Question on rebuilt head

[bummininca]

I have finally timed my 92 m50 the correct way and now find I did some damage to valves (no big suprise) from my first failed attempt. I have gone looking for repair facilites and rebuilt heads on-line and it has raised some questions. According to one site if I were to put a rebuilt head on my car with 140,000 miles I run a good chance of blowing out the bottom end because of the increased compression. Now this is one of the things I worried about when I consisered this project in the first place. I have considered doing the valve job myself to save money but this would be my first time doing one and I'm not sure if I should try with such a precise engine. I guess my biggest question is the one of blowing out the bottom end, how likely is this to happen and how soon? Second would be, Is it worth $400 to $600 to take this chance or am I just setting myself up for more problems?

[Jon K]

You will have absolutely no problems.

The issue you read about regarding raised compression is that if they have to mill the head flat, they are removing material bringing the squish area down and the compression up. Stock head gasket is 0.070" thick - if you remove material, you need to compensate with a thicker head gasket. I'd say do the valve replacement yourself but between lapping the valves and requiring a somewhat specific dual valve spring compressor for your '92, i would just let a shop handle it. Explain to them your concern about remove material to flat and potentially raising compression and they should be understanding and make sure to remove none or minimal.

SHOULD they have to remove headgasket material, I can point you to MLS (multi layered steel) headgaskets that are more targeted for performance in mind, but happen to come in various thicknesses for the M50 motor to compensate for any slight raise in compression.

[Booster]

You will have absolutely no problems.

The issue you read about regarding raised compression is that if they have to mill the head flat, they are removing material bringing the squish area down and the compression up. Stock head gasket is 0.070" thick - if you remove material, you need to compensate with a thicker head gasket. I'd say do the valve replacement yourself but between lapping the valves and requiring a somewhat specific dual valve spring compressor for your '92, i would just let a shop handle it. Explain to them your concern about remove material to flat and potentially raising compression and they should be understanding and make sure to remove none or minimal.

SHOULD they have to remove headgasket material, I can point you to MLS (multi layered steel) headgaskets that are more targeted for performance in mind, but happen to come in various thicknesses for the M50 motor to compensate for any slight raise in compression.

Speaking of this Jon.....which MHG thickness did you decide to go with on your new build ?
..........Vinny

[Jon K]

Vinny I am going with a 0.140" MLS HG, which will put the compression at 8.3:1

[Booster]

Vinny I am going with a 0.140" MLS HG, which will put the compression at 8.3:1

Very nice. I can't recall if your going forged aftermarkets internals or prepping your factory parts ?
...........V'