302 or 351?
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Cross-Country
Joined: Jan 2005
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302 or 351?
1990 F-250 302, Mazda 5 spd. I bought it with no muffler and virtually no valve cover gaskets. After repairing both, I noticed that the engine has a disturbing knock. Whether it's a rod or piston, I don't know yet.
It's coming out next week and I have a choice. I have a fairly decent 351 that's been sitting for awhile that could be made to work with some parts swapping or I could hopefully repair the 302 and run that. The 302 has real good compression and runs well except for the knock.
My real question has to do with the smog stuff. There's enough difference that it's not just a straight across swap. The cat being the major difference. The air injection system is considerably more complex on the 351 and I don't know how much of the 302 electronics will work. Could I fake a stroker 302 by swapping all of the 302 smog onto the 351? Could I still pass emissions?
I'd like the greater torque of the 351 but it's just a work truck so I don't necessarily need the power and the 302 seems to be getting good mileage.
Your thoughts please?
It's coming out next week and I have a choice. I have a fairly decent 351 that's been sitting for awhile that could be made to work with some parts swapping or I could hopefully repair the 302 and run that. The 302 has real good compression and runs well except for the knock.
My real question has to do with the smog stuff. There's enough difference that it's not just a straight across swap. The cat being the major difference. The air injection system is considerably more complex on the 351 and I don't know how much of the 302 electronics will work. Could I fake a stroker 302 by swapping all of the 302 smog onto the 351? Could I still pass emissions?
I'd like the greater torque of the 351 but it's just a work truck so I don't necessarily need the power and the 302 seems to be getting good mileage.
Your thoughts please?
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
All the 5.0 smog stuff will work on the 5.8 and vise versa with the exception of the tube that goes across the back of the motor between the heads or the exhaust manifolds.. depending if the motor is from a 1/2 ton or something heavier. Functionally the system is the same, it pumps air into the heads or exhaust manifolds at cold start and diverts that downstream to the cats or completely bypasses everything as the engine and exhaust warm up, there are just differences in the way it's plumbed and the valves.
BTW.. the 5.8 block is physically larger than the 5.0 version so the intake, distributor, oilpan, and timing cover won't interchange, and engine balance is also different so a different flywheel is also needed.
BTW.. the 5.8 block is physically larger than the 5.0 version so the intake, distributor, oilpan, and timing cover won't interchange, and engine balance is also different so a different flywheel is also needed.
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Cross-Country
Joined: Jan 2005
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Forgot about the flywheel. Made that mistake once years ago.
The block is taller so intake and dist is different but all else is the same. Dropped one in a '64 falcon back in '84.
What about the electrics and would running a 351 through a 302 cat work?
The block is taller so intake and dist is different but all else is the same. Dropped one in a '64 falcon back in '84.
What about the electrics and would running a 351 through a 302 cat work?
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