Need some expertise
#1
Need some expertise
Ive got a 76 cutlass with a small block 350 and BOP turbo 350, all stock, i found alisting on craigslist of a 425 olds, did aome digging its actually a 1974 455, with 74 smog heads, but the guy swears up and down its a 425, how can i tell for a fact that its a 425, and how can i tell if the previous owner did it right and swapped crank, rods, and pistons?
#2
Look at the deck above the water pump for block ID. Also l ID the heads, look at the head casting letters and numbers. Sounds like you may have done this already? Post the numbers here.
To answer the last part youd need to disassemble it.
Ask to hear it run. Take a compression check.
To answer the last part youd need to disassemble it.
Ask to hear it run. Take a compression check.
Last edited by droldsmorland; September 14th, 2018 at 10:09 AM.
#4
Ive got a 76 cutlass with a small block 350 and BOP turbo 350, all stock, i found alisting on craigslist of a 425 olds, did aome digging its actually a 1974 455, with 74 smog heads, but the guy swears up and down its a 425, how can i tell for a fact that its a 425, and how can i tell if the previous owner did it right and swapped crank, rods, and pistons?
#5
Are there casting numbers on the end of rhe 425 cranks and what are they? And if i happen to determine it is a 425 crank is it pretty safe to say whoever swapped it did rods and pistons because otherwise they just plain wouldnt work or the head would get smacked etc.
#7
If only it were that easy. The FORGING number (since all 425 cranks are forged, not cast) is on a counterweight. You'd have to drop the pan to see it. Again, the ONLY way to check this without tearing the motor apart is to measure the stroke through a spark plug hole.
#8
Actually, there is one other thing you can try. If you have access to an inspection camera that can fit between the flexplate and the block, you might be able to see the notch in the crankshaft output flange. Cast 455 cranks have a "U" shaped notch like this:
425 cranks have a sharp-corner "L" shaped notch like this:
And for completeness, the extremely rare forged 455 cranks (don't hold your breath) have a rounded "L" shaped notch like this:
425 cranks have a sharp-corner "L" shaped notch like this:
And for completeness, the extremely rare forged 455 cranks (don't hold your breath) have a rounded "L" shaped notch like this:
#9
The flange is different between the cast 455 and forged 425 cranks.
The forged crank has a "check mark" shaped notch whereas the cast crank has a "U" shaped notch.
edit: Joe posted while I was trying to get that picture of the N crank to load. I finally gave up on it.
The forged crank has a "check mark" shaped notch whereas the cast crank has a "U" shaped notch.
edit: Joe posted while I was trying to get that picture of the N crank to load. I finally gave up on it.
#11
#12
#13
You realize that we've already spent waaaay more time talking about this than it takes to just slip a dowel in the spark plug hole and check the stroke, right?
#14
Well lets examine the situation shall we, i am trying to get as much info as i possibly can, the engine is currently 2 hours away from me ntm it will not turnover, so, i was trying to gather as much information as possible as to not get screwed over on this, thank you
#15
Well lets examine the situation shall we, i am trying to get as much info as i possibly can, the engine is currently 2 hours away from me ntm it will not turnover, so, i was trying to gather as much information as possible as to not get screwed over on this, thank you
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