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72 Buick Skylark, crank/flexplate issue


Guest boostedjetta
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Guest boostedjetta

I have a 1972 Buick Skylark Sun coupe with a 5.7 350/350 trans. I recently purchased a crank from Summit. Stock specs nothing special. Problem is my 160T flexplate that was originally on the motor will not bolt up. Simple right...go get a Chevy 168T/153T flexplate and starter. Nope.....still wont bolt up. I know BOP....but summit cant tell me exactly what flexplate to use either. Why? I don't want to keep purchasing and returning flexplates nor do I want to pull my engine and rebuild it again because of this crank. Everything went in perfect torqued to speck etc. Its a 2 pieces rear main crank. My torque converter lined up to the flexplate. Everyone keeps telling me there is not a 160T flexplate for these cars but there is.....I have one. lmao. Any help would be greatly appreciated. Someone has to have had this issue before. lol

I can post pics or any other info that will help. Just lmk whats needed, tyvm

Edited by MrEarl
edit title to make easier to search in future (see edit history)
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The problem is you are trying to buy a part to put on a chevy and your Buick is not a chevy. Go to http://www.taperformance.com/products.asp?cat=61 and get the proper Buick flywheel. GM made 4 completely different 350 cubic inch engines back in the day and practically zero parts will interchange, as you have found out. Summit doesn't really know anything if its not a chevy.

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Guest boostedjetta

TY Brad....I was originally told it was a Chevy crank. I was not the one that actually purchased the crank. I have since found out it is a Buick crank. I got the order details made some calls etc. I still have the issue of my flex plate not bolting up. I get 4 bolts in a 2 out. I have rotated it 360 degreese and flipped it both ways. JIC. I ordered 2 flex plates from Oreilly today, another 160t and a 166t both Buick. Hopefully one will solve my problem. I have heard bad things about the pioneer flex plates......any opinions?

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Even among Chevy small block flexplates, there are two different bolt patterns, depending upon if it's a rope rear main seal or if it's a full-circle rear main seal.

In general, if there's no misalignment issues, any flexplate should last a good bit. If there's some misalignment issue which caused the original flex plate to break, unless that issue is figured out and fixed, even an OEM flexplate will break. Be sure to replace any lock washers which might be on the flexplate bolts with new ones of the same type and also ensure all torque values in tightening the bolts are correct.

Usually, the tooth count on the ring gear is dependent upon the diameter of the flywheel or flexplate. Be sure what you put back is really correct for your vehicle. Might need to get some factory literature to determine that, rather than relying upon another (possibly questionable) source for that information.

Sometimes, if there's any questions on what fits what, dealing with a known vendor (TAPerf) in this case, might be money-saved in the long run . . . although there might be a little more time involved in getting the parts.

You can also go to the Summitt website to verify what's in their catalog, if needed. Same for rockauto and others.

ALSO . . . be sure to check the bearing clearances BEFORE you close things back up. This will ensure you know what the clearances are PLUS that the bearings match the crank journals in diameter and such.

Please keep us posted.

NTX5467

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I'm not sure where they found two part numbers for your Buick application. Rockauto lists only one in two brands, ATP and Pioneer. The part numbers are, respectfully, Z118 and FRA101. The O'Reilly website listed only one flexplate for your application, the Pioneer FRA101.

After I downloaded the Pioneer Automotive flexplate catalog, the FRA101 fits many small block Buick V-8s, the 455s are different. Getting back into the "Illustrations" section of that catalog, the FRA101 is detailed to be 160 tooth, 13.42" OD. No difference between 350 2bbl and 4bbl applications, for BUICK engines.

In the front section of the catalog, there are pictures of failed flexplates and what made them fail. Being just over 400 pages, it takes a while to download, but might be worth it in helping to diagnose your problems. www.pioneerautoinc.com/catalogs/ click on the picture of the flexplate catalog.

Hope this helps,

NTX5467

Edited by NTX5467 (see edit history)
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Guest boostedjetta

Well thanks for all the info. I got it sorted out and I now have the correct flex plate. It was 160 tooth and is a Buick 350 crank. The pioneer flex plate lined up and tranny is going in tonight. Thanks for the help and ill post pics of the motor and car in the appropriate section soon.

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Guest boostedjetta

TY NTX5467. trans is in everything bolted up. I will be putting lines and fluid in tonight after a tune up on a Hyundai for a girl from work. lol...things I do for beer and a pretty face.

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