stroked flathead

[grantlysv8]

hi, am needing info on stroked flathead engine, 99a-59a block-factory releived type, i have 4 inch crank,floater rods and bearings i need to know if to use stroked pistons or stock cm8 type pistons with stock gudgeon pin location
all info gratefully received thanks grant

[maud]

If you don't get an answer here, go to fordbarn.com flatheads is their game.

[Smokin Joe]

You're using the 51-53 merc crank. Use the 51-53 merc pistons, rods and bearings.
The 59A uses 1 bearing per throw. (2 rods per bearing)
The merc uses individual bearings.
The merc pistons have a different pin hight than the earlier Ford pistons due to the 1/4" stroke.

Wait till 286 sees this, there are other options for the rods that I'm sure he knows better than I do.
I sprung for the ROSS pistons and bored to 3 5/16"
That gives a 276 cid instead of a 239 stock 59A.
If you bore that big, order the big bore gasket.
You can still bore to 3 3/8" later.
Probably as far as you want to go in a street motor that has to idle in traffic.

[286merc]

If that is a true 1949-53 Merc crank it then depends on what floater rods you have. If you have the wide journal 29A they can be used along with the matching bearings BUT you would be better off with the 8BA style IMO. I have never been a fan of a single oil hole in the crank servicing 2 rods.
You also need Merc pistons in either case, I would stay with 4 ring types.

If that crank is an old style welded up & offset ground then you MUST use the full floaters.

Also be sure to use the early flywheel. And protect your investment with the late oil pump/pickup/screen. The Melling M19 is the pump you want.

[grantlysv8]

hi 286, thanks for the reply-crank is a nice original 4 inch 20 thou under mains and rods all tested machined and ready to go i have a full set of 8ba 3-3\4 rods,do these work with the merc pistons(same length?) i just thought the 21a rods were needed, but have spares for both-i have virgin 59a and 99a blocks all factory releived type some with raised deck intakes any idea on which is a better block i think internaly their the same but the merc(99a seem to be a nicer casting) have read these are supposed to be thicker in the casting but i dont know for sure i have 2 good late truck oil pumps chopped flywheel ground 8ba cam johnsons waggot heads(aussie) so im ready to start-i may have few questins to come so i hope thats ok im here to learn as much as i can get my brain to absorb,thanks for your time-grant

[286merc]

Hi Grant. All 8BA rods and bearings are the same, the pin location in the pistons is what changes between the cranks.
Rods should be rebuilt, the small end in particular tends to get out of round.
The early Merc block has a reputation of being the thickest casting. The only ones Ive fooled with have been the generic 46-8 59A style and have had no problems taking out to 3 5/16; sonics are always very good.
I spend most of my time on the 8BA but the past few years Ive done up a few 59A for customers.

The 21A rods are the 42 and earlier with the small journal. These are used on an offset ground Ford crank with the journals cut to size. You need 29A rods for a Merc crank if you decide to go that route. Of cource you can always stroke the Merc and use the 21A; I believe there is some minor web interference needing grinding.

Ask away, several flatty guys hang here.

Carl