No Top end
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No Top end
[font size="1" color="#FF0000"]LAST EDITED ON 20-Aug-01 AT 08:35 PM (EST)[/font][p]I just put a new 300 I6 in an 86 F-150. The truck runs great but I am getting no top end out of the motor. It's everything it can do to hit 65 mph. Any suggestions would be helpful. Thanks
Elder User
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From: SF Bay area
No Top end
[font size="1" color="#FF0000"]LAST EDITED ON 20-Aug-01 AT 08:56 PM (EST)[/font][p]As per your description, I can only think you have really low rear axle gears. My '60 has 5.83's in it and pretty much tops out at 60mph...with the engine spinning at 3850 or so rpm's. just a thought.
Wayne 60 F-350
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http://home.pacbell.net/whomrig
Wayne 60 F-350
http://home.pacbell.net/whomrig
Posting Guru
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From: Nebraska
No Top end
Check your exhaust, especially the cat. converters. These can become clogged over time and can cause a drastic decrease in power, at least from my experience.
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1986 F-150 4x4 300 I6 NP435
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1986 F-150 4x4 300 I6 NP435
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No Top end
I took the cats off this truck. I have the same year as you do but mine has the manual with overdrive. You have to be going at least 45-50mph before you shift into 4th gear. I am at a loss. It runs great until I get up around 55-65mph and then the motor seems to be lagging.
Post Fiend
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From: Dryden, ON, Canada
No Top end
How does it do if you leave it in 3rd? Mine ued to have the 3spd/OD and 2.75's, it only turned ~1425 at 60 in O/D, and the 300's torque peak is @ 2000 rpm, it would barely accelerate in 4th until you hit 80...
Evan MacDonald
82 F100 FlareSide 4wd
HD 300-6 9.5:1 CR
Clifford 270H cam
Hedman Hedder
SBC valved 66 240 head
Headlight Relays - Delanty Style
NP435(6.69 low)
NP 205
3.55 Geared ARB'd 9" & Trac-Locked TTB
31x10.50/15 Cooper Discoverer LT's
Evan MacDonald
82 F100 FlareSide 4wd
HD 300-6 9.5:1 CR
Clifford 270H cam
Hedman Hedder
SBC valved 66 240 head
Headlight Relays - Delanty Style
NP435(6.69 low)
NP 205
3.55 Geared ARB'd 9" & Trac-Locked TTB
31x10.50/15 Cooper Discoverer LT's
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No Top end
It's possible it is the cats, but I doubt it. if this were the case you would seem to be lacking power as soon as you got moving through local streets. I think it could be your gears. I had a 1999 F-150xtl with the 3.55 gears and she was great off the line, but didn't have too much of a top speed after I put the chip in...top was 120, I expected more. Now I have a 1986 F-250 HD with the 4.11s and this truck, though much heavier than her predecesor, rips even faster off the line, basically tosses you back in the seat, but peaks out at 85 or so. And I have no cats on it, and you can feel all the power, there's none lacking whatsoever. So yeah, I say it's your gear ratio.
Ryan
1986 F-250 HD 4x4
351W, Edelbrock 351W Performer Intake
Holley 750 4bbl
Flowmaster Dual Chambered Exhaust
Ryan
1986 F-250 HD 4x4
351W, Edelbrock 351W Performer Intake
Holley 750 4bbl
Flowmaster Dual Chambered Exhaust
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No Top end
It does fine in third. Forth is more or less a waste UNLESS YOU ARE GOING OFF A CLIFF. I guess I need to find a new tranny.
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No Top end
My 1987 4x4 has a 300 and about the same top end that you do. I can bury the speedometer in third, but she can barely hold 70 on a flat highway, and on a hill she will drop to 60 or lower. I have 3.08 gears, no cats, a Flowmaster torque tube, and a K&N filter. I have heard some people talk about how powerful and efficient their 300 motors are, but mine has never been that way. I am selling her to get a 351 powered F-250 in a week or so, and the lack of power is part of the reason. She pulls well in low range, but running in 2wd with a heavy load she really suffers and eats clutches like they're going out of style. My only thought for you is to check your carb. Is the choke fully releasing? That and maybe an EGR or advanced timing problem is all I can think of. Good luck.
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No Top end
listen closely to the other guy's advice- the rear axle ratio has a lot to do with the" feel" of power. if you have 3.08 gears, you won't feel anything but the need to down shift.
you will go through clutches because you slip the clutch to get more rpm's then let it grab.
before i spent money on a 351 or another truck, I would drive some other vehicles with different gears and see it for yourself.
as for the transmission being the problem, this is somewhat true, but more likely it is the final drive ratio that is causing your complaints with the performance.
you will go through clutches because you slip the clutch to get more rpm's then let it grab.
before i spent money on a 351 or another truck, I would drive some other vehicles with different gears and see it for yourself.
as for the transmission being the problem, this is somewhat true, but more likely it is the final drive ratio that is causing your complaints with the performance.
Post Fiend
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From: Metro Detroit (Redford)
No Top end
erich64: What engine was in the '86 F150 before you put in the new 300? Must of been a V8. I had an '84 F150 that had a 4 speed OD manual. Also had a 2.47 rear end. Fourth gear was only acceptable on the freeway and then you really had to put your foot into it if you hit a headwind going 70. I think they geared it for max mileage at 55 mph and the wind resistance at 70 is too much. For half the life of the truck I never used 4th gear. In third gear it would turn the same RPM as my '95 F150 turns in its 5th gear OD. First was not very low either and if yours is the same tranny, then a higher rear end would make the whole thing more drivable. If you have a 2.47, I'd try a 3.55. I just got a rear end assembly from the junkyard for 250 dollars. Not bad if you can install it yourself (I didn't).
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No Top end
I'm sorry, I should clarify that replacing my 300 is only partially due to lack of power. I know that my gears aren't the best for acceleration, but compared with other similarly geared trucks mine performs poorly. In addition, I need a long bed to work out of, which I don't have now, and with the loads I carry I need a 250, not a slightly modified 150 like I have now. By the time I re-geared my truck, replaced the A/C compressor, increased my pitiful 16 gallon gas capacity and hopped up the engine a little, I would have spent a fortune and still not have a long bed. I'm sure a five speed would make my truck more liveable by narrowing the gaps between gears, but then again it wouldn't last 195K miles like my SROD. The 300 is a great motor for work, but the way my truck is set up won't allow it to reach it's full potential.
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No Top end
The truck has always had a 300 in it. I will have to look and see
what the rear axle gear ratio is. I have had 2 trucks(Ford of course) with 4 speeds and they had the granny low that didn't get
used much either. The man that owned the truck before me pulled a
18 foot bass boat with a double axle trailer and said it did fine. I think it must be an emmisions problem. I can change out the rear chunk easy enough. It would give me a chance to put a
locker in. Won't my wife be happy!!!!!!!!!!!!!!!!!!!!!!
erich64
what the rear axle gear ratio is. I have had 2 trucks(Ford of course) with 4 speeds and they had the granny low that didn't get
used much either. The man that owned the truck before me pulled a
18 foot bass boat with a double axle trailer and said it did fine. I think it must be an emmisions problem. I can change out the rear chunk easy enough. It would give me a chance to put a
locker in. Won't my wife be happy!!!!!!!!!!!!!!!!!!!!!!
erich64