flex plate on 73 with zz4 350 new engine.
#1
flex plate on 73 with zz4 350 new engine.
I have recently bought a zz4 350 Performance Crate Engine (brand new) to replace my stock 350 in my 1973 Corvette Stingray. The engine claims to be internally balanced yet there is a weight on the flex-plate usually used when you externally balance an engine (maybe wrong flexplate was put on from factory).
My question is this:
1.Can I use my flex-plate that is on my stock 350 -1973 Corvette on the new zz4 350 Engine?
Thank you have a nice day.
My question is this:
1.Can I use my flex-plate that is on my stock 350 -1973 Corvette on the new zz4 350 Engine?
Thank you have a nice day.
#3
#4
Team Owner
AFAIK all GM factory SBC type engines, like a ZZ4 are externally balanced......someone will jump in I am sure, IF I"m rong....
#5
Also is there a reason why the flex-plate has a weight tack welded to the back of the flex plate (side closest to engine) if the engine states it is internally balanced? And once again any suggestions on solutions to my problem stated in the posts above?
Thanks in advance.
Thanks in advance.
#6
Leave it the way it came from the factory, the only thing to check would be sure the converter bolts line up....there are two patterns on it....
AFAIK all GM factory SBC type engines, like a ZZ4 are externally balanced......someone will jump in I am sure, IF I"m rong....
AFAIK all GM factory SBC type engines, like a ZZ4 are externally balanced......someone will jump in I am sure, IF I"m rong....
heres the link http://store.summitracing.com/partde...9&autoview=sku
Along with every other website I saw said internally balanced.
#7
Racer
The weight that you see on the flexplate is correct, it's there to correct the imbalance caused by the elimination of the flyweight on the older style pre '86 crankshaft flanges, owing to the one pc seal type mounting flange being completely round.
The front balancer is a neutral balnce type, as it is the same as the older 350 crankshaft up front.
The front balancer is a neutral balnce type, as it is the same as the older 350 crankshaft up front.
#8
Team Owner
I have the print off from summit and they list it as internally balanced in the description
heres the link http://store.summitracing.com/partde...9&autoview=sku
Along with every other website I saw said internally balanced.
heres the link http://store.summitracing.com/partde...9&autoview=sku
Along with every other website I saw said internally balanced.
still don't recall ever seeing a GM flexplate with no weight on it....
also my engine is not actually a ZZ4 has the 113 alum heads, and a '89 4 bolt truck roller engine, roller can/etc....but it does have a weight on the flex plate too....
always did....
right out of the shop that built it.....AFAIK, it's the same short block as a ZZ4.....
http://www.gmhorsepower.com/350-ZZ4-Turn-Key.php says they are EXTERNAL.....
Last edited by mrvette; 01-08-2009 at 10:15 PM.
#9
I really appreciate everyones help I will pass this info along to my mechanic and see what he makes of it.
I was told by my mechanic I have to use the flex-plate off of my stock engine that came with it. Hmmm...
Thank you and if you think of anything else that pertains to this please post your thoughts.
Thanks again.
I was told by my mechanic I have to use the flex-plate off of my stock engine that came with it. Hmmm...
Thank you and if you think of anything else that pertains to this please post your thoughts.
Thanks again.
Last edited by cherrynutz; 01-08-2009 at 10:24 PM.
#10
Drifting
I'm a little thick between the ears..............can you explain? What if you remove the flexplate and install a flywheel?
#11
Le Mans Master
You have to use a flywheel specifically for the 1986 and newer engines. The bolt pattern is different on the end of the crank. That's what I did for mine which is a '78 Vette with a ZZ4. I have the part number somewhere if you need it.
#12
Drifting
OK. Nope no problem, thanks for the offer. I did the same thing, installing the newer flywheel, I was just a little confused by the explaination regarding the weight thinking I may have created an unbalanced condition. Thanks
#13
Before I get confused by others posting in asking there own questions.
Please tell me what I need to do to get my zz4 350 to work in my 73 vette in a simple straight forward answer regarding the flexplate . Buy another one? if so what part number and where do I get it?
PS: I have a 400 turbo transmission not manual, I thought flywheel was for manual?
Last edited by cherrynutz; 01-09-2009 at 02:48 PM.
#14
Safety Car
I have the 350 H.O. with the one piece rear main seal and the flexplate is externally balanced. I used a part number from the manual to get the proper flexplate. I don't know if your new flexplate has a part number anywhere on it but that may be helpful. My guess is that you'll be just fine with the flexplate supplied with the engine, regardless of what the "mechanic" or Summit says.
#15
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Leave it the way it came from the factory, the only thing to check would be sure the converter bolts line up....there are two patterns on it....
AFAIK all GM factory SBC type engines, like a ZZ4 are externally balanced......someone will jump in I am sure, IF I"m rong....
AFAIK all GM factory SBC type engines, like a ZZ4 are externally balanced......someone will jump in I am sure, IF I"m rong....
Not so the second part. From everything I have ever read or heard all Chevy small block engines up to the 400 are internally balanced. Because of the lack of internal room for the rotating crank throws, the 400 is externally balanced.
