Performance Part 302 engine

[Cresee]

Have just recently pick up a 1972 302 long block with 1968 close chambered heads with bored 60 over pistons. Other than that it is a stock build. Thinking about using the current heads because the build is only a month old. Not sure of current compression? I think it may be 9:8:1 based on the current state. Possibly a little over 300 horse with comparable torque.  Would like to add a new intake manifold, four barrel carburetor, headers and a nice performance camshaft and torque converter if needed. that would also go well when I think about changing the heads down the road. With the amount of performance parts available I thought I would look to get some information from the people who have had similar builds done.  What are your thoughts or experiences? I also have a c-4 and a AOD transmission. 

Also looking to update the suspension currently has  and  possibly put some disc brakes on the front end.  Any other suggestion will be appreciated.

 

[Jeff73Mach1]

.060 over on a 302 block is too much to trust it to a performance rebuild. Shelby managed to get 271 out of a stock bore 289, but most 302's made no more than 225 from the factory so I doubt you are at 300. I would not try and hot rod that engine. If you want more power start with a block that is bored no more than .030 over.

Between the AOD and the C-4, I would choose the AOD for its overdrive and I would pair it with a 3.89 or 3.70 rear gear. This will allow you to get acceleration and maintain driveability at freeway speeds. Lower gears (higher numerical )are also easier on the engine as the gear multiplication means the engine is under a somewhat lighter load.

 

[Don C]

Boring and raising compression will do little to raise your horsepower by itself. Your biggest limitation is the stock camshaft. What carburetor and intake are you currently using?

A stock '72 302 made around 140 horsepower at the crank.

You can calculate your compression here

https://www.7173mustangs.com/thread-engine-and-compression-calculations?pid=199290#pid199290

I agree with Jeff about the .060 bore, too much, and not suitable for a performance engine.

 

[Jeff73Mach1]

A stock 72 engine was rated at 135 HP but that is net horsepower. In 71 they measured gross horsepower which gives a different and higher number, even though the engines had not really changed in any significant manner.

 

[Cresee]

I do think current horsepower is probably 225 max. Have not decided on the intake, carburator or camshaft yet. Looking to see what thoughts are out there for a good combination. Just looking to build a nice street cruiser with some get up go when needed

 

[Spike Morelli]

I'm not sure if this will apply directly to your build, but some years back, I read an article in a Mustang magazine, where they took a 2 bbl 289 mustang with an automatic, and put it on a chassis dyno, to get a baseline of horsepower output to the rear wheels. Then, they removed the iron 2 bbl manifold and carb, and replaced it with a stock 4 bbl manifold and Autolite 4100 4 bbl ( two sizes were made, this first one was the smaller 480 cfm unit ). Not suprisingly, horsepower to the rear wheels jumped up. Then, they removed the 480 cfm carb, and put the larger 600 cfm 4100 Autolite carb on. Horsepower figures to the rear wheels DROPPED a bit with the bigger carb! Ford, in their infinite wisdom knew what they were doing, as the 480 cfm carb is what an automatic trans car got from the factory, and the 600 cfm carb was used in four- speed cars, as well as larger engines, like the Hi-Po 289 and the 390.

The point is, if you are running an automatic trans, don't go for a big carb, stay at 500 to 600 cfm with vacuum secondaries or you probably will be throwing away torque and horsepower. Anyway, I wish I had saved that article...I think it was in an old Mustang Monthly magazine.

 

[barnett468]

Have just recently pick up a 1972 302 long block with 1968 close chambered heads with bored 60 over pistons.

It is complete junk at .060" unless you live at the north pole.

 

[Ed Raver]

Barnette468 is correct. At .060 overbore you will have overheating problems and some spare parts when it is over. Better aftermarket blocks are readily available and not all that expensive. Its like a good foundation on your home.    Ed

 

[Spike Morelli]

.

 Shelby managed to get 271 out of a stock bore 289, but most 302's made no more than 225 from the factory so I doubt you are at 300.

What is more accurate about the 289, is that Ford, not Shelby American, delivered 289 Hi-Po engines as built from the production line, at 271 horsepower. To that, Shelby American added external modifications ( carb, intake, headers ), to achieve 306 horsepower from the factory Hi-Po "K" engine, in Cobras and GT-350s. It is a matter of historical fact that the 289 was/is capable of more. Many different builds of this engine came from Shelby American back then, to compete in assorted classes of road racing and drag racing. The 390 horsepower , Weber carbed, LeMans cammed , competition ported cylinder head 289 engine comes to mind, such as was raced in early GT-40s. These were all standard bore, non-stroker engines. In 1967, Ford was making forged steel cranks and four bolt racing blocks for the 289. And.....that was then.  Imagine what the little 289 is capable of with today's technology?

 

[Carolina_Mountain_Mustangs]

I do not know that I would be afraid of the .060" over bore. You might want to have someone do a sonic check of the wall thickness and see if there was core shift in the casting giving a thin spot. I know we bored them to .060" back in the 60's when I worked in engine shop. Put domed TRW pistons in and bumped the compression up over 13 - 1. They really sound good and crisp with high compression. We built for circle track and drag racers. I know one that for 13 years on strip before he tore it down ran in the high 12's back then in stock body 65 mustang coupe.
You are only talking about 5 human hairs thicker if just .030" over bore per wall.
My old boss Roger Ingram use to build 289 and lap the heads to the block and no head gaskets to get all the compression he could. We built a Pontiac 303 for Buck Baker when he was running a Firebird in the NASCAR version of Trans Am. No head gaskets on it either. Had to get oversize lifters ground the new blocks had the lifter holes too big letting too much oil out and burning bearings out. We always shot for .0001" for bore dia. and straightness. The engine ran on track for 2,000 miles and did not blow. We got it back and did not let GM have it back, lol. They did not know what all we did to it. GM had sent the crazy Ram Air V tunnel port heads to use but we did not no way a 303 CI motor would run with those heads. Probably to big for a 421. Roger even experimented with choke boring so that the cylinders are straight when heated up. They do in most all air cooled air craft engines. He even played with on flatheads having the front cylinders larger dia. because the cooling water kept the front cylinders cooler so clearance was less.
I know my 73 with 351 H code that I bought as built he had put the LH head gasket on backwards. When I pulled the heads it is bored .050" over and has flat topped pistons, cam, 4-V performer intake with holley on the 2-V heads. MSD ignition. I has AC, PS and does not have any issues with heat with a stock radiator and flex fan. Have driven in 90 deg. + heat and was at Pigeon Forge Tenn. at a rod run and it was bumper to bumper crawling traffic for miles and no over heat. I did take the transmission cooler lines out of radiator and put stand alone fan cooled Hayden transmission cooler on. I run non ethanol 90 with Lucas Oil gas additive.  I know drag racers here go .080" on Cleveland as long as the casting is good and have no issues.
I would give the engine a try have good clean radiator and us distilled water and 50% antifreeze mix. Don't go crazy with timing and put the Lucas oil gas additive in to lube the valves and upper cylinder with non ethanol 90 octane fuel. Just be sure to put head gaskets on the correct way.