ironically, while everyone will be at home with the lock down, I will be working anyway so I wont get a chance to work on the car till thursday...

I'll keep ya'll posted,

Cheers, Gareth

 

[Grimes]

Don’t forget to measure the piston protrusion for me. I used a dial indicator to do it properly but this photo captured my initial WTF moment as I was installing the new pistons. Shows what protrusion is quite nicely.

 

[Immortality]

YUp. Pop top pistons....

That's why we use .060 thick head gaskets.

 

[Grimes]

YUp. Pop top pistons....

That's why we use .060 thick head gaskets.

0.045 over the block wasn't gonna' cut it I'm afraid. -0.025 pistons had to go in with the thinnest head gaskets I had on hand. The block machinist and I took a while to work it out, but a few thou off the block and the original factory set up protruding to the extreme accounted for the measurement and the tendency my engine had to knock a little bit under mild loads. We stripped a couple of ecotecs and found .020 over two blocks and one at 0.030.

 

[Immortality]

Yeah 0.045" is a bit much.

Does seem like a lot of variation in the factory machining tolerances.

If I remember I'll measure mine when the heads go back on next week.

 

[Grimes]

When I ran into this I googled for hours and couldn't come up with much, not even from this forum. It'd be interesting to build a data set to see what's out there. We concluded that my engine in factory form was running a lot tighter than the ~0.035 you're supposed to allow for piston to head clearance. It had no signs of impact on the pistons and I got shy of 500,000kms from the engine. The machinist took 0.004 off each bank and we found a block with 0.030 from factory. ~0.040 might just be the 'technical limit' for ecotecs.

 

[Immortality]

Most engine builders aim for 0.040" quench or the piston to head clearance but factory tolerances are normally more generous. Interestingly I can't find any mention to this specification in my literature. Will have to do a more thorough search I think.

I'd be surprised if mine are more than .020" proud of the deck surface just going off feel with my fine calibrated finger tip.