f1oo motor size serial number search

[thebannister8]

hi guys--been awhile---please help---absolutely stumped.. i have a 67 f100... i have a 6 cyc motor...my vin# starts with f10arb ---the -a- should indicate that i have a 240 motor.....im not convinced...ive taken all the serial numbers i could find and shown them to 2 local engine builders and ford...they all have looked them up in theyre books and come up with nothing---theres--i think--1 on the block,,and 2 on the intake mani fold....short of taking it apart and micing the cyclider i need to know what i have for parts......i have a 6 cyc 200 in my mustang ..and the thing is tiny....what ever i have in my truck is gigantic...its the original motor-------------any tips or clues-------thanks.... steve

[FORDification]

The A in your code does indeed mean you have/had a 240. Don't confuse the size of that little 200 with your 240, they're completely different animals....no parts interchangeability AFAIK.

[willowbilly3]

If you can find a number on the head you might try running that. The only two engines in the family are the 240 and 300. Although the heads will interchange, I have been told the 240 head is slightly thinner (requiring shorter pushrods) so it should have it's own number. This difference is not noticable to the naked eye.

[thebannister8]

thanks for the info guys---i think what was running through my mind is that the 240 would be slightly larger then the 200 and the 300 would be noticably larger.......i suppose the 200 could be viewed as a small block and the 240 and 300 viewed as a big block---------------the differences in the 240/300 being noticable only in internal measurements......does that sound like a fair assesment------thanks again--steve

[willowbilly3]

The 240-300 look identical. Both sides of the valve cover are basically smooth. The 200 belongs to the 144-170 family and the sides of the valve cover are wavey with indentations. The only truck that ever got the 140-200 was the Ranchero.
While the 240-300 are mostly found in trucks, the large passenger cars did get the 240 from 1965 on for a few years.

[NM5K]

the differences in the 240/300 being noticable only in internal measurements......does that sound like a fair assesment.>>>>>>>>>>>>

Yep, As Willowbilly noted, they look the same from the outside. The main difference being the 240 has a shorter stroke than the 300. "3.18 vs 3.98 inches stroke. Both engines have the same 4 inch bore. The 240 has a higher compression ratio, and revs a bit higher. "Max HP at 4000 rpm vs 3600 rpm for the 300. " This is another tipoff.. In the VIN, you will see a number for horsepower at a certain RPM. For the 300, that RPM is 3600. If it's a 240, that RPM number *should* read 4000. Both are good engines. I have a 300 in my 68 F-250, but the guy I work with has a 74 F-100 with a 240.. To me, they sound slightly different, I imagine due to the stroke difference, and my rebuilt engine sounds the same as my original one, so I don't think it's a fluke...Actually, if anything, I think the 240 is the smoothest of the two, but of course, the 300 has a good bit more torque at low rpm's. MK

[FORDification]

...and I'm sure I read somewhere that the 300 heads will bolt right up to the 240, raising the compression a bit for better performance.

[willowbilly3]

The heads interchange but you have to use the corresponding pushrods as the 240 uses ones that are like 1/8 inch shorter.. I'm not sure on the comp. ratio but it seems I had heard one way or the other would bump it up a little.

[thebannister8]

you guys are all really bright----i appreciate everyones input, and im learned alot....my plans are for a full restoration-----of course over time..but for now i want to get to enjoying my truck ,,instead of staringat it on the side of the house....thanks again....steve

[NM5K]

and I'm sure I read somewhere that the 300 heads will bolt right up to the 240, raising the compression a bit for better performance.>>>>

I think usually, it's the other way around. Many like to stick the 240 heads on the 300's for the reason you describe. Sticking the 300 heads on a 240 would lower compression if I'm thinking this right... MK

[FORDification]

You're probably right....I researched this out last summer when trying to figure out whether or not to keep the 240 in my truck, but once I decided to go with the 390, I think I pretty much forgot everything I'd learned.