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Author Topic:   SBC 400 -- Ideas & Suggestions
Deak-Jr
Dirt Forum Racer

Total posts: 81
posted January 28, 2004 12:49 PM  
Looking for some suggestions from folks smarter than myself (which includes pretty much everyone, yuk yuk).

We are hopefully going to get a 400 under the hood this year. Pure stock '84 Monte Carlo, dirt.

A little more info -- I am planning to run 6.42 final this year (1.88 in 2nd of a 4-spd Muncie, and 3.42 R/P). At 6.42, I think I want to go to 255/60/15 in the back (maybe 245/60/15 LR if needed). I don't know the math but I'm guesstimating we shouldn't be too much above 6000 that way, on a semi-banked 3/8ths which is more often rutty than tacky. Occasionally it's smooth and slick ...

Anyway, we got a 400 donated from a fella who deals in older GM stuff. Tore it down and it is in very good condition. (Code on it is "CTY"; one of the old manuals we have shows this out of a 1970 Nova, having been hooked up to a Hydramatic and s'posed to have put out 375 HP stock).

The block is good, short of boiling/cleaning & honing. The pistons look good. The crank was run out on #3 (getting welded & machined to re-use) but otherwise good.

We're wondering about some ideas on heads & cam, to get us some decent low-end power while not going nuts on compression. One of our friends preaches the bible of Vortec as per the heads. I wonder what size the most common were (64cc?) ... and what kind of compression (ball-park) we'd be getting w/the stock setup on this 400. Also, we have the stock cam out of the block but if we can get some better low-end oomph without risking the hook from Mr. Vacuum Gauge Checker with an aftermarket Comp product or something, I'm all for it.

We run at a few different tracks -- one of 'em is a "pay us $25 at the gate and you're legal" kind of place.

But the other (a very nice 1/4-mile high-banked) checks and enforces a little more -- we're wanting to be legal for there. Have to register 12# vacuum, OEM intake/heads, Q-jet or other stock 2 or 4 barrel, etc.

Any ideas, suggestions, insults, accusations of being miserly, etc., are very welcome.

[This message has been edited by Deak-Jr (edited January 28, 2004).]

Raz_900
Dirt Forum Champ
Total posts: 635
posted January 28, 2004 07:48 PM  
Couple things come to mind... First, the 400's NEVER made 375hp stock. The 396/402 big block (sometimes called the 400 BB) maybe, but not a SB 400. The factory killed them with lame compression and weak heads & cam.

Anyway, I'd recommend dumping the stock rods and pistons. At the least, get a set of 350 5.7" rods redone with ARP bolts. Speed Pro Hypereutectic flat top pistons should be fine and can be had for around $150. Vortecs are a good choice for heads. They have 64cc chambers and flow well out of the box even with 1.94" and 1.5" valves. Although, they need some work to run over .450" lift. With the Vortecs and flat tops you'll have around 10:1-11:1 depending on if the block or heads get milled.

I'd also recommend ditching that rearend (stock 10 bolt?) and putting a 9inch Ford. Throw a 6.00 or 6.20 gear in it and rebuild the tranny with only 3rd and 4th gears. I'm assuming you don't use 1st at all? I've never understood why some people setup a car to only have 1 gear when there's an option to have 2. I run a powerglide and most people at my track run 4spds although a few ran a TH350 last year and a couple more a switching to a 'glide this year. The TH350 guys ran 2nd and 3rd and compared to my 'glide (1.82 1st) just got killed on restarts. The 'glide really pickups if you're near the front and with a good valvebody shifts faster than anyone can kick a clutch and pull the shifter.

I'd run a prepped Q-jet and 1 5/8" headers if you're allowed. 1 3/4" headers would flow better up high, but you're not going to run where they would help make power. A cam in the 230@.050" range should still be able to pull 12" at 900ish rpm on a 400 and peak around 5800-6000.

But, that's all just my $.02.

77k
Dirt Maniac

Total posts: 174
posted January 28, 2004 09:28 PM  
I run a 590 gear at our 3/8,but run smaller tires.I like using the good felpro head gaskets like the 1004,about $30 each,but reuseable and i have never had trouble with them and have reused them a lot. 5.7 rods,like X rods the best.vortec or double humps.Midwest motorsports has a 510 hyd cam that should pull more than 12lbs.We have an engine builder in ok that will sell you a cam that will pull 17 18 lbs for factory stocks.{about $180 for cam and lifts,but fast] I might a set of trw pistons with rods.I think the may have a small dome.

77k
Dirt Maniac

Total posts: 174
posted January 28, 2004 11:27 PM  
saw 400 cranks in part mart for $40.952-873-5412.

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