Need help ID'ing a 390
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Freshman User
Joined: Mar 2003
Posts: 43
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From: Northern California
Need help ID'ing a 390
I just bought a 390 that was in a '74 f150 4x4. I'm pretty sure it's not the original motor since it has what looks like a factory 4bbl manifold. Didn't trucks only come with 2bbl?
Anyway, it also has a tag riveted or screwed to the front of the driverside head that says, "Stock Number J023581 Rebuilt Engine Power-Pak"
I'm still trying to get in touch with the original owner to see if he knows it's history, but I thought I'd try here as well.
Aside from completely pulling it apart, I don't know of any other ways of determining what I have.
Any info or suggestions are welcome...
Thanks,
Mark
Anyway, it also has a tag riveted or screwed to the front of the driverside head that says, "Stock Number J023581 Rebuilt Engine Power-Pak"
I'm still trying to get in touch with the original owner to see if he knows it's history, but I thought I'd try here as well.
Aside from completely pulling it apart, I don't know of any other ways of determining what I have.
Any info or suggestions are welcome...
Thanks,
Mark
Post Fiend
Joined: Feb 2000
Posts: 5,130
Likes: 8
From: Brea CA
Need help ID'ing a 390
Hi Mark and welcome to FTE!!
A little history first:
Pickups got a 390 4V starting in ’74.
4X4’s never got a 390, ever.
The 360 never got a 4V intake.
Ok, now to tell if you really have a 390 you have to check the stroke. Put the engine at TDC, remove the #1 and #4 spark plugs, insert a small wooden dowel into #1 making sure it’s parallel with the bore, mark the dowel at the top of the spark plug hole threads. Now do the same thing on the #4 hole and you should have two lines on your dowel. Measure the distance between the lines and that’s your stroke. Let us know what the measurement is, I don’t want to influence the result.
Can’t tell you anything about the rebuilder tag on it but it sounds interesting. Wonder what their power-pak consists of. I think the previous owner is your best bet.
Welcome again and enjoy the site!
Barry
A little history first:
Pickups got a 390 4V starting in ’74.
4X4’s never got a 390, ever.
The 360 never got a 4V intake.
Ok, now to tell if you really have a 390 you have to check the stroke. Put the engine at TDC, remove the #1 and #4 spark plugs, insert a small wooden dowel into #1 making sure it’s parallel with the bore, mark the dowel at the top of the spark plug hole threads. Now do the same thing on the #4 hole and you should have two lines on your dowel. Measure the distance between the lines and that’s your stroke. Let us know what the measurement is, I don’t want to influence the result.
Can’t tell you anything about the rebuilder tag on it but it sounds interesting. Wonder what their power-pak consists of. I think the previous owner is your best bet.
Welcome again and enjoy the site!
Barry
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Freshman User
Joined: Mar 2003
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From: Northern California
Need help ID'ing a 390
Thanks guys... I knew I could depend on a very quick reply :-)
ok... I just checked the stroke and as far as I can tell, it measures 3 7/8"...
A good freind also suggested testing the compression by hotwiring it. Can you instruct me as to what to hook up where? I tried hooking up a battery... ground to (-) terminal and the starter to the (+) terminal with nothing happening. I'm probably missing something here...
I pulled the plugs and they're all even in color and wear... slightly tan on the electrodes, if that helps...
Thanks again,
Mark
ok... I just checked the stroke and as far as I can tell, it measures 3 7/8"...
A good freind also suggested testing the compression by hotwiring it. Can you instruct me as to what to hook up where? I tried hooking up a battery... ground to (-) terminal and the starter to the (+) terminal with nothing happening. I'm probably missing something here...
I pulled the plugs and they're all even in color and wear... slightly tan on the electrodes, if that helps...
Thanks again,
Mark
Post Fiend
Joined: Feb 2000
Posts: 5,130
Likes: 8
From: Brea CA
Need help ID'ing a 390
Hi Mike, thanks!
