409 truck block

[bones68cam]

Hello! Long time reader, first time poster. Maybe you all can clear something up for me. I just recently aquired some 348/409 parts: '58 348 complete, '58 348 long block, '60 348 long block, and a complete rebuilt 409. My question is the 409 has 3819333 heads and the block casting number is 3857656. Before I got this stuff I ran a casting numbers list from Mortec to double check everything when i got there. On Mortec's list they do not list 656 as a truck motor, just 64-65 409.
This is a truck motor isn't it? Also, are 3758379 heads worth anything for performance? I also got a bunch of misc. stuff so if anybody is looking for dated heads. intakes(2 bar. or 3-2s) let me know. Thanks for the info!

[Bungy]

That 409 casting number was used for both trucks and passenger cars. The only way to tell the difference is to remove the head and see if it has the notches at the top of the cylinders. If it does, its a truck block. Since it has the 333 heads there is a very good chance its a truck block. The 656 truck blocks are way more common then the passenger versions. As far as the 379 heads, you won't get much in the way of performance out of them. Port the 333 heads and add big valves and you'll do pretty good. JMO

[SteveD409]

I don't know how accurate this is (doubt that it is), but I was once told you can tell a truck 409 block from a car 409 block by looking at the front mounting bosses. These are used with a horseshoe bracket to mount the engines in trucks so all four bosses are drilled and tapped. Only the bosses on the driver's side are drilled and tapped on passenger car blocks. I have two bare 409 blocks and it holds true for them-my 656 truck block is totally drilled and tapped. My 814 car block is only drilled and tapped on the driver's side. BUT, the 814 in my Biscayne (correctly marked QB and with non-matching partial VIN) has all four holes drilled and tapped. I've never had the head off this one so I can't say 100% that the numbers haven't been buggered with.

SteveD

[bobs409]

I think I recall Aubrey saying something like that once.

Is that what you said Aubrey?

[CDNpontiac409guy]

Yes Bob, Steve... that's an easy way to tell. You CAN drill the car block, but plugging the holes in a truck block is a lot more difficult.
Steve, I'd be suspecting that yours is a truck block.