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Engine swap

Posted By Jeff Wright 8 Months Ago
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Jeff Wright
Posted 8 Months Ago
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Geoff,

It has 11x24.5. It'll do about 65 top speed. That's down hill costing in neutral. Lol

Jeff

Jeff Wright
Posted 8 Months Ago
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Geoff,

I was thinking that was pretty low running bobtail. My 85' with get a little more than that loaded. When I run it bobtail I was close to 7.5 to almost 8 miles per gallon. Mind you my 85' has a 13 speed OD in it, with 4.11 rears. That's why I haven't ran that 88' with that L10 in it much, because I figured it should be getting a little better than what it is. It has a 9 speed no OD. So I don't know, that's why I'm thinking if I swap engines I'm going to look at maybe swapping a few other things, and see if that does the trick or not. I guess I shall see.

Jeff

Grab another gear and keep on trucking!
Geoff Weeks
Posted 8 Months Ago
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Jeff Wright (4/27/2021)
Yeah that is true. I think it currently has 4.11 rears in it. 

Jeff 

Grab another gear and keep on trucking! 

With direct trans and 4.11, it would top out at 61 with 11x 22.5 rubber, bit faster on tall 24.5  
 With that set[up the truck was built for 55 MPH, 
 I'm trying to remember what the L-10 I drove would do flat out, I'm thinking 65 MPH

Geoff Weeks
Posted 8 Months Ago
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It can be hard to gauge MPG Bobtail on that short a run, but 5??? I used to get low 6's running a L-10 around Chicago loaded with equipment. 5 sounds low. I can get upper 7's low 8s towing an empty 48' trailer, depending on the wind, with both of my Cummins.
 The L-10 I drove was a mid 80's OAC 300Hp. It had a RTX 11609B IIRC (O/D top gear) and I don't remember the rear ratio  off hand.
 If you are only getting 5 Bobtail, I would be looking at the engine or drivetrain for something that isn't right.
Jeff Wright
Posted 8 Months Ago
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curdog,

          It has RT11609A 9 speed direct. When I bought from the folks that originally owned it, I drove it 600 miles from GA to TN where I live. Mind you I was running bobtail, I got 5 miles to a gallon of fuel. I might need to change out transmission and rears. I haven't done any long runs with it yet, so I don't know what type of fuel mileage I'd get on a long run. 

Jeff 

Grab another gear and keep on trucking!
curdog
Posted 8 Months Ago
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If you're just on two lane roads, and set of 4.33's might help if you're direct in top gear, or better still 4.88's with a OD. 
I spent a lot of time here in the mountains with a 8.3 8LL and 4.33's. It'll run high 50's for speed loaded (we ran 44-46K). It took a pretty good hill to have to go for low range, but 5th would go about 25mph. Just before I changed to my current job they gave me a new IH with the A26 8LL and 4.33's and it was quite a help. They now have gone to 4.88's and I would like to pull a load or two with one to see the difference for myself.
There's nothing to be gained with a 70 mph truck on two lane roads in the mountains. Gear it for the conditions.
Jeff Wright
Posted 8 Months Ago
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Yeah that is true. I think it currently has 4.11 rears in it. 

Jeff 

Grab another gear and keep on trucking! 
curdog
Posted 8 Months Ago
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Depending on what you want to do with the truck, re gearing the differentials may be an easier route.
Jeff Wright
Posted 8 Months Ago
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Guys, 
           I do believe that if I took that L10 out I'd have enough room to put a bigger engine in that truck. I still have plenty of room in the dog house to get the engine in there. But as most of y'all have mentioned then you run into the problem of getting to the back of the engine. I have a 85' LTL9000 with a Big Cam 350 and I didn't think it was tilted, I could be wrong. I'll have to look tomorrow when I get home. I know that L10 is tilted. Talking about a engine that will be a pain for me to mess with, that's my 69' N series Ford with the 250 Cummins. That engine is crammed up underneath the cab. Going back to the truck with the L10, the reason for thinking of putting a M11 was same engine, just longer stroke and more electrical on it. So I was thinking it would be easier to swap out. That truck that I have to L10 in originally came from southeast Georgia. Flat country down there, so I'm sure it did a decent job. Here in Tennessee with all these hills is a little different story. Hence why I'm wanting to re-power it. 

Jeff 
Grab another gear and keep on trucking! 
        
curdog
Posted 8 Months Ago
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Yes, I would have been  hauling hot mix right now, but this new gig with them pays a lot more. I still get to drive 40k miles a year, but in a pickup now.


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