[Magna83]

I am under the impression that the 73 302 block is the same as a 68 ford 302. Is it possible to take a 73 302 which is pitiful horsepower (mostly due to crap compression ratio form domed piston headeds) and since I am rebuilding it anyway, put in the guts (master rebuild kit) of a 68 302 to get more horsepower out of it? If i am wrong, please point me in a direction of how to get more power form a 73 302.

oh and if the answer is get a 351 or a 429, I would if i had one of those laying around. but I dont.
thanks gang

 

[SlipKid]

The 73 block is identical to the 68. There's a '73 in my 65. But it has 65 heads, intake, carb, water pump, timing cover, valve covers, exhaust manifolds, etc. I am not sure about using 73 heads (some one else will chime in) versus the advantage (if any) of finding a pair of older heads. Good luck.

 

[Al Newman]

The '73 motor does not have domed pistons. They are dished. The heads are large chambered, also. The combination makes very little power. Flat topped pistons will help. 1965-68 heads will help. 1975 heads will help. Most any aftermarket iron or aluminum heads will help. A camshaft change will help.
Best,
Al

 

[22GT]

I am under the impression that the 73 302 block is the same as a 68 ford 302. Is it possible to take a 73 302 which is pitiful horsepower (mostly due to crap compression ratio form domed piston headeds) and since I am rebuilding it anyway, put in the guts (master rebuild kit) of a 68 302 to get more horsepower out of it? If i am wrong, please point me in a direction of how to get more power form a 73 302.

oh and if the answer is get a 351 or a 429, I would if i had one of those laying around. but I dont.
thanks gang

The 68 2V and 73 2V both had dished (not domed) pistons. Simply order flat-top pistons. The C3AZ-V camshaft was the same, and was pretty lame.

A little headwork is in order. Have screw-in studs installed, port-match the exhaust ports to a set of 289HP exhaust manifolds.

http://www.mustangbarn.com/PDFs/Port Matching.pdf

Use a C9OZ-6250-C hydraulic camshaft. Have your distributor curved to BOSS 302 specs. Install a Performer RPM manifold and 500 cfm carburetor.

You should see more than 300 hp, which is about 100 more than you have now, with a smooth, daily-driveable engine. You also won't break the bank doing it, notice I haven't mentioned exotic ignition, etc. You don't need them.

 

[Magna83]

I apologize on the domed part, I know I meant dished but working over night fries my brain at about 3 am.

Thanks for chiming in with your thoughts guys I really appreciate it. 22gt is there anything you know?
Will a machine shop be able to port-match the exhaust ports? or is this something I have to find a specialty shop to do? Hoping to get money for christmas so I can break the engine down and get it cleaned up and order a 68 rebuild kit (flat head pistons though).

 

[kenash]

I apologize on the domed part, I know I meant dished but working over night fries my brain at about 3 am.

Thanks for chiming in with your thoughts guys I really appreciate it. 22gt is there anything you know?
Will a machine shop be able to port-match the exhaust ports? or is this something I have to find a specialty shop to do? Hoping to get money for christmas so I can break the engine down and get it cleaned up and order a 68 rebuild kit (flat head pistons though).

Hi,
Port matching is something you can do with a few port grinding bits and a basic understanding of the approach. See.......
http://www.mustangbarn.com/PDFs/Port Matching.pdf
Any good "trust worthy" performance oriented shop can do it. You'll pay through the nose, though. It's like anything else, when you choose to hand off labor intensive work.
Happy Holidays!

 

[Woodchuck]

A couple corrections here....

The '73 heads are not "open chambered". The '72-74 heads were 58.2cc chambers (SMALLER than the 63cc '68 heads) and had 1.78" intakes, vs. the 1.67" intakes of the '68 head. As 22GT says, by all means do some simple port work to remove thermactor bumps, if any, and to port match the intake and exhaust.

I AM a little confused, though about what year the CAR is. If this engine is going into a '68, then use whichever block is in better condition, the '73 heads, the '68 front cover and whichever crank and rod set is in better shape. Use the '68 balancer, etc. If the engine is going in a '73, then you may want to simply sell off the '68 as a complete engine and rebuild the '73.

For pistons, I'd be thinking something along the lines of THESE which should be great for all around use giving you a static CR around 11.0:1. A good intake like the Weiand Stealth, a well tuned Autolite 4100, the C9OZ-6250-C camshaft and some repro HiPo manifolds and it should be quite the little screamer.

