239 crankshaft in 221 block

[Al ONT]

Well folks I have been reading posts and learning from you about flathead V8 Fords here since buying our 47 pickup last spring. The Oil pressure was low so I decided as a winter project to tear the motor down and repair as needed. Truck and motor is pretty much original with 24 bolt heads and I was expecting to find a 3 3/16" bore motor. To my surprise it is a 3 1/16" bore and has a small con rod journal crank with bearing shells inserts locked into the rods. And lastly the thrust shoulder on the rear of the crank has worn almost completely away letting the shaft move forward till the front crank throw was rubbing against the block at the main bearing. This is a Canadian truck and motor. In my research I have discovered that Ford Canada used this motor from 45 to 46 that has the crank throws drilled with two holes as to lube each conn rod bearing per the Canadian 41 to 47 Ford chassis parts catalogue.
So I tell you that story to explain why I'm asking if anyone has had any experience with installing the more popular 239 crank and connecting rods in a 221 block. It's not looking like I'm going to have much luck at finding a crank and new bearings for this unique motor.

[Brian]

Yes, the 239 crank will fit into the block BUT, the larger conrods will not fit down the bores. Incidently, if your existing crank measures up ok, normal floater bearings [81A prefix] will fit both the crank and the rods. They are the same size as your existing shell bearings. These floaters are comparatively cheap and easy to find.You are not stuck with trying to source those Canadian shell bearings.

[40 Deluxe]

To start with, the 239 crank has larger rod journals so the rods will not fit through a 3 1/16" bore. You will have to bore the block to 3 3/16" or larger. Or have the 239 crank rod journals ground down to 221 size.

[Al ONT]

Thanks for the reply and sharing your knowledge . My crank journals would cleanup with a regrind I believe but because the shoulder that normally would contact the thrust bearing has been worn away I need to find another crank. If I can use floater bearings in my rods then perhaps I will continue the hunt for a replacement crank.

[Brian]

One advantage of using those 'lock-in' rods, is that they haven't had 'floater' bearings spinning within them, consequently the big end tunnels tend to be still std and round and don't need resizing. Obviously, measure everything up to verify exactly what you have. If the thrust faces on your current crank are worn, it may be possible to grind them a bit wider and use rear main bearings that have the wider thrust faces. Ford did make oversize on the thrust faces rear main bearings.

[Dodge]

Sponsored Links (Register now to hide all advertisements)

You can also have good crank shop weld up the thrust surface and re-use that crank.

[rotorwrench]

If a 4 inch Mercury crank can be put in a 1937 21-stud motor then anything is possible. The Tex Smith book "The Complete Ford Flathead V8" had the article on this engine that was run in a 35 Ford coupe for the Great American Race. They had to do a lot of machine work on the crank plus the resleeved the whole engine to run 3 3/16" pistons for a full 255 CID. The crank counterweights were trimmed to fit the block, the snout was trimmed with a new key way cut, and the journals were all cut down to 221 specs for floater bearings and early type 221 mains. They used a special seal on the rear main but I don't know what that was. It may have been a conversion set up but I don't know for sure.

[Bruce Lancaster]

The big rods CAN be used with the small bore...Ron has described the process on here. It simply involves non-standard assembly order, pistons in from the bottom. I'm to tired to think it all through but the tech is on here, used advanced search to limit search to Ron posts.
Also, another direction, most 221 24 studs accept the big bore fine. Any Canadian markings on yours? I think Canada did make a 51A block for a while.

[Bored&Stroked]

One question for all of you -- I've never seen the small cod rods with non-floating (tanged) bearings - only 91A and 21A rods with full-floaters. Where the heck do you get those bearings?

[Brian]

The notched 21A conrods are Canadian, also used in some English stuff such as Pilots, [which used a different bearing again, having a flange on one side]. Finding these lock in bearings these days is like finding rocking horse dodo's; the easy solution is to just run floaters.

