How to tell a truck block from a car block, without pulling heads

[jim_ss409]

This question seems to come along quite often so I thought I'd take a couple of pictures that show something to look for.
I'm not 100% sure this is foolproof but all the truck blocks I've seen have threaded holes in the bosses on the passenger side front of the block, just ahead of the fuel pump.
The truck front motor mount bolted onto the block there.

Here's a truck block...




Here's a passenger car block...



Notice that the bosses are not drilled and threaded on the passenger car block.
It could be that those bosses were drilled on replacement blocks in order to make them more universal, I don't know about that, but most of the time,,, if the bosses are drilled, it's probably a truck block.

If anybody knows more about this, please chime in.

EDIT... After reading some of the posts below you'll see that several passenger car blocks are drilled and threaded on both sides. So, you can't assume a drilled block is a truck block.

It does appear that most if not all of the truck blocks are drilled on both sides so if you spot a block that is not drilled on the passengers side, it's a good bet that it's a passenger car block.

 

[Don Jacks]

For us "little motor" guys,does same thing apply to the 348's???

 

[chevymusclecars]

Jim
I would agree but when I was 16 I put a 409 in my 55 Chevy and used the front mount by drilling and modifying the side mounts off a 6 cylinder. To do this I drilled and tapped the passenger side of the block to install the mounts. The same would have been true for anyone who mounted the engine using the front mounted adapters that were used back then.

I do think that engines that are not drilled are definitely passenger car engines but there is still the possibility that a drilled block is also a passenger car engine.
Bill

 

[wally72974]

I read somewhere that ALL truck blocks left the factory with those passenger side bosses drilled.
So if you run across a 409 with those bosses drilled there's a chance it's not a passenger block.
Like Bill said, if it's not drilled then it's defiantly a passenger car block.

 

[Ronnie Russell]

99% true but there are exceptions. I traveled to Amarillo, Tx with Brian Thompson to pick up a #656 engine he bought on-line. A true truck engine in every aspect. #333s, truck intake, truck pistons, etc. .. Right side bosses were undrilled.

 

[wally72974]

For us "little motor" guys,does same thing apply to the 348's???

The 348's car blocks and truck blocks have the same cylinder notch cut out so I don't think anyone really worries to much if
if it came out of a car or truck. With the 409's however it makes a bigger difference.
I have a 1960 Impala 348 that does not have the bosses drilled and I had a 7655 348
truck block that did have the bosses drilled. I guess it could be that the 348's were the same
as a 409 when it comes to car and truck blocks.

 

[wally72974]

99% true but there are exceptions. I traveled to Amarillo, Tx with Brian Thompson to pick up a #656 engine he bought on-line. A true truck engine in every aspect. #333s, truck intake, truck pistons, etc. .. Right side bosses were undrilled.

So was it a passenger block? Did it have the truck relief notches in it? Or was it a passenger block with all of the truck crap in it or on it?

 

[chevymusclecars]

99% true but there are exceptions. I traveled to Amarillo, Tx with Brian Thompson to pick up a #656 engine he bought on-line. A true truck engine in every aspect. #333s, truck intake, truck pistons, etc. .. Right side bosses were undrilled.

My understanding is the holes were drilled for brake air pumps and such but I wonder if replacements were drilled. Do you remember if the engine was stamped?

Bill

 

[wally72974]

I love this thread!! I have heard so much crap about truck engines being tall decks and other crap from people
who think they know that having guys like you that do know is a real blessing. However it is fun to listen
to those other people from time to time. Especially when they think that the truck 348 or 409 they got isn't worth anything!!

 

[oldskydog]

Some truck installations used the horseshoe front mount that bolted to those holes. Some were side mounted.

 

[63impalass409]

I have a 60 348 011 casting 011 code fh date k 28 60 that is a car block that it is drilled, two 63 814 car qg coded motors both of which I put together and one has holes drilled but the other not, so what up with that?