Mark, looks like a 390 although your measured stroke is a tad longer, good enough for gov. work!
I take it the engine is on a stand. The plug color looks good, if you had a bad cylinder it would be pumping oil.
Starter should have turned over, did you hear anything or get any sparks?
Barry
Mark, looks like a 390 although your measured stroke is a tad longer, good enough for gov. work!
I take it the engine is on a stand. The plug color looks good, if you had a bad cylinder it would be pumping oil.
Starter should have turned over, did you hear anything or get any sparks?
Barry
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Freshman User
Joined: Mar 2003
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From: Northern California
Need help ID'ing a 390
yeah, I got sparks but no turning... I'm going to give it another try since I turned it over by hand to check the stroke.
Actually, it's propped up in the bed of my truck with 2x4's, 4x4's and tie downs. The hoist won't be here till this evening and I'm a little anxious... :-P
Mark
Actually, it's propped up in the bed of my truck with 2x4's, 4x4's and tie downs. The hoist won't be here till this evening and I'm a little anxious... :-P
Mark
Postmaster
Joined: Nov 2002
Posts: 3,447
Likes: 1
From: Littleton, CO
Need help ID'ing a 390
Mark:
be careful with that pig while you goof with it. One thought, is there a tranny hooked up? You will of course need a flywheel/flexplate to turn the engine. I would suggest you disconnect ALL plug wires at the cap. I have seen too many anxious folks mess something up....
When you hooked the poss side of the battery to the starter, you should have had it at least spinning. Maybe it's a bad starter?
--Mike
be careful with that pig while you goof with it. One thought, is there a tranny hooked up? You will of course need a flywheel/flexplate to turn the engine. I would suggest you disconnect ALL plug wires at the cap. I have seen too many anxious folks mess something up....
When you hooked the poss side of the battery to the starter, you should have had it at least spinning. Maybe it's a bad starter?
--Mike
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Freshman User
Joined: Mar 2003
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From: Northern California
Need help ID'ing a 390
ok... here's the latest skinny...
I took the motor to a freinds shop and we found a short in the wiring so we hooked a battery directly to the starter hot and ground and the engine turned nicely.
I checked the compression and got 125 - 135 across all cylinders. Not the greatest but at least they're somewhat even.
We did, however, find water in the oil when it pumped out all over the bed of my truck. There's a small hole in the oil filter from where the last owner set the engine down in a field. Small draw back.
Second draw back is the hoist is not coming after all. Big 4 Rents, here I come...
Thanks,
Mark
I took the motor to a freinds shop and we found a short in the wiring so we hooked a battery directly to the starter hot and ground and the engine turned nicely.
I checked the compression and got 125 - 135 across all cylinders. Not the greatest but at least they're somewhat even.
We did, however, find water in the oil when it pumped out all over the bed of my truck. There's a small hole in the oil filter from where the last owner set the engine down in a field. Small draw back.
Second draw back is the hoist is not coming after all. Big 4 Rents, here I come...
Thanks,
Mark
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Senior User
Joined: Apr 2003
Posts: 126
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From: Louisville, KY
Need help ID'ing a 390
I will check when I get home.
The speed shop measure the crank before the turned it. I check this morning myself (short block is still in my garage). We both confirm that it has a 3.78 stroke.
The speed shop measure the crank before the turned it. I check this morning myself (short block is still in my garage). We both confirm that it has a 3.78 stroke.
Senior User
Joined: Apr 2003
Posts: 126
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From: Louisville, KY
Need help ID'ing a 390
Sorry for the delay. Here is the VIN: f26ylc15159
Let me know what info you can get from this VIN. My local Ford dealer can't even find it in their computers since this is before the modern standardized VIN numbers.
Let me know what info you can get from this VIN. My local Ford dealer can't even find it in their computers since this is before the modern standardized VIN numbers.
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From: Minneapolis, MN
Need help ID'ing a 390