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75 302 into a 81 F-150

Hey all. I am needing to put a new engine in my 1980 F150 4x4 and, it came factory with the 302 but somewhere along the line, someone stuck a 351 W in it. My question is, I found a 75 302 that came out of a truck and need to know if I am going to have to change the flywheel or something like that.
 

Fellro

Moderator
Staff member
Yes, keep the flexplate with the 302, and the 351W with it. The balance is different.
 
Well, I am suspecting the person who swapped in the 351W didnt change the flywheel as my engine basically shook itself apart. I only drove it for a few months and it had an odd vibration before the engine blew. I dont know. Anyways, so, keep the flywheel from the 302 but use the flexplate from the 351 is what your saying?
 

Fellro

Moderator
Staff member
There is two different weights depending on build year for the W as well. Also, unless you have a manual transmission, flywheel = flexplate. Auto transmissions don't actually have a flywheel, is is actually called a flexplate.
 
OK. I really dont know much about the 351 Windsor that is in the truck as the guy I got it from told me it was a Cleveland which was BS. I have no idea what all they did to it or anything as he said they gave it a mild "build" so, your guess is as good as mine LOL. I just didnt want there to be an issue with the new motor and the starter not engaging the flywheel. Thanks for the help.
 

Fellro

Moderator
Staff member
A 351C will bolt to the trans and maybe motor mounts, and that is about where the common parts end.

As long as you use a flexplate (flywheel) that is proper for a 302, you should be fine. If the motor doesn't come with one, I suggest buying a new one for safety sake. They aren't any too expensive generally.
 

mtflat

Flatheads Forever
2,559
147
75 and 80 302 should both be a 28 oz imbalance. Wasn't it 82 when Ford changed to 50 oz imbalance? Hard to guess what the 351 was from?
 

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