1984 Cylinder Head

[FernandoBunster]

Is there a difference between a '84 633 and a 635 head? Are they interchangeable?

[GI Jonas]

I want to say that they are different but also interchangeable.With the earlier being more crack prone than the later?

[86GT635]

I know the bore was smaller on the 3.3. So you'd have a different shape at the beginning of the combustion chamber. Also, the 3.3 has a hotter cam than the 3.4.

[CW6er]

Check this out, it might be of use:

http://www.firstfives.org/faq/cylinder_head/cylinder_head_faq.htm

[FernandoBunster]

Thanks to all. Very helpful.