Cummins 4BT & Diesel Conversions Forums banner
1 - 15 of 15 Posts

·
Registered
Joined
·
94 Posts
Discussion Starter · #1 ·
I am new here and this is my first post. My plan is to build a 4bt for the best possible highway MPG. I plan to use a 64 IHC short bed 1/2 ton. I have rebuilt the frame with the larger (12 in brakes) and rebuilt the springs from a heavy duty 1/2 ton IHC. Belive it or not the IHC V-8s were very heavy 778lb for the 266, 780lb for the 304, and 803lb for the 345. So I think the truck will handle the weight OK. I plan to use a Dodge NV4500 and my IHC Dana 44 with 3.54 or 3.25 gears in it and 29in tall tires. This will be a 2wd truck. Do you guys think the Dana 44 will be up to the task? Will a 9in Ford be a better choice? Not sure of the weight of this truck but suppose its about the same as any 1/2 ton of that era. What is the best model of 4bt for me to be looking for? What do you think my MPG might be at 65 to 70 mph? (i know that may be a loaded question). Any advice form you guys will be appreciated.
 

·
Registered
Joined
·
180 Posts
Yay! bounce Another one of us IH guys! :rasta:

Your combination is much different than mine (see my signature) so I can't really offer you any advice; I just wanted to welcome a fellow Binder driver! I think that you will be okay on the front end weight, and your mileage will vary with how often you find your foot stuffed to the carpet, but you will be happy with the swap when you are done. Good luck!
 

·
Registered
Joined
·
82 Posts
I'd find a 9" from a Ford truck, one is bound to fit. As for gearing, 3.00 might even work well, I'm assuming hte 29 inch tall tires are 31X10.50R15?
I'm also considering a 1/2-ton swap, I'm curious as to why you're using a 'granny-gear' 5-speed instead of something like a Tremec TKO.

CD
 

·
Registered
Joined
·
3,391 Posts
I don't know as you'd want 3.23 gears, might be a little too high? You want the engine to be running in the 'sweet spot' at cruising speed, say 1,700 to 1,900 rpm. Otherwise if it's too far off the power curve you can end up with your foot in it just to keep up momentum. Seems to me the 3.54's would be better. Maybe others with tall gears and a .79 overdrive can share their knowledge....
 

·
Registered
Joined
·
98 Posts
I don't know as you'd want 3.23 gears, might be a little too high? You want the engine to be running in the 'sweet spot' at cruising speed, say 1,700 to 1,900 rpm. Otherwise if it's too far off the power curve you can end up with your foot in it just to keep up momentum. Seems to me the 3.54's would be better. Maybe others with tall gears and a .79 overdrive can share their knowledge....
With 3.55 gears and overdrive and 35" tires I got 37mpg highway, Between 30 and 32 country/city driving. I then switched to 33" tires and dropped down to around 27mpgs country/city, so take from that what you will...
 

·
Registered
Joined
·
3,391 Posts
Ha ha, hey, Dougal, that IHC that Blueflame is talking about is similar to my truck in some ways: about as aerodynamic as a box of crackers! Aero upgrades aren't an option, believe me. Of course you're right, that's a major factor in mileage, but sometimes it can't be applied to vintage vehicles.
 

·
Registered
Joined
·
94 Posts
Discussion Starter · #8 · (Edited)
Boy what a great response. Thanks Guys.
IHCRAcer, yes Iv been a binder pilot since about 1969 when I bought my first, a 49 KB1. It was my first engine swap. First a Ford 223 6 cly then in 73 a 292 Ford Y block, and then in 78 a Pontiac 400 and Camaro subframe. I still have that cab. I also have a 70 3/4 4x4 that started out as a 2wd camper special and a 60 B150 School bus made into a motorhome. I have also parted out several D series 3/4 ton 4x4s. Good to be among friends.
CREEPING DEATH, yes the more I think about it a Ford 9in would be a better choice and they are plentiful and easy to adapt to my truck. One side benifit of going to the later model IHC 12in brakes was that it also gave me the 5 on 5 1/2 in wheel bolt pattern of the Ford PU. so thats were I will look for one. About my trans choice, thats not carved in stone. I just assumed any trans heavy enough to do to job would be a granny type trans. Im not familiar with the Tremec TKO. Tell me more! Whats it used in and what are the gear ratios? As far as my rear end ratio I need to sit down and do the math to see what would be the best for me.
 

·
Registered
Joined
·
335 Posts
local okie

Hey blueflame...what part of OK are you from? Im a Oologah boy myself....nice to have you here bounce
 

·
Registered
Joined
·
82 Posts
Im not familiar with the Tremec TKO. Tell me more! Whats it used in and what are the gear ratios? As far as my rear end ratio I need to sit down and do the math to see what would be the best for me.
It's used in late Mustangs and high-performance applications, some are rated for over 600 foot-pounds. I'm not sure it's suited for the 4BT but it seems to be ideal for light-duty on-road applications.

CD
 

·
Registered
Joined
·
10 Posts
I have a Tremec TKO I plan to use in a 1/2 ton suburban.
One thing I can see right away is the input bearing housing that slides into the bellhousing is around 4.85 diameter and the hole in the bell is 5.125. I am going to press a spacer on the housing to take this up.
Also it has a 26 spline input shaft which will require finding the appropriate clutch disc. The 4bt I have came with a 10 spline.
The granny gear may not be all that useful if the truck gets a lot of street and highway use.
 

·
Registered
Joined
·
10 Posts
I should add that the TKO I have is for GM application.
The Ford TKO may not have the same issues going into a Ford bellhousing.
 

·
Registered
Joined
·
82 Posts
I have a Tremec TKO I plan to use in a 1/2 ton suburban.
One thing I can see right away is the input bearing housing that slides into the bellhousing is around 4.85 diameter and the hole in the bell is 5.125. I am going to press a spacer on the housing to take this up.
Also it has a 26 spline input shaft which will require finding the appropriate clutch disc. The 4bt I have came with a 10 spline.
The granny gear may not be all that useful if the truck gets a lot of street and highway use.
The Tremec is available with the 10-spline (standard Ford IIRC) input, but I'm not sure about the register size. What type of Suburban? I was under the impression the post-59 GM bellhousings all had the 4.85 measurement.

CD
 

·
Registered
Joined
·
10 Posts
the suburban is 1983 but the bellhousing is from an 80s stepvan. I believe the 70s and 80s chevy trucks with the sm465 have the 5.125 index hole and the passenger cars have the smaller one making interchangability more of a problem. the tremec I have uses the passenger index snout, hence the need for a spacer.
Sorry if this got off the original topic.
 
1 - 15 of 15 Posts
Top