These setups would be rare in the USA, however, down here in NZ, we got our stuff from Canada and Britain, so we come across this stuff occasionally. The Canaks also made big journal lock in bearings/rods which ran on double drilled journals. Again, these bearings are easily substituted for conventional 99A style floaters.

[Al ONT]

Well I'm just back from looking at a 221 crank from a 36 Ford and learned they used a slinger and not the rope seal my 47 block uses. Well there I looked at a 239 crank which looks identical to the 221 I have with the exception of journal size. Could I use a 239 and have the crank throws ground down to1.999 for my 221 rods? If so should it be balanced again? I have attached a couple pictures of my crank you can see the wear on thrust shoulder.

[rotorwrench]

Cutting it down the required amount would make it necessary to balance it in my book but sure, it can be done.

[Greg58]

Other than the wear you mensioned your crank looks fairly good, depending on where you are you should be able to find a machine shop that will repair it. Engine rebuilders repair crankshafts all the time, on one like yours they usually ask you to send the new bearings in with the crank to match the repair.

[flatjack9]

Those cranks are routinely offset ground to 1.999 when looking to add an 1/8th in. stroke to either a Ford or Merc crank. So no problem.

[flatheadmurre]

I wonder if it wouldn´t be cheaper to just bore the block to 239 instead.
By the time you have ground down the pins to 2" and balanced the rotating assembly you spent some money.
Grinding pins down is not the same cost as normal crankgrinding cause it takes more time.
Or why not a 8ba assembly.

[Bored&Stroked]

Me - I'd bore the block to 3 3/16 and put a later crank and rods in it - the cheapest solution would be an 8BA assembly - as the bearings are really cheap and not hard to setup. Since you'd have to buy pistons anyway, maybe find a good Merc 4" crank and bring it up to 255 cubic inches. Going from a 221 to a 255 will make a noticeable difference. There is no reason to invest hundreds of dollars in that old crank - or to offset grind a 239 crank to fit 221 rods. I'd much rather go the 8BA or 8CM route.

Rods: If you're going to have a set of the newer 8BA rods rebuilt (which can approach $200 if they need new bushings), then consider buying a NOS set from SoCal out West - I believe they are about $225 - and they're really nice. (Is what I just did for a guy).

When done, you'll have a completely rebuilt lower end, new pistons/rings - the works.

Top-End: Since you have it all apart, you should consider a complete valve job and make sure you have the 49-53 style 1-piece valve guides and valves (which this engine might already have).

Performance Mods: And . . . since you're doing that . . . maybe a very mild performance cam . . . a manifold with two 97 carbs and headers. Also, a 49-53 oil pump and pickup. Then, you might want a cool set of aluminum heads . . . . then . . . .

Do it the Best You Can - You Won't Regret It: Oh Hell, see how it goes! It always starts out with one thing I'm going to fix and get by on the cheap - pretty soon, I'm building a whole engine! LOL The main point is that if you have the engine all torn down, try to fix it as best as you can afford - because nobody ever pays you back for the time and work it takes to do all of this. If you want and can spend the money on a few 'upgrades', your truck will be all the more fun to drive. (just my opinion).

If you need anything, feel free to ping me - be happy to help.

B&S

[Ol' Ron]

B&s x 2

[rotorwrench]

One thing that may need to be done is notching for clearance between the cylinders when using 8BA type rods. The 221 blocks are a little tight in that area but I don't know how much would be necessary if any. This is assuming that the C51A block is similar to the 41A and prewar 221 blocks.

[Al ONT]

Thanks for the input. So you fellows with experience have had no issue boring the 221 block out to 3 3/16"? It does seem like a good idea to use the 8BA bottom end if It fits. My goal is to make this a dependable motor that will cruise on the highway at 50 to 55 mph. Which it was doing before tear down all be it with about 15 psi oil pressure and close to 0 psi at idle. I would like it externally to look like a stock motor. I have attached a picture of the truck to give you idea what I'm working on.

[Chuck Sea/Tac]

Post 6 have thrust welded up and finished .