anyone runnin a 406 smallblock?

[Blue85]

Anyone here have a 406 smallblock under thier hood, someone was telling me it is is a good motor to build, but I have heard the 400 blocks arent a good thing to start building anything with, any input?

[svgould]

I have one brand new installed, but it currently hasn't been started.....hopefully this weekend. IMO they are an awesome motor, just remember to drill the steam holes in the heads and you should have no problems. Most of the problems you hear of are the result of somebody installing different heads and not drilling out the steam holes. Anyway, I should have more feedback for you in the next couple of weeks.

[67-72williso]

I have one in the C-20 truck I`m running, not bad torque. I just put a Comp Cams 4x4 cam to help with that. I use it for towing a trailer, empty (4100)lbs.The gears are tall 3.07. The bad part is they run hot in the summer. There Isn`t much cooling between the cylinders.
Later Willis

[uncle]

You can open up that hole to improve your cooling.

[Dual quad]

I've got one in the garage waiting for a rebuild. The 400's have 4.125" bore and 3.75" stroke to get the displacement in the SBC package. Due to the bore spacing, the bores in the casting are actually siamesed, thus there is no coolant flow between them. GM got around this by using steam holes in the cylinder heads to provide a flow path and to vent trapped vapour.

As svgould said, the bad reputation (overheating) comes from folks that used 350 heads (no steam holes) on this block. If you can find one, the 400 SBC can be built for not much more $$ than a 350. You end up with a fatter torque and HP curve. If you do one, swap the stock rods for 5.7" units.

If you're serious, do yourself a favour and pick up this book http://www.themotorbookstore.com/big-inch-chevy.html

[427V8]

I have a 400 bored .030 over and stroked to 4". Do the math and comes to 434 inches. it dynoed a bit under 500 hp and just over 500 ft lbs. I have over 400 ft lbs from 2400 rpm ( the dyno couldn't go any lower) to 6000 rpm. It pushes the car into the 12's in the 1/4. It is in the Vette, a known hard to cool car, and using the origional 4 row brass radiator it cools just fine, like 212 even on a 95 degree summer day.

A friend of move has a 406 built a little stronger in an S10 that puts him into the low 12's No cooling problems either using the stock single row alum radiator.

The only thing to remember is to drill steam holes in the heads for low speed cooling and to toss the factory smog heads and use ANYTHING else!

Perfect engine for a truck

[ed455]

I'm building a 434 in a Dart block and have a 406 with less than 5 miles on it im my truck now. Make a hair under 500 hp. I'm looking to sell it to finance my 434. I'm a sick man. I need help. The 406 is scary fast and I still want MORE . . .

[Kid]

71 chev. p/u long bed, & put a 400 (.030 over) with 5.7 rods, KB pistions, vortec heads. Has 9.2to 1 comp. Comp. cams with .481 lift (if I remember correctly) A good stump puller, & will jump around cars when passing. Terrible on gas, & about 5200 RPM she quits pulling as hard.
(I guess I'm used to the 336CI in the drag car) the 400 will make a larger cam seem mellow. I am not sold on that longer stroke. Just my opinion

[ed455]

Yeah, the cam in my 406 has 235/240@.050 which would be really lumpy in a 350 and is relatively tame in the 406. It idles at 700 RPM with no problem once it's warmed up.

[davidh]

I have a mild 400 .30 over in a 81 1/2 4x4 short bed. It has 882 heads, the 350HP 327 cam, Hypereutic pistons(flat top). The cam sounds mild with the 400. Has aluminum intake, headers, good quadrajet. It runs really good. I am impressed with it, pulls hard. no mileage but it wouldn't matter in a lifted truck with 33's anyway. The truck is for sale and I will miss it when it leaves. I recenty bought another old caprice for it's 400 motor too. Might drop it in my 68.

[Ed ke6bnl]

my boy has one in his 4x4 70 chevy short bed 400 ci motor ran cool when we got it and it started running warmer we check timing, stat, rad, we replaced the clutch fan with a GM 1ton clutch fan the thing runs ICE COLD again. as it use to. Ed ke6bnl

Originally Posted by Dual quad

I've got one in the garage waiting for a rebuild. The 400's have 4.125" bore and 3.75" stroke to get the displacement in the SBC package. Due to the bore spacing, the bores in the casting are actually siamesed, thus there is no coolant flow between them. GM got around this by using steam holes in the cylinder heads to provide a flow path and to vent trapped vapour.

As svgould said, the bad reputation (overheating) comes from folks that used 350 heads (no steam holes) on this block. If you can find one, the 400 SBC can be built for not much more $$ than a 350. You end up with a fatter torque and HP curve. If you do one, swap the stock rods for 5.7" units.

If you're serious, do yourself a favour and pick up this book http://www.themotorbookstore.com/big-inch-chevy.html