 

[Ronnie Russell]

The block did not have a ex side notch. So, one could say it was a passenger car block with truck guts. I don't think you can every use the word "all" to describe what is correct and incorrect for 409s. It was the early 1960s. Sure, they had rules and guide lines but line supervisors were human beings. If they had an order to fill and were out of a particular part, I'm sure there were some liberties taken. Did they worry about somebody discovering a mis-numbered part 50 years later? I think not. By the way, the block I mentioned was an irrigation engine. Hundreds if not thousands were used in irrigation applications. Evidently they did not need the right side bosses drilled. Maybe the irrigation engines need 1 point more c;.r. Who knows. This discussion reminds me on the factory tach discussion. Almost everyone will say all 62-409-409 came with factory tachs. One of my close friends bought a '62 409-409 in Jan, '62 that did not have a factory tach. You can go by your factory charts, manuals, order sheets, whatever,,, and believe they were absolute. My opinion is there were exceptions. We all have the right to believe what we wish.

 

[Rickys61]

I just checked the two 348 blocks I have at home, the 872 is not drilled and tapped, the 011 FH is.. Casting date is C 15 60...

 

[wally72974]

The block did not have a ex side notch. So, one could say it was a passenger car block with truck guts. I don't think you can every use the word "all" to describe what is correct and incorrect for 409s. It was the early 1960s. Sure, they had rules and guide lines but line supervisors were human beings. If they had an order to fill and were out of a particular part, I'm sure there were some liberties taken. Did they worry about somebody discovering a mis-numbered part 50 years later? I think not. By the way, the block I mentioned was an irrigation engine. Hundreds if not thousands were used in irrigation applications. Evidently they did not need the right side bosses drilled. Maybe the irrigation engines need 1 point more c;.r. Who knows. This discussion reminds me on the factory tach discussion. Almost everyone will say all 62-409-409 came with factory tachs. One of my close friends bought a '62 409-409 in Jan, '62 that did not have a factory tach. You can go by your factory charts, manuals, order sheets, whatever,,, and believe they were absolute. My opinion is there were exceptions. We all have the right to believe what we wish.

So your "truck block" still fits what we are saying. If there are no drilled bosses on the passenger side it is a car block for sure. All truck blocks have the bosses on both sides drilled. If the passenger side is not drilled
it is for sure a car block. If both sides are drilled then it could be either or depending if the holes were added later.

 

[wally72974]

The block did not have a ex side notch. So, one could say it was a passenger car block with truck guts. I don't think you can every use the word "all" to describe what is correct and incorrect for 409s. It was the early 1960s. Sure, they had rules and guide lines but line supervisors were human beings. If they had an order to fill and were out of a particular part, I'm sure there were some liberties taken. Did they worry about somebody discovering a mis-numbered part 50 years later? I think not. By the way, the block I mentioned was an irrigation engine. Hundreds if not thousands were used in irrigation applications. Evidently they did not need the right side bosses drilled. Maybe the irrigation engines need 1 point more c;.r. Who knows. This discussion reminds me on the factory tach discussion. Almost everyone will say all 62-409-409 came with factory tachs. One of my close friends bought a '62 409-409 in Jan, '62 that did not have a factory tach. You can go by your factory charts, manuals, order sheets, whatever,,, and believe they were absolute. My opinion is there were exceptions. We all have the right to believe what we wish.

I should rephrase what I said earlier. I believe Ron is right too. There are always going to be that one guy that has something that isn't what it's was suppose to be.
I think it can be summed up as most of the time it is this way and be prepared for it once in a great while not be the way it should.

 

[Topstrap]

My first 409 came out of a flatbed truck and is drilled, still had the front mounts on it like the old 57 chevy design.

Dennis

 

[Jim409_Pontiac]

I think the lesson to be learned here is nothing is carved in stone. If someone is selling a 409 and the front holes are drilled and tapped you need to proceed with caution and presume it is probably a truck block. You need to investigate further if you really want it.
As always, it's buyer beware.

 

[oldskydog]

Borescope.

 

[Jim409_Pontiac]

Yes

 

[Ronnie Russell]

I believe I know why Jim started this thread. Jim , as always, wants to educate and help new members. Nobody has done more in this area. And, he succeeded. After re-reading my post, I must apologize., much too pessimistic and negative. My post was my honest opinion but I certainly could have worded it differently. Cecils suggestion of a borescope is great and maybe I could offer a suggestion that still might make it a little easier for someone who is trying to determine if the engine he is buying is a truck or passenger car short block. I've never used a borescope so I don't know if it can go down a spark plug hole and then turn up to view the notch. I don't know. But if the user knows that a truck piston does not have an intake valve relief and the 340 and 409-425 hp piston do have an intake valve relief, that would be easier to see.