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I bought the '77 in 1986. I just drove by a lot one rainy night and saw it, it was dark, after hours. I was able to read the miles (35,xxx) with a flashlight, the lot was in a small city about 45 minutes from my home. I called the lot the next day, was told what it was, how much they were asking, etc. I made them an offer somewhat less than they were asking, I had not driven it, but I was willing to take a risk. I told the guy (who was partners with a local city police officer over there), that if they would take "5 thousand", I'd be there about 7 pm. They were asking nearer to 6. He hesitated, then said OK, said he'd have it gassed and ready. Wife come home from work, we drove over after a quick supper.
It was like 11pm when we got back home. I had test driven it, it run fair, but it still had a 2 barrel factory carb under a Holley air cleaner, and Morosso valve covers, but it was all stock except for two Cherry Bombs exiting under the bed sides in front of the wheels, it was loud. The next day I was off work, I took it to an exhaust shop and had new pipes and turbo mufflers put on, exits behind the rear wheels. Then I took it to show my wrecker operator buddy, he said it run pretty good for a 351M but that it could be a 400 ... but he said most all were 351Ms. I had verified the vin when I bought it, comparing, etc to the title, It was before internet.
Everything I bought to do anything to the engine, I bought for a 351M. Belts, plugs, intake, cam, lifters, timing chain, gaskets, bearings. I never questioned it, I've put bearings in it twice now, I had a 351M. There were times I've said 400 at a parts store because I learned, they were virtually the same, and I know some parts people will just look up a 351 (it's all they hear I think).
I'm out doing some looking, spraying my evap fittings, etc. today. I was messing with the button in the door that turns on the dome light, got it to work too. I guess it was dirty.
Now ... the silly part.
I've never looked my vin up to decode it but maybe I should have?
Last edited by tbear853; Aug 17, 2023 at 02:25 PM.
Reason: forgot a title
OK tbear,,,,, I'll bite what am I missing here what was decoded? .
Well, I think the S = 400? What ever it'll likely run just the same. Now I wish I had looked for a number on the crank when I did the bearings not long ago.
Six of one, half dozen of the other. 351M or 400.........
I agree, not a lot of difference there, it's a better runner if it's a 351M than it is if it's a 400. I think was maybe 12 hp difference stock. With a shorter stroke of a 351M comes less swept area in the cylinders, which is like "less friction" sapping away precious power, less ring traveling distance in 300,000 miles. .
Just playing with numbers ... Assuming the same gearing, same tires, same speeds ... 60 mph & 2,500 rpm. Each piston travels the length of the stroke twice per revolution, once up, once down.
A 351M with 3.5" stroke, each piston travels 1,458.3 feet in that one minute / mile @ 60 mph. X 8 = 11,666.4 feet or 2.209 miles of total piston travel.
A 400 with a 4.0" stroke, each piston travels 1,666.7 feet in that one minute / mile @ 60mph. X 8 = 13,333.6 feet or 2.525 miles of total piston travel.
A 351M has the same piston travel in 1.145 miles as a 400 does in 1.000 mile. One can move the decimals and keep same ratio like say "114,500 miles to 100,000 miles".
in 100,000 miles of high gear running, each 351M piston travels just 27,612 miles in the bore, but each 400 piston travels all of 31,562 miles in it's bore.
Now, having looked at that ... I think I maybe prefer to still believe that it is a 351M after all? I'll ust say "351M ... I think" when asked "What's in it?" if asked.
Originally Posted by beardedcap
Good thing you marked out the serial number, I was going to find it and steal it
I'll add to this thread that it has the lighter of the three different HBs and that the aluminum riveted on the door plate that everyone looks closest at says "H", so I think it's very likely just a mistake in printing that white sticker. Only way I can explain the difference. I just don't recall ever noticing the difference in 37+ years.
The sequence number is what makes a serial number unique anyway ... they likely sold a few "F14SNY....." (s) as well as a few "F14HNY....." (s) ... but it was the sequence number that was not duplicated.. The number on the frame would be the whole correct one ... and I might someday think to look at it. I checked and my title says "H" too & I'm inclined to believe Ford's original invoice is where the vin was taken from when sold new, likely a selling dealer just compared invoice to the plate.
Update: Frame number matches the warranty plate. "H" it is.
400's had a 1 year chance 1971 and it was a torque machine, 72 and it was over, be hard pressed to tell a 400 from a 351M by the seat of the pants. I had a 78 351M Bronco. I never asked it for much and it always started and got me down the highway even in blizzard conditions. Wasn't a bad engine design, just destroyed by regulations.
I agree, not a lot of difference there, it's a better runner if it's a 351M than it is if it's a 400. I think was maybe 12 hp difference stock. With a shorter stroke of a 351M comes less swept area in the cylinders, which is like "less friction" sapping away precious power, less ring traveling distance in 300,000 miles. .
I'll ust say "351M ... I think" when asked "What's in it?" if asked.
"H" it is.
