3sp To 4sp
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Joined: Jan 2001
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3sp To 4sp
I currently have a 3 speed manual joined to a 390cid.
I would like to know what would be a good 4 speed manual transmission that will bolt on and be inexpensive to buy.
Gas mileage being the main reason to exchange. The truck is a 1967 F100, so it may be the original tranny .. engine is obviously not original to this truck.
Any help appreciated ..
Thanks,
Gary
I would like to know what would be a good 4 speed manual transmission that will bolt on and be inexpensive to buy.
Gas mileage being the main reason to exchange. The truck is a 1967 F100, so it may be the original tranny .. engine is obviously not original to this truck.
Any help appreciated ..
Thanks,
Gary
Cargo Master
Joined: Aug 2000
Posts: 2,931
Likes: 12
From: SW Michigan
3sp To 4sp
Gary, a four speed won't help mileage unless it has overdrive. There are four speed overdrives available however. If memory serves you should be looking at mid 70s to mid 80s trucks. The transmissions with the shifter coming out of the top cover are thought to be stronger than the ones with the shifter bolted on to the side of the case. The bolt pattern on the front of the trans should fit the bell you have now. On another thought, what axle ratio do you have? and might some taller gears help. The mighty FE seems to do well with 2.75 or 3.00 gears. DF
Fleet Mechanic
Joined: Nov 1999
Posts: 1,415
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From: Lower 48
3sp To 4sp
The 352, 360, and 390 were the same block. You might have a 352 which would have been a stock offering for '67. I agree with DF, just changing to a 4 speed is not going to change anything for mileage because the final drive is still 1:1. What you're going to get by going to a 4 speed is outrageous bottom end pulling power, and that is a bolt in swap. If you're after mileage you might consider an overdrive 4th or even a 5 speed. The ZF 5 speed is the one you want but they're a bit spendy. If you don't need or want the bottom end pulling power I also suggest a gear change, or you can do both a gear change and go to a 4 speed then you should have the best of both world's - low RPM at highway speed and stump pulling bottom end. Remember this FE blocks were never known for good mileage. The best I ever got out of my 390 with a 4 speed and 3:08 rears was 11, but it was 10-11 loaded or empty, fast or slow.
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