Small block 400

[Linville33]

Just picked up a 83 scotsdale. Has a small block 400 in it. Sounds like a rocker knock. Was wondering what's a good build without breaking the bank

 

[MikeB]

By "good build" I assume you mean rebuilding the engine, right? That "tick" could be a simple fix, like a lifter adjustment, or it could mean a collapsed lifter or wiped cam lobe.

Do you have to keep the emission equipment in place?

What is your transmission type, tire height, and rear axle ratio?

How do you plan to use the truck? Will you tow with it?

I can at least tell you that stock 400 cylinder heads severely limit performance potential, but if you're looking for lots of low RPM torque, they will work OK with a mild cam, small 4bbl carb, and dual exhaust.

 

[Linville33]

Sorry should have added that lol. Fixing the rocker tick this week sometime. It will be built to be streetable but to tear the mud up on the weekends, currently it has stock tires on in but will be getting 38's and a 8 inch lift. Has a 700r4 trans 208 t case but gonna be swapping to a sm465 and a 205. will tow a boat with it. What heads should i look to put on it?

 

[MadOgre]

Honestly the best use for a 400 SB is to have the crankshaft journals milled to fit a 350 SB

Those big main bearing journals severely rob power and with the stock heads not really a lot to be gained over stock.

You could make a 350 perform better

Or even better a 383

 

[morrow07]

I respectfully disagree. 5.7 rods, good heads (iron heads are fine), and a nice cam on a 400 will put better numbers down then a 350 or 377 any day of the week. The low end grunt, which is what the truck will need, will be at least 450 ft/lbs.

Sent from my C771 using Tapatalk 2

 

[350runner]

vortec heads and headers simple big power

Sent from the dust in front of you!

 

[MikeB]

I respectfully disagree. 5.7 rods, good heads (iron heads are fine), and a nice cam on a 400 will put better numbers down then a 350 or 377 any day of the week. The low end grunt, which is what the truck will need, will be at least 450 ft/lbs.

Sent from my C771 using Tapatalk 2

I mostly agree. Even a stock 400 in good condition will make more torque than a 350 and do it at 1000 rpm lower. That's why Chevy used the 400 in station wagons and pickups. And it sounds like TQ is what the OP needs.

If money is a factor, I'd look into rebuilding the stock heads, unless they have only 1.84/1.50 valves. You should be able to find a rebuilt pair with bigger 1.94/1.50 valves, like those used on some 350s. Even take-off heads from a base 350 Goodwrench engine would probably work better than stock 400 heads, and they'd be 40+ years newer. (Be sure to note the head casting number when you have the valve covers off. You never know what might have been done to the engine over the years.)

Also, something like an Edelbrock 2103 cam & lifter kit is inexpensive and should work well. It's got 10 degrees more intake duration than their entry level 350 cam.

 

[hirschdalechevy]

My old yellow 77 I built a 400 sbc , quench motor , 9.8 to 1 , comp cam , afr heads and out of all the trucks I have had with pumped up 350's , this 400 blew them all out of the water.

If it were me I would be thinking D dish pistons , square decked block and bad boy heads , and if you want to skimp on the heads , vortec's would be my next choice. Vortec's work well but they dont stack up to aftermarket heads , imo.

 

[CSFJ]

I was always told that the 400 heads were a little different in the cooling openings to account for the cylinders having shared walls. That the 400 heads would work on other small blocks but not the other way around. Any truth to this?

 

[Linville33]

Thanks for the replies guys. Yea I don't plan on this thing to do 150 mph but low end torque is what I want/need. I don't know much about aftermarket cams. What's a good lift? Duration?

 

[hirschdalechevy]

I was always told that the 400 heads were a little different in the cooling openings to account for the cylinders having shared walls. That the 400 heads would work on other small blocks but not the other way around. Any truth to this?

The 400 head's have steam hole's so you can use any smallblock head on a 400 but they have to be drilled and you must use 400 head gasket's.

 

[CSFJ]

That's what I had always heard. Never thought about drilling the steam holes in a head off of a different block though. Gotta remember that one.

 

[hirschdalechevy]

Thanks for the replies guys. Yea I don't plan on this thing to do 150 mph but low end torque is what I want/need. I don't know much about aftermarket cams. What's a good lift? Duration?

There is lots of things to think about here first , tire size , gears , what are you going to do with the truck , etc...... but I will just tell you my set up (mean)

77 1/2 ton , 4.56 geared 8 lugs , turbo 400/205 , 38 inch ground hawgs.

407 smallblock
scat crank , cast steel 9-400-3750-5700
5.7 rods
square decked block
forged 22cc d-dished piston's at 0 deck
felpro .039 head gaskets
afr 180 heads , 65cc
eddie intake
comp xe268h cam 224/230 dur at 0.050 ,477/480 lift 110 lsa
crane , springs , locks , retainers , rockers , push rods
cloyes true roller chain
doug thorley headers etc...

My daily driver at the time , never broke down , very fast , won a lot of street truck mud bogs with it , 4 wheeled it all the time , great set up , must have a good 4 row radiator to keep things cool , pump gas.

Save some money , the vortec heads work great for torque , but they dont do well after 4500 rpm or so and you have to watch the lift of your cam.

Figure out your compression you want to run , (quench is the way to go) , then selct your cam to keep the cylinder pressure high , (165ish for iron heads , 185ish for aluminum heads) and you will be on your way.

Yes there is a lot more to it but this should get you started.

That set up I had was 400hp or better all day long and over 400lbs torque at 2000 rpm all day long and I would guess about 475ish at 4500 rpm , crazy fun to drive in a big truck and would run out to 6000 rpm.

hope this helps , I only mess with big blocks now in my square's.

 

[MadOgre]

I dunno I guess some peoples breaking the bank is not the same as mine lol.

As soon as you mention aluminum heads. I think the bank is broken!

 

[Linville33]

There is lots of things to think about here first , tire size , gears , what are you going to do with the truck , etc...... but I will just tell you my set up (mean)

77 1/2 ton , 4.56 geared 8 lugs , turbo 400/205 , 38 inch ground hawgs.

407 smallblock
scat crank , cast steel 9-400-3750-5700
5.7 rods
square decked block
forged 22cc d-dished piston's at 0 deck
felpro .039 head gaskets
afr 180 heads , 65cc
eddie intake
comp xe268h cam 224/230 dur at 0.050 ,477/480 lift 110 lsa
crane , springs , locks , retainers , rockers , push rods
cloyes true roller chain
doug thorley headers etc...

My daily driver at the time , never broke down , very fast , won a lot of street truck mud bogs with it , 4 wheeled it all the time , great set up , must have a good 4 row radiator to keep things cool , pump gas.

Save some money , the vortec heads work great for torque , but they dont do well after 4500 rpm or so and you have to watch the lift of your cam.

Figure out your compression you want to run , (quench is the way to go) , then selct your cam to keep the cylinder pressure high , (165ish for iron heads , 185ish for aluminum heads) and you will be on your way.

Yes there is a lot more to it but this should get you started.

That set up I had was 400hp or better all day long and over 400lbs torque at 2000 rpm all day long and I would guess about 475ish at 4500 rpm , crazy fun to drive in a big truck and would run out to 6000 rpm.

hope this helps , I only mess with big blocks now in my square's.

Thanks man, sound solid. I wanna run 38's 8 in lift. trying to get an sm465 and a 205. will be a "daily driver" by that I mean drive it when I want it on the street but when I wanna beat on it I want it to be solid and able to take the abuse