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Discussion Starter #1
I am building a 1957 Chevy Hardtop with a 1968 327 and a 700r4 trans. I was assembling drivetrain and discovered the flywheel (flex plate ) for the 327 will not bolt to the torque converter for the 700r4. I have been told the bolt pattern is the same on all converters but this does not appear to be the case. The 327 had a powerglide trans originally and I assume this is the same flywheel. Has anyone had this problem before and how did you resolve it. Trifive is a great site and everone is always so helpful I am hoping someone can help me solve this puzzle. Your help will be greatly appreciated.
 

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Byron, try a turbo 350 flexplate. it comes in two diameters. That power glide is pretty much alone. :anim_25:
 

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Flex plates

Byron, After market flex plates are usually doubled drilled for small and large bolt patterns to accommodate Powerglides, TH350,TH-400 and the 700-R4 (except for 400 ci V8)
 

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Discussion Starter #4
Auggie, Thanks for the info. I had an old 350 flex plate for reference but the center hole that fits over the crankshaft was smaller than the '68 327 crank end. From what you are saying I can get a 350 flex plate with a larger center hole to fit the 327, is that correct? Thanks again for your help.
 

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Auggie, Thanks for the info. I had an old 350 flex plate for reference but the center hole that fits over the crankshaft was smaller than the '68 327 crank end. From what you are saying I can get a 350 flex plate with a larger center hole to fit the 327, is that correct? Thanks again for your help.
I'm surprised the one you have don't fit. There are several 327/350 cars here on the forum. Maybe someone can comment on why yours don't fit. :confused0006:

BTW: There are two different flex-plates, one is a little larger that the other. It has to do with the numbers of teeth. Get the wrong one and you end up with a stater change.
 

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I'm running a 327 large journal engine with a 700r4. I used a '91 Caprice flexplate. It should bolt right in. The tranny came from an old 350ci cop car I bought from our police department at auction. $32 at Advance Auto Parts. But I'm betting on a starter change. :anim_25: Jason
 

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As far as the flexplate fitting the engine, all small blocks 1985 and older have the same pilot hole and bolt pattern. 86 and up (one piece main seal) have a smaller hole and tighter bolt circle.

There are two common bolt patterns for the torque converter to flexplate connection. I think there's at least one other bolt pattern not so common, it wouldn't have been used on a V8. Either the "early" or "late" flexplate can be bought with the double bolt pattern for the torque converter.

Check your auto supply for Pioneer brand replacement flex plates. They should have something to match up. Or try Summit or Jeg's.
 

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Byron, After market flex plates are usually doubled drilled for small and large bolt patterns to accommodate Powerglides, TH350,TH-400 and the 700-R4 (except for 400 ci V8)
Will I not be able to put a 700r4 behind a 400 V8 ?? Or are you saying you can't get the double bolt pattern, but can get one or the other. I am (was) going to put that combo in my 57. :confused0006:
 

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Will I not be able to put a 700r4 behind a 400 V8 ?? Or are you saying you can't get the double bolt pattern, but can get one or the other. I am (was) going to put that combo in my 57. :confused0006:
Is the flex-plate balanced on the 400 engine, different compared to the others ?
 

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The 400 flex plate has a weight, where the flexplates for other pre-85 small blocks do not. You can get a 400 flex plate with both torque converter bolt patterns. In fact I think the only GM replacement for 400s has both patterns. If you could ever find a GM one. You can also get the same one in the aftermarket.

And the weight for the 400 is not the same as the weight for a 454.
 

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I have a 327 year unknown backed by a 700R again year unknown and it works quite well... Hope you get it sorted out... Later, Dave
 

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400 flex plate

Yes a 400" flex plate is different it will have a balance weight welded near the outer ring. also I think all 400 flex plates are 168 tooth so make sure your starter matches the ring gear.:D
 

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Is the flex-plate balanced on the 400 engine, different compared to the others ?
I know its got the weights on it for balance. I have the eng and 700r bolted together at the bell flange but don't have the flex plate bolted to the TC yet. I just put them together to get the eng & trans mounts in the right place. And it's 100+ out in the garage so it'll be a while b4 I get it checked out.
 

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Discussion Starter #15
Thanks for all the great info!!! That's one thing I like about this site. People are so good to help and you can get lots of useful input. Thanks to all, Byron
 

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Rick is correct. He sparked my memory. I got my flexplate from Summit. My earlier info is not correct. Hope I didn't cause confusion. Jason
 
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