I am trying to identify this crankshaft and the only #'s I find are what looks like 4577 then the crank is ground because of balancing. There is GM T cast on the other end and the # 26 but I can't find anything else. Does anyone know of a crank with the number 4577 somewhere in the part #, this crank is in a 327. I will try to post another picture. Thanks, Tim
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Re: crankshaft ID
Another picture of the # 26 toward the rear of the crankshaft.
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Re: crankshaft ID
Picture of the GM T on the rear of the crankshaft.
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Re: crankshaft ID
Tim,
My 67 327-300 crankshaft has the same numbers on it. Original motor just recently disassembled.Comment
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Re: crankshaft ID
It looks like the No 3 rod/piston is in the No 7 position?Comment
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Re: crankshaft ID
That's a forged steel crankshaft that was used for both 300 and 350 HP engines beginning in about 1966. The earlier '62 to '65 forging was ID 2680.
Both crank forgings were Tuffrided and drilled/threaded at the nose for SHP/FI engines, but not for the 300 HP engines.
Both versions are very durable. For the SHP/FI version I don't recommend turning down the journals unless absolutely necessary as this will remove the Tufftride treatment and reduce fatigue resistance somewhat.
Turning the 300 HP versions that were not Tufftrided will have virtually no effect on durability.
Used 2680 and 4577 cranks should be qualified by Magnaflux inspection and checked for straightness. If they pass, they will last virtually forever in a road application as long as the bearings never get oil starved, and qualified Tufftrided cranks are okay for a road racing engine to 7500 revs.
DukeComment
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Re: crankshaft ID
Thanks John and Duke,
This crank is standard on the rods and mains and is drilled for a bolt except someone made the hole larger to 1/2" fine thread. If I understand you correctly this 4577 crank has the surface treatment and is the replacement to the 2680 SHP part. From the pictures can you tell if these rods are the early rods or later 66 up GM rods? The rods are resized/reconditioned and it almost looks like they are a mixture according to pictures in the archives.
Thanks again, TimComment
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Re: crankshaft ID
If the crankshaft does not have an OE nose thread size, it may have been drilled/tapped in the field. I'm not sure how to positively ID a Tufftrided cranshaft other than doing a hardness test, but I've never seen any specs. It's usually a reasonable assumption to assume the crank is Tufftrided if the nose is drilled/tapped for the 8" balancer center bolt.
I can ID one rod as early in the second and third photos. It (or they different rods) lacks the hump of additional material adjacent to the bolt seat that reinforces this notoriously weak area.
DukeComment
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Re: crankshaft ID
Crankshaft forge # 4577 is a '62-'65 SHP replacement crank. Courtesy Alan Colvin.
I think I only see three different rods in your engine. #7, #8 and #2. It appears #7 which is stamped #3 on the cap is an early rod. #8 with no visible stamp and #2 which looks like 2 on the cap appear to be late rods. It's a little difficult to see from the camera angle. If someone could post a picture of the late rod, you could readily identify what you have for sure. When looked at from an end view, the later rods have two pronounced humps at 10 and 2 o'clock above the crank pin.Comment
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Re: crankshaft ID
The subject of non-threaded cranks worries me. I'll soon be reassembling a 327 300, no thread in front of crank. The methods for installing the balancer seem pretty crude; warm up balacer with propane torch and drive on with lead hammer.
Does this really work OK? I've never done this type, only threaded ones, which require some effort, too.
Thanks for any advice.Comment
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Re: crankshaft ID
I've never removed and installed a 300 HP balancer either.
DukeComment
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i used a electric hot plate to heat the balancer
hub to get even heat.do not get it too hot or you will burn the hub oil sealComment
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Re: i used a electric hot plate to heat the balanc
How about drilling and tapping the crankshaft. If I heat the balacer too much I can mess up the rubber and also mess up the seal. Too cold and it won't go on or damage thrust bearing? Sounds like a Goldilocks porridge thing.Comment
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Re: i used a electric hot plate to heat the balanc
just make sure you use neverseize on the crank snout when you hammer it on.if you have the engine on a engine stand wedge some wood between the back end of the crankshaft and the engine stand to back up the crank while hammering on the balancer and you will not be loading the thrust bearing. i have hammered them on with out any heat so it can be done.make sure to put some oil or grease on the outside of the balancer snout to lube the seal on start upComment
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Re: i used a electric hot plate to heat the balanc
Clem Thanks for the positive reply. I'll do it your way, with fingers crossed and cranshaft backed up.Comment
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