348

[david f]

I would like to know how to turn a 348 into a 409

[1958 delivery]

Buy some new valve cover decals and new fender emblems!



Just kidding :rofl

[dq409]

Buy some new valve cover decals and new fender emblems!



Just kidding :rofl


:rofl :rofl That IS the cheapest way !!!!:rofl

Other then that there are tricks to beef up and stroke the 348 to make it run like a 409.
Boring it out that big is ify,,,,
Do a search on this site and you will find all kinds of info.,,,dq

[jim_ss409]

I think that the simple answer is you can't. But you can get close or even bigger with the right combination of parts. Apparently, some of the #655 348 truck blocks can be bored out to 4.312 (409 size) but most 348's won't go that big. But, you can use a crank and rods from a 409 along with 348 pistons. That gets you up to about 380ci with a .030 overbore. And If you wan't to go bigger yet you can use a crank from a 396-427 Big Block. There's some machining required with that swap but it'll put your 348 up to about 408ci with a .030 overbore or about 414ci at .060 over. There's a few things you'd want to know before jumping in to a job like this but if you decide to do it there's people on this forum that know the answers.

[1958 delivery]

How thick are the cyl walls for typical 348 blocks. Are they still thick enough when bored 60 over?

[fatride]

I had mine bored .060, thinnest was .110" .100 is good.

[1958 delivery]

Do you know if that thickness is pretty common for the 348. I ask, because if I ever rebuild my 348 I would not bother with the stock crank. So I'm wondering if 348's pretty much go 60 with out problems. I'm very familiar with BB and SB but have limited experience with W's.

[jim_ss409]

Here's what Curt Harvey said about 348 blocks in a magazine article...

"Usually .030 over is no problem but .060 requires sonic-checking the block"

[tripower]

I just bored my 5011 block .060 with no problems. I'm using the 3.76 crank with the 6.385 rod.:brow
Check out this thread...http://www.348-409.com/forum/showthread.php?t=8778

[fatride]

Here's what Curt Harvey said about 348 blocks in a magazine article...

"Usually .030 over is no problem but .060 requires sonic-checking the block"

Yes, I had mine sonic tested.

[1958 delivery]

There was another thread a week or so ago about what happened to Curt Harvey. I saw him about 6 months ago selling parts at a swap meet. He said he was in Hemet, Calif I believe.

[W Head]

I punched out my 59 block .125 about 5 years ago and have had no problems. Also punched out a 327 .30 over and got a small hole into the water jacket, you just never know!!!!

W Head

59 El Camino 348-3,2s
59 Impala 409-2,4s

[fatride]

I have the readout of my 348 sonic test around here somewhere, when I find it I will scan and post. I hope it agrees with my last post. :rolleyes:

[SSpev]

I don't beleave sonic testing will find "small holes". If you bore one and get a small hole it is most likly an inclusion fron the casting process. I had a 327 3 years ago that had a hole in one cylinder and 2 in another. They weren't there at 30, but showed at 60. Put 2 sleeves.

[fatride]

I have the readout of my 348 sonic test around here somewhere, when I find it I will scan and post. I hope it agrees with my last post. :rolleyes:

Sonic test before the .060" bore.

[tripowerguy]

Fatride had your block been bored before you went .60 over? I have a stock 348 block that has never been bored and I was wondering if I go .60 over that the machine shop is going to charge a lot to take that much out. Also on another thread some were talking about welding on a crank as if it were a bad thing. In the old days that was the only way to make a stroker, weld on the bottom of the throws and grind it round. There were a lot of fuelers and blown gas cars running them without failure. The reason I say that is I have a 409 crank but it has a small crack around the center main oil hole.:eek: Roy

[rstreet]

Fatride had your block been bored before you went .60 over? I have a stock 348 block that has never been bored and I was wondering if I go .60 over that the machine shop is going to charge a lot to take that much out. Also on another thread some were talking about welding on a crank as if it were a bad thing. In the old days that was the only way to make a stroker, weld on the bottom of the throws and grind it round. There were a lot of fuelers and blown gas cars running them without failure. The reason I say that is I have a 409 crank but it has a small crack around the center main oil hole.:eek: Roy

oh,oh I think there might be another "boat anchor"...Seriously I am sure it will be ok in a non race unstressed application

[tripower]

I just got the results of the sonic test today on my 5011 block and after a rough bore of .060 the thinnest wall was .125. Once we final hone I will still be above the .120 range...:clap :clap :clap

[fatride]

Fatride had your block been bored before you went .60 over? I have a stock 348 block that has never been bored and I was wondering if I go .60 over that the machine shop is going to charge a lot to take that much out. Also on another thread some were talking about welding on a crank as if it were a bad thing. In the old days that was the only way to make a stroker, weld on the bottom of the throws and grind it round. There were a lot of fuelers and blown gas cars running them without failure. The reason I say that is I have a 409 crank but it has a small crack around the center main oil hole.:eek: Roy


Roy
I don't think the machine shop charges more for a .060" bore compaired to a .030" bore. Last bore and hone I had done @ .030 was $125.00.

[models916]

My guy charges more for double pass on the bore. Con't take 60 out in one pass.