Hey guys,

I could use some input here. My 289 block needs rebuilt. The factory heads have already been rebuilt about a year ago. There was barely a ring groove but I will know more once the motor is pulled. I am looking for the cheapest way to rebuild the block but increase the power at the same time. I am hoping to use my old pistons and just glaze the cylinders, and install new rings, cam bearings, etc.

I have been considering swapping the heads for a set of GT40P heads while I am doing this. I will be running a 268H competition cam, holley 650, and aluminum intake. I also have the hipo exhaust manifolds.

What kind of improvement can I expect by going with the GT40P heads and are they worth adding for another $300.00 or so?

Thanks in advance!

 

The GT40p heads will require special headers for those heads. But they will be a fair improvement on stock 289 heads, unless you had port work done etc.

As far as the rebuild, you'll be much better off purchasing better pistons and rings. Something like a basic KB with a god moly ring package, and then use a custom grind hydraulic roller cam conversion. It'll be a bit more money, but it'll last way longer, make much better power, be more reliable and get better mileage.

Just for a comparison sake, I'm running Mahle pistons and plasma-moly rings in my 302.....with somewhere around 200-250k mi on it so far, had the heads off recently, and it has 0 ring ridge and cylinder wall wear. Can still see the cross hatch. But, the piston/ring set I'm using is about $700.

 

I like the C9OZ-6250-C hydraulic version of the 289HP cam. Smooth, daily driver quality, with 300+ power potential.

As for the heads, the only thing wrong with your stockers [since they're rebuilt] is the exhaust ports suck. Since you are removing them to work on the block anyway, this excellent upgrade will cost you nothing, except a couple hours work:

289/302 Cylinder Head Port Matching

 

It's not necessarily cheap but I like the idea of new pistons as well..If there is a ridge in the cylinders they likely need replacing anyway and a rering will be a short lived improvement...I would do your homework with the pistons and try to end up with close to 10:1 compression..Do the math and don't just take the pistons advertised listed compression ratio as gospel as I have discovered they can be well off the mark sometimes..A set of longtube headers would be a nice improvement over the HiPOs if you are looking for extra power as well..

 

I'd avoid the P heads. If you go that route, you're pretty much stuck with them unless you budget later for new heads and headers, because P-head specific headers are pricey and don't usually work on non-P heads.

Keep in mind that you'll need valve springs and screw in studs to match either the cam you selected or a roller cam.

 

Thanks 2+2 for the port match link. Would love to do this, but not so confident that I won't screw it up! lol

 

Thanks 2+2 for the port match link. I would love to do this, but not confident that I wouldn't screw it up! lol

 

Excellent advice. I had long tubes at one time and absolutely hated them, other than the power increase.

 

the cam you mention with heads is one of those that would allow your engine spin up to 6000+ rpm and still make power. However I'm not sure if the conrod bolts will hold up. it would be a nice improvement on top, but would the bottom end be up for that?
Maybe choose a cam with a torque curve lower in the rpm band ... I don't know the specs of the one that 2+2 posted. 2+2 any idea where this would sit?

 

The C9OZ-6250-C is a hydraulic version of the C3OZ-6250-C. The C9 is 290°/290° (218°/218°@.050") .470"/.470". Excellent power from idle to low 5000's.

This is the dyno card from a 67 289 with a C9OZ-6250-C.