Thread: 4 inch crank in a 221, will it work?

Tweet

my good flatty block is a 221. i was planning on a 4 inch crank for it. a few people ive talked to said it will not fit because the rods will hit the lower part of the cylinder. i guess this is not a problem with the 239s. i dont know if the blocks are cast different. i know the bore is different. anyone here have any experience with this?? if all else fails, ill just use my 3.75 crank. im not building a race car or anything. just want that cool flathead look and sound!

bob

I see no one has any answers yet....difficult to find facts on this. But I have a few books...the 221 rods have a smaller crank end and will not fit the Merc 4" crank. You would have to get 8BA, 0BA or 29A rods. Journal diameters on all were 2.139", but 8BA and 0BA rods could only be used with insert bearings and on journals with two oil-feed holes. The 221 engine rods were 1.999" at the journal end and designated "21A". The rod lengths are the same at 7". Hope this helps some.

The 221 if it's a 21 stud engine if I recall is not as good of a candidate for a bunch of performance mods as the later 24 stud version.

So, with the above said, I guess that we need more info from the OP before much more discussion, i.e., year of motor, type of water pump (head or block mount) as there are some differences as to what can be easily used.

I did a little internet surfing for you and found this thread on another forum that might shed some light on the process. What you are discussing starts on post # 13 on there, but the whole thread has some good info.

http://www.jalopyjournal.com/forum/s...athead+stroker

Don

thanks for the input guys! my 221 is a 24 stud from a 41 ford with sleeves, which according to itoldyousos post should be original. it has the block mounted water pumps. if i found a merc 4 inch crank, my intentions would have been to have the crank stroked (i think its an extra 1/8) and use my 41 style rods. more people are telling me to just leave it a 221 since im not building a speed demon. im still up in the air. i have plenty of time since my goal with the car now is to get the frame and suspension done, then the motor.

bob

which 221 do you have the flathead or the small block ford which came out in 62-63???

flathead.

bob

The '41 engine has the "floating" rod bearings, the 4" Merc has modern shells. The cranks are drilled differently, only one hole for floating bearings, two holes for shells.