Hi everyone. I'm new to the board. I have a 65 gto tri power 4 speed 3.55 posi. My question is this. I have a chance at a pair of 6X heads. Will they bolt up to a 65 389 block? Will the 65 intake bolt up to the heads? These are the good heads with the screw in studs and guide plates. Any and all answers and opinions appreciated. Thanks

Hi everyone. I'm new to the board. I have a 65 gto tri power 4 speed 3.55 posi. My question is this. I have a chance at a pair of 6X heads. Will they bolt up to a 65 389 block? Will the 65 intake bolt up to the heads? These are the good heads with the screw in studs and guide plates. Any and all answers and opinions appreciated. Thanks

I believe they will bolt up,but the valve angle is not the same as your 65 heads,valve reliefs in pistons may not work.

they will work with the 65 389 do not go to wild on the cam the stock cam will work a stock cam for 65. on the intake will need a gasket that fits the heat riser hole

I'm running a Crane single pattern cam. 290 duration and 454 lift. Will this cam work with these heads or will there be valve interference with the pistons? Thanks.

Compression may be on the low side unless the heads are milled. As previously noted valve reliefs may be a problem.

to make sure you have the valve relefs are ok this is a old trick put a thin layer of clay about 1/4 of a in then put the head on with some bolts just hand thght with no head gasket put on one set rocker arms with the pushrods set them at 18 lbs then rotate the motor 2 times slow take the head back off see how far the valve and piston cleared by how thin the clay is you need at lest .090 or you can e-mail me at [email protected] with your phone #



65 GTO 455 525HP
69 GTO mantching #s all the way

The 6X heads are great heads for a street 455 combo but you will end up with very low compression on a 389 due to the smaller bore and shorter stroke. To achieve even 9.0:1 you will need to mill the crap out of them. Then you will also have to mill the intake side of the heads as well to assure proper fit and may even loose proper intake manifold alignment in the process. Also milling the heads that much may cause piston to valve contact. I think another head choice may be an easier road.

Tim C