Which flywheel do i use?

[Respected_Cutlass]

This is my motor,

14093638...350...87-95...2 or 4...Roller or flat tappet cam, one-piece rear seal

I have a thm350 transmission. How do I choose the flywheel? Thanks

The 86 1500 has the flywheel listed for a thm350

the 87-95 has the flywheel for my motor but not the trans, THM700, 4l80, 4l60

 

[jrm81bu]

You will have to look at the convertor bolt circles to be absolutely sure. You HAVE to match the flexplate to your motor. That particular motor should have a weighted flexplate unlike the earlier 350's. A stock flexplate should work but if you go to the parts store, have them pull it out for you and see if it has a dual pattern(six holes instead of three) for the convertor. If it has 6 you're good to go. If it only has 3 then you should get the bolt circle diameter and check it against your convertor.

 

[anakputa]

I have a one-piece rear externally balanced flexplate that I had behind my engine 350 and 700R4 for 6 months until I switch it to a 5 spd manual.

87 Chevrolet 350, One Piece main rear main, externally balanced, automatic transmission, dual pattern flexplate. $45.00 Plus shipping.

 

[Respected_Cutlass]

I had bought one and it had a weight on it. Then this one guy I know says I got the wrong one because the weighted ones are only for 454s and 400s. Other than the weight it fits perfectly with 6 holes. I went back and got another one w/o the weight but this one had the center hole being way too big. So if do you think this guy i know could be wrong and the weight will be alright? Also, did I word it right?, using context clues I'm starting to believe flywheel is used for manual transmissions and flexplate is used for automatics...?

 

[anakputa]

Flexplates = Automatics.. Here's a picture of the Flexplate- The hole in the middle of the bolt holes is large rollpin

 

[jrm81bu]

For most part you're friend is right. That is until GM came out with the one-piece rear seal engines. For example the 400 is externally balanced using a weighted balancer and flexplate and an older 350 is internally balanced and does not use a weight on either the balancer or flexplate. Then beginning with the one-piece rear seal engines, GM started using a weighted flexplate and a non-weighted balancer. So go ahead and go back and get the one you had, it was right.

 

[Respected_Cutlass]

Thanks y'all. Very informative and I'm sure my friend will be glad to learn something new