Making a 409 out of a 348

[60impala]

For years I have been looking for a 409 motor. I have found overpriced truck motors and WAY overpriced real stuff.

A few months ago I answered an ad for 409 parts. The guy wasn't sure of what all he had cuz the parts were at the machine shop and he had to look at em first b4 he could figure a price. Another call to the guy and he's busy doing other stuff and hadn't looked at the 409 stuff.

Well I saved his number and wrote it off. I've spent too much time chasing down stuff from vague people.

A few weeks ago guy calls me and says he has the parts and since I was the first guy to call on em I had first crack.

We made a deal and he dropped off the parts today.

I'm stoked cuz I have a 348 industrial motor that is the only 348 block you can bore to a 409.

I have everything but the cam to build a 409 motor.

340hp 409 heads

348 motor that will become the 409

 

[Ronnie Russell]

60impala, You would have to bore the 348,,,, .187 to reach 409 std. size. Don't think you can do that. You might be able to go .125 oversize. Will need to sonic test to make sure. Those appear to be an old set of Jahn's power slot pistons. Also, from what I can see, it looks like you have passenger side dip stick,, that is a good thing. Good luck with your build. Keep us updated.

 

[60impala]

When I got the 348 I ran the casting numbers here and recall reading where that block casting was the only one with enough meat to bore out to 409 std size. I'll jot down the casting number and post it.

FWIW, the 348 ran a combine it's whole life in N. Texas.

 

[Tom Kochtanek]

Nice purchase!

Glad to learn that you're in the game after searching for a long time, and that you made a good deal on the components. Tell us what your plans are, gonna go back with the 348 crank, etc. Good set of heads! That industrial didn't have the aftermarket dual quads, did it?

Maybe after sonic checking the block you can report back. Likely that it's a "655" 348 truck block from 1965, correct? I recall there are some other castings as well for the 348, but not from memory.

Maybe think about using a 409 crank and taking the bores out to .100 or .125, that'll give you some cubic inches .

I hate to say it, but getting the "starter kit" is just the beginning of your expenses, they can add up quickly! Best to have a plan then start saving up for new reciprocating parts (crank, rods, pistons) and new cyclical parts (cam, valves, springs, etal).

Good luck!

TomK

 

[oldskydog]

When I got the 348 I ran the casting numbers here and recall reading where that block casting was the only one with enough meat to bore out to 409 std size. I'll jot down the casting number and post it.

FWIW, the 348 ran a combine it's whole life in N. Texas.

If you read the rest of the discussions you should find that that claim is not substantiated and seems to be mostly rumor. The only way to tell for sure is to sonic check the block. GM would not pour extra metal into the cylinder walls unnecessarily. It costs more and the bean counters usually win those arguments.
If you want a quick check before spending the $ on a sonic check, pop a freeze plug on the side and try to insert a pencil between the cylinder walls in the water jacket. If you can easily pass the pencil through, I wouldn''t bother spending the money on the sonic check for the purpose of boring to 409 specs. If you can't pass the pencil through, let us know.

 

[jim_ss409]

Here's a link to a discussion about a 434ci 348 stroker...
http://www.348-409.com/forum/showthread.php?t=15170&highlight=348+stroker

 

[1958 delivery]

I seriously doubt the block can be bored any where near the 409 size. However, it would be possible if GM made under bore 348's out of the 409 block in 65 since they were going away very shortly. I've heard some claims that some late 283 blocks were under bored 327's in the final years.

 

[threeimpalas]

Going .030" over stock and using a 396/427 crank will get you pretty close to a "409". Within a cubic inch and a lil' bit.

I wouldn't attempt to bore it out to 409 size, even if there is enough wall thickness to do it. The less you take out now, the more there will be available for future rebuilds.

 

[petepedlar]

I agree with threeimpalas........ that 409 dust will be on the stock market some day.



Dave

 

[Tom Kochtanek]

Funny you mention!

Dave, I laughed when you mentioned "409 dust".

Some might have realized this about me, but I keep just about EVERYTHING when I take stuff apart or work on parts.

When I "relieved" the lower portions of my 409 truck block to make way fo rthe 396/427 stroker crank, I of course gathered up all the dust and put it in a little pouch. I have some salt from Bonneville in a similar pouch. Odd, but fond memories!

I think it was Wrench who got me going on this path. He once quipped that "409 oil" from an oil change would probably sell on Ebay . Never tested that one, but if someone can sell condiments (catsup, mustard, etc.) from various fast food places, then 409 derivatives could be next!

Cheers,
TomK

 

[bignbad60]

348 40 over w/ 3.75 crank = 409ci

 

[buildit]

Bore size on a #655 block.

A couple of years ago, I built a 397 inch engine based on a 655 block with a 409 crank and BBC rods. This is +.125 (4.250) bore size. This maintained a minimum of .110 cylinder wall thickness. I had to shift the bore centers .010 on three holes, just to maintain that thickness.

 

[Phil Reed]

You got a 409 crank and the 340HP heads..............a .030" over 348 block and 409 crank is 383 cubic inches!!! Put the 2x4 intake on and you would have a great street engine!!!!

 

[petepedlar]

I like Phil's idea........ good valve job, clean up the bowls & some SS valves...... great engine !!!!!!! You could always put in a good hyd roller cam if you wanted to get trick & have a little more power.

Dave

 

[models916]

348 block

409 crank in the 348 block runs great. The long stroke makes it happen. 396 crank would be even better. On the street the stroke make it all happen.

 

[RCE1962]

See chart.

http://www.348-409.com/forum/showthread.php?t=12330&highlight=rce1962

 

[60impala]

Thanks for all the info.

The block casting # on the 348 is. 3857655, suffix is. TI2I78G

Posting from my phone. Will be easier to research the numbers when I get home.

The pistons are Jahns power slot. 1138.