71 F250 cruising speed

[monadrew]

I just got my stock 71 F250 with a 360 and auto tranny going recently..I have driven it to work for the past 2 days 64 miles round trip but it does not seem to want to go over 60mph. The motor seems to winding really hi but I am getting about 12 miles to the gallon. It is a camper special could this be the gearing or could I be having tranny problems??

[Madman]

12 sounds about normal for a big block, but I could cruise at higher speed than that in my 71 F250 4x4. Does it seem to be missing or having poor detonation at the 60 MPH point?

[HIO Silver]

Yer rig prolly has 4.11 rear gears like my 71 F250 360/4-speed. 60 mph is comfortable but it has some legs left. 12 mpg is good.

Ya sure yer carb linkage is adjusted correctly with no interference from hoses and such? The throttle butterflies should be perfectly vertical at wide open tbrottle.

[monadrew]

It has no missing not sluggish it just seems to be wound out I'm afraid to push it any more..Is there any way to tell what gears you have without tearing it all apart? It should have 3 speeds with the auto tranny right?

[Ranchero50]

Yep, two shifts on a C6. 4.10's and an anemic 360 = 50 mph cruise. Mine would easily turn 70 but felt like it was hurting at 75.

Best thing to do is set the base timing to @ 15` btdc and make sure it isn't detonating there. It'll feel like a different motor vs. the retarded 7` btdc factory set point.

[ThinLizzy13]

My old 66 F250 had 4.56 gears and would turn 3400 RPM at 70. Had no problem cruising at that speed, it was just loud. When I first started driving it I was afraid to go over 55 due to the noise. Going from driving a modern vehicle to an older vehicle I was initially afraid to rev it up.

My 67 F250 has 4.10 gears with a 352 and will easily cruise at 65-70.

If 60 is its top speed there's definitely something going on. I'd try what ranchero recommends.

[monadrew]

Upon further testing the tranny does not seem to be shifting into high gear, that would explain a lot.. Time to take it to a shop I guess.

[Madman]

Upon further testing the tranny does not seem to be shifting into high gear, that would explain a lot.. Time to take it to a shop I guess.

Well that would do it!

[idaho_cowboy]

Upon further testing the tranny does not seem to be shifting into high gear, that would explain a lot.. Time to take it to a shop I guess.

Before I read this.. I was just going to say.. Ain't going into 3rd. Equivalent to running what, about a 5.44 geared rear-end. If you have a 3.73, which is likely.

- Joseph