The Stovebolt Site Forums The Shop Area General Truck Talk Realistic Speeds and gas milage for T-5 bolts???

After reading the post on 'stock bolts' I thought I'd ask about my truck:

I've got a '51 1/2 ton with a 261, T-5, HEI, '2 x 2bbl' Carter-Webbers on an Offy, Fentons, 12-bolt posi 3.73:1 rear diff, radials, and front disc brakes w/bearing conversion. I'm still finishing up the wiring and body work, and am wondering:

1. What can I expect by way of highway speeds?

2. What can I expect by way of gas milage?

Thanks!

Sounds like a nice setup.I am not familiar with the T5 tranny.If it is an overdrive unit you should be up to running any highway speed you want to.I am running a 350 V/8 with a 700R4 OD tranny,3:90 gears and i can run with the best of them.70 or 80 MPH with no problems.

Gotta add some more here on this subject.Gearing is usually the key to what kinda speed ya want to drive.My daily driver is an 03 Ranger,with a 4 cyl.and 5 sp.Probably 3.73 gears.It will run at any speed I want it to 70,or 80,even 90 it handles it just fine,and also gets 30 MPG which tells me that fifth gear is an overdrive.I am sure the old 216 sixes and especially the 235s have that kinda running capability if they are geared right.When these trucks were built they had 3:90 and 4.11 gears which means they are set up to run 45 to 50 MPH max.Put in a 3:08 or so rear,or an overdrive tranny and you will be set to run at todays highway speeds.When I first got my 55 it already had a 350 V/8 in it with an m22 4 sp.At 65 MPH it was turning about 2800 RPM and sounded like the engine was ready to blow.I switched to a 700R4 OD tranny and now it cruises at65 at about 1800 RPM,and is still using the original 3:90 rear.Seems to me that a way to much emphasis is put on how much power your engine has.I think Joker is running a T5 tranny and 2:72 gears in his 52 and has a nice driving setup.

see my website for what I have but I can run as fast as I want on the hi-way,,, but I usually run around 62 - 65 on the hiway.....although I figure mine is in good shape. they are still old trucks......still drives straight and true......love it.. mileage about 18 to 21 depending on how much I use the over drive........

Out of curiosity, NM51, how long has it taken you to get that far? I'm working on a very similar setup but have just passed the teardown stage. My motor is at the machine shop right now. I've been working for about 6 months. How long until I see the light of day?!

Take into account that I just started my own company and just had our second child...

Red Green-

It all depends on how much time you can spend each day or week, and how much work your truck needs. I've been working on this truck for a year but havn't had time to turn a wrench in about 10 weeks, and there have been a couple of other long breaks along the way.

Part way through my project I decided to replace the cab and fenders. So I had to look for those and then waited 6+ weeks to get them back from the sandblaster.

Once you get the engine back it shouldn't take you too long if you don't have to do any body work. Once I got the engine back from the machine shop I spent a couple of weekends putting it together slowly, measuring everything, platigauging all the bearings, etc... Then painting the engine and getting everything to fit just right took time. Once the engine is together getting into the truck and getting it running doesn't take too long. What takes time is all the little details.

The more work I do, the more I admire the rolling restored and rods out there!

I can't help you with the gas mileage end of things, but speedwise...

Here's a nifty calculator. Have a look .

You'll need to know what your tranny gear ratios are (usually on a T5, Fifth is .7:1 or .9:1, and Fourth is 1:1), Tire Diameter in inches, and how high you'll be revving the old 261.

I think that it's safe to say that with a .7:1 OD, you'll be getting in the 20mpg range at the lowest. Probably closer to what my car gets (28-30)

I wouldn't expect more than 21 to 22 mph. For the 302 gmc I am building, I'm not expecting more than 17 mpg, and I'm hoping I won't be getting less than 13. Advance Design trucks aren't known for there aero dynamics. Better than Task Force trucks I suppose.

Just got mine legally on the road this past weekend...flat land,stock 56-235, Fentons, Holley/weber 5200, T-5 w/.72 OD, 3.08 diff.,29" dia. rear tire.

Would pull smoothly in 4th(1:1) from 1000rpm.
1600rpm in 4th= 45mph, in 5th about 60mph. 2000 RPM in 4th, about 55mph, in 5th 75mph. Can't vouch for accuracy of my chase car speedo but these are in the ballpark.

What impressed me the most was the low-end torque from 1000RPM up!!! Could short-shift up without any lugging or bucking. It's no road-rocket but I was after mileage and extended engine life with this truck. I think I've hit the right combo even though on paper the rpm's look kinda low. The book says the 235 makes max. torque at 2000 RPM but I found that from 1000 up to 2000 was all I really needed.

A 3.73 should be a little quicker off the line but should give you a reasonable cruise RPM. My second surprise was how well it handled with the 235/70/15's on the front with no sway bar or steering stabilizer (yet) and the Camaro Z swaybar on the rear. Tracked straight...no wander or body roll. I am a happy camper!!

As for fuel mileage....can't help here as I need to scout up some speedo gears and get calibrated. I'm shooting for 20mpg!

Dave