Hey there. So I've got an 83 F250 with a 71 block 460, that was bored, cammed..... and then blown up. For an easy swap, I'm just throwing the 74 bored 460 I have, to eliminate on transmission conversions for the time being. Problem I've run into is the balance. 70s 460s are supposed to be internal, no? Any way to tell without ripping it apart when there are no plates on it when I got it? Hoping to use the plates that were on the one out of the 83, the 71 block, on the 74 block 460, but there appears to be a weight on the back of the flex plate from the 71.
If that wasn't very clear I apologize in advance.

Thanks in advance, Stephanie.

 

External bal. will have a hatchet weight behind the harmon. bal.

 

ALL 1968/78 and some 1979 460 engines are internally balanced.

1971/73 429; 1971/78 and some 1979 460 internal balanced block casting numbers: D1VE-6015-AB or A1B or A2B
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Mid-year 1979, FoMoCo changed the 460, it's externally balanced with a weighted crank spacer (located behind the harmonic balancer).

The block casting number is D9TE-6015-AB

No 460's in F100's after 1976, no 460's in Passenger Cars after 1978, no 460's in F150's after 1979, no 460's in 1980/82 F250/350's.

 

Flex plate weights should be to balance the flex plate itself from the manufacturer. As said above, external balance is done by hatchet weight on harmonic balancer.

 

Maybe one of you guys could answer this question: I've been told that the ONLY difference between the harmonic balancers on 460 engines is the hatchet weight for the later externally balanced engines. All the harmonic balancers themselves are supposedly neutrally balanced. Does anyone know if this is true?

My balancer is showing signs of failure (rubber starting to squeeze out) and I need to replace it. NAPA has discontinued listing the part for internally balanced engines, but not for externally balanced engines.