Hi guys I have a 1967 V6 225 in good shape. block casting 1381623. heads B1358676R The crank is set up with a pilot bearing for a manual transmission. I need to use this engine with a TH350 auto. So here is the question: I am pretty sure I can have the crank machined to work with an automatic transmission's torque converter. HOWEVER, I have access to a good crank from a 1983 231 (3.8L) Buick V-6. could I just swap the 3.8L crank into the 3.7L block? same bore size different stroke right? any reason the swap wouldnt work? what are the big differences between a 225 and a 231 V6? Thanks for any input.
The 231 crank won't work from an '83. Around '78 Buick went to the even-fire engine and the crank actually has offset throws from cylinder to cylinder instead of the common shared type like most regular engines. '77 and earlier would probably work. I thought the difference between the two engines is that the 231 is just a .030" over 225. No difference in throw distance(stroke). I know from 455 experience I don't think it would matter if the pilot bushing is in there because it sits in the deepest recess of the crank while the converter uses the larger outer recess. If it is a true bushing it should be removable. Unless you are saying the actual steel part needs to be machined for the converter to fit. There should be a bronze bushing in there because you don't want the trans pilot shaft going steel to steel. If it is a bushing you should be able to remove it with a puller. I also read an old trick where you pack the the pilot hole and recess behind the bushing with heavy grease and then get a drift/shaft(old input shaft) that fills the pilot hole as tight as possible while still able to slide it in and out. You strike the shaft sharply and the hydraulic pressure should push out the bushing.
Thanks Mike I found you are right about the pilot bushing. I actually took the crank and put it up on end on an inverted TH350 converter. everything fits fine. So i guess the pilot bushing is a non issue. Ive had this 225 apart for about a week ad I am trying to decide how to proceed. Same old thing. You can really get dragged into a build. I think I am going to just regasket it and get it in a car and drive it til it breaks. Thanks for the thoughts on the odd-fire even fire cranks. I know the bore of the 225 is 3.750"
You can pack the hole with grease and take a bolt or steel dowel close to the hole diameter and drive it in the hole. This will effectively jack the bushing out in nine out of ten cases. Jim
