The Ford Barn

rotorwrench · 03-23-2020, 12:59 PM

There is little known about 21 studders that have thicker cylinder walls so I can't say on that subject. There is oddball stuff in Ford Manufacturing on both sides of the Detroit river. Most 221 engines were limited to about 3 3/16" max. Most tin can sleeve engines were prewar. I haven't seen any post war. The early 99A blocks had thick cylinder walls but I think that only lasted till just before the 1941 changes.

They had replacement pistons just for the prewar tin can sleeved engines. Remove the sleeves and hone it was all that was needed with those. The reason they went to the 24-stud was so they could get more bore out of it. Those late 21-stud engines had the lower head bolts that were very close to the bore edge. Going with 24 studs spread them out farther and added better sealing as a benefit. They were preparing for the 99A block for the Mercury and trucks. Even though they are a little different than the 221, they still shared a lot of design similarities and they all went down the pouring line in similar flasks.

03-23-2020, 12:59 PM	#21
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,425	Re: What do i have here...21-stud hybrid ? There is little known about 21 studders that have thicker cylinder walls so I can't say on that subject. There is oddball stuff in Ford Manufacturing on both sides of the Detroit river. Most 221 engines were limited to about 3 3/16" max. Most tin can sleeve engines were prewar. I haven't seen any post war. The early 99A blocks had thick cylinder walls but I think that only lasted till just before the 1941 changes. They had replacement pistons just for the prewar tin can sleeved engines. Remove the sleeves and hone it was all that was needed with those. The reason they went to the 24-stud was so they could get more bore out of it. Those late 21-stud engines had the lower head bolts that were very close to the bore edge. Going with 24 studs spread them out farther and added better sealing as a benefit. They were preparing for the 99A block for the Mercury and trucks. Even though they are a little different than the 221, they still shared a lot of design similarities and they all went down the pouring line in similar flasks.