[Bill Eveland]

I'm helping a local guy put his car together. I havn't ran into this but his old 389 heads valves weren't seating and be bought some 6x heads.

What's required as far as alt and pc brackets or is there anyway to make this work? I have a ps off a 68 engine with brackets but didn't know if that would help.

[Ollie]

Check the CR. Late model head will have large combustion chambers the the CR will be too low on a 389.

[jwcfbd]

I've got a 65 389 in my Bird so if you need any other pictures just let me know. I'll have to check to see what heads I have but hopefully this picture helps.

[scooter1966]

I had that setup on my car for a short time. it was a 66 389, with 6x heads. I was running the stock 66 p/s pump and the 66 brackets for both p/s and alt.

*** X2 on what Ollie stated, the compression will be low, i think i calculated something like 7 to 1.

[Bill Eveland]

well he bought them without asking me, worst part is one is a 6x-4 the other 6x-8. Is does have aftermarket flat tops .060 over. I havn't been over to check it out, just a phone conversation.

[gtofreek]

Originally Posted by Bill Eveland

well he bought them without asking me, worst part is one is a 6x-4 the other 6x-8. Is does have aftermarket flat tops .060 over. I havn't been over to check it out, just a phone conversation.

The chambers on the two heads are totally different. Not just in CC size, but more in the size of the cut they made to make them open chamber. The 6X-4 head had that cut made with a much smaller diameter ball mill than the 6X-8 head. I would not use them both on the same engine.

[Bill Eveland]

Well I know whats right and I tried telling the guy and he just wants it up and running on all 8 cylinders. One of the cylinders with his other heads had 0 compression from the valves and the repair was too much for what they were.

[panhead59]

If the guy needs a pair of heads, there are several in the for sale section that will work and are ready to go.

[geeteeohguy]

Can't believe nobody's mentioned this yet, so I'll give it a go: '67 and up heads have a different valve angle than '66 and earlier heads. If you use '67 and later heads on a '66-earlier engine, the valves will hit the pistons if you have a lot of camshaft lift. The piston reliefs are in different locations! So be sure to check piston to valve clearance before fire-up......

[Engine-Ear]

My $0.02: I would have him buy a matched pair of heads (there are plenty out there at a good price)...in fact, why not buy a pair from Steve Snyder (Indiana Pontiacs) off of one of his '65-'66 parts cars?

ALSO, if he's unwilling to get a proper pair (let alone a matched pair!) of heads, I would decline assisting him, because YOU will be the cause as to why the thing runs weird / badly / etc., even though we all know differently...

[gtofreek]

Originally Posted by geeteeohguy

Can't believe nobody's mentioned this yet, so I'll give it a go: '67 and up heads have a different valve angle than '66 and earlier heads. If you use '67 and later heads on a '66-earlier engine, the valves will hit the pistons if you have a lot of camshaft lift. The piston reliefs are in different locations! So be sure to check piston to valve clearance before fire-up......

I didn't mention this because the 6X heads have such deep combustion chambers that the valves would have around .300" free drop with the head gasket, before they even get to the deck surface. He would need a camshaft that was around 280° @ .050", or bigger in order to start running into piston to valve clearance issues. It would be a lot different story if he was installing RAIV heads that don't have a lot of valve free drop.

[Skip Fix]

Paul is right the 6Xs are so deep you really don't need valve notches! I think they are over .200 deeper than my RAIV heads to the leading edge of the valve.

http://forums.maxperformanceinc.com/...=chamber+depth

[Bill Eveland]

The biggest issue with what he has the aluminum 66 alt/ps bracket only has one hole that will bolt bolt to the 6x heads because of the bolt pattern and doesn't put the ps at the correct angle. He got another set up but stepped out the ps pump for a 3 belt configuration.