flexplate/flywheel question Please Help

[1986GMCLB]

I need to order a flexplate/flywheel and a tq converter
i have a 1986 GMC with a 305 and the 7004r transmission.
i just want stock.

i don't know if i have a 1 or 2 piece rear main seal.
and i don't know the teeth. the truck is all stock..

http://www.summitracing.com/parts/SUM-G103SFI/

http://www.summitracing.com/parts/SUM-G104SFI/

http://www.summitracing.com/parts/SUM-G2704-12/

http://www.summitracing.com/parts/HUP-GM22TOW/

[thesickc10]

153 tooth starter the bolt holes are in line and 168 tooth starter the bolt holes are staggered. pull the number off of your motor and look post it on here someone will tell you what year it is so we can figure 1 or 2 piece seal.

[1986GMCLB]

starter bolts are not in line

the truck is all original i only have 71k on it.
like i said it is a 1986

[thesickc10]

well it will be 168 tooth flexplate but im not sure when gm went to 1 piece seal hopefully someone else chimes in.

[rcbildr]

I think 87 is the first year of the 1 piece rear main seal.

[1986GMCLB]

saw the build sheet. it was built feb 28, 1986

[1986GMCLB]

just got off the phone with summit they said
this flexplate
http://www.summitracing.com/parts/SUM-G104SFI/

and this converter will work

http://www.summitracing.com/parts/HUP-GM22TOW/

are they right????

[durty harry]

Originally Posted by rcbildr

I think 87 is the first year of the 1 piece rear main seal.

86 was the first year of the 1 peice rear main seal

[nascarmikeb]

Originally Posted by durty harry

86 was the first year of the 1 peice rear main seal

so i see a bunch of comments about either the 1 piece or 2 piece real seal. What are the benefits/drawbacks of each? what do most people prefer?

[raceman6135]

My 1986 C20 with the 350 engine and Turbo 400 transmission has a one-piece rear main seal. Therefore, it has the external weight attached to the flexplate, like in this photo:



Also, mine has the 168-tooth version with the staggered starter bolts.

Flexplates are NOT interchangeable between one-piece and two-piece rear main seal crankshafts.

[1986GMCLB]

Originally Posted by raceman6135

My 1986 C20 with the 350 engine and Turbo 400 transmission has a one-piece rear main seal. Therefore, it has the external weight attached to the flexplate, like in this photo:



Also, mine has the 168-tooth version with the staggered starter bolts.

Flexplates are NOT interchangeable between one-piece and two-piece rear main seal crankshafts.

so the two parts that summit said that are ok to buy they are correct??

http://www.summitracing.com/parts/HUP-GM22TOW/

http://www.summitracing.com/parts/SUM-G104SFI/

[raceman6135]

From the info on their website, it looks like they should work, yup.

GM used 2 different diameters of bolt circles for the torque convertor (10.75" and 11.50"), and neither the convertor they suggested nor the flexplate state what size they are, so you may want to inquire when you place your order.

Most performance aftermarket flexplates and torque convertors come drilled for both bolt patterns, but better to ask first before you give them your money.

[1986GMCLB]

lol well got the trans off and the tq converter and put the new flexplate on. and said to myself what the hell start the motor to see if the knock is gone..nope still there..so now going to take oil pan off replace oil pump and check crank..hopefully i caught it in time. if not i will put the pump on and drive it put in some motor honey..keep an eye out for a 350.
at least i can return tq converter all i did was open the box..

the funny part of all this the motor does not shake at all just purr's like a new engine..
i was told if it had a rod knock or anything it would be shaking..but it just sits there purring no missing at all

[piecesparts]

I have one other thing that you should check, before removing the oil pan. Change out the fuel pump and see if the knock goes away. I have had fuel pumps close to failure sound like a knock from the engine. Check out the old flexplate for cracks, the stock factory ones tend to crack from the ballooning of the torque converter and then they make a lot of noise. I always replace mine with a SFI rated, heavy duty flex plate just to make sure that I don't have that happen twice.

