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MG Midget and Sprite Technical - unleaded hed modification

hi, can anyone tell me what modifications are required to convert a 1500cc midget head to make it run on unleaded fuel.
thanks
dave
da cook

Valve seat inserts.

Having said that, the Triumph head has relatively hard valve seats as stock and doesn't suffer too greatly from valve seat regression when running on unleaded fuel.
Deborah Evans

thanks for that deborah, i took the head off as i suspected a blown gasket due to pressurisation of the coolant system, the gasket was fine but it looks like cylinders 3 and 4 have been bouncing bricks in there for a few 1000 miles, the bores and pistons are fine so i think this ws an old problem. i have noticed though that the pistons in 3 and 4 are almost level with the top of the bore and 1 and 2 are a couple of mm lower which makes me think that they have been replaced at some time. it also looks like the head has been skimmed and i wondered if i should change the head or have it skimmed again and if i did would it increase the compression ratio too much? one last thing can anyone tell me where the drain plug for the coolant is, according to the exploded drawing in the book its under the manifold but all i can find is a blank 20mm plug but when i removed this it was just a blind hole and all the coolant remained in the head and block even after pulling off all the rubber hoses.
da cook

With my TR6 I put in all hardened valves but only hardened exhaust seats.

Knowing that the exhaust are the ones that get hot I decided this path for a couple reasons.
1) If both intake and exhaust seats are installed the distance between them is very small. I wanted better support to hold them in.
2) Because I had more room to work with I was able to find exhaust seats that are a little more robust than the ones used if both are used.

After more than 4 years and 20,000 miles it has worked out very well. And I do drive it. For example, one morning last summer my brother and I left on a drive. When we returned 4 days later we had been in Wisconsin, Illinois, Missouri, Kansas, Oklahoma, and Arkansas.
tomshobby

This thread was discussed on 11/06/2010

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.