59A 221 239 casting thickness

pooch

pooch

Well-known member
Is the 59A 221 and 239 block identical as cast except for bore size ?

ie, can I take a 221 3/16th straight out to 3 3/16th with same cylinder wall thickness and no dramas?

Is all else in both engines the same , ie crank/rods/ etc?
 
I've never built the smaller 221 cube engines - though I've taken a few apart. Conventional flathead wisdom says that they do not have the same OD thickness in the bores as the bigger 3 3/16 239 cube engines. In other words you can't bore a 221 out to the same 'max bore' as a 239. I've not sonic tested these blocks - which is what I'd want to do to truly understand 'myth' from 'fact'. What I've heard the most is that about the max you can bore out a 221 is to 3 3/16. Now I know that to be true with a 39-42 221 engines, but have NOT validated this with the 59x 221 replacement engines. Does anybody know for sure???

The rods on a 221 are either 91A or 21A (they use the full-floating bearings) - and they have smaller big-ends for the 2" crankshaft journal. The 221 engines all used the 2" crank journal - which are different than the 239 engines. The other reason for the smaller big-end sizes is so that they fit through the bores during assembly.

The 239 engines use the 29A full-floater rods -- which are for the larger 2.138 rod journals. You can't swap rods between the 221 and 239 engines . . . but you can swap the whole rotating assembly (if your rods fit through the bores). There is really no reason to swap either direction on a stock 221 or 239 - within the 59x series (stroke is the same).

One of the 'hot combinations' back in the say was to use the 91A or 21A rods with an 'offset stroked' 49-53 4" Merc crank . . . giving you a 4 1/8" stroke from an off-the-shelf crankshaft. Basically you take the larger 2.138 journals of the Merc crack, offset grind them to the 2" size and you gain an 1/8" of stroke. You could do the same with the 3 3/4" stroke 59A 239 crankshaft - to achieve a 3 7/8 stroke (just not something that was done all that often).

Good luck!

B&S
 
Pooch ,think about it ,when making those 3-1/16 bore blocks by the thousands,would they waste all that cast iron on a thicker bore,.
Lawrie
 
Lawrie said:
Pooch ,think about it ,when making those 3-1/16 bore blocks by the thousands,would they waste all that cast iron on a thicker bore,.
Lawrie
Click to expand...
But it would require two different cores, so there is a cost trade off. No idea which way it went, but it could have been for a common casting process.
 
Thanks all .

I forgot about the smaller rods and crank .

I was just thinking whether to take a trailer to the next swap meet to see if the 221 engine was there that I saw at the last swap.

The swaps are only 75 kms apart so a very good chance if it did not sell.

I may have a new set of standard 239 pistons over, and even tho the 221 lookd good in the bores, I need a minimum of 239 cubes for my bus .
 
The 221 usually takes 3/16 + .040 if the rust isn´t bad so taking it to 239 std gives you room for another rebuild, after that it´s sleeving.
Keep it 239 and add some compression if you need more power.
 
Is it just milling the heads for more compression ?

I think I have read here about minimum .040 piston to head clearance ?

What is clearance on a stock engine ?
 
Be interesting to know if Ford used a differen core for the 221 version of there 59 series block, I just doubt it. As for the piston to head clearance, I don't think it raises the CR much, but it does improve combustion , which give more power and economy.
 
The cores are different...all the 1/16 59ab ive come across so far can´t be bored as much as the 3/16.
Not only to save metal but also for heat transfer i assume.
 
Yes, the 3 1/16 blocks of the 59 series WILL NOT handle much more than 3 3/16 bore size. They are different.
 
The 41A replacement block cores (circa late 1944) were a combination of the 59 series outer shell and the prewar 221 design. It has the characteristics of both series and of course it generally has the 59 on the back too. It's hard to tell what it is until you open it up and look inside.
 
Learn sumpin every day, just didn't think Ford would bother with changine the cores as the valve angle is different than the early blocks. Had a block that had no number on the bell housing, but had all the measurments of a 59 with 1/6" sleeves in a 3 1/16 bore. I couldn't get the sleeves out with out boring them out. This is wher the stuiped factor came into effect. The boring bar was not centerd right and I hit the block, not the sleeve. Now I had a block that I just bored out 1/4 inch, as was concerned that I might be near the plumbing, so I had the block sonic tested. I still had 170" wall left, so I punched it out to 3 3/8. Jim Harvy has it.
 
I sound like somebody made the sleeves a bit too tight on that one. Maybe they took a 3 3/16" 59 engine and sleeved it to 3 1/16". Nothing surprises me much on this old stuff any more. I've heard of quite a few 59 series engines that didn't have the 59 on the back bell. There are other things like the deck port shapes that give away what they are.
 
Good discussion gang - good to know that what I always 'believed' to be true is actually true. (Doesn't always happen that way). This is important information to know in that I would surely not value a 221 block the same as a 239 (given what I do to them) - hence the reason I haven't built a 221 24 stud engine in my lifetime.
 
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