id just like to know how fast you guys have gone, and what motor/tranny/gear ratio your running with. me, i got my 77 f250 highboy with a 351m a c6 auto up to 100mph, and i could have gone faster, but the speedo only goes up to 100

the reason im asking, im going to be puttin a np435 and either a 400m or a 460 in my 78 f250, and i want to know how fast i can expect to go. i want a 4 speed, but i also want a truck that has no problem pegging the 100mph speedo. what do you guys think? 4 speed good enuf? or should i go with the c6 thats currently in it?

 

[QUOTE=Psycho_bob_1977]i i want a 4 speed, but i also want a truck that has no problem pegging the 100mph speedo. what do you guys think? QUOTE]

I don't think going 100mph in a truck with a modern suspension and four wheel disc brakes is a good idea, much less doing 100 in a truck built with the ancient technology of our trucks. I'm not saying it's not possible, I'm just saying it's not a good idea.

Having said that, I've been up to 85 mph in my Bronco which has a C6, 3.50 gears and a built 400. It had lots more power too. Not smart.

 

Both transmissions have a final drive 1:1, the C6 will have more parasitic loss; so on the one criteria given, the manual box will give a slightly higher top speed. Top speed is primarily dependent on HP available and drag. Either engine, modestly equiped, should meet your goal.
I don't know my top speed (it gets way too scary), but it is well in excess of 100 with a F150 400 C6/3.00/15" tires.

 

If it's a 2wd, go with a 460, keep the c6. I had the speedo wrapped back around to the 30MPH mark before I got nervous and let off. That's with 3.50's. It still had lots of top to go yet, but my names not Evel.

 

My GPS says 101MPH, that was coming off the bridge outside of Portland, Maine.

79 F150, 2.75 gears, 351M C6. its really stable at high speeds.

 

I had a '76 F150 4x4 (full time 4 wheel until I had a conversion kit put in). It had a 360 bored to a 390 with RV cam, headers & straight exhaust. I don't know the gear ratio. I had her up to 95 MPH after getting her out of a shop from a accident that diamond her frame and broke off a foot of frame. I needed to see if she had a shimmy or not. She didn't!

 

I hit 90-100 and it feels like somethings just plain going to explode. I've got no tach so I've got no idea what RPM I'm turning to get there but it's loud . . . yes, I'm an idiot.

 

well ive got my 460 to about 130mph with 3:50 gears and a C6 tranny. and that was when i raced my dads mustang GT he said he let off at 125mph but i didnt...

 

75mph with a 5 mile downhill straight shot.
79 F-150 4x4 w/ a 6" Skyjacker lift, 35x14.5 boggers, 351m, 4spd, 3.50 gears... maybe the flowmasters get me up to 75 i dunno

 

70 was a bit much for my 78' 300 4spd 4x4 . But trucks werent meant to go fast, so I'm not worried!

 

I've gone 85 in my 77 F150 4X4 460 C-6 3.50 gears and 33 inch tires. After 70, it just dont feel right. Its alot better than when I got it since ive replaced all the tie rods and shocks.

 

A 78 was my first F150. The speedometer only went to 85. I had it to the P in MPH. I am assuming about 105. All I can say is this thing was so light at that speed it almost didn't feel like it was touching the road.
This was a 351M with 3.55? rear end. Did this a couple of times, but not for long.

 

90 when I first got the truck, now its 80mph downhill on a highway, 74 f100 custom, np435, 235/75R15 tires, I dont know the rearend gears. I wont try any faster than that anymore. I'll keep pace with MG86TA if I'm in a hurry, otherwise I keep it at about 65. I changed a valve cover gasket the other day and found chunks of valve seals on the cylinder head, I dont think I need to be going that fast. My tach reads about 2600 rpm (maybe 2700 rpm) at 65 mph. Wish I had an overdrive transmission. I would rather have quick accelleration than top speed.

My 75 f100, 302, C6 is a beast though. The fastest I have gone is 85, and it is totally effortless on the motor. Guess I'm gettin old, just dont feel the need for top end speed. I do love to stomp it, hear the dual exhaust (especially the few seconds before it shifts), and feel the rush of getting to cruising altitude.

 

my 76 hi-boy with a np 435, stroked 351 w, and 410 gears with 35 inch tires will do 100mph no problem. that is obviously in 4 th gear and the rpms at 4700. the engine spins to 6grand, so i am sure she has more. i should try it sometime. truck feels great at 100, and crusises perfectly down the freeway at 80mph

 

'77 2wd 302, 2v carb, C-4, 235/65 tires & unkown rears (3.03?) would go a whole lot faster than I wanted to ride in it - easily 85mph.

I know its off-topic - but since you could get the same engine & tranney in the late '70's - I had an '86 Bronco, 300cid 6cyl, 4spd OD tranny, 3.55rears, 30x9.5 tires that would do 78mph if you really stretched her out. It was a custom, all vinyl, no headliner - weighed about 3600 lbs. My '94 XLT with its fuel injected 302 & 4spd AOD would get on up around 90 or so. 'Course, it weighed about 1500lbs more than the '86.

I'm going to pick up a '74 highboy from NC in about 3 weeks and drive it back to FL. 360, 4spd & 4.10's w/31' tires. Don't expect a top speed report - I'll be suprised if I let it get over 60.