Please Help!! Internal or external??

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dusterboyy440

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Alright so im about to buy a flexplate for my 67 440 hp and it asks you whether the crank is internally or externally balanced. I called the machine shop who built my motor and they dont seem to remember what kind of crank it is [-( Is there anyway to tell without having to pull the pan?? Please help me!!!!!!!!!!!!
 
i have no idea which it is...i was wondering if there is a way to tell with markings or something because the motor is already togethor
 
I'm pretty sure the harmonic balancer for the forged crank is much skinnier than the one for a cast crank.
 
'67 440's came stock with forged cranks, but that doesn't mean that someone didn't put a cast on in it at some time.

You may have to pull the pan unless you can tell on the crank flange if the casting/forging line is wide or narrow. if it is wide "forged crank" if it is narrow "cast crank"


CHuck
 
exactly...now explain the narrow or wide line on the flange..any pics on the diffrences?
 
becaise id rather not pull the pan if there is a way to tell from looking at the outside
 
I'll try. There is a line running down the center of the crank lengthwise. depending on wether is was cast or forged will determine how wide that parting line is. As Chuck said, if its wide, you have a forged crank and vice versa. I think the wide one will be about half an inch or so and the narrow one about an eighth of an inch wide. I've seen them vary a little and am going on memory. Chuck?
 
Do you know what year the motor is and is it the original crank? Did it come with a balancer and you're just going to buy a new one? Here is a picture of my motor showing the balancer. It has a forged crank.

motor.JPG
 
yea its a 67 440 hp...dont know if its the original crank...i dont have the balancer that the guy had on the motor..and you would of thought the shop would of wrote it down but owell
 
It's exactly what Chuck said Dusterboy. You have to determine whether you've got a forged crank or cast crank before you go any further and this can only be done by removing the pan. I'll attach some pictures below that make it easy to tell and you can also run the casting number off the crank
http://www.moparts.com/Tech/Archive/bb/22.html This also a picture that shows the different vibration dampeners.
http://www.moparts.com/Tech/Archive/motor/8.html
and casting numbers for cranks

http://www.mopar1.us/bigblock.html

Terry
 
yea i jus didnt know if there was a way to tell the diffrence without removing the pan.. wats that notch cut out for ? is that the flange chuck was talking about?

frontduster2.JPG


frontmotor.JPG
 
Hell I sent my cast crank out to be balanced when i did my build because i ran popups and lightened the rods so i think mine is internally balanced due to the mallory metal swinging. So couldnt any motor be internal if its got custom pistons and rods. Just depends if it was sent out for balancing
 
Kind of a stupid question on my part - I assume you did not have the internals balanced ? If you did, it has to be internally balanced then, since you did not provide a balancer for this purpose to the engine shop. They would only be able to balance it neutral. Then a neutral flex plate and vib dampner will be needed.

Do you have the old stuff from when the motor was dis-assembled ? that would tell you as well. The externally balanced dampers will have a bell crank shaped weight on the front of them and be marked as such for external balance, the neutrals have no offset weights and look symetrical.

There is no way I no of to determine what the crank is - without examining it as described above, pull the pan and look for: thin sharp parting line = cast crank, thick 3/8" or so parting line = forged crank.

Another thought - do you have the part number or casting number of the crank ? You may be able to find out that way.
 
If they internally balanced it, they would have to used mallory and your balance job would have cost around $500. So if the balance charge is $150-$250 then its an internally balanced motor. If they didn't balance it at all, then I'd question your engine shop.
 
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