had to ask..
390 help!
Thread Starter
|
Junior User
Joined: Jan 2006
Posts: 82
Likes: 0
390 help!
Hey everyone, I dropped a 390 into my 78 F-150 last winter, it got a edelbrock performer intake, 600 edelbrock carb, hedman headers, true duals, new fuel pump and good valve job. Its hooked onto a manual 4 speed. Im runnin 33 inch tall tires and this thing is gutless at highway speeds. Does anyone know of something that could help me? Would switching carbs to maybe a Holley 650 dp? Any other opinions on how I could boost some power without digging in too much, keep in mind its my daily driver. Thanks everyone.
Cargo Master
Joined: Apr 2004
Posts: 2,574
Likes: 4
From: Golden, CO
What gear ratio is in the rear axle? It could be the taller tires have caused the cruise RPMs to drop out the bottom of the powerband. Does it **** and git if you downshift to third?
Find out what your axle ratio is and use the RPM calculator to find out where your cruise RPMs are...unless you have a tachometer of course. LOL
Here is the link: https://www.ford-trucks.com/calculat...php/p-mph_rpm/
Edit: Bobby...LMAO!
Find out what your axle ratio is and use the RPM calculator to find out where your cruise RPMs are...unless you have a tachometer of course. LOL
Here is the link: https://www.ford-trucks.com/calculat...php/p-mph_rpm/
Edit: Bobby...LMAO!
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
My first thought was a tall gear with the tall tires. Aren't 235 75s about 29" tall?
Put in a shorter gear for more power, and it probably will use more gas, so keep that in mind.
John
Put in a shorter gear for more power, and it probably will use more gas, so keep that in mind.
John
FE "Freakin Expensive"
Joined: Dec 2003
Posts: 6,461
Likes: 4
From: Smith Mountain Lake, VA
Yeah you must be running some freeway flyers in the reaend? Cause I run a semi built 390/C6 in my Truck altho I had 3:70's out back and still run the 33" tall tires and it ran fine...But I know run a 4:10's gear in the back with the 33's and it uses more gas, but its a little snappier when passing on the highway..
I think years ago when I changed over to the 3:73"s I took out something like a 3:20ish gear set? Been so long....But I dont drive mine every day either..So a tank of gas on a weekend of cruising is No biggy...
RJ
I think years ago when I changed over to the 3:73"s I took out something like a 3:20ish gear set? Been so long....But I dont drive mine every day either..So a tank of gas on a weekend of cruising is No biggy...
RJ
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
In addition to the gearing questions the others have posted, what components is the that 390 built of, other than the intake, carb & exhuast? Cam? pistons? compression ratio? Heads? Igniton components? running points? What's the timing set at ? And are you sure it's a 390?
Logistics Pro
Joined: Oct 2005
Posts: 3,785
Likes: 4
From: Mddl A MexCans
Trending Topics
Cargo Master
Joined: Apr 2004
Posts: 2,574
Likes: 4
From: Golden, CO
Originally Posted by baddad457
In addition to the gearing questions the others have posted, what components is the that 390 built of, other than the intake, carb & exhuast? Cam? pistons? compression ratio? Heads? Igniton components? running points? What's the timing set at ? And are you sure it's a 390?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
I have never run a hi performance FE, but several 352s a 390 with modest mods. I have felt my doggiest 352 was still pretty strong.
Someone had put a 390 2 barrel in one 66 that I owned and that was the pullingest motor I had ever seen. I don't care how fast you were running if you mashed the gas you could feel it pulling. I have run 352s with 4 barrels that felt like they ran out of breath and didn't have much response above 75 mph.
The 390 was turning a C-O-M through a 3.00 gear 235 tires. You could be running 100 mph and mash the gas and feel it pulling. A real Arg arg arg setup. IMHO
John
Someone had put a 390 2 barrel in one 66 that I owned and that was the pullingest motor I had ever seen. I don't care how fast you were running if you mashed the gas you could feel it pulling. I have run 352s with 4 barrels that felt like they ran out of breath and didn't have much response above 75 mph.
The 390 was turning a C-O-M through a 3.00 gear 235 tires. You could be running 100 mph and mash the gas and feel it pulling. A real Arg arg arg setup. IMHO
John
Senior User
Joined: Jan 2007
Posts: 320
Likes: 0
From: modesto,ca
i have a 67 f-250 with a mild built 390. edelbrock performer 390 intake, edelbrock cam (.484 lift), edelbrock 750. backed by a c-6 tranny. stock rear end with 3.73 gears and rear tires 33.5x12.5x16.5.
smokes the tires and cruising down the highway still have power when needed to pass all the slow pokes. plus im running dual exhaust with power sticks..
for some strange reason people move out of my way........(hmmmm could they be hearing me coming up behind them or they see the shiny grill in rear view mirror.) lol
smokes the tires and cruising down the highway still have power when needed to pass all the slow pokes. plus im running dual exhaust with power sticks..
for some strange reason people move out of my way........(hmmmm could they be hearing me coming up behind them or they see the shiny grill in rear view mirror.) lol
Logistics Pro
Joined: Oct 2005
Posts: 3,785
Likes: 4
From: Mddl A MexCans
Originally Posted by 78F150classic
Hmm my gears must be way high because I can barley make my tires squeek. I do have a manual too but still, Am I doing something wrong here or what?
Thread Starter
|
Junior User
Joined: Jan 2006
Posts: 82
Likes: 0
I dumped the clutch one night because some chevy guys was talkin smart about I about lifted my front end off the ground, but then broke a u joint... So once spring come ill let her open and but her in low and see what happens.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
I guess I can't find an end to get a grip on, but with tires ranging from $60-180.00 a piece and gas from over, to way over $3.00 a gallon why is one wanting to smoke the living hell out of something that costs so much to do?
John
John