Cheap V8 Mods For A '65

[Rich Jensen]

Hi,

Friend of mine picked up a 65 Mustang (Jan. 13 build date) with the straight 6, etc., in pieces for like $1500. It originally had a manual, but someone fitted it with an automatic at some point in time. It had a factory I-6, that had been taken out of the engine bay, and an interior in surprisingly good shape (except for the headliner which was full of mouse turds and stink). Body needs a fair amount of work, as it was fitted with a replacement right rear quarter that was bondoed on by some guy using, I think, a mason's trowel or a spade, and there's a lot of hail damage or some kids got destructive with small pebbles and stones.

Anyway, because of the need for a new dashboard cover and a lot of body work (including a respray over a terrible paint job---they even painted the interior door panels!??!) he's looking to save some money on the engine, but still have something with ~ 275 hp. or so.

He's got a 3-speed manual, and will buy a new diff, so that's taken care of. He also picked up a '71 302 (rated at 210hp., I think). He's looking at boring out the block and adding a performance cam. I've suggested picking up a used set of GT40P heads from an Explorer, but we're not sure what to do with the intake/carburetor setup. While I suppose we could put the intake from those engines on, we'd have to do an aftermarket PFI system which would seem to be making this process more complicated than it needs to be.

I would think that with the late 90s 5.0s being rated at 225hp in factory tune, we should be able to bump that up 20% with a larger displacement engine, an aggressive tune and no emissions equip., which would get us about where he wants to be.

So, any suggestions as far as a good intake & carb. to use with the GT40 heads? Also any suggestions for how we could go about this differently? We're in South Dakota, so we don't have to emissions test the vehicle.

 

[2+2GT]

The GT40P head is not a good choice, since it also forces you to get unique headers that allow the use of the P heads. You'd save money and get nearly as much power if you used your iron heads, and port-matched them to the exhaust. Have the stock distributor curved to BOSS 302 specs. Use a cam something like the C9OZ-6250-C hydraulic cam, a 600 cfm carb, and performer rpm. A real low-cost build, and yet could actually get you over 300 hp.

 

[Rich Jensen]

"performer rpm"?

Also, stock intake is fine?

Edit: Never mind. Googled the first question and answered the second.

Thanks for the info. Guy's torn between replacing the bottom end of the engine and leaving it as is, aside from the bearings which definitely need to be replaced.

 

[bartl]

If he's going to use the '71 302 and it still has its original heads, then port and port match the intake and exhaust (careful keeping the exhaust port just a teeny bit smaller than the manifold/header), use a decent dual-plane intake manifold like the Weiand Stealth, a 600cfm Holley Carb (I'd use list O-4776 which is a dual-feed, double pumper, mechanical secondary), recurve the dizzy to Boss302 specs and me, myself, and I would use either the C9OZ-6250-C hydraulic version of the HiPo cam or run link lifters and an E-303 roller cam. Either way you'll be (should be) looking at screw in rocker studs and improved springs. For exhaust you could get away with some repro HiPo manifolds, '69-70 351W manifolds or the headers of your choice.

As far as the bottom end goes, if the crank is decent and can be polished, fine. New bearings, check the rods for size and use ARP fasteners. Single true roller timing set should be fine. If you want some extra juice and don't mind some noise when cold, you can install the pistons on the rods with the arrows pointing rearward which reduces the side loading intentionally put there by the engineers to keep cold engines quiet.

 

[Rich Jensen]

He's looking at boring out the block .30. It doesn't seem like these mods should overstress the block. Thoughts?

 

[pocketlint]

Boring it 0.030 over, making it a 306, you wont overstress the engine. Many people do that overbore when they rebuild an engine anyway. Ideally, a nice set of aluminum heads would be a good upgrade, but they can get pricey. You can easliy gain a lot horsepower with an agressive cam and the right air intake system. I put the Performer RPM and 600 cfm Holley carb on the 351 I'm rebuilding. The performer is about the tallest intake I can go and still fit under the stock hood of my 66. But the 302 block will be a little shorter. And the 65 motor mounts will give you about an extra inch hood clearance too, over the 66 mounts. You may be able to get an Air Gap or a Victor Jr. in there, if you can find one cheap. As the saying goes: there's no replacement for displacement.

 

[7991LXnSHO]

There other inexpensive gt-40 heads than the gt 40 P ones, and they will work as easy as the stock heads.
Edelbrock performer or air gap will be nice, depending on where you want your power.