In reference to 4K heads,what is the difference,if any,between a head that has a welch plug at the back of it and one that has a metal plate and screws at the rear. Are they both 4K heads?

Edited November 8, 201213 yr by oldie

Welsh plug head is a 3k bigport head. Old and overpriced but you can flog them for 150 bucks to some ke70 wannabe drift king!!

So whats the big deal about 3k big port heads.It wont be for sale as its on an engine I want to use and I'm not interested in pulling it off.

They're big! That's really it. Ports at the manifold face are 30mm wide, vs around 25mm for most other K heads.

...will also have some numbers on the spark plug side and some shitty valve stem seals.

I had my 5k head faced and the ports matched to a 32mm manifold for 150 bucks, which is what some people are asking for a bigport head.