Azrael91966669

im confused as im getting differant options on summit and autozone and all the other differant sites

car is a 91 camaro rs the tq converter is stock from tbi the trans is from an 85 iroc
engine is a zz3 crate engine dont know year

gm list the part as
Flexplate, 153-Tooth, External Engine Balance, 1-Piece Rear Main Seal, Chevy, 5.0/5.7L, Each
seems like this plate is ment for 87-89 -- 93-97
they also offer this plate as internal balance

now i believe i used my factory flexplate and its listed as
Flexplate, 168-Tooth, Internal Engine Balance, 1-Piece Rear Main Seal, Chevy, 5.0/5.7L, Each
seems that this plate is ment for 90-92
they also offer this plate as external balance

starter a hitq mini


i have had a vibration on the car since i installed the engine i cant remember if i reused my factory plate or if i used what came on the engine

how can i tell the differance just by looking at it?

also what gives on offering 4 differant flexplates and what the hell is with 90-92 being differant

sofakingdom

iTrader: (1)

1-pc RMS motors are all INTERNALLY balanced, with the last little bit of INTERNAL weight mounted on the flex plate or flywheel. They therefore look "external" to the uneducated naked eye, but they're NOT. "Internal" vs "external" balance isn't about where the weight is mounted; it's about the rods being long enough to allow large enough counterweights in the CENTER positions on the crank, for complete balancing.

The only externally balanced SBC is the 400.

Nothing is different about 90-92. No idea why the parts listing is like that. Could be something as simple as a typo.

AFAIK these cars pretty much all used the smaller one, on account of starter clearance to the exhaust.

Personally I'd use the small flex plate if the starter accommodates it.

Azrael91966669

its odd as tci sells a balancer flexplate combo that only fits 90-92 cars its 168 teeth
even autozone list the 90-92 but only as tpi cars as 168 87-89 153

i figured the engine is internaly balanced but its very hard trying to pick the correct parts from jegs or summit when they show 4 differant flex plates for these

its not like its just one site with a typo its just about all of them jegs summit advance napa federated autozone car parts warehouse all show at lest 2 seperate flywheels 168 or 153 or that one is external and the other internal really annoying

ok to jegs and summit external means there is a weight on the flywheel internal means there is no weight on the flywheel why do they have to make it so confuseing

sofakingdom

iTrader: (1)

No idea; it's really, NOT.

I think someone advised you to get a 12.8" (153 tooth) flex plate for 1-pc RMS (86-up) applications (any; sheet metal wrinkles don't matter). I second that advice. Screw the confusion; let the confused enjoy their own confusion without your company. You now know what to buy.

Azrael91966669

they also make 153 in 2 seperate tq converter bolt patterns so thats even more confuseing
gm says the zz3 came with a 153 so thats what im gonna get but the interal external had me confused then the 2 seperate converter bolt patters

sofakingdom

iTrader: (1)

The only 2 bolt patterns are the SAE one for 350, 400, and Powerglide; and the metric one for the newer ones, which is a close equivalent to the SAE. Sort of like, your wheels are 5 on 4¾", but BMW wheels which are 5 on 120mm, will fit, because there's only about a sheet of paper of difference between 4¾" and 120mm. Point being, you can buy either one, and in the unlikely case it doesn't fit your transmission, you can elongate the holes about half a RCH and then it will work fine.

You're overthinking this. Seriously. It's really not all that tough.

ZZ3 Z28

I have a ZZ3 engine in my '86 and the flex plate is the 12-3/4 inch 153 tooth, GM part # 14088765. This flex plate came with my engine package. The ZZ3 H.O. engine assembly has a one piece rear crankshaft seal and a 3.00 inch diameter flywheel flange bolt pattern. (Small block V8 engines 1955 through 1985 had a 3.58" diameter flywheel flange bolt pattern.)

According to the ZZ3 Installation and Service Manual, "Due to revisions in the crankshaft design, an H.O. 350 engine must have a counterbalanced flywheel (or flexplate) for proper engine balance."

vetteoz

iTrader: (13)

TH350 and TH400 convertors came in either 10.75" or 11.50" PCD
Most aftermarket flexplates have both patterns ( 6 holes) ;
http://www.summitracing.com/parts/BMM-20238/

OEM ones only have a single pattern , the GM part # 14088765 listed above is for 10.75" convertors only

vetteoz

iTrader: (13)

Bad wording adding to the confusion
As SK noted above ,the balance arrangement ( internal ) of the engine is the same ;
only the position of the balance weight moved from the crank flange to the flexplate

ZZ3 Z28

Yes, I should have added that my ZZ3 is mated to the original-to-the-car, with upgrades, 700R4 transmission.

Azrael91966669

my assumption was that it used the 153 internal balance with the conterbalanced weight on the flywheel .
just useing summit site got me confused as i looked up a flexplate for a 91 camaro and the only one that pops up is a package balancer and flexplate combo but its 168 tooth .
i then went to autozone and it showed 168 for for 91
and 153 for an 89 i just thought it was odd i then checked for my 94 lt1 and its also 153 so at that point is when i figured i might want to make a topic on here to figure it all out .