Gutless 390
Thread Starter
|
Freshman User
Joined: Feb 2009
Posts: 32
Likes: 0
Gutless 390
I've got a '76 f-150, 4x4 with a 390 in it. I have put a lift and 35 inch tires on the truck. I use it primarily for off road. Even in low the engine seems a little doggy, and has a hard time keeping those 35's spinning in the mud. As far as I know everything is pretty much stock, 2 barrel carb, and true dual exhuast. I would like to be able to get a respectable amount of power out of the engine, but don't want to spend more than $500. I have already rebuilt the carb, new plugs and wires, and put a choke on it. Someday I would like to maybe turn it into a 427 or 428. I've been told i can put a 400 crank in it, but don't know if that yields more power . Fuel milage is of little concern because this is my fun truck, i just want it to have more power at the axles. Any advice?
Post Fiend
Joined: Aug 2008
Posts: 6,751
Likes: 3
From: Sin City
Are you sure it's a 390? If you haven't measured the stroke, it could be a 360. A 360 can be made into a 390 with the 390 crank, rods and pistons. With a 428 crank, you can turn the 390 into a 410. What is your axle ratio? Is your compression good on all cylinders? Ignition timing good? Edelbrock Performer and a 600-650 CFM 4 barrell will help.
Thread Starter
|
Freshman User
Joined: Feb 2009
Posts: 32
Likes: 0
Truck was given to me several years ago by my grandpa, he put the engine in himself and I have always been told it was a 390, but I guess i don't know for sure, I have never had the engine apart. Axle ratio is stock, i would assume around 3.5
Logistics Pro
Joined: Oct 2005
Posts: 3,785
Likes: 4
From: Mddl A MexCans
I'd verify it is in fact a 390, my self me thinks no. A fun truck ? headers and a 4bbl carb/intake and some port dusting will help even a 360 and probably doable for 5 bills if you have connections for exhaust mods etc.. and as noted for a mud truck (gears gears gears)
Posting Guru
Joined: Dec 2004
Posts: 1,474
Likes: 5
From: Shasta Lake, Ca.
a easy test for a basic idea of what it is , here what you do, Get a wooden Dowl, remove one plug and bring the piston to TDC. stick the dowl in and mark it, Now bring the piston to BDC and place the dowl back in and remark it. Now measure the marks, if its about 3 1/2 inches it stroked for 352 or 360, if it is about 3 3/4 it is stroked for a 390. Hope this helps
Post Fiend
Joined: Aug 2008
Posts: 6,751
Likes: 3
From: Sin City
You don't have to take the engine apart to measure stroke, use a dowel inside one of the spark plug holes while turning the engine over by hand. Make a mark on the dowel when the piston is at the bottom of it's stroke, and another at the top. 360 stroke is 3.50" and 390 is 3.78. If you post the numbers off your warranty plate, someone on here will be able to tell you your axle ratios. The number should also be on a tag on your axle. 35" tires and a high (numerically low) ratio will seem gutless too.
(oops, a little late here, thanks Madathlon)
(oops, a little late here, thanks Madathlon)
Postmaster
Joined: Aug 2005
Posts: 2,760
Likes: 8
From: Gadsden Purchase
Oh crap. :/
Don't look now, but you got a 360. :(
Your grandpa might've got lied to or something. :/
"assume"?
Just cut that crap out, you hear? LOL ;)
Check for a tag on the axle/s! :)
Also, for the heck of it, post the VIN plate numbers/letters from the door...
http://www.panix.com/~alvinj/file12/F150tag.jpg
(type in a x or two as place markers in the serial number)
Alvin in AZ
F150 360FE T18 changed axle ratio from 3.25 to 3.50 myself
F15YL = F150, Y=360FE L=Michigan plant
133"= wheel base = long bed
H4 = 3.25 4-pinion + Traction Lok + 31 spline axles
J = power steering front axle
Don't look now, but you got a 360. :(
Your grandpa might've got lied to or something. :/
"assume"?
Just cut that crap out, you hear? LOL ;)
Check for a tag on the axle/s! :)
Also, for the heck of it, post the VIN plate numbers/letters from the door...
http://www.panix.com/~alvinj/file12/F150tag.jpg
(type in a x or two as place markers in the serial number)
Alvin in AZ
F150 360FE T18 changed axle ratio from 3.25 to 3.50 myself
F15YL = F150, Y=360FE L=Michigan plant
133"= wheel base = long bed
H4 = 3.25 4-pinion + Traction Lok + 31 spline axles
J = power steering front axle
Last edited by Alvin in AZ; Feb 11, 2009 at 09:24 PM. Reason: can't scan a picture of the axle tags tonight
Trending Topics
Postmaster
Joined: Jul 2003
Posts: 3,934
Likes: 0
From: iowa
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Postmaster
Joined: Aug 2005
Posts: 2,760
Likes: 8
From: Gadsden Purchase
Yeah, I assume;) that's right, Bill the ND said so and others too.
But the engine's been changed out. ;)
Could the whole problem be the axle's gear ratio tho? :)
Alvin in AZ
But the engine's been changed out. ;)
Could the whole problem be the axle's gear ratio tho? :)
Alvin in AZ
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
Start looking at the gear ratio first. Whether you have a thumper engine or not the 35s are changing the actual ratio. The 360 is not a 390 but does have decent power for a daily driver. IMHO
Get the truck on level ground and with a friend helping push the truck 1 complete tire rotation while counting the driveshaft revs. This will give you a quick and close idea of what the actual rear time ratio is.
John
Get the truck on level ground and with a friend helping push the truck 1 complete tire rotation while counting the driveshaft revs. This will give you a quick and close idea of what the actual rear time ratio is.
John
Thread Starter
|
Freshman User
Joined: Feb 2009
Posts: 32
Likes: 0
I have thought of axle regearing myself, but all the ones i have found have been very expensive, and i would prefer to get the engine running to its full potential ( 4 barrel, and maybe headers) before i shell out the cash for gears.
Senior User
Joined: May 2007
Posts: 150
Likes: 0
With 35" tires, anything will feel gutless unless your running 4.11s or better. You can get away with less with a 4 spd and starting out in granny gear. I wouldn't be afraid of 4.56s or even 4.88s with 35s you'll still have plenty of top speed for the highway. Outside of a good tuneup, gears will be by far the best bang for your buck. Your 2 barrel and stock cam are getting you as good or better off-idle torque than a four barrel, big intake, and bigger cam will. Those mods will only really help after you can get the engine up into the power bank, and that takes gearing.
you can find yukon ring and pinion for $189 all day, low 200s for reverse cut dana 44 gears. Also 4.11-4.09s are all over the junk yards in older trucks.
you can find yukon ring and pinion for $189 all day, low 200s for reverse cut dana 44 gears. Also 4.11-4.09s are all over the junk yards in older trucks.