Motor too tight
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1st Gear
Joined: May 2025
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Motor too tight
I have a recently rebuilt 1982 ford f150. It has the 3 speed auto and a 351w. After much trouble come to learn the motor is too tight and struggles to crank when warm. I’ve replaced both starter and battery. I was wondering if anyone knew of what kind of high output starter would fit best in this truck. Keep in mind the truck has long tube headers that take up lots of space. Thanks!
Laughing Gas
Joined: Feb 2016
Posts: 817
Likes: 27
A PMGR starter may be your best bet.
Depending on the warm crank profile, it could be a heat-soaked starter (slow crank) or timing that’s too advanced (which has a distinct kickback to it, especially if well advanced). Long tube headers are likely not helping your heat soak. I would convert to a PMGR. Heed the proper wiring to avoid starter run-on.
Depending on the warm crank profile, it could be a heat-soaked starter (slow crank) or timing that’s too advanced (which has a distinct kickback to it, especially if well advanced). Long tube headers are likely not helping your heat soak. I would convert to a PMGR. Heed the proper wiring to avoid starter run-on.
Lead Driver
Joined: Nov 2013
Posts: 7,174
Likes: 1,174
Ten minutes with a voltmeter, 3 simple test hookups, and you will have your answer:
https://www.ford-trucks.com/forums/1...w-starter.html
Please note a warm engine puts the maximum load on the starter system. If the system is marginal, and this is very likely, it can handle the reduced load when the engine is cold. But when warm and the poor starter system has to work harder? Not so much.
Run the test. Report back with your results. I've taken the liberty of composing a reply you can use. Feel free to copy/paste or use your own words:
"You are amazing. I followed your simple test and it led me directly to the problem. I fixed it with no wasted time or money. I now realize the nice things everyone says about you are really true. I didn't think one person could be so wonderful and yet so modest, but it's the truth. I bet you smell nice, too."
Tuned
Joined: Dec 2024
Posts: 445
Likes: 94
From: Texas, near Houston
I have a recently rebuilt 1982 ford f150. It has the 3 speed auto and a 351w. After much trouble come to learn the motor is too tight and struggles to crank when warm. I’ve replaced both starter and battery. I was wondering if anyone knew of what kind of high output starter would fit best in this truck. Keep in mind the truck has long tube headers that take up lots of space. Thanks!
FTE Legend
Joined: Nov 2015
Posts: 30,912
Likes: 4,123
From: Angier, NC
You might check and see, if im not mistaken. Some of the older trucks ran 2 -12v wires to the ign coil +. One from the ign switch and the other from the S- tart on the ignition relay by the battery. This gave the coil a little boost during crank- up. And seemed to help with my sons 83’ 351w a few months back.
Because the wires are joined the coil gets a lower volts from the resister wire from switch to the solenoid.
Now when the solenoid sends power to the starter it also sends 12 volts to the "I" lug that not sends a full 12 volts to the coil for a hotter spark when starting.
Once the key is turned to run and the starter stops so dose the 12 volts to the coil.
Now from what I seen posted the ICM (box or TFI) may send a full 12 volts but also retards timing (white wire to ICM) for easier starting.
I have not looked much into this as my truck runs so I "dont fix it"
From what I seen posted if he sprays starting fluid it wants to fire but stops when it uses it all up.
So that tells me it is a fuel issue or lack of fuel and being he has LPG that is all new to 99.99% of us so cant help much.
Dave ----
Lead Driver
Joined: Nov 2013
Posts: 7,174
Likes: 1,174
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