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v6manta

2010-01-27 - 2010-01-27 Started building the V6 Heads up

I started building up the heads for the V6, although it was freezing cold up the garage so I mainly drank tea. I did manage to lap in 24 valves though.

The exhaust valves could do with a bit more lapping because they have a wider seat contact to help cool them a bit and I ran out of muscle power! The V6 isn't the best cooled engine in the world so there's no point in going too thin on the exhaust valve seat.

I don't like 3-angle valve cuts, I don't see the point of them on a properly ported head. There is a lot to gain by the valve seat, and to then cut it back to just three angles seems a bit strange. There are still a lot of people quoting 3-angle seats as some sort of upgrade though, even though virtually every head I've looked at since the 90's has that from the factory as a minimum!

Anyway enough rambling, this is what I think a valve seat should look like (Actually a bit better radiusing would be nice, but who's perfect eh?) I radis around the seat area, trying to blend into the seat face without removing too much of the valve face or sinking any areas of it because otherwise you will need a big cut to get a sealing face.

Then, you can just ask the machine shop for a light cut (about 1.5mm wide seat contact for the inlets) and once lapped in, the job's a good 'un.

You can see a bit of paint from where I was matching the inlet to the manifolds, I'll clean the rest of that out at the weekend with some thinners.

I went to Ring Engineering in Hayes, Middx to get the valve seats cut for a couple of reasons, and I can recommend them. Lapping the valves in has been easy, there aren't any bad cuts or nightmare seats. The reasons I went to Ring:

  • When you ask for a light cut, the do what you ask and understand that they shouldn't cut out all your hard work!
  • They can cut seats concentric with the valve guide, even when you have cutback the valve guild in the port. Some people can't do this because of how their seat cutting tools align with the guide. They need a flat surface on the end of the guide nearest the valve seat to align properly.