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new clutch and flywheel

buffblazer

buffblazer

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im pulling my old 86 350 block out and putting in a 69-79 gen block. now i know im switching to a 2 piece rear main seal, my question is when ordering my clutch and flywheel can i just say i have a 76 chevy truck with a 350? is there gonna be a difference between a clutch and flywheel kit for a 76 and say a 84? reason i ask is when i went and priced the clutches and flywheels they were different prices for the 76 and the 84. is there anything different about the clutch and the hardware that comes with the 76 and then the 84? i know the old ones used a mechanical slave cylinder and mine is hydro. could that be the difference?
 
Just remember that the flywheel from the 86 will not bolt onto the 69-79 crank. The bolt circle is a different size and the 86 and later are also externally balanced. This means you need a new flywheel along with a clutch kit.
 
4X4HIGH said:
Just remember that the flywheel from the 86 will not bolt onto the 69-79 crank. The bolt circle is a different size and the 86 and later are also externally balanced. This means you need a new flywheel along with a clutch kit.
Click to expand...

thats why im wondering if i just order a flywheel and clutch kit for an 84 will i be ok? and what you mean externaly balanced? i assume you mean a harmonic balancer on the front and ?????what on the rear? just wondering because i was going to use my harmonic balancer from my 86 on the 69-79 gen block
 
you need to order the parts sepratly.
you need an early flywheel and and early harmonic balancer.
you need a later model clutch pressure plate and throughout bearing.
I have an early model flywheel for a small block i could sell but shipping would hurt you're best bet is probably an auto parts or summit/jegs as well as for the harmonic balancer.

the engines where balanced differently so one is externally balanced and one internally balanced. by swaping parts from early and late you will put the motor out of balance and eat up the crank bearings along with everything else. This happens alot on a 383 conversion as the 400 crank was balanced different than a 350.
 
You can use the harmonic balancer from the 86 engine, the only SBC that was externally balanced on both the front and rear was the 400. The later engines (86-up) are only externally balanced on the rear, the front balancer is still a neutral balance.
 
Balancing has nothing to do with the block. External balanced engines use an external weight on the flywheel/flexplate and in the case of a SBC 400 on the harmonic balancer as well.

Here is a pic of an external balanced flexplate, take note of the welded on weight near the inside portion of the teeth. http://store.summitracing.com/large...+Heavy+Duty+Flexplates&img=hup-hp1452_grp.jpg

That pic happens to show both the early 400 flexplate on the left and the later SBC external balanced flexplates on the right.

Here is a pic of a factory 400 SBC external balanced harmonic balancer. It's kinda hard to see since the pic is from the front side but if you look carefully on the lower left you can see that the balancer is not completely full round. The weight is actually removed in an area of the outer ring on these balancers. http://store.summitracing.com/large...et+Performance+Balancers&img=pio-872004_w.jpg
 
ok so just to ge this straight. i can run my 86 350 harmonic balancer on my 69-79 gen block and i can buy a mid 80's flywheel and clutch combo so that its for a hydro set up but still for a 2 piece rear main seal. correct?
 
buffblazer said:
ok so just to ge this straight. i can run my 86 350 harmonic balancer on my 69-79 gen block and i can buy a mid 80's flywheel and clutch combo so that its for a hydro set up but still for a 2 piece rear main seal. correct?
Click to expand...

That is correct.

The only unknown for me though is if GM used the same diameter clutch on non hydro versus hydro clutch systems. Some flywheels only have one bolt pattern on them for say an 11" clutch and others have two bolt patterns for say 11" and 12" clutch size. This will be the only variable.
 
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