Is there any modern powertrain that could be installed in a 1951 F1 that wouldn't require altering the frame or body of the truck? If I made changes to the truck I would like it to be bolt on/off so the truck could be put back to original very easily if desired.

 

Your pretty limited in that respect. A Ford 302 with a C4 automatic can be installed without hacking up the transmission crossmember, just barely. The new engine crossmember can be bolted in, need some radiator mods, exhaust, etc. With the stock rear end, that will be spinning pretty fast, if you anticipate highway driving. You can change out the rear axle to a '48-'50 with its 3.72 (vs. stock '51-'52 3.92) or put in a 9" axle from a '57-'72 without significant mods, and get down as low as you care to go.

I'd decide first if you will ever really go back to stock. It's honestly not likely being non-stock will hurt its value very much.

 

I have a the basic setup that Ross describes (289/C4/9"). Here are my general observations - while it can be done without modifying the frame, it works much better with a couple of minor mods.

The main limiting factors are the factory motor mounts and the trans crossmember. The PO on my truck didn't cut anything. He made some very tall motor mounts so the oil filter would clear the stock motor mount. This high mount also allowed him to mount the C4 to the top of the trans crossmember - barely. If you do this, you will have to make a modified trans cover in the cab to clear the top of the trans - no big deal, but finding a stock one uncut is tough. You also have to watch the top of the trans bellhousing contacting the cab.

By removing the stock motor mounts (just drilling out the rivets, which can easily be replaced later with bolts), the engine can be mounted significantly lower.

I then did a minor recess in the stock trans crossmember to mount the C4 mounting pad to. The cut only dropped it about a half inch, but gave me a better mating surface for the trans support pad.

The stock rearend can be removed and a 9" with more friendly gears put in it's place with no damage to the stock rearend. You will, however, need to have a driveshaft modified to mate things together.

Just my observations on this combo. I am very happy with it overall. Can't think of a reason to go back to stock, but that is just my opinion.

 

Not to start a ****storm, but to be completely honest the easiest swap with the least amount of mods would be a Chevy small block with powerglide or T350 (auto) or T5 (std with OD).

 

With no other changes, AX, i.e., stock suspension/steering, the Chevy combo offers no advantage. A T5 requires complete removal of the center section of the stock trans crossmember with any engine.

 

I don't agree Ross, but the charter of this BB restricts any debate. If anyone wants to hear my opinion, reasoning, or debate this, PM or email me an email addy so we can take it off here, otherwise I will say no more on the subject.
You are correct that virtually any tranny but a stock 48-52 offering will require modifying the tranny crossmember on an F1.

 

how will you stop in traffic when almost all other auto have great brakes here you are 65 year drums, make one change and you got a whole other problem

 

The OEM drums are more than adequate for daily driving, unless you cowboy drive, carry or tow heavy loads or live in the mountains. I would put in new (NOT rebuilt or ebay Chinese clones) wheel cylinders, hard and flex lines and a dual chamber master cylinder for safety tho.

 

Willard my 49 came to me with a 56 nailhead Buick running thru the stock remaining drive train. The steering box was the only area modified. If you run a sbc with the era front motor mount and the era adapter for the sbc to flathead transmission the rest of the drivetrain stays stock and there is not a problem with the stock steering box. The weak link will be the stock light duty f-1/car transmission. I cured that by replacing the stock transmission with the heavy duty 3 speed from 48-52. In your case, you will lose the column shifter for a floor shifter. My radiator came with a relocated inlet and outlet. If doing it today, I would buy a bolt in radiator made for sbc.
I drove Willard many years and cross country with the Buick mated to the stock remaining drivetrain.
This gets you a modern engine but not a transmission change. I do not believe that there is a way to get an automatic transmission without relocating/replacing the stock transmission cross member. Simply put they are all too long.

 

I will stand up and agree with Ross. I've done it. The least amount of mods will come with the 302/C4 combo. They can be installed without any floor, firewall, steering or rad mount mods if installed in the 6 cylinder location, and the trans mount lines right up with the crossmember. It still requires welding here and there to do it right, but it's pretty painless overall. For a simple installation, it's the right way to go, imho.

 

yes a 239 EBA flathead

 

Why would you want to convert it back anyhow? F1s aren't rare, one with a modern engine and transmission that is easy to drive, can keep up with traffic and gets decent gas mileage is worth more than one with a stock engine and crashbox that is difficult to shift, won't go over 45, gets <10MPG, always leaks oil and requires near constant maintenance with difficult to get parts.

 

 

 

When I want modern, comfort and luxury I drive my '12 BEEMER..

When I want simple, functional, mindless leisure I drive my stock '48 F-1.

For me, costly, time consuming mods (disc brakes, suspension, power steering or let's see, maybe a navigation system or self park feature) would take away the feeling I get of simpler times when driving my Ms. Ellie.

My biggest thrill comes from driving her not changing her..

Of course if I had to commute to work with my F-1..that changes everything.