Cylinder head identification?

[rabbie6]

So I bought a head at a swap meet a couple of weeks ago. I asked what year the motor was and it the head alone was for sale. Yes, it is, off a 1978 - perfect! Or so I thought

After knocking a valve out to see if the head is in better shape than the one I have I found the valve does NOT fit down the valve guides of the other head I have?!

So, looked for differences.

The head I have has 392 embossed on it but the head I picked up has 40.

What have I bought?

Can I use either head? Should the valves fit the guides in both? Just a matter of reaming the guides a little? Seemed like more than a little though….

 

[dirtdigger]

You have a 77-78 supersport head 410 casting number, not usable on a K motor without some modifications.

 

[rabbie6]

Damn, thought they would be interchangeable. What sort of modifications?

Could I at least use the valves for my K model head or are the guides different also?

Thanks for the help

 

[dirtdigger]

The valves are larger and use different spring retainers in the F head so no you cant use them. You have to modify a couple of stud holes with sleeves or you will leak oil. The combustion chamber is also larger so you will loose a fair amount of compression if you use this head on a K bottom end unless you use the correct pistons. If all you need is valves and guides go to cyclex or better yet just send you head to them and have them rebuild it for you and it will be done correct and better than new.

 

[grewth]

The valve drain passages are visibly different on the big valve F2/F3 heads, that's one thing that I have learned.
Usually, you get some dealer trying to sell what is supposed to be a big valve head, but it's actually just an old K2 head painted black.

 

[Oscar Meyer]

Damn, thought they would be interchangeable. What sort of modifications?

Could I at least use the valves for my K model head or are the guides different also?

Thanks for the help

I see you are in Canada. Contact this guy, he has a ton of parts.
https://hoarderjoes.wordpress.com/