Terry
#16
Instructor
Before I get confused by others posting in asking there own questions.
Please tell me what I need to do to get my zz4 350 to work in my 73 vette in a simple straight forward answer regarding the flexplate . Buy another one? if so what part number and where do I get it?
PS: I have a 400 turbo transmission not manual, I thought flywheel was for manual?
Please tell me what I need to do to get my zz4 350 to work in my 73 vette in a simple straight forward answer regarding the flexplate . Buy another one? if so what part number and where do I get it?
PS: I have a 400 turbo transmission not manual, I thought flywheel was for manual?
I have a ZZ4 in my 76 vette and I had to change flexplate that came with the ZZ4 engine, because it had 153 teeth on the ring gear and I believe it has only one bolt pattern on it for the converter.
What I'm guessing is you need the larger diameter flex plate that has 168 teeth on the ring gear and has dual bolt pattern for the converter.
I had to use the larger flex plate (168 teeth) because that is the same diameter as the original flex plate, other wise the starter wont work, by the way they both have a weight spot welded to it, you can not use the original flex plate.
There is a way to tell which size flex plate you have by looking at the starter mounting bolts, if they are in line with each other it is a 153 tooth. If the strarter mounting bolts are stagered then it uses a 168 tooth flex plate.
Hope that helps
Ulf
#17
Le Mans Master
All 1 piece main rear SBC's (1986 and up, including the ZZ4) use an externally balanced flywheel or flexplate due to the change in the rear of the crank.
You cannot use your stock 1973 flexplate. It has the wrong bolt pattern and is internally balanced.
The ZZ4 comes with a 153 tooth 12.75" diameter flexplate. Measure your current flexplate. If it is 12.75" diameter, everything will bolt up. If it is 14" in diameter, you have two choices.
1) Use the 12.75" diameter flexplate and get a new starter.
2) Swap the flexplate for a 14" diameter flexplate for late model one piece seal blocks and use your old starter.
Here are the GM part numbers for flexplates that will fit the ZZ4:
Part.........Year of....Outside....Crank Flange...Converter......Starter Ring
Number.....Engine.....Diameter..Bolt Pattern....Bolt Pattern....Gear Teeth.....Technical Notes
14088765..1986–up...12.75".....3.00".... .........10.75"...........153........... ....For one-piece crank seal
12554824..1986–up...14".........3.00"... ...........11.50" ..........168...............Heavy-duty flexplate with increased thickness for one-piece crank seal
14088761..1986–up...14".........3.00" .............10.75"&11.50"..168......... ......For one-piece crank seal
You cannot use your stock 1973 flexplate. It has the wrong bolt pattern and is internally balanced.
The ZZ4 comes with a 153 tooth 12.75" diameter flexplate. Measure your current flexplate. If it is 12.75" diameter, everything will bolt up. If it is 14" in diameter, you have two choices.
1) Use the 12.75" diameter flexplate and get a new starter.
2) Swap the flexplate for a 14" diameter flexplate for late model one piece seal blocks and use your old starter.
Here are the GM part numbers for flexplates that will fit the ZZ4:
Part.........Year of....Outside....Crank Flange...Converter......Starter Ring
Number.....Engine.....Diameter..Bolt Pattern....Bolt Pattern....Gear Teeth.....Technical Notes
14088765..1986–up...12.75".....3.00".... .........10.75"...........153........... ....For one-piece crank seal
12554824..1986–up...14".........3.00"... ...........11.50" ..........168...............Heavy-duty flexplate with increased thickness for one-piece crank seal
14088761..1986–up...14".........3.00" .............10.75"&11.50"..168......... ......For one-piece crank seal
Last edited by SteveG75; 01-09-2009 at 10:12 PM.
#18
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All 1 piece main rear SBC's (1986 and up, including the ZZ4) use an externally balanced flywheel or flexplate due to the change in the rear of the crank.
You cannot use your stock 1973 flexplate. It has the wrong bolt pattern and is internally balanced.
The ZZ4 comes with a 153 tooth 12.75" diameter flexplate. Measure your current flexplate. If it is 12.75" diameter, everything will bolt up. If it is 14" in diameter, you have two choices.
1) Use the 12.75" diameter flexplate and get a new starter.
2) Swap the flexplate for a 14" diameter flexplate for late model one piece seal blocks and use your old starter.
You cannot use your stock 1973 flexplate. It has the wrong bolt pattern and is internally balanced.
The ZZ4 comes with a 153 tooth 12.75" diameter flexplate. Measure your current flexplate. If it is 12.75" diameter, everything will bolt up. If it is 14" in diameter, you have two choices.
1) Use the 12.75" diameter flexplate and get a new starter.
2) Swap the flexplate for a 14" diameter flexplate for late model one piece seal blocks and use your old starter.
#19
Got her all done. I got videos over at http://www.youtube.com/cherrynutz
And thanks to all for your insightful help I appreciate it.
And thanks to all for your insightful help I appreciate it.
Last edited by cherrynutz; 04-14-2009 at 09:25 PM. Reason: forgot something