Transmission help
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 214
Likes: 0
From: North Carolina
i do have a 3.25..finally got home for thanksgiving and checked it out. terrible news for me because my gas mileage is already bad...i was wanting a 3.55 or 3.73..but i dont know if i can afford to drive it..UNLESS i can find either a four speed or a 3 speed with overdrive that would hook up to a 390 fairly easily...and not too expensive..any suggestions on that?
Posting Guru
Joined: Mar 2006
Posts: 1,182
Likes: 1
i do have a 3.25..finally got home for thanksgiving and checked it out. terrible news for me because my gas mileage is already bad...i was wanting a 3.55 or 3.73..but i dont know if i can afford to drive it..UNLESS i can find either a four speed or a 3 speed with overdrive that would hook up to a 390 fairly easily...and not too expensive..any suggestions on that?
i think you may have it backwards- a 3.25 would give you better mileage than a 3.73, because the motor will be turning less RPM at any given speed. the 390 has plenty of power to pull 3.25 gears without lugging.
there is no overdrive transmission that will hook up to a 390 easily, so that one's completely out.
its a FE...you're not going to get good mileage, ever. the best i ever got in my '68 F100 w/390 and manual tranny was 16mpg on the highway. that was with a well-tuned 2 barrel carb.
you'll be way ahead to just pay the extra $ for the gas, rather than chasing expensive modifications that won't net you much mpg gain.
Moderator
Joined: Aug 2002
Posts: 6,099
Likes: 380
From: Southern California
The 390 was a true truck engine...meaning it was a workhorse & never known for mpg's....though a gear vendor overdrive unit would bolt on, they are a little pricey. With a cam & gear change, you might get 2-3 mpg...and that would likely be hwy mileage.
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 214
Likes: 0
From: North Carolina
yeah i meant that i would get worst gas mileage because of the 3.55 or 3.73, because its shorter gears...i get 8-9 mpg combined now with a 650 holley 4bbl...im not looking for good gas mileage i just would rather it not go any lower..haha. ive got a 270 comp cam in it now..and im planning on getting my trans rebuilt this summer unless i can find a better trans to help my mileage out once i get a different rear end..four gears is better than 3 the way i look at it. are there any straight drive trannys that would hook up to a 390 without a full out mod?
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 214
Likes: 0
From: North Carolina
and this is my daily vehicle when im home from college, but as soon as i can get another vehicle with good gas mileage im turning this truck into a full out hot rod, thats why im not overly concerned with my mileage going down too much..but it would still be nice to maintain it at a decent rate..if that makes sense?
Posting Guru
Joined: Feb 2010
Posts: 2,006
Likes: 2
From: CASA GRANDE AZ
try tuning the carb , different jets , power valve and keeping the foot out will help some !
what size tires are you running ? a high stall converter will use more gas than a lower stall converter will ! a good shift kit and higher pump pressure will help with the tranny !
what size tires are you running ? a high stall converter will use more gas than a lower stall converter will ! a good shift kit and higher pump pressure will help with the tranny !
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 214
Likes: 0
From: North Carolina
my carb has been tuned..i had it tweaked by a man that knows his carbs, im eventually going to get a bigger one though..ive got 18in rims..not sure of the diameter of the tires. ive got a 6-8 psi pump with a regulator turned to 5 psi now, thats as low as i could go before she started starving. i need the stall at least at 2000 because my cam has me idling about 1000-1100..i'd like to get it down to 700 rpm or so...
Posting Guru
Joined: Mar 2006
Posts: 1,182
Likes: 1
my carb has been tuned..i had it tweaked by a man that knows his carbs, im eventually going to get a bigger one though..ive got 18in rims..not sure of the diameter of the tires. ive got a 6-8 psi pump with a regulator turned to 5 psi now, thats as low as i could go before she started starving. i need the stall at least at 2000 because my cam has me idling about 1000-1100..i'd like to get it down to 700 rpm or so...
if the beast is idling too high, check your initial timing, and your carb idle settings.
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
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 214
Likes: 0
From: North Carolina
well, the stock converter locks and starts pulling at a low rpm so my truck starts pulling early from the cam and will choke its self off if its idled too low..if i can get more slip at a lower rpm because the converter wont lock until a higher rpm my idle can be lowered.
Posting Guru
Joined: Feb 2010
Posts: 2,006
Likes: 2
From: CASA GRANDE AZ
IS THIS THE CAM THAT YOU HAVE ?
if so it says it is good for stock converters !
i dont think your cam is your problem , your engine should be idling around 700-800 RPMs
i believe your carb is set to rich or a vacuum leak or both !
33-226-4 - Magnum
if so it says it is good for stock converters !
i dont think your cam is your problem , your engine should be idling around 700-800 RPMs
i believe your carb is set to rich or a vacuum leak or both !
33-226-4 - Magnum
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 214
Likes: 0
From: North Carolina
yeah thats it, thats wierd. my carb is running where it needs to be..smells perfect. i have it ideled up..i can turn it down but as soon as i put it in drive you gotta throttle and ride the brakes or it will choke off until you get tacked up a little...it pulls hard since i put that cam on there. the trans has never been messed with..im thinking thats what the problem is... it pings when you put it in reverse..it did a few years of sitting so it probably needs going through. another reason i would want the converter is because you'll receive more power to the wheels if you drop the gas..instead of pulling at say 1100 rpm you would be tacked up to 2000 or 2400 and then it would pull full out (i guess the auto trans way of "dropping the clutch") i would really like to get rid of the c6 and get a little more performance
Posting Guru
Joined: Mar 2006
Posts: 1,182
Likes: 1
i'm with CJ- you've got a problem somewhere under the hood. the Comp Cams website says specifically "this is the largest cam you can run with a stock converter", so the cam/converter combo shouldn't be causing the engine to choke off.
Posting Guru
Joined: Feb 2010
Posts: 2,006
Likes: 2
From: CASA GRANDE AZ
if it pings in reverse i would double check the timing !
did you put any rocker arms in that had a different ratio than the stock ones ?
the timing chain and gears , were they put in straight up , retarded , advanced ?
the carb , did you use a spread bore adapter or a spread bore manifold ! some of the adapters were plain junk and would cause a vacuum leak , thats because they come from CHINA !
did you put any rocker arms in that had a different ratio than the stock ones ?
the timing chain and gears , were they put in straight up , retarded , advanced ?
the carb , did you use a spread bore adapter or a spread bore manifold ! some of the adapters were plain junk and would cause a vacuum leak , thats because they come from CHINA !
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 214
Likes: 0
From: North Carolina
you gotta take my word for it..its definietly not the carb, its golden. the truck runs like a top until you idle it too low..im gonna check the vacuum lines, they aint that old but they may have been damaged when i was pulling the motor out for rebuild...the very first thought that came to my mind was the modulator in the trans..maybe it was allowing the trans to start in a higher gear or something. i definitely need a rebuild though. i'm liking this forum..i get to think out loud with people helping me out! haha