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Old 11-29-2011, 07:28 PM
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Wake up a 400 SBC or not ?

I have a stock 400 sbc , standard bore ,rods,crank and heads . The only parts not stock are the carb ( 650 Demon ) , Edelbrock performer intake , the shorty block hugger headers , an MSD HEI distributor and a cam of unknown specs that I will probably change out anyway . It's in a very light weight 3 window coupe . The stated factory compression ratio is between 8.5:1 and 9.0:1 The engine has under 1000 miles on it after rebuild .
I would like to "wake it up " a little without getting too carried away .
Can this be done by just replacing the upper end ie. heads ,cam and lifters , and not get into the short block ? Would it be worth doing ?
What cc's are the factory heads ?
Would it help performance by using heads with a smaller combustion chamber and larger valves ? How much compression could I get it up to without changing the rotating assembly ?
If this is a reasonable approach , I would like some specific reccommendations such as brand , part # 's , specifications and real world expectations .
Not looking to set the world on fire or anything like that , and it is already pretty quick for the street but running a stock motor in my streetrod is killing me . I'd appreciate any knowledgeable input . Thanks !

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Old 11-30-2011, 12:43 PM
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Did a little reading ( DUH )

I got to looking around the shop and found some sbc books and " How to rebuild your SBC " by David Vizard has some of the info I have been asking about . I want to run it by some of you much more knowledgeable guys for your thoughts . The book has a real good chart showing the different heads and their specs and a chart showing what the different heads should do to my specific setup . I have the "882" heads on my 400 and the chart shows them to be 76 cc that gives me a C.R. of 8.2 :1 It also shows a 69cc head brings it up to 8.7:1 , 64cc @9.1:1 and 57cc heads bring it up to 9.7:1
Which head volume /compression ratio would be most desirable for my street driven coupe that has to run on pump gas ? I would like some input on which cam to run with that specific C.R. And iron or aluminum ? Thanks in advance for any input . choptop26
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Old 11-30-2011, 01:18 PM
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To original poster. If Your block has already been rebuilt then it should be strong enough for a top end upgrade. It really depends on what you are Really looking for. More HP or a tq monster. But with a 400 you can have the best of both. I did a budget build that with something like this.

Heads: Eq heads 180cc with 64cc chambers
Intake: Professional Products Air Gap intake
Cam: LUNATI voodoo 268 227/233@50 with 489/504 lift
Comp cam 1.5 roller tip rocker arms
1 5/8 long tube headers

This is a TORQUE MONSTER with good streetable HP.
This combo pulls hard to 5800 and will blow a tire off at WOT from a dead stop. And will get loose from 30-45 MPH AND it opens up.

It helps if vehicle has rear gears. With a combo like this in a light vehicle, gears 3.73 or lower would Really wake IT up.
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Old 11-30-2011, 03:11 PM
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Now we're gettin somewhere !

This sounds like what I am looking for . Looking at the EQ website and found the 180cc runners and 64cc chamber in a cast iron head . Is this what you used ? Offered in angle plug or straight for $400 each . 2.02 int and 1.60 exh. What kind of vacuum do you get at idle ? How is the idle ? What octane gas do you run ? Sorry for all the questions but just trying to nail down the characteristics . If you run an auto , what stall do you run ? Thanks for the help .
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Old 11-30-2011, 04:57 PM
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your bottom end will be fine if just rebuilt..i replaced a set of heads on my 350 and after 80,000 miles could still see the hone marks..once your heads are off check cylinders for signs of falts..
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Old 12-01-2011, 05:32 AM
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You will love this combo if you have some gears.
I bought My heads from a nearby machine shop Guy who was cleaning out shop for less than 300 buck-$Deal$
This engine idles choppy with 15" of vacuum.
Our premium here is 93 octane. It runs on that But Have ran it on 89 with no problems also. For more info, I Have a 10.7 compression 520+ hp 406 that runs great on 93 here.
Also, try a 750 Holley with vacuum secondaries. When u put your foot in it, hold on AND keep it straight.
And we run a Turbo 350 trans.. stall converter is 11" 2200.
Its right Where you WANT it for this combo if you are looking for a Street Toy.

