I recently purchased a 1961 Plymouth Savoy 2 door sedan, it is a slant 6 with 3 speed on the column. I haven't transported the vehicle yet, but I know enough about the vehicle that I already have some questions. VIN is 2111121696, which means:
2 = Plymouth 6 cylinder
1 = Low (Savoy)
1 = Year, 1961
1 = Plant, Detroit
121696 = Serial/production number
The car originally had a slant six based on the VIN, but I know that the engine block in the car now has 5 water jacket freeze plugs on the driver side and the cylinder head is a "peanut" head versus the "drool tube" head. This suggests the engine is a 1975 or newer slant six. I'm curious how this update was done and if the transmission is original to the car or updated as well. My questions are as follows:
Did the 1960 and 1961 slant 6 engines have the "old style" crank flange prior to 1962 like the rest of the Mopar engines of the period? Or did slant 6s have the 6 hole asymmetric bolt pattern from the time the engine was introduced?
Since the crank register (diameter) on the slant 6 increased in about 1968, how would this impact using the original trans? Would a flywheel of the same vintage as the engine simply solve this issue?
Posted 2019-04-16 11:03 PM (#581001 - in reply to #580926) Subject: Re: Slant 6 crank flanges
Location: Muskego, WI
I found this information from a seemingly knowledgeable member on the "for A bodies only" forum:
"The mini starter swap didn't work for you because the Canadian-built Slant-6 cars kept the starter drive and ring gear dimensions that had been used only in '60-'61 in the States. The Canadian cars had a direct-drive Prestolite ("Auto-Lite") starter similar to the US '60-'61 Slant-6 starters.
The gear-reduction starter, first used in '62 on everything in the US and on V8s in Canada, introduced a new starter drive/ring gear geometry. The drive pinion has ten teeth and is ø32.5mm (vs the '60-'61 US and -'66 Canada, with 9 teeth and ø25.4mm).
There is no parts store off-the-shelf starter that will directly replace the early-type \6 starter. If you want to run a mini starter, you'd either need to custom-build one or swap in a torque converter or flywheel (as applicable) with the later ring gear on it, then you can use the same mini starters you read about other people using, including the '91 318 item you bought."
So whoever swapped the newer engine into the car, they must have updated the flywheel as the crank register diameter (or pilot hub) increased in 1968. The original 1961 flywheel wound not fit onto the 1975 & later crank, so a later flywheel would have been needed to mate the engine to the original trans. A 1962 or later starter would then be required to match the flywheel.