350 HO from gmgoodwrench

[Dunc03]

I am replacing my 86 305 with a the 350 Ho from gmgoodwrench. I have heard a number of times that the flexplate has to be change in some applications. My motor came with a one piece rear main seal, and I know that flexplates differ between the one piece and two piece rear main seal. IF my flexplate is alreay matched up to the one piece, will I still have to buy a different flexplate for the new motor being that it is a one piece too. And while I'm asking will the harmonic balancer be the same. Once again thanks for the help and info.

 

[83ZZ502_Jimmy]

It will most likely work. but I have heard that 86 motors were way weird in that regard.
IMO it would not hurt to get a new flexplate. It is a good time to change it and with a new motor, I say go ahead. It doesnt cost a whole lot. It is cheap insurance. That new motor will have a lot of new found power.

My .02,
John

 

[ramjet gmc]

My 86 305 had a 2 peace main seal I had to but a new flywheel for a 1 peace

 

[Dunc03]

The only conformation I have on an 86 having a one piece is this site, so it is very possible that I'm wrong. I think I will get the flexplate now, that way I won't have the headache later, thanks for the info.

 

[sosamantx]

i'd say that the flexplate will work (since it is a 1 piece rear main seal). but, the harmonic balancer will not work!! i thought it was because of a balancing issue, but from what i've read, it's a timing mark issue, i think it's like 45 degrees off (something like that).

http://www.sallee-chevrolet.com/Discus/board.html <-- good message board!!

http://www.sallee-chevrolet.com/Discus/messages/653/2392.html?ThursdayMay3020021139am <-- not sure if this will work, but it's the thread about the timing marks that i was refering to. /forums/images/icons/wink.gif

 

[EDdaTREE]

Go to www.paceparts.com and look around. You can call the 800 number for the info you need. Check their prices for motors, too.