First AMC

mwouda

Alright guys, just wondering if you can help me with this. This is my first AMC and I am so glad I kept it in my jeep instead of doing what everyone else does and go for the chevy swap. My question is, how much horsepower can I expect from my 304. Its a '78 bored .030 over edelbrock performer package, cam, intake, 600 carb,all new valves with edelbrock springs and retainers, standard headers, mallory unilite dizzy, msd 6al ing box. Again, this is my first AMC, so I have no Idea and not really sure if I can relate it to a chevy 5.0 litre. Any help would be great. Thanks :sa:

AMX69PHATTY

The stock '70 304 with 9.0:1 CR was rated at 210 HP & 305 lb-ft. With the changed parts add what 20%, so maybe 250 HP ?

Mudrat

Sounds like a routine re-build and 250 HP will be in the ball park. What's the cam like? Give up the specs and we'll shoot it throu desktop dyno and see.

hotratz

mwouda wrote
Alright guys, just wondering if you can help me with this. This is my first AMC and I am so glad I kept it in my jeep instead of doing what everyone else does and go for the chevy swap. My question is, how much horsepower can I expect from my 304. Its a '78 bored .030 over edelbrock performer package, cam, intake, 600 carb,all new valves with edelbrock springs and retainers, standard headers, mallory unilite dizzy, msd 6al ing box. Again, this is my first AMC, so I have no Idea and not really sure if I can relate it to a chevy 5.0 litre. Any help would be great. Thanks :sa:

I think you might be dealing with a little less initial HP.

According to some sources these are the numbers for 304 factory HP through the years.

The 304 in¬? (5.0 L) produced 210 hp (157 kW) in 1970-71 and was built starting in 1970. Later models produced less power from the factory, going down yearly. 1972-78 models were rated at 150 hp. It was rated at 130 hp in 1979, the last year it was installed in passenger cars, and 125 hp in 1980-81, the last years it was used in Jeep vehicles

zero cool

Keep in mind that the drop from 71 to 72 is mostly due to the change from SAE gross to SAE net. Basically, before 72, they used SAE gross horsepower numbers. They would put the engine on a stand, hook up externally powered oil pumps, water pumps, generators. They would bolt on headers with open pipes and velocity stacks on the carburetor. Needless to say, engines set up like this didn't run the same as they did when they were installed in the vehicle so the HP numbers weren't realistic. Starting in 1972, they switched to SAE net ratings. They had to run the engine with the stock oil pump, water pump, alternator, air conditioning compressor, factor air cleaner and exhaust as it was installed in the vehicle. Most ratings dropped around 30-40% when they made the switch. Realistically, there's not much difference between the 210 HP 1971 and the 150 HP 1972 engines. The only thing that changed is the way they rated horsepower.