Thread: 400 SB Q's

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I'm starting to do some research for a budget race /muscle car I would like to start building this summer. I was thinking about a mid 80's Monte Carlo with a Chevy 400 Small block and Muncie M22 4-speed. I've been tinkering around on desktop dyno 2000 and I've got a pretty stout combo. I want to set the car up for road course racing and occational street floggings.

Block: Chevy 400 SB 4.125 Bore/3.75 Stroke
Cylinder Heads: Air Flow Research 220 CC Race Ready 66 CC chambers w. 2.080 int/1.600 exh valves
12.5:1 Compression
900 CFM carb on Tunnel Ram Intake Manifold
Large diameter long tube headers
and a tweaked version of the ZZ4 camshaft.
Cam Specs:
LCA - 116 | Intake Centerline - 114.5 | Int. Duration - 275 | Ehx. Duration - 300 | Int. Lift - .575 | Exh. Lift - .610 | 1 degree advanced timing

DD2K says this engine should make 633 HP @ 6500 RPM and 571 FT LBS @ 5000 RPM.

Would spinning to 7K be safe assuming the rotating assy. is forged? Is 12.5:1 compression too high to run on 93 or 94 octane? Should a solid lifter camshaft be used? Does a 305 and a 400 SB mount the same way or would different motor mounts be required? There are probably more questions I'm forgetting, if I think of any later I'll post them up.

Thanks, Chris

305's and 400's have the same mounting places. 12:1 is too high for pump gas, you could mix up a little laquer thinner ( mostly made up of Xylene and Toulene, 2 common ingredeints found in octain boosters, that do the octain boosting ) in the gas to incerease octain. You'r gonna have a lot of work getting the tunnel ram to work, the engine has to pull a negative preassure and with a regular intake, it's normally ok and not a hassle but with a tunnel ram, theres a lot of volume in the tunnal ram and it will be hard to get it to run a negative preassure with all the volume it has to work with. I think that you'd want an M-21 Close ratio Or a richmond 4spd as the M-22 " Rock Crusher " is kinda rare and pricey. Myself, I'd use a 350 instead of a 400 because the 400 has siamese bores.

I suppose I could mix up some toulene (sp) with 93 or make the trip down to the ZAZZ! station and fill up with 100 leaded. If I was to set it up to run on pump gas what do you think is the most compression I could get away with? I was favoring the 400 over the 350 or 383 because everyone has a 350 and it made a little more power. What are the disadvantages of siamesed bores?

I forgot to add in the last post, DD2K showed the difference between a single plane and a tunnel ram and barely noticable. I'm a youngin and I'm still learning so bear with me, I'll catch on eventually.

Originally posted by LSChriSS
I suppose I could mix up some toulene (sp) with 93 or make the trip down to the ZAZZ! station and fill up with 100 leaded. If I was to set it up to run on pump gas what do you think is the most compression I could get away with? I was favoring the 400 over the 350 or 383 because everyone has a 350 and it made a little more power. What are the disadvantages of siamesed bores?

Pump gas, 10:1 max.

The siamese bores tend to be a lot harder to work with, with the water jackets where they are and stuff, 350 is a lot easier to work with, specially if your a beginner. Personally, I'd make an 8:1 motor and mount a 6-71 or 8-71 Blower on it, I'd be a runner for shure.

I would strongly advise you not to use the cam you mention....With a 116 lsa you are heading for trouble from the get go....You want to be more around 108....

The reason for this is because of the 12:1 compression! with higher compression you need more overlap to cool the cylinder/piston....with a wider angle your going to generate way more cylinder pressure/heat than you can deal with....it may run at idle but as soon as you hit the gas it will rattle/melt itself....
DD2K will not compensate for this ....the real world ...that cam works on the newer more efficient head/cylinder combos....

Other than that....the rest of the combo is spot on...I would call the cam maker of your choice and talk to them and let them pick you a cam.....to use that compression for an occasional street floging your going to have to "overcam" it slightly to bleed off a little low end clyinder pressure just to keep it safe....

DD2K only realizes "perfect" scenerios and does not warn of mismatched parts....this can be noted by a high Volumetric Efficiency with a low Base Fuel Consumption....

I would really stick with the 400 especially if you already have it regardless....theres no replacement for Displacement!....

If you want more power out of it with a milder cam...stroke it...450+ inches can be had for a little more money....

My next project is a 465cu.in. stock block small block...I am heading to the engineers this weekend to see if my idea is feesable? I have a 700hp 341cu.in. (stroked 327) and have built a 365 sb using a 350 block and 350 crank and adding some parts from around the shop....this engine was way hairier than any 383 ever....

As of right now I don't have a block, or the car for that matter. Just throwing out ideas. I'd like to have atleast 600 hp and 500 ft lbs with a nice flat torque curve so it can really dig out of the corners. I'd like to shift it at about 7k because that seems very doable without having to use "un-obtanium" internals. I am open to pretty much any engine block/displacement as long as it's a chevy small block.

well take a look at Jegs and find the 454 mowtown small block...pricey...but garenteed...and is right where you want to be....you may be able to build it for less....?

well what do you expect... horsepower come with a pricetag....I am scared of that price too...

Monte Carlos are a popular swap for Gen III small blocks like the LS1 and LS6. They can make a ton of power and still be pretty smooth running. They are also 100 pound lighter than a SBC and are available with a decent 6 speed transmission. If you want to build more cubic inches, you can get an LS2 crate motor or start with one of the 6 liter motors from a Cadillac escalade. They are stroking these out past 427, in fact the new Corvette LS7 is based on the same engine.

Check out http://www.ls1tech.com

I am curious what road courses you plan to run this car on, and what class you hope to be competitive in.

Just some other options to consider.

Pat