Unleaded cylinder heads

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Unleaded cylinder heads

Post  Stuart B on Thu Sep 27, 2012 8:34 pm

I have an MG Metro engine which I am about to re-fit into my Elf. As it has a 12H996AA engine number I have ascertained that it is a pre-84 leaded head.

Apart from a vernier timing wheel, lcb and RC 40 exhaust the engine is standard. It has been lightened and balanced. It has a single 1 1/2 " SU on a water heated manifold.

Three questions:

Is it worth skimming the head to raise the compression ratio from 10.5:1 or will that just casue problems ?

Assuming the head is in good condition how much should I budget for a conversion to unleaded ?

Once I put the engine back in the car should I adjust the engine timing to run on unleaded fuel ?



Stuart B

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Re: Unleaded cylinder heads

Post  catmint on Sun Sep 30, 2012 6:19 pm

Hi Stuart

Hope all is well

compression ratio could/should already be be that as the MG head was higher compression, which to be honest could be a little high for 95 petrol, which I seem to recall is ideal at about 9.5 :1 (which is what H runs at), tho 98 petrol will be OK

I think the last time I had seats done it was about £30 per seat, but if you are just going to potter about in it then additive should be fine

The dizzy may need retarding a couple of degrees for 95, see what it pinks like when you get it on the road

Will we see you at the Hexham ?



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Head skimming

Post  john&gina on Tue May 14, 2013 1:38 pm

In my opinion skimming the head could cause problems with the crankshaft. 10:1 is quite high for an a class anyway. If you do go down this route
you might consider having the crank nitrided, although this process is quite expensive.
Hope this is of some help.
John Whipp amimi retired motor engineer.


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Re: Unleaded cylinder heads

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