[Raven Blayde]

I'm curious about just how "Bad" I could build my 400. To start off with, we'll take a look at what I already have. Car-68' Firebird with 3:73 posi rear. Engine- .030 72' 400, SpeedPro forged pistons, CAT H-beam rods, 72cc d-port heads flowing 240cfm @ .500, Holley SD intake, 750cfm DP carb, Headman 1.75' headers. Tranny is a 400 automatic with around 2800-3000rpm stall. If I go the "400" route, I'm looking to try a solid cam and Nitrous also. Wanna keep it "Pump Gas Safe" as well. I've been researching and considering the 455 "Stroker" deal as some of you guys know, but I'm also curious as to what the 400 is capable of doing as well before I decide for sure. 11's posible? Thanks in advance

[D. Miles]

11's are definatley possible! 400's are always under estimated but they have great potential. First, with the 72 cc heads and pump gas it will be ok on the street keeping timing to a minimum like around 32-34 degrees but be careful as detonation is still highly possible. Since your heads flow 240 CFM, thats a good start, 500+ HP is a realistic goal. The Holley Street Dominator will help too. 400's do like to turn a bit more RPM so 4.10 gears might be a thought but keep the 3.73's if you are definatley going with nitrous. And for your converter, alot of people look at us like we are crazy but we swear by 8" converters, even on the street. If you have one built by ATI, from our experience they are usually tight as far as foot braking (all of ours can only be pushed to 2400-2600 on the footbrake) and act the same and sometimes even better than some 10" converters (we have had 10" converters stall to 3500 on the footbrake but slip all the way through the RPM ranges and never lock up making a 10" "3500 stall" converter trap 6600 RPM at 8-10 MPH less than a 4500 stall 8" converter trapping at 6000) making them very streetable and since they are coverters built for high HP engines, they will hold up better than some of those "off the shelf or catolog" converters. I HIGHLY recommend this and especially for a 400... Go with a bit more carb too, aleast 850 CFM.

Let me give you a tried and true combo thats currently in my dads car that has been 10.61 @ 124 in mid June heat.

.030 400 with Speed Pro flat top forged pistons - stock rods - 240 CFM #16 iron D-ports - Warrior intake with 9375 Holley 1050 Dominator - Lunati solid flat tappet cam 262/272 @ .050 .575/.578 lift 106 LSA installed @ 104 - 2" Hedman Hedders W/Flowmaster Scavenger Collectors - 8" 4500 stall converter W/ATI T-400 reverse valve body trans - 4.33 gears W/ 29.5-10.5 slicks in a 3000 lb. 79 Grand Prix

My dad shifts at 6200 and traps around 6200. We have never built an all out 400 with like a roller cam and steel or aluminum rods and a set of "good" heads but since I only have 1 455 left for myself, I just might try one in the future... Thanks D. Miles

[Jeff Walker]

With the right cam you definitely have the ability to hit the 11's. You probably are going to want a higher stall converter though. Also with the 72cc heads and a flat top piston, I think you will be on the edge for pump gas compatibility.

[uneasyrider]

Running in the 11's on a street strip Poncho isn't the problem is how you want to do it. In that hp range (approx. 500) you can build a stroker or a screemer. I'd run the stock stroke and turn some rpms just to watch the "tuner" guys turn their heads as you pull over 400cid to 7,000+rpm. A 4.25inch stroker is an over square engine and they generally aren't rpm engines. The long stroke engines tend to shove the piston into the side of the bore more than the short stroke. For the street though if you want the engine to last as long as possable a stroker turning 6,000 and less is the way to go IMO.

[screamingchief]

I agree,11's are attainable with a 400 with the right hardware in a light chassis,that's what my race car being built to do,pretty much the same hardware your talking about using here,my car's a bit lighter though,all glass FE and decklid,no interior and such,appx. 3000-3100 lbs. less driver.

My plan is low twelves/high elevens NA,then spray it to get into the tens.

This way I can bracket race it easily as well.

My 400 is really similar to this,forged 2262F30's,6.625" eagle H-beam rods,670 heads that probably flow about 220-230 cfm or so,solid cams like these being discussed (first motor uses a crower custom solid #E-27941,the first back-up motor uses a comp 290b6,the third back-up will use a similar solid cam,maybe a custom bullet/ultradyne solid) .

Did I mention I'm planning on running these 400's real hard???

The multiple motors will allow me to upgrade/update one while running the other,then just rotate them and upgrade/update the next one,it will be a program to explore the limits of 400's built with more or less "basic" hardware.

I would say the 3.73's are the absolute minimum gear to use,would prefer 3.90's or 4.10's for best results,with the 3.73's you might try a slightly shorter and wider tire to bring up the "effective" gear ratio somewhat.

