Steve in Colorado
Dec 21st, 99, 05:20 AM
I keep hearing you guys talk about the sb 406. It's very obvious a lot of you out there know what you are talking about, so is this the bad boy to build? Is the 406 just a 400 bored slightly? (please excuse my ignorance) How much can you bore a 400 before you start getting heating problems? I always heard that is why the quit making the 400 sb anyway due to the heating probs. I really want to build a screamer, is this the way to go? Thanks for the help.
By the way, I really appreciate your help on the 5-speed conversion. I just got my Tremec 5-speed and plan on putting it in after the 1st of the year.
Dec 21st, 99, 05:55 AM
A 406 is simply a 400 bored .030" over. Just like a 350 bored to 355. Overheating problems are a fallacy, only due to careless assembly. 400's have steam holes that the 350's do not, and many a careless builder has forgotten to add these small steam holes to the head gasket and the heads themselves. If these 2 details are noted, then there is NO overheating problem.
406 is a smoking torque monster, see bad to the bone 406 in CHP I think, about 2 months ago. It is easy to get 500+ ft-lbs of torque and 450+ Hp from one. Put aluminum heads on one and you have BB torque from a featherweight mouse. I love mine...
P.S. Start a tire replacement fund, you'll need it.
1969 Z28, 406SB
Dec 21st, 99, 07:30 AM
One more note on the overbore. Going .030" is pretty trivial, no reliability problems there, but going any further may be asking for trouble. There are guys out there that go .060" over on a 400 without trouble, but it's definitely not recommended. With the siamese bores of the 400, things like bore shift can become an issue if you go .060" or more. Gaskets, and gasket blowout between cylinders also becomes more likely. Besides, there is really no reason to go more than .030" over unless there are severe problems with the block, in which case you wouldn't want to use it anyway.
1969 Z28, 406SB
Dec 22nd, 99, 02:06 PM
Shawn's got it exactly right! The SB 400 has been given a bad rep due to people not doing things properly. If done right it is the baddest small block out there!
70 & 1/2 RS
SB406 & M20 4spd
70 Malibu 350/TH400
Gold member #103
Dec 23rd, 99, 05:17 AM
I agree completely! 400's are great, +.030 or not. I ran one years ago, with small valve 327 heads, crane blazer cam, and 650 double pumper. Had it in a '67 camaro ragtop and later put it in a 69 vette 4 speed. It idled at 650, reved to 6000, pushed the camaro to 13.20's on street tires. In the vette, I used to show off by putting the trans in 4th, my right foot on the dash, and dropping the clutch (uphill!!) BIG TIME TORQUE MONSTER! (don't forget to drill the steam holes in the heads)
Dec 24th, 99, 09:14 AM
start a tire fund...lmao..love it...i have a 406 in my 68 Camaro,350 th w/ shift kit, and a 2.73 posi (soon to be changed to 4.11's) and run 13.5's spinning to the 60'er...on street radials. no problems with overheating at all.so i say **** on the people who think a 400 is a p.o.s.
Dec 25th, 99, 06:45 PM
I'd like to add the 400 block MUST BE BORED AND HONED WITH A TORQUE PLATE. I purchased a rebuilt 400 for use in a pickup truck and it had 60% leak down on all cylinders after a year of use. When torn down it had visible shiny stripes on the cylinder walls where the rings were hitting and the dark stripes were where the rings were NOT hitting.
Why'd I tear it down? They put a welded cast iron crank in it and it broke. I paid extra for that engine too. It was a "motor home" quality engine for severe use.
FYI Chevy builds HD quality engines for use in their one ton chassis with molly rings, tri metal bearings, and stainless steel exhaust valves. They last about twice as long as the standard engines under the same conditions.
Dec 26th, 99, 02:52 PM
I built a 400 a few years back for a 4wd Blazer. It was a great motor - I bored it .040 over, put in flattop pistons, stock 350 heads, a Crane Comp-u-cam for an IROC-Z, and the stock TBI and computer with a custom chip. It was really sweet- had gobs of power and got better gas mileage than the original 350. Never had a single worry about overheating even though I towed heavy loads and ran all over the mountains at very high altitudes.
I'm now building a 400 for my '69. Technically, it'll be a 408 since I had to bore the block .040 over to clean up a scratch. I would have been happy to hold it to .030 but I couldn't. I'm generally following the "Bad to the Bone" motor buildup Shawn referred to. I'm using dished hyperuetectic pistons, 350 (5.7") rods, Edelbrock Performer RPM heads, Intake, and 750 carb, and a Comp Cams 230/236 @ .050 Extreme Energy Cam. I'll add the steam holes to the heads and for extra security I'm using a Stewart high volume water pump which is an improvement over the stock pump.
I'm guessing the power should be similar to the magazine motor and slightly better than Edelbrock gets out of their 350 RPM kit - so somewhere in the 450 hp range. Tires will definitely be a problem.
Oct 18th, 07, 01:45 PM
A lot of peope dont no much about a 406 small block i am just here to tell u they are a power house and tire burner u just have to know how to build one ive got a set of vorteck heads, a crane blazzer cam 288 488 with 1.6 roller rockers, headers and 3inch exuast all the way out the back, with a 800 holley double pumper the turbo 350 trany can barely hold the tourqe coming from the 406 sm its a mean motor!!
Oct 18th, 07, 05:59 PM
My 406 I put in this year 472 HP @5600, 495# tor @ 4400
With street tires, closed exhaust 12.68 @113 MPH w/2.0 60' 1/4
Oct 18th, 07, 07:59 PM
I think this is the oldest post I've ever seen resurected!
Oct 18th, 07, 10:55 PM
Wow, this is an old post. In fact so old, it's back when they still thought you need the steam holes......:D ;)
Oct 19th, 07, 03:39 AM
my 406 is ready to go in.
found it cheap at a yard sale
put in longer light weight rods
its got everything but the kitchen sink.
Oct 19th, 07, 07:51 AM
I just completed my second 406, this one with a 11:1 and lightweight rotating assembly. Revs like a ferrari? I can't wait to get to the track maybe next weekend. My first one was a mild 406 that would still fry tires on demand. The new one is much stronger, even pulls hard in third gear (automatic w/3:73 rear)