I am trying to build a 1935 model 8, twin port. I have recently purchased 2 pairs of exhaust nuts for a model 8 but both pairs appear to be a smidge too big. The nuts are 50.96mm diameter inside to the thread but the head stubs are 50.75mm diameter.The head is cast with a number 1823M on the bottom & a letter J. On the top of the head, right hand side, appears a letter L. Can anyone confirm that this is a Model 8 head? The stud holes all line up ok & it fits the barrel & rocker box ok. I was told that the 250 head had smaller exhaust stubs.
Cheers
Chris F
My 500/600 heads are marked 1722..the stubs are between 51.8 and 52mm. The depth of thread would give in internal on the nut of 50.96..john
i'm not used to playing with mm..Your stub diameter is only a couple of thou off 2 inches..The nuts you have look like their for 2 1/16th stubs..john
Looks like you may have M9 nuts!
P.
Are the nuts for your exhaust finned or straight?
If they are finned you can get the bare castings from the spares shop and if you know someone with a lathe they are fairly easy to machine to size.
here are some that i made..john
Could the threads be worn on the head. A set machined to fit may be the best solution.
Thanks for replies. The sets that I bought were straight. I will get a set of finned castings off Les & talk nicely to a friend with a lathe. Threads on the stubs don't look too badly worn. The straight nuts don't even bite & wobble about when on the stubs so are quite a bit larger than the stub.This made me wonder if the head was correct.
Cheers
Chris