[devarsity61]

ok I have a good 400 block that is ready to have machine work done. I also have some vortec heads that need to be worked. what are some ideas for the block and heads. I would like to stroke the 400 to a 406 what do u think

[techinspector1]

Originally Posted by devarsity61

I would like to stroke the 400 to a 406 what do u think

To stroke a 400 to a 406, you need to offset grind the crank from 3.750" to 3.800".

You other guys needn't start on me. I'm tired and going to bed.

[cool rockin daddy]

"Stroke" an engine to gain a whole SIX cubic inches. Cut it out. Okay? Just cut it out.

[Bowtie man]

Best way is to take some metal out of the cylinder walls.

[cool rockin daddy]

To gain SIX cubic inches? Why would anyone bother?

[Greg T]

I stroked my 400 once. Got arrested for indecent exposure.



.

[LS-57]

A 406 is a very common build, it is a 400 bored over with a ton of options. I believe it was John Lingenfelter (could be wrong) who built the "first" one in the '80's & they took off from there. The early ones used 350 rods (longer) with custom pistons. Today it is still a common way to go but the options are endless. Scat and others now have stroker kits to bring it to a 427 and 434.
Punch in 406 Chev small block in your search engine & research it. It is easy to get over 400hp and over 400 torque & still run pump gas.
I know of 3 406 builds in my area. I'm running one in my '86 Monte Carlo SS & expect a low 13 in the quarter on regular pump gas. The factory 400 has 5.5" rods, a 350 has 5.75" rods which where the most common way to go till recently when the 6" rods became available. It is easy to push over 400hp with over 400 torque reliably on pump gas on a proper modern 406 combination.
Here are a few documented builds including parts list
http://www.chevyhiperformance.com/te...ild/index.html
http://www.superchevy.com/technical/...ine/index.html
http://www.youtube.com/watch?v=c9KSsRGy_7I&NR=1

I'd say go for it & enjoy

[68NovaSS]

Originally Posted by LS-57

A 406 is a very common build, it is a 400 bored over with a ton of options. I believe it was John Lingenfelter (could be wrong) who built the "first" one in the '80's & they took off from there. The early ones used 350 rods (longer) with custom pistons. Today it is still a common way to go but the options are endless. Scat and others now have stroker kits to bring it to a 427 and 434.
The factory 400 has 5.5" rods, a 350 has 5.75" rods which where the most common way to go till recently when the 6" rods became available. It is easy to push over 400hp with over 400 torque reliably on pump gas on a proper modern 406 combination.

Rod length has absolutely nothing to do with making a 406, and boring a 400 isn't what a "stroker" 406 is all about, it was made to increase the size and power potential of a 350, just as the 383 setup was designed to do.

Stroking a motor is all about changing crank journal throw, rod length is only a matter of preference and determines what compression height piston is required.

Boring a 400 .030 to 406 is chump change, isn't going to make any appreciable gain, and won't be a "stroker". I'm not saying a GM 400 can't be made to make power, just clarifying things for some who may not know the difference.

[cool rockin daddy]

THANK you, 68NovaSS. That was my point exactly. Seemed to go right over the heads of LS-57 and Bowtie man.

[cobalt327]

Originally Posted by LS-57

I believe it was John Lingenfelter (could be wrong) who built the "first" one in the '80's & they took off from there. The early ones used 350 rods (longer) with custom pistons.

The ONLY thing that would make any sense is if you are talking about a 383 SBC stroker. The 406 is a 0.030" over 400- and was "made" the first time a 400 engine was ever rebuilt, likely within days of when the engine was released into production in 1970.

Scat and others now have stroker kits to bring it to a 427 and 434.

To use a 4" crank in a production block requires a small base circle cam, clearancing, and at least a partial fill of Hardblok to keep it from leaking from where the clearancing hit the water jackets. All a 434 is, is a 0.030" overbore of the standard 400 block w/a 4" crank.

The factory 400 has 5.5" rods

You are wrong by 0.065".

FWIW, a 4" crank in a 0.020" over 4" nominal bore SBC block also nets you 406 cid.

[LS-57]

This thread started by a guy who called the thread "Max horsepower from a sbc 400". Some guys who don't know what a 406 is tore into him so I responded by providing a few facts that went over most of their heads.
I stand corrected on the original 400 rod length. Thank you & oops, my mistake. I never mentioned that rod length changes the size of on engine so I don't know why I'm being torn apart for that, what you didn't consider is that the rod length generates torque and horsepower and that was my point.
To compare 406 to a 383 shows a lack of understanding of what a 406 is. A 383 starts as a 350sbc and needs revs to produce power. It has a sharp torque & hp curve where as a 406 stroker starts as a 400sbc and produces horsepower and torque just off idle with a relatively flat curve on both. Pretty hard to compare those don't you think?
Is a 406 stroker that unheard of on this forum? Looks like some of you really need to do some homework on a particular engine before you make a comment. Look at the links I provided and do some research, who knows, you may like what you see.
Let's all play nice & learn from each other because isn't that what this forum is for?

[ap72]

The most common 406 is not a "stroker" but an over bored 400 as already stated.

A 383 can have a flat or peaky tq curve depending on how you build it, just like a 406 or even a 283.

Longer rods do slightly change an engine's characteristics, but longer is NOT always better.

I just had to post those corrections for the new guys that may find this thread through google and not know any better, most of the regular members here already know these things.

[nofearengineer]

Yes, can we please kill once and for all the notion that increasing stroke has diddly to do with increasing torque?

[RippinRon]

For comparisons sake between a 350 and a 383 if all things are equal other than the stroke the 383 would make more torque. It comes down to displacement.

[68NovaSS]

Originally Posted by LS-57

To compare 406 to a 383 shows a lack of understanding of what a 406 is. A 383 starts as a 350sbc and needs revs to produce power. It has a sharp torque & hp curve where as a 406 stroker starts as a 400sbc and produces horsepower and torque just off idle with a relatively flat curve on both. Pretty hard to compare those don't you think?

Is a 406 stroker that unheard of on this forum?

That's ridiculous. It's all in the build where power comes in, other than obvious benefits of a few more inches from the 400. Don't believe everything you read in magazines.

Again, you aren't talking stroker with the last statement, you're talking about a .030 over 400.

You're not being "torn apart", not even close, if you were, you'd know it. Lighten up.