How much can you bore and stroke a 350? - Third Generation F-Body Message Boards

avro206 · 10-29-2008, 10:10 PM

Enough for 400 CID?

I saw this on ebay. They say you can bore to 4.125X3.75 stroke and get a 400

http://cgi.ebay.com/ebaymotors/Parts...=p4506.c0.m245

They claim you can bore it but I looked it up on crate engine depot and GM says no. 4.09 max

http://www.crateenginedepot.com/stor...83-P679C0.aspx

I was thinking a 3rd gen "Formula 400" would be cool
(complete with door decals and 6.6L on the cowl)

Maybe a FIRST intake or something.....

327??? · 10-29-2008, 11:30 PM

You can not bore a 350 to 4.125, 383 is the most common. I have heard of larger motors, like 396", but I don't know what kind of clearancing you would have to do.

You can bore aftermarket blocks more than standard blocks.

ccook-92-305 · 10-30-2008, 12:12 AM

x2
cant bore a 350 that far or ull be waay into the water jackets. a longer stroke would be the only way to do it.

with a stock 350 bore (4") and a 4" stroke youll have a 402

a 350 .030 over at (4.030)and a 4" stroke youll have a 408

a 383 is a .030 over 350 and a 3.75 stroke

avro206 · 10-30-2008, 06:30 AM

despite this paticular block?

vette9190 · 10-30-2008, 06:40 AM

Since You are asking about a Bowtie Block and Not a production block you can bore it more then usuall.
Part number 10051183 GM Bowtie Block can actually be bore out to 4.155" so yes you could do a 400 if you want. I think the popular build is technically a 406 though but who cares about a few inches right. With the right stuff you can go as large as 427ci on a small block,maybe bigger with really high end blocks.
Oh and retail is about $1000.00 not the $1979.00 they say.
be carefull because part number 10051181 will only bore up to 4.030"

Atilla the Fun · 10-30-2008, 10:45 AM

I'm a professional automotive machinist. For a street engine, with a production 350, 4.030" is the max for any power adder. for low-rpm torque, 4.080" is okay. If you fill the water jackets with filler, a tall-fill for racing will give a 350 block a max bore of 4.125". No production 400 should ever go past 4.185", even with a tall-fill.
As for stroke, If you have the money, you can get a 4.125" stroke into a production block, but this won't survive any power adder. 4" of stroke is the practical upper limit. 4.185" bore and 4" stroke gives 440 cubic inches. 4.125" bore and 4" stroke is 427.65 cubic inches.
If you need more, go big-block or aftermarket block.

Brando5641 · 10-31-2008, 11:52 AM

Quote:

Originally Posted by ccook-92-305

x2
cant bore a 350 that far or ull be waay into the water jackets. a longer stroke would be the only way to do it.

with a stock 350 bore (4") and a 4" stroke youll have a 402

a 350 .030 over at (4.030)and a 4" stroke youll have a 408

a 383 is a .030 over 350 and a 3.75 stroke

402 and 408??

Sonix · 10-31-2008, 12:40 PM

That's right Brando
There's a guy on here that has a 350 block making 408 cubes. Factory block I think. Probably had to clearance the crap out of it to get that big stroke in there, but it works.

Brando5641 · 11-01-2008, 11:08 AM

huh..... ok cool

Fullsizewagon · 11-01-2008, 01:51 PM

Nice info there vette & Atilla. What's this filler thing btw., never heard about it..

Atilla the Fun · 11-01-2008, 01:54 PM

It's basically an epoxy/iron mix, it comes as a powder, you mix it with water, and pour it in your water jackets, before machining. If you're just trying to save a block you over-clearanced for a stroker crank, just do a half inch. If it's an alcohol-fieled drag car, fill the jackets to the bottom of the inlet hole from the water pump.

Orr89RocZ · 11-01-2008, 03:49 PM

T&L engines sells a 408 setup based on the 350 GM block...ZZ4 late model 1 piece roller block

My buddy has one

Shadow Z · 09-19-2009, 12:33 AM

Quote:

Originally Posted by Atilla the Fun

It's basically an epoxy/iron mix, it comes as a powder, you mix it with water, and pour it in your water jackets, before machining. If you're just trying to save a block you over-clearanced for a stroker crank, just do a half inch. If it's an alcohol-fieled drag car, fill the jackets to the bottom of the inlet hole from the water pump.

Well Atilla, I chose you while digging up this old thread, oh great one! Haha, but anyway, would it be safe at all to stroke a stock 350 to a 402?

I don't have $20,000 to go out and buy a complete turn-key 632, so I'll get as many cubes out of my stock 350 block as I can!

Saabster · 09-19-2009, 07:08 AM

I've heard as high as 450's cubes with 400 block and a mega stroke, but the clearancing on such a motor is a real pain with it's huge stroke.

For a standard 4' bore block, 383 is all you get.

Shadow Z · 09-25-2009, 09:02 PM

There's stroker kits available for a 388. That's a 4.060 bore with the 3.750 stroke, I would never go all the way to a 4.060 bore, but has anyone ever stroked an original 350 block beyond 3.750?

I was told block clearancing is real simple to do, but I'm not sure if it'd be safe to stretch the limits of my block that much.

I checked out some engine displacement calculators, and saw that a 3.900 stroke and a 4.030 bore comes out to a 6.5 liter 398 C.I. Anyone know if that would be safe? I'm no master engine builder, but I think stroking the engine an extra 150 thousandths of an inch beyond a 383 would be do-able.

Atilla the Fun · 09-28-2009, 12:03 PM

Sorry I've been away. Where did you find a 3.90" stroke crank?

Shadow Z · 09-28-2009, 01:24 PM

I didn't find one for Chevy, BUT, Lunati makes a 3.90 inch stroke crank, for small block Fords.

I imagine if they already have one done up for a Ford, it wouldn't be a totally custom job. Orr89RocZ posted about a 408 small block, so I did a little searching, found T&L engines, and apparently with a tad of block machining, a 4 inch stroke crank will fit into a factory 350 block.

Atilla the Fun · 09-28-2009, 05:09 PM

Quote:

Originally Posted by Saabster

I've heard as high as 450's cubes with 400 block and a mega stroke, but the clearancing on such a motor is a real pain with it's huge stroke.

For a standard 4' bore block, 383 is all you get.

WRONG! go back and re-read the entire thread. I've built several 414-ci 350s myself, all of which are still running. One of them just broke into the high tens in the 1/4 mile. A 414 is a 4.060" bore and a 4" stroke.

Air_Adam · 09-29-2009, 08:12 PM

There are 3.875" stroke cranks out there - lots of LT1 guys use them to build Gen II 396ci engines. The LT1 (Gen II) and the regular 350 with a 1pc rear seal use the same cranks. There are a few 427ci-ish LT1's out there too, but they don't come around very often.

basiccamaro · 09-29-2009, 10:20 PM

The "new" thing seems to be 400 inch 350-based engines. Popular Hot Rodding has a story about building one for their "Project Talledega" Chevelle Laguna (spelling?). They are putting a 4" stroke crank in a 350 block. I think they have to use 5.85" rods, it's real tight clearance to the bottom of the piston skirts to the crank counterweights as well as to the oil pan rails. This makes a "square" motor- a 4" bore and a 4" stroke and is a torquey combination.

I've seen mention of this in a few other magazines as well. I love Chevy 400's, but the 350 block does not have the siamesed cylinder walls to worry about and are a bit easier and cheaper to find.