Please give your opinions on this combo

[DW]

I have a 65 K-Code with what I believe to be the original motor rebuilt to original specs. I want to give it a boost without doing anything exteme so I can go back original if need be. I have a Holley 650DP (4777) and a Ford Hi-Rise manifold, similar to the Cobra intake used by Shelby on the GT350. I don't want to screw with the original heads, so I'd like to try a set of Powerheads with the Holley/Cobra induction combo, and a set of Doug's Tri-Y's. Assuming the cam is a K-Code cam, my understanding is that the specs are:

Intake: 0.477" Lift with 0.022" Valve Lash with 1.6:1 Rocker Arms
Intake Opens 25 Degrees BTDC and Closes 70 Degrees ABDC, 275 Degrees Duration

Exhaust: 0.477" Lift with 0.022" Valve Lash with 1.6:1 Rocker Arms
Exhaust Opens 73 Degrees BBDC and Closes 22 Degrees ATDC, 275 Degrees Duration

Lobe Centers is 114 Degrees.

I got this off the K-Code site and it's supposed to be from the company that ground the original K cam.

Can you tell me if you think this is a good combo? The car supposedly makes 271hp is stock form, and mine runs pretty strong so I have no reason to doubt it. What do you think my gains will be? Also, anyone have any idea if the larger valves in the Powerheads will crash my pistons? I have no idea if the pistons have valve reliefs, I would assume not.

 

['69Stang]

I am assuming that you want to keep the cam you have in the motor and just upgrade around that (the short block). The 650 Holley DP, with hi-rise dual plane and tri-y headers are a great match with a 2.5" dual exhaust system. Regarding the heads I would forget about the Powerheads and go straight for a set of AFR 165's. They really seem to be the undisputed leader for a bolt on set of aftermarket heads.
If you want to keep the engine looking "totally stock" then that is a different story. In that case you may want to consider a set of iron GT-40 heads and have those ported. In fact you might be able to find a ported set for $500-$600.

 

[DW]

You're right 69Stang, I don't want to replace the cam since if I decide to sell it, I want be able to quickly and easily put it back stock. The cam is really the part I'm unsure about which is why I posted the specs. I don't know if it's enough cam to fully take advantage of the other mods.

I also don't want to go the aluminum route as I'm trying to keep the cost down and I want to keep it looking "vintage", as you mentioned. I hadn't thought of GT-40 heads, but I had a set of those when I had a 93 Cobra a few years back. Will those bolt up to the 65 block and intake with no modifications? I had thought one of the advantages of the Powerheads was the larger valves (1.60/1.94). Do the GT-40's have bigger valves than the stock 289 heads that I've got now? I know they flow better. What is the chamber size on the GT-40's? My stock heads are supposed to have 54cc chambers and it seems most late model heads have 58cc or 60cc. I don't want to lose any compression because that would negate some of the gains from the other mods. Or would that be negligible?

 

[allcarfan]

your car may have been rated at 271 back in the 60s...but I dont know what kind of HP that would translate to today...being they were measured different.

I think you have a healthy combo there. However, if you have the heads off, id go ahead and swap in a little more radical cam. Also, the GT40s would be a really good choice.

 

[302 coupe]

why not have the k code heads ported and fitted with bigger valves. Its not a visible mod until the heads are moved. Same as the cam....the difference would be completely undetectable until you hit the gas.

 

['69Stang]

You're right 69Stang, I don't want to replace the cam since if I decide to sell it, I want be able to quickly and easily put it back stock. The cam is really the part I'm unsure about which is why I posted the specs. I don't know if it's enough cam to fully take advantage of the other mods.

I also don't want to go the aluminum route as I'm trying to keep the cost down and I want to keep it looking "vintage", as you mentioned. I hadn't thought of GT-40 heads, but I had a set of those when I had a 93 Cobra a few years back. Will those bolt up to the 65 block and intake with no modifications? I had thought one of the advantages of the Powerheads was the larger valves (1.60/1.94). Do the GT-40's have bigger valves than the stock 289 heads that I've got now? I know they flow better. What is the chamber size on the GT-40's? My stock heads are supposed to have 54cc chambers and it seems most late model heads have 58cc or 60cc. I don't want to lose any compression because that would negate some of the gains from the other mods. Or would that be negligible?

I had a set of GT-40's and had them milled to 54cc's to keep the compression up too, it was no problem. And, yes, the GT-40's do have bigger valves I believe they are 1.84 intakes and 1.54 exhausts. You could always have your 289 heads ported and have slightly larger valves put in and it should perform really well. I think your cam should be fine for fun street performance. But, you could get a step-up in cam that would probably idle the same but put out much better performnce. I even think that Lunati had a modern replacement of the old K-code solid cam that was a step-up but idled the same.
My feeling is that a set of ported GT-40's would probably out perform a set of ported 289 heads, but the difference might be marginal.