 

[Magna83]

Ok, clearing up the confusion. The body is a 67, originally a 289. I just got the car (yay) needs bunches of work, but I'm really excited for it. The motor is one the guy threw in (not actually in the car). It is a 302 from 73 I believe (assuming the carb tag isnt lying I'll know more as i tear it down). That being said. I read that as the 70's progressed horsepower took a dive in the 302 I want to get some power back, I read that 68 was the year the 302 had the most power stock.

SO, I was hoping that I could replace some of the bits and pieces and get make the 73 more powerful.
Am I making any more sense?

 

[Woodchuck]

Ok, clearing up the confusion. The body is a 67, originally a 289. I just got the car (yay) needs bunches of work, but I'm really excited for it. The motor is one the guy threw in (not actually in the car). It is a 302 from 73 I believe (assuming the carb tag isnt lying I'll know more as i tear it down). That being said. I read that as the 70's progressed horsepower took a dive in the 302 I want to get some power back, I read that 68 was the year the 302 had the most power stock.

SO, I was hoping that I could replace some of the bits and pieces and get make the 73 more powerful.
Am I making any more sense?

Horsepower plummeted in '72 because the automakers switched from SAE Brake Horsepower to SAE Net Horsepower. That said, a 302 is a 302 is a 302. Just rebuild what you've got - you'll be buying new pistons for the overbore anyway and the '73 heads are fine.

 

[Magna83]

Thank you for the advice. I appreciate it. I'll check out those pistons, intake and manifolds you suggested.

 

[CDs68]

Im running a '73 302 in my '68. bore .30, Edlebrock Heads RPM [I beleive... only see my car once a week ], RPM intake, 650cfm edlebrock carb w/elec. choke, AL6 MSD, E303 cam, Headman Shorty headers....Can’t quite remember the rest, I built it about 10 years ago. I’m at 400+ HP

 

[22GT]

It is a 302 from 73 I believe (assuming the carb tag isnt lying I'll know more as i tear it down).

It would be a lot better to look at the casting and date code by the starter.

 

[ScottsGT]

Sounds like your a noob at this engine building thing. Do yourself a favor and talk to the machine shop about your head work and the money you are going to drop into them vs. the horsepower gains if you port them. Then compare the prices of your heads to aftermarket aluminum heads and think used aluminum heads.
Ex: 13 years ago when I started my project I got excited about building my motor first, not realizing I was years away from that stage. I priced out head work at a local shop that was about $600 for everything.
Went to a swap meet and found a set of Trick Flow heads with one season of passes at the strip for the same price as the machine shop labor.

 

[22GT]

I priced out head work at a local shop that was about $600 for everything.

If the heads don't need to be rebuilt, port-matching them produces stunning results for $0, if you have or can borrow a die grinder.

 

[frdnut]

The 73 block is identical to the 68. . .

There is one important difference..The 73-76 blocks had an extra .020 or so added on to the deck hieght...This will hurt your compression if you use the 68 pistons..To fix the issue just have the machine shop mill the deck back to the 8.2 deck height and you will be good to go.

 

[frdnut]

A couple corrections here....

The '73 heads are not "open chambered". The '72-74 heads were 58.2cc chambers (SMALLER than the 63cc '68 heads) and had 1.78" intakes, vs. the 1.67" intakes of the '68 head. As 22GT says, by all means do some simple port work to remove thermactor bumps, if any, and to port match the intake and exhaust.

.

We have been over the valve sizes before..Not sure why you keep posting this incorrect info?..68 heads would have the same size valves as the 73s..

 

[22GT]

22gt is there anything you know?
Will a machine shop be able to port-match the exhaust ports? or is this something I have to find a specialty shop to do? Hoping to get money for Christmas so I can break the engine down and get it cleaned up and order a 68 rebuild kit (flat head pistons though).

Port matching is no problem. The fellow I mention from time to time who dynoed his engine after following my recommendations had never done it before. He watched me do one port, then he did the other seven like it at home.

 

[Woodchuck]

We have been over the valve sizes before..Not sure why you keep posting this incorrect info?..68 heads would have the same size valves as the 73s..

Sorry, I was thinking of the '68 289 heads. Yes, both '68 & '73 have 1.78" intakes which, if I was having the heads redone anyway with hardened seats, would replace with 1.94" intakes and 1.60" exhausts.