[1986GMCLB]

Originally Posted by piecesparts

I have one other thing that you should check, before removing the oil pan. Change out the fuel pump and see if the knock goes away. I have had fuel pumps close to failure sound like a knock from the engine. Check out the old flexplate for cracks, the stock factory ones tend to crack from the ballooning of the torque converter and then they make a lot of noise. I always replace mine with a SFI rated, heavy duty flex plate just to make sure that I don't have that happen twice.

well i did put the new flexplate on and it is a sfi one..i started motor and the noise is still there with tranny out

[piecesparts]

Originally Posted by 1986GMCLB

well i did put the new flexplate on and it is a sfi one..i started motor and the noise is still there with tranny out

As I also stated replace the fuel pump and see if the noise goes away. It is a rather common thing for them to sound like a rod knocking when they are going bad.

[1986GMCLB]

Originally Posted by piecesparts

As I also stated replace the fuel pump and see if the noise goes away. It is a rather common thing for them to sound like a rod knocking when they are going bad.

really? fuel pump?
meaning it is not keeping up..
the knock sounds bad even at idle sounds like something is going to come thru the block and if you rev it, it gets louder and faster..like a rod

i replaced the oil pump and found that the drive shaft was messed up..
im about done with this motor..think im going to pull it and scrap it, save for a crate 350

[piecesparts]

Originally Posted by 1986GMCLB

really? fuel pump?
meaning it is not keeping up..
the knock sounds bad even at idle sounds like something is going to come thru the block and if you rev it, it gets louder and faster..like a rod

i replaced the oil pump and found that the drive shaft was messed up..
im about done with this motor..think im going to pull it and scrap it, save for a crate 350

Get a new fuel pump and try it, you have nothing to lose. If you get a new motor, then use the new pump on it. I thought that was an absurd thing, when I first experienced it, but I know better now.

[1986GMCLB]

Motor is done..and I'm done with this wimpy 305..ant throwing more money at it..saving money and going to clean up the engine bay..and by spring going to put in a crate 350..
then she we run and run good...
http://www.jegs.com/i/Chevrolet+Perf...67353/10002/-1

[THE "10" SILVERADO]

Originally Posted by 1986GMCLB

Motor is done..and I'm done with this wimpy 305..ant throwing more money at it..saving money and going to clean up the engine bay..and by spring going to put in a crate 350..
then she we run and run good...
http://www.jegs.com/i/Chevrolet+Perf...67353/10002/-1

That's what I did. Kept having problems with the old 350 so I bought a GM Delco and said to heck with it. Pull the trans out as well while your at it and see about getting it rebuilt. Would suck to put in a nice new engine and have your trans go out.

[1986GMCLB]

Originally Posted by THE "10" SILVERADO

That's what I did. Kept having problems with the old 350 so I bought a GM Delco and said to heck with it. Pull the trans out as well while your at it and see about getting it rebuilt. Would suck to put in a nice new engine and have your trans go out.

Tranny is out. it was already rebuilt..so when the new motor gos in i will have a brand new truck...woohoo
and still way better then a brand new 2012

[1986GMCLB]

Originally Posted by THE "10" SILVERADO

That's what I did. Kept having problems with the old 350 so I bought a GM Delco and said to heck with it. Pull the trans out as well while your at it and see about getting it rebuilt. Would suck to put in a nice new engine and have your trans go out.

So i did it. got the crate 350 just waiting on a few parts and we be putting this in..

[Slonaker]

I put that same 350 in my '86. Your old 305 had the one piece rear main seal, but the new engine (if it is the 10067353 that you linked to...) is a 2 piece. I bought a flexplate for an '85, which had the two piece rear main seal, and you will need to do the same.



Slonaker

[1986GMCLB]

Originally Posted by Slonaker

I put that same 350 in my '86. Your old 305 had the one piece rear main seal, but the new engine (if it is the 10067353 that you linked to...) is a 2 piece. I bought a flexplate for an '85, which had the two piece rear main seal, and you will need to do the same.



Slonaker

Nope my 305 was a 2 piece..in 86 there was a code break and i have the 2 piece