And yeah,plan on another convertor up around 3600-3800 stall minimum with a big solid,and let them know you plan on spraying it and how much,this will greatly affect the convertor build,you'll wanna tight unit,so when you spray it the stall wont go thru the roof!

You'll want the balloon plates too!
Spend the money for a quality convertor here,you wont regret it!!!
Continental,ATI,PTC all good choices.

And I'll be using a rev.manual valvebody,so I wont need any vacuum to operate the modulator.

Also agree you'll probably want a bit bigger carb,I'm starting with torker II with a 4780/800 holley DP,and I wish it was the 850,these would be the minimum IMO,would love to have a couple victor/dominator combos on hand to use,but too much $$$$ for me right now.

And I plan on upgrading to bigger primary headers with the heavy nitrous use,1 3/4" is the bare minimum IMO.

Make sure the valvetrain is up to the task,invest in a stud girdle for high RPM stabillity.

I'm not the least bit concerned about pump gas use though,mine is race only,the least it will see is 100 octane unleaded,likely run mostly leaded 104-108 octane.

Dont plan on having much idle vacuum,so power brakes are out!

I'm sure that more will come to mind,I'll drop back in if I think of anything,if you want to know more about what I'm up to with my race car,click the link in my sig,it's all nearing completion and such,kinda been longer than I hoped,but that's what I get for juggling three projects at once,two of which rely on my current shoestring budget.

HTH.

[Raven Blayde]

Thanks for the input guys! I'm actually just looking to get deep into the 12's on engine and use a "Mild" nirous setup (Probably the 125hp "Power Shot" or something) to break into the 11's. Since I live 2 hours from the race track, I only get to go once or twice a year, so 99 percent of the cars life is street duty. I have been known to do some local "Street Stalking" late nights during the weekends and the old Firebird used to love those 5.0's and Corvettes I definantly want to put the compression in the "Safe" zone and don't care to dish those pistons a little to get it there. I do have the Comp 290B solid already here, but this is probably gonna be a bit much for the 400 if I drop her down to the 9.5:1 range. Last year, I had everything listed above in the car (No nitrous though) with a Crower 229/239, 108 degree lobe seperation, .483/.501 lift hydralic cam (Used 1.5 rockers) and had her down to 13.00 while having a spark plug not even firing. Wish it had lived long enough to get a pass in with all plugs firing. lol... I was actually pretty happy with how it ran (When it ran right) but couldn't help but wonder all the time I drove it how it would have ran with a solid cam and juice. The more I study and research, the more I'm leaning towards keeping it a 400.

[Will]

Get the heads ported a little more, into the 260 cfm range or buy a set of aftermarket heads, either ported KREs or Edelbrocks.

Stick a Crower 60310 solid cam in it with a set of 1.65 rockers, a 3500 stall and hang on.

Also - what exhaust system behind the headers? 3" mandrel bent with good mufflers would be a very good idea.

[sixt8bird]

I have pretty much the same set up as you and am in the mid 12s with a very heavy 3800 race weight 1968 Bird. My heads arent ported and am using the Crane Commander 226-234 with 1.65s, Holley SD with 800 Holley DP. I also have 3:73s and 3,000 stall. With a very poor nitrous set up, WAY RICH like off the scale fuel rich my time was 12.01 @ 111 and then a 12.12 at 114.4 bouncing way hard on the rev limiter 6200. If I can get the nitrous set up to run less rich I am thinking mid 11s. as I have also gone with taller tires. You have ported heads so you should be making more power than me and also like you, I only hit the track a couple times a year and the rest is street driving. I love my combo as its so street friendly.

[goquick]

Raven, Your cam will work fine if you dropped the compression, just advance it 2 more degrees. Personally, I'd keep the compression.

[Raven Blayde]

Thanks for the many replies from everyone! goquick- You really think the 290B would work okay with the 400??? That would be cool if it did! Would save me from having to go "Cam Shopping" again. I was afraid the cam would be too much for the 400, but maybe not?

[goquick]

Look at it this way; You already own it and going cam shopping for a cam that is just a tad smaller is going to do what? Like I said, advance it the couple degrees and enjoy it. bY ADVANCING IT, YOU WILL PUT IT WHERE A LITTLE SMALLER CAM RPM RANGE OF POWER, ONLY YOUR MID AND UPPER RPM POWER WILL WIN EVERY TIME.I 'd go with what you have.

[Raven Blayde]

Thanks goquick! You just made my day

[Colin]

I think 11's would be fairly easy. I have a fairly mild 400 in a Ventura (3400 lbs) that runs 12.7's in the 1/4 on plain street tires with a 4 speed and 3.90 gear. I could easily run quicker with a sticky tire but Im afraid of breaking the 4 speed.