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ok guys need some newbie help ! I jumped head first into building me a hot rod out of a 1971 f100 , Its got a old worn out 302 in it with what looks to be a rebuilt C4 tranny. I am swapping the 302 out to a 351w jasper built . Going to attempt the swap out this weekend , as I was checking my list not sure on the flex plate ... after reading miles of bad info I am coming here for advice. My 351w already has a 164 tooth flex plate on it, now...if the old motor<302> is the 157 tooth can I swap flex plates with out killing my 351W , there seems to be some confusion out there on the net. I am not sure until I pull the 302 but since its the early C4 I fear its got the 157 flex plate on the 302. This would be the wrong bell housing for my larger 164 tooth flex plate? I understand < maybe> all 351w had 28oz harmonic balance weight? help !
After reading more it appears as long as the flex plate is matched with the harmonic balance it will work and all 351w were 28oz , so a 157 tooth or a 164 tooth will work on a 351w as long as they are 28oz ?
What year is the 351W? The harmonic balancer & flex plate must match, otherwise a vibration will result that will eventually tear the center from the flex plate.
1981, due to emissions requirements, Ford changed the 351W flex plates and harmonic balancers.
Harmonic balancers have FoMoCo ID engineering numbers stamped on them. Post the number, I'll give you the part number of the matching flex plate and its applications.
All 351 W are 28 oz. , 302s are 28 oz. up to 81 , after that they are 50 oz. I had an early c/4 ,66 year, and it was 164 tooth and 28oz. I changed to a 85 302 and it is 50oz. So i had to get a 50 oz. , 164 tooth AOD flex plate to make the starter fit and keep it balanced correct. C/4s can come with few different sizes of flex plates depending on the years and what engine they were behind.
112372 is stamped on the harmonic bal on my 351w.. thanks for your reply! I just wanted someone to discuss my project " motor swap" ..I live in a nice little subdivision and the neighborhood is not real thrilled about my project in the driveway !!! so I don't have many people to talk to about this!! I should have the 302 pulled out this evening ..I will know then if my bell housing on the c4 is the small or large < i need the large> I am hoping to just leave the 351w like it is... its a jasper rebuild with the flexplate and all the pullys already installed ! if the bellhousing is the larger one my 164 tooth flex plate should fit!