351 vs 302
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Joined: Jan 2007
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From: Washington
351 vs 302
It's been a while since I've been to FTE. I just recently picked up another truck, and have some questions for all you pros.
It's a 91 f150 with a 351w that has no oil pressure, though it does run and drive. (drove it 40 miles home with a bouncing oil pressure gauge and no brakes
) So it needs a new motor, and I have several choices before me:
- I already have a low mile '94 302 long block that I could swap in. What would be involved in this swap? ECM, exhaust hookup, wiring issues, engine mount location, trans hookup, etc. Is it basically a bolt in with a few minor changes?
- Would it be feasible to rebuild the bottom end of the 351 and get many more years of life out of it. New bearings and crank basically.
- What is the general opinion of a 302 vs 351 for truck in which the primary duties are commuting and light hauling of 800lbs or less.
It's a 91 f150 with a 351w that has no oil pressure, though it does run and drive. (drove it 40 miles home with a bouncing oil pressure gauge and no brakes
) So it needs a new motor, and I have several choices before me:- I already have a low mile '94 302 long block that I could swap in. What would be involved in this swap? ECM, exhaust hookup, wiring issues, engine mount location, trans hookup, etc. Is it basically a bolt in with a few minor changes?
- Would it be feasible to rebuild the bottom end of the 351 and get many more years of life out of it. New bearings and crank basically.
- What is the general opinion of a 302 vs 351 for truck in which the primary duties are commuting and light hauling of 800lbs or less.
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
Both of these motors will get the job done but the 5.8 is the better truck motor no question. If you did use the 5.0 you would need a complete 5.0 EFI intake and a 50oz flexplate or flywheel to match whatever trans the truck has, and the exhaust Y-pipe would need a little editing to fit the smaller 5.0 block, but you could get away without a PCM swap if it came down to it. Both motors use the same wiring and sensors, same engine mounts and transmissions, same fuel line connections, and same accessory brackets so this is a relatively easy swap.
Posting Guru
Joined: May 2012
Posts: 1,271
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From: Franklin, IN
If all your doing is commuting with occasional hauling then id say go for the 302. My 302 serves as my DD and and tows my trail rig around and im happy with it. Unloaded you wont notice much of a decrease in power and you will gain a few mpg.
Lead Driver
Joined: Jul 2007
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From: Rhode Island
The factory oil pressure gauge is just a glorified light. It's connected to a switch that automatically puts the gauge in the middle as long as there is ~5-7 PSI of oil.
But the gauge, switch, etc..are made with the cheapest, bargain-basement parts Ford could get. So before you sentence the engine to death, hook up a mechanical oil pressure gauge.
But the gauge, switch, etc..are made with the cheapest, bargain-basement parts Ford could get. So before you sentence the engine to death, hook up a mechanical oil pressure gauge.
Senior User
Joined: Feb 2003
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From: Greenville, NC
Sounds like a bad gauge sender to me. Mine had the same symptoms (would bounce off 0.) However there was no knocking when it did so (like you would expect if there actually was no oil pressure) so I gambled, changed out the sender, and now my gauge reads normally (in the center.)
Logistics Pro
Joined: Mar 2011
Posts: 4,197
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From: Central Wisconsin
I'm gonna agree with these guys here, sounds like a bad gauge not a bad motor...Especially if you drove it 40 miles. that's plenty of time to blow it up with no oil pressure.
But if the motor is junk, I'd say since you have the 302, just put it in.
But if the motor is junk, I'd say since you have the 302, just put it in.
Senior User
Joined: Jul 2012
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My old 91 302 would eat my low mile 96 351w for breakfast... That is all the experience I have with the two really.
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Logistics Pro
Joined: Mar 2011
Posts: 4,197
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From: Central Wisconsin
If that really is the case, something was DRASTICALLY wrong with your 351w. That is one of the best years for the 351w, and based on the numbers that each motor would put out, your 302 should feel like a dog compared to that 351w.
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Senior User
Joined: Jun 2009
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From: Durham, CA
I just swapped a 92 351W into my '95 in place of the aging 302 & I'll never go back as far as a truck engine! Swap the oil press sending unit or get a no kidding oil press check. 40 miles w/ no oil psi and I'd think she'd lockup due to heat/ friction! Sounds like your engine is fine & its a gauge/ sender problem.
Posting Guru
Joined: Dec 2008
Posts: 1,226
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From: Rusty, Maine
The factory oil pressure gauge is just a glorified light. It's connected to a switch that automatically puts the gauge in the middle as long as there is ~5-7 PSI of oil.
But the gauge, switch, etc..are made with the cheapest, bargain-basement parts Ford could get. So before you sentence the engine to death, hook up a mechanical oil pressure gauge.
But the gauge, switch, etc..are made with the cheapest, bargain-basement parts Ford could get. So before you sentence the engine to death, hook up a mechanical oil pressure gauge.
Senior User
Joined: Jul 2012
Posts: 223
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My 91 had shorty headers, and true dual x piped exhaust exit before passenger rear tire. That was it except bumped timing. It barked tires like a **** when I punch it.
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