Just found out my 620 has a cracked cylinder head (wasn't running anyways). I've been doing some research on a replacement head and found out there's quite a few.

A87, U67, W58, closed chamber, open chamber... anyone want to give me a good direction to head? Point me towards more information or even just opinion...

onesixteenth wrote:Just found out my 620 has a cracked cylinder head (wasn't running anyways). I've been doing some research on a replacement head and found out there's quite a few.

A87, U67, W58, closed chamber, open chamber... anyone want to give me a good direction to head? Point me towards more information or even just opinion...

My Choice #

1= A87 closed chamber/ square exhaust ports- better compression and larger valves

2= W58 closed chamber/ Round exhaust ports- ditto ^

3= A87 open/ square exhaust ports

4= U67 (they are all open)/ square exhaust port- larger ports and valves

5= W58 open/ round exhaust ports.

Thanks Phleb!

I also found this site (you guys probably know it already) that was pretty helpful in explaining all the differences:

http://www.olddatsuns.com/html/tech/head_ID_2.htm

I have the head with the steel liners in the exhaust ports. Except that one port (#1 exhaust) doesn't have a liner in it. Is that a problem? Is that normal? Anybody know where I can get one? Is there a special tool or technique for installing them?

It's missing a liner?

They are a pain to get out. I don't think you would need to install a new one, because I doubt you could.

Do you have a pic?

those steel liners are actually cast into the cylinder head. I'm not sure how well the head would run, since the exhaust on #1 would be flowing substantially different than the other three.

The A87 head is one of the best. NISMO catalog sells new peanut chamber heads for the L engines. But a U67 is hard to find in the states. You will see alot of W58 heads, and then the A87 ones after that.

onesixteenth wrote:Just found out my 620 has a cracked cylinder head (wasn't running anyways). I've been doing some research on a replacement head and found out there's quite a few.

A87, U67, W58, closed chamber, open chamber... anyone want to give me a good direction to head? Point me towards more information or even just opinion...

You will not be able to install a new one in there. The head halfs has the liners installed before they were asssembled. I had a W58 head on my L20B. It take about an hour each to take them out. Installed a 280deg Comp cam and it ran really well with a Weber DGAS 38 carb and Offy intake.

If you cant take the other ones out, you should get another head on there cause the flow will be disturbed and robbing power and efficiency from you.

pastric wrote:I have the head with the steel liners in the exhaust ports. Except that one port (#1 exhaust) doesn't have a liner in it. Is that a problem? Is that normal? Anybody know where I can get one? Is there a special tool or technique for installing them?