Some around here think its a big block When I stand on it.

If your build comes out anything like the one that's here, YOU'LL LOVE IT..

Last edited by VARS_85MONTE; 12-01-2011 at 05:38 AM.
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Old 12-01-2011, 06:06 AM
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I have a SB 406 I rebuilt. 10 under crank, resized and balanced rods, cast Silvolite flat tops, Comp Cams 270H, Holley 750 w/vac sec, Weiand X-Celerator manifold port matched to rebuilt 76cc heads with all new valves, guides, springs and roller tipped rockers, turning a th350 through a 500 over converter, cranking the stock Dana 44 with 390:1 gears in the truck pictured above.
I haven't really got to really ring it out yet to see what it'll do, but I did open it up one time and about crapped my pants. Both tires lit up all the way through 1st and 2nd, started going sideways then I let go.
I have no idea what my horsepower rating is.

Last edited by Busted Knuckles; 12-01-2011 at 06:18 AM.
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Old 12-01-2011, 12:55 PM
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Yes !!!

We are on the right track . Dang Vars , you bout had those heads given to you ! That's great . I'd never get that lucky seeing how I'm pretty rural and will have to have the big brown truck bring'em . I have a question for you though . I see that there are other heads out there with the 64cc chambers and 180cc int. runners made of aluminum . I don't know the answer but something tells me I would be better off with the aluminum since it is supposed to help guard against pinging over an iron head of the same specs . Is this true ? Speedway offers some Flo-Teks for $350 each and they are aluminum / 64cc/180cc . What do you think ?
Sounds like you are making a BUNCH of HP/TQ Knuckles . Any Idea what your compression ratio is ? I guess you accomplished a bump in comp. with the pistons as opposed to the way I am going to try to do it ( smaller cc combustion chambers ) . Wonder what the difference is in the final analysis . Let me know what you guys think of the alum. vs. the iron heads . Thanks again !!!
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Old 12-01-2011, 01:49 PM
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Not real sure, but with my heads and flat tops and 030" overbore, I think I figured it out once to be about 10.5:1. But I really haven't even dialed in the timing or mixture settings yet.
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Old 12-01-2011, 03:26 PM
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I got a 406sbc with dual 390 holley (780CFM total) on a Edlebrock TR1X Tunnel Ram with AFR227 heads. 11:1 power forge pistons. Comp cam 280H with 1.6 roller rockers connected to a TH350 tranny with a 3500RPM converter and 410 gears. When I hit the pedal to the floor and you better hang on to your dear life. It will leave a brown stain under the seat. My 69 Chevelle will fly sideways

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Old 12-01-2011, 04:46 PM
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Aluminum is a big plus, weight reduction and if more forgiving to compression and pump gas. I think for that price it could be worth it.
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Old 12-01-2011, 04:55 PM
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Guess I'll poke around and see if anyone has anything good or bad to say about the Flo-Tek heads from Speedway . We'll see what the good guys of Hotrodders Bulletin board have to say about'em . Thanks
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Old 12-01-2011, 05:07 PM
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I also have a 10.7 406. I run it on pump gas- 93 here

Brodix ik 200 heads
LUNATI voodoo hydraulic roller 535/550 lift
AIR gap and 750 dp Holley

522 HP/ 555 ft lbs.

In a 85 Monte Carlo with 3.73 gears.
Turbo 350 with 3000 stall

HELL ON WHEELS!!!
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Old 12-01-2011, 07:33 PM
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I'm new to this site but I thought I'd put my 2 cents worth in here. To original poster... What casting # on the heads you have now? Probably 487, 993, 997 or possibly 441. If 1970 441 castings you have 80cc chambers. A 400 sbc will run like crazy built with the right parts. Double hump cylinder heads ported properly will give good compression and airflow to support 450hp easy with a 400sbc.
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Old 12-02-2011, 05:17 AM
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Whatever heads you end up using, make sure they have the steam holes between the cylinders that are unique to the sb400. If they're not there, use a 400 head gasket as a template to drill the holes. Heads from any other smallblock will not have these holes.
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