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300 Cubic Inch Inline Canadian 6 Cyl

300 Cubic Inch Canadian 6 cylinder Truck Motor

Specifications

Bore & Stroke: 4.00″ x 3.98″ 
Compression Ratio: 8.0-8.9:1

1965-1972 
Brake Horsepower: 170 @ 3800 rpm 
Torque: 283 lbs.-ft. @ 1600 rpm

1973-1974 
Net Horsepower: 101 @ 3000 rpm 
Net Torque: 223 lbs.-ft. @ 1600rpm

1975-1977 
Some were the same as ’73-’74 others 
were bumped up to 120nhp @ 3400 rpm 
with the same torque specification.

1978-1986 
Horsepower ratings varied from 101nhp, 115nhp, 117nhp 
and 120nhp @ 3000-3400rpm. Torque ratings remained 
223 lbs.-ft. @ 1600 rpm.

1987 – 1993 
Switched from carbureted to electronic fuel injection. 
Compression ratio was 8.8:1 
Brake Horsepower: 145 @ 3400 rpm 
Torque: 265 lbs.-ft. @ 2000 rpm

1994-1996 
Brake Horsepower: 150 @ 3400 rpm 
Torque: 260 lbs.-ft. @ 2000 rpm

Performance Modifications

Carbureted

Air Intake: Most people seem to like K&N’s, but any filter open 
360* is an improvement over stock.

Carburetors: A Holley 390cfm 4bbl is the most popular choice and 
works best especially with stock cam, a lot of people are happy with 
500cfm Edelbrocks too though. Only use a 4bbl with an Offenhauser 
or Clifford 4bbl intake, use a 2bbl with an adaptor plate.

Intakes:  Both Offenhauser and Clifford make a 4bbl intake for the 300. 
Offenhauser seems to be the favorite because it’s cheaper and just as good. 
Clifford makes 2 and 3 carb intakes also.

Headers; Headman and Clifford are both good choices, of course Headman is 
cheaper.

Camshafts: Both Clifford and Isky make a wide range of camshafts.

Ignition: Any performance ignition, MSD is most popular.

Heads: You can have porting; polishing, bigger valves also putting on a 
240 head will raise compression.

Exhaust: High flow mufflers, dual cats, no cats, hollowing out cats. 
2 1/4″ True duals with split headers is suppose to work the best.

Electronic Fuel Injection

Same kind of stuff except instead of slapping on a bigger carb, since fuel 
injection doesn’t use one, duh, you’ll want bigger injectors and maybe you can 
find a bigger throttle body that will fit.

Turbo: Some people have had custom manifolds made and used the turbo of 
Chevy diesels; there are no kits for this so it would be a custom job.

Chips: To my knowledge there are no performance chips for the 300.

Common Problems

Ford’s 300 inline 6 is a fairly problem free engine for 200,000 to 300,000 
miles if properly maintained. Common problems with the carbed models 
are vacuum leaks, just little ones can cause hesitation, rough idle, etc. 
The stock Carter 1bbl carb seems to like rebuilds too.  On the automatic 
transmission models some people have problems with overheating, this can 
be fixed with a cross-flow radiator and flex fan or a electronic fan.  Besides 
that if they’re over revved the 300 is known to throw rods or have early valve train 
failure.

I am not very familiar with the fuel-injected models so I don’t have a whole lot 
of advise to offer with them