matchek

Hi would you please tell me where the engine code is? Is right above the water pump? It is several numbers and then ends with a letter?

There are also 6 numbers on the each side of the block - what do they mean?

joe_padavano

The number above the water pump is the block casting number and tells you the displacement and year range of the engine.



The six digit numbers above the center exhaust ports are not on the block, they are on the heads and those are the head casting numbers.




In 1967, the engine unit number was stamped on the end of the RH cylinder head, though if the heads have ever been off the engine, they may have been installed on opposite sides (50-50 chance) so the unit number may be on the back of the LH head.

matchek

Hi Joe, thank you so much, here is what I found.

On the passenger side of the engine, it reads:
383821 (this is consistent with your pic)
On the drivers side of the engine, it reads:
394548 ( I don't know if this means anything
By the water pump, it reads:
389244D
The number on the passenger side front head reads:
M189229

Do I have a 400 or a 425 Engine?

Thank you!

matchek

I see, looks like I have one 383821 head that matches your head number.

joe_padavano

389244D is a 1966-67 425 block
383821 is a 1965 "A" head casting and not original to this motor.
384548 is a 1967-69 "C" head casting and likely is original to the motor
M189229 is on the 1965 head and means that THAT HEAD came off of a 1965 425 2bbl motor. Unfortunately it won't tell you anything about the rest of the motor since that head isn't original.

joe_padavano

That photo was only intended to be an example of what the cylinder head casting number looks like.

matchek

Thank you Joe - appreciate it!

matchek

The drivers Head starts with a "R", which was indicative of coming on a '67 425 - 4bbl. I believe both the M's and R's were to come with 10.25:1 CR researching online and in Chiltons.

In the Olds 65-67 year range, I take the 400 and 425 's fit the same exhaust manifold? I guess what I am getting at, is if I have a 425 engine, is it hard to plop back a 400 someday without modifications? Were the 400 and 425 relatively interchangeable?

Also, taking stamping and cast numbers aside, is there a way to measure a 400, 425, 455, etc., to distinguish the difference without the numbers (ie., width, depth, etc)? I know this is not ideal, I was just wondering if it was possible to distinguish with a tape measure as well. I could not find anywhere the width and depth of Olds engines.

joe_padavano

Every Olds big block (short stroke 400, long stroke 400, 425, and 455) are externally identical. In some cases, they even use the same heads and intake. Casting numbers (or disassembly) are the only way to tell them apart.

matchek

Thank you Joe!

By the way, as far as pistons, are the pistons on the 65-67 425, the same as say the 68 455? Or are the 425 pistons special only to the 425?

joe_padavano

The bore is the same but the pistons are different due to the different compression height (the distance from the piston pin to the top of the piston). 425s have a shorter stroke than 455s and thus longer rods (7" vs. 6.7").

lemoldsnut

So Mat,

Same info I gave you. You have a 425 and you have a 1965 A head and a later C head 67-69

Without taking the engine apart you can not tell what is in it. Only guess.

425 is a great motor. I would never miss match heads. Joe is a very informed person with a vast amount of Olds Knowledge. Probably up there with the most informed Olds person. In fact I bet the info you are using to reference came from him.

Larry

matchek

Thanks Larry, I understand - I was just trying to understand what I had IF what I had was done by the book. The only way to tell is to take it apart.

I found this reference helpful:
https://books.google.com/books?id=eT...20head&f=false

By the way, if the pistons on the 65-67 425 and the 68 455 have the same bore, are the pistons the same, it is just the connecting rods are different? Or the actual height of the actual piston (not the connecting rod) different too.

The reason why I ask is hear that 455 parts are easy to find and 425 not so much.

matchek

FYI, that reference is called the "Ultimate American V-8 Engine Data Book".

joe_padavano

I thought this was pretty clear:

joe_padavano

All I can say is that after only a few seconds of skimming that reference, I've already found several technical errors...

matchek

Thank you Joe - I get it now. I was visualizing it differently at first. I was stuck on the connecting rod length.

matchek

Both Larry and Joe and have enormous depths of Olds knowledge. I wish both of you would author Olds reference books. I really appreciate your help.

matchek

By the way, to understand correctly, if one started out with 425 block (D block), is it possible to rebuild this motor, with applicable heads, pistons, crankshaft, connecting rods, etc, to achieve not only displacement of 425 (as its original), but also 455 ci? Meaning, can I take a 425 block, and put a longer stroke crank and pistons in it to make it like a 68 455?

I think the answer is yes, as what Larry was pointing out, if it not original, there are several ways to rebuild an engine to achieve various displacements and horsepower.

This is a new concept for me as all this motor mixing and matching possibilities.

joe_padavano

Yes, and this has been done both ways (425 in a 455 block and vice-versa). So long as you use the entire reciprocating assembly as a matched set (crank, rods, and pistons), you get either a 425 or 455 in either block. The only thing to look out for is the lifter bank angle among the various 425 blocks. The cam needs to be ground to match the lifter bank angle. Also, the crank flange bolt pattern is different between the 425 crank and the 455 crank, so you need the flexplate that matches the crank.

Koda

Joe could you comment about how the G block 400 fits into this regarding stroke similarities? I think it uses the same measurement rotating assembly as a 455, but smaller bore pistons.

joe_padavano

It's actually really simple. All 425s and short stroke 400s (1965-67 BBOs) use the same 3.98" stroke crank and the same 7" rods. All 455s and long stroke 400s use the same 4.250" stroke crank and the same 6.7" rods. I assume that the crank was the expensive part of the engine, which is why Olds went to the small bore 400 when the long stroke crank was released (given the 400 cu in limit imposed by GM on the A-body cars).

rreggie

Im under the impression that Iding a 67 head from the passenger side by the stamped number can only be matched to the protecto plate. I only currently have a parcel picture of the protecto plate and it a bit hard to read.. the number stamped in the right head is V 20410g the vin id is 165227 full vin being 388177m165297 Dose the stamped numbers on the head come back to the vin ?or only to the procto plate ?. FYI all the engine casting numbers are corect just trying to see if these are the original heads

I have purchased this rare 442 but dont have it home yet
Almost bought the one in Downers Grove IL currently advertised but this one has a much better body . If anyone need a non biased option on that car I have seen it frist hand hit me up .See you all friday in chicago .

joe_padavano

The 1967-earlier stamped numbers are engine unit numbers, not VIN derivatives. They do NOT "match" the VIN. The only linkage between a 1967-earlier unit number (engine or trans) and the VIN is the P-O-P (or the build sheet if you can find one). From your engine unit number, we do know that the "V" prefix indicates a 400 motor and the "G" suffix indicates high compression.

rreggie

Thank you for responding I appreciate your important. I'll post some pictures when I get the car home.