Just picked up a solid 1986 E150 Sportsmobile pop-up for my long-suffering wife's retirement present. It's got a 351w and C6 automatic that gets about 12 mpg. Looking to swap in a 300 inch-six with 4-speed overdrive manual trans, will need clutch pedal and linkage as well. Any leads appreciated! I'm in New England.

 

Are you doing the swap for gas mileage? I had a 300 six in one and my 302 gets better mileage.

 

@Rusty Baker: Thank you for field data. I had been wondering about that, as the Windsors prob breathe more efficiently, and the 51 cubic inch displacement difference is not large.

Motivation partly mpg, partly simplicity of maintenance. Am also considering swapping in just an AOD transmission, in place of the C6. May end up trying it both ways, over next few years, depending on what I can find for parts.

 

I did get 340,000 miles on the 300 6, and then the truck caught on fire. It was still running good at the time.

 

Don't expect miracles. I have the exact drive train (4.9 w/ 4speed overdrive) in my 87 f150 ( 105k miles) which you are seeking. I am not a lead foot by any means. With 3.55. gears, I get 13-15 mpg. To me, that little bit of gain is not worth the money or effort. I would expect mileage to be even worse in a van. The AOD won't offer much unless your driving is mostly highway with speeds above 45 mph. That's when the OD engages.The 4.9 is also no speed demon either. Save your money and keep your present drive train in good shape.

 

Thanks Raski.

FWIW, and for others who may be interested, averaged just under 18mpg with a 1980 E150 300-inch six and 3-speed straight-drive, at around 65mph, on several long trips. That's with a canoe on the roof, though otherwise pretty much an 'empty box' of a van. Stock except for a cheap 'Thrush Hush' type muffler.

The 3-speed manual trans is 1:1 straight-through 'gear ratio' in top gear. I am going to see whether the 0.67:1 ratio of the overdrive gives further gains.

I also had a 1976 with the same drivetrain. The 76 would spin one tire for 10-20' in first (not much weight of course), and both had plenty of passing power on rural 2-lanes. I never wanted for power with either one but, again, both were empty.

Another reason for the swap is ease of maintenance.

 

Wouldn't surprise me if axle ratio wasn't a big factor, in highway MPG on these E150s.

I never checked the ratio in the 1980, but it was an ex-Sears repair truck, with manual steering, no radio (from the factory anyway), and a 3-on-the-tree shifter. I wonder if it didn't have a 'economy' axle ratio.

Am seeking 300-inch six, clutch pedal and linkage, 4-speed overdrive, and driveshaft, from E150. Any leads appreciated!