Cylinder head problems/Interchangeability

[dlh98370]

All,
I removed the cylinder head from my US 1756 engine in my 131project and discovered cracks between the valve seats between two of the bores, cylinders 2 & 3. I have a spare cylinder head with 4239436 cast into the head. I think is is a 1608 cylinder head and it seems to be in good condition. I was not able to identify it positively from the information given in the Croft book. What I would like to find out is the following:
1.)Is there a guide with pictures that show the work that needs to be done to the head so it can be used on the 1756 block? I find references to such a guide on this site but I have not been able to find it.
2.)Does this cylinder head require the use of leaded fuel?
Thanks
dlh98370

[SteveNZ]

1) Sorry, I don't have any photos but if you place an 84mm bore head gasket on the 1608 head you will soon spot the problem. Its the front coolant gallery. It needs to be welded over. It can be welded over completely IMO.

[Christoph Thuerey]

Hi,

cracks between the valve seats appear quite often. I have seen them on brand new heads.
Normally nothing to worry about, but do not install new seats!

Regards Christoph

[Guy Croft]

2) You can rung those heads almost indefinitely on unleaded fuel. I gave up doing 'unleaded conversions years ago'.
Especially if you fit bronze guides and new OE spec ex valves with stellite coating on the contact face..


The whole issue of 'unleaded' was very badly handled and the reality is that most mfr changed to super-hard valve seat materials. So, when you work on a used one (and there are numerous examples in the GC Virtual Workshop - Peugeot 16v springs to mind) you find that the seats are more-or-less OK (but usually out of round) but the valve contact faces are heavily deformed.

There is an article (just updated with a photo) at:

http://guy-croft.com/viewtopic.php?f=1& ... 1216#p1216

GC.