Can any one tell me if this casting #3873457n may be a flywheel that would work on a '91 454/c20 engine for my '65? I realise a casting # can be used for more than 1 part but it may eliminate the part also. I may be able to supply a pic if need be.
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Re: MkV Flywheel
Frank-----
I don't have any reference for the 3873457N casting number. If that's, indeed, the casting number, though, then I can't see how it could be applicable to your engine. This is a casting number that originated in 1965, or so. The externally balanced 454, and flywheels for it, didn't come along until late 1969.
Check the flywheel number more carefully, though, to see if it is actually "3993457N". That number would be applicable to a Mark IV 454 big block. Also, check the rear surface of the flywheel for the presence of a counterweight. This will appear as a "rectangular" portion of the casting near the periphery which extends above the normal circular pattern of the peripherial raised ridge. It will be about 3" long. For the flywheel to be a 454 flywheel, regardless of casting number, it must have this weight. Beware of small block 400 cid balancers, though, as they look the same in this respect. I don't have the casting number for the 400 flywheel, but it would NOT be 3873457N.
If the number is "3993457" AND if the engine is a Mark IV, then this flywheel will work perfectly. You can identify the engine as a Mark IV by the fuel pump. If the engine has a mechanical fuel pump boss, then it's a Mark IV. If it doesn't, then it's a Mark V and this flywheel won't work properly. One caveat: there are a VERY small number of Mark V blocks that DO have a fuel pump boss. These blocks were NEVER used in PRODUCTION and were SERVICE-only pieces. It's VERY unlikley that you have one.In Appreciation of John Hinckley -
Addendum
Frank----
I just noticed that, apparently, you've already identified the engine as a Mark V (I guess I should have paid more attention to the title of your post). In that case and as far as I know, only the following 2 flywheel casting numbers will work for you:
with forged crankshaft-----1409XXXX. Unfortunately, I don't have the last 4 digits of this crankshaft part number, but I believe that 3 of them are "171"
with cast crankshaft-----14096805
The above are the only 2 flywheel casting numbers that I know of that will work with a Gen5/6 big block. There may be others, but I am almost certain that they will be 8 DIGIT part numbers and that none will be 7 digit part numbers (the suffix "N", if present, does not count as a digit).In Appreciation of John HinckleyComment
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Re: Addendum
Hey Joe, Thanks for the info. Sure wish I had your resourses. Sure appreciate your research. I'm trying to put together this assembly over the 'net. One fellow has a complete 91 tbi454 less flywheel for sale and another is sure that this flywheel was on his 502 crate engine in his '65. I understand that a MkIV flywheel will not physically fit a MkV. The engine had vibration so he is convinced now that the MkV 454 flywheel is different from the 502. Anyway he has now ordered a fancy dual disc set up and does not need the flywheel. I did phone my local GM dealer about p&a for a '92 454 flywheel and he assured me that there was only one part# for all 92 454's but I'm not convinced considering the cast/forged thing. I'm not making any moves untill I know whats what. Are there any other issues I need to be aware of, bell housing, clutch, clutch linkage, starter etc that I should be considering?Comment
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Re: Addendum
Frank-----
I'm not so sure that a Mark IV flywheel won't physically bolt up to a Mark V crank flange. I used to think that the bolt flange pattern was different, but now that I know that it isn't, I'm not so sure that the different flywheels won't bolt on. The dowel pin location might prevent it, though. They are not FUNCTIONALLY interchangeable, though, assuming that one wants the correct mechanical parts on an engine. In any event, I can't imagine that ANY flywheel with the casting number that you mentioned would be right for a 454 or 502, whether it be Mark IV, V, or VI. If there is no counterweight cast into the rear surface, it's not the right one for an externally balanced big block, which is the case for all 454 and 502 engines EXCEPT those that have been converted to internal balance by adding heavy metal to the crank counterweights and rebalancing. The new 8.1L big block is internally balanced, but uses a different flywheel altogether.
Your Chevrolet dealer is incorrect regarding his contention that there is only one flywheel. The Mark V nodular iron crank flywheel is GM PART #14096987. The forged steel crank Mark V flywheel is GM #10101169. (NOTE: these are PART numbers for finished flywheels and NOT a casting number). However, they are correct that there is only 1 that is specified for the 1991 Mark V engine that you have. That one is the GM #10101169 and that's definitely the one you need. Unfortunately, it's also the most expensive of the 2 I mentioned at a GM list price of about 300 bucks.
The bellhousing from a 65 should bolt to the Mark V block with no problems. However, either of these flywheel are 14", 168 tooth flywheels. That means they won't fit within any bellhousing originally used for 1965 Corvettes. You'll need a GM #3899621 bellhousing or a GM #469697 bellhousing which will also bolt to the Mark V block. Since you'll be using this bellhousing and flywheel, you'll need to use an 11" clutch and not the 10.4" originally used for all 1965 Corvettes. I don't think that the 10101169 flywheel is dual drilled for both clutch sizes.
Your 1965 starter won't work with the above bellhousing/flywheel. You'll need to either change the starter nose or change to a starter already set-up for the 14" flywheel.
Mark V blocks usually don't have the threaded boss necessary for clutch cross shaft attachment. However, add-on brackets are available from sources like Scoggins-Dickey or Sallee Chevrolet.
The rest of your 65 clutch linkage should work ok.In Appreciation of John HinckleyComment
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Re: Addendum
I forgot about the clutch shaft pivot hole..........Comment
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Re: Addendum
Frank-----
The clutch cross shaft mounting problem is "solveable" with the aftermarket bracket. However, if you want to use a mechanical fuel pump, that part is not "solveable" with a Gen V/VI big block UNLESS you can locate a block casting #12550313. You won't find this block in ANY PRODUCTION engine out of a truck---it is a SERVICE-only piece. You can purchase one, though, from GM as a BARE block for $1,395 GM list under GM PART #12561353. Or, you can get one as a complete, assembled 454 engine under GM #12568774 for $6,585 GM list (about $5000, discounted)In Appreciation of John HinckleyComment
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Re: Addendum
Joe, I'm planing to use the F.I. so it would be an electric fuel pump. If the early flywheel does in fact bolt on to the later crank that would explain a couple things.Comment
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