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  #1 (permalink)  
Old 12-07-2004, 01:38 PM
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400 SBC Newbie

I'm new to the 400 SBC and have read a lot of the posts here on the 400 SBC.

It is a stock 400 from 1971 (Block - 3951511)

I can't remember the Casting number on the heads.

The motor is attached to a 350 Tranny with a 3500 Stall in a 1967 Camaro.

The car has 3.73 12 Bolt rear end.

Now, my question is, what Cam should I get?

I'm leaning towards:
CompCams 268 Xtreme Energy camshaft

I'm unable financially to get new heads right now, but I have a guy that I'm trading some other parts for that is going to port, polish, and gasket match the heads for me.

I have an Edlebrock Performer Intake (Which I will probably keep because of the low revving of the 400) with a Holley 650.

Should I get the heads done?
What Cam should I get?
Should I wait until I can get them all done at the same time?

Will the porting, polishing, and gasket matching help/hurt my performance?

Sorry for the very basic questions...just trying to do the best with what I have.

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Old 12-07-2004, 02:37 PM
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That is a small cam for a 400sbc.

You gave a lot of info but I didn't follow exactly.

The heads are currently on a 350 with a 3500 stall...or?

What vehicle do you have?
gears?
stall & trans?

What is its intended purpose?
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Old 12-07-2004, 04:37 PM
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NXS,
If you read the post your questions are already answered.

Camaroguy,
Was this the set up before you decided on an upgrade?
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Old 12-07-2004, 04:41 PM
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Well if its going into that Camaro with 3.73s and a 3500 stall I'd use a Comp 292 and yes, get the heads ported by your freind.
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Old 12-07-2004, 04:43 PM
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I agree that if you are getting a good deal on the porting that it is the way to go. I would go with an XE274H at the smallest.


Adam
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Old 12-07-2004, 06:02 PM
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Maybe I'm missing the point of some of this advice, but why put a high-rpm cam in a low-revving engine?
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Old 12-07-2004, 06:09 PM
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Why put a low revving engine in front of a 3500 stall and 3.73 gears?
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Old 12-07-2004, 06:26 PM
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If its a stock 400 with the stock heads, you are probably looking at 8.5:1 compression so you would want a camshaft to match this. The Xe268 cam would be excellent if the 400 is completely stock. Using that 400 motor with a stock bottom end along with a 3500 stall, that motor will not last long though. It is only going to leave you appr. 1500 usable rpm from 3500-5000. Stock 400's are not good for turning rpms with the big end of the stock rod with a stock bolt being the major flaw along with the rod-stroke ratio. Stock 400's are designed for torque at a low rpm. I would go with your combination except go with a 2000-2400 rpm stall. If you can get the heads done also, it won't hurt a thing. Street 400's can easily use a 200cc intake port and stockers are around 160.
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Old 12-07-2004, 06:38 PM
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Quote:
Originally posted by tornado-tech
If its a stock 400 with the stock heads, you are probably looking at 8.5:1 compression so you would want a camshaft to match this. The Xe268 cam would be excellent if the 400 is completely stock. Using that 400 motor with a stock bottom end along with a 3500 stall, that motor will not last long though. It is only going to leave you appr. 1500 usable rpm from 3500-5000. Stock 400's are not good for turning rpms with the big end of the stock rod with a stock bolt being the major flaw along with the rod-stroke ratio. Stock 400's are designed for torque at a low rpm. I would go with your combination except go with a 2000-2400 rpm stall. If you can get the heads done also, it won't hurt a thing. Street 400's can easily use a 200cc intake port and stockers are around 160.
I agree. The XE268 will help bring back some low RPM cylinder pressure lost due to the low compression.

On my 400 I went with a 114o lobe sep. It helps keep your torque curve nice and flat. That is good. With a 400 the torque will already be high. Spreading it out over a larger powerband will net excellent street manners.

I went with a 2,400 stall. I have a lot bigger cam in mine. I recommend a 1,800 to 2,000 stall for yours. I also kept my stock gearing. This enables me to stay within my peak torque range longer. The extra torque of the 400 will allow you to run lower numeric gearing and still get off the line easy.

I have Sportsman II heads. They came stock at 200cc. My set is ported to the max. I still have more bottom end than I know what to do with.
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Old 12-07-2004, 07:09 PM
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Hey Camaroguy, is this a race car, street-strip, driver or what?
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Old 12-07-2004, 10:35 PM
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I also used the XE268 in my 406. It's the largest XE cam for a stock converter. It would break the tires loose with a 2.41 rear gear!

The reason I asked about the prior set-up was because that stall seemed way high.
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Old 12-08-2004, 06:48 AM
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OK, sorry for the delay on gettig back to this topic.

I bought the car with the tranny but no motor.

I put the 400 SBC in it later.

The 400 SBC is completely stock. I only put headers, edlebrock Performer, and the Holley Carb.

I called the guy that I bought the car from last night to verify that it is a 3500 stall, however he said it was only a 2500 stall.

So, I apologize for misleading anyone it is a 2000 Stall rather than a 3500.


The car will be used for Cruise In's, street playing (stop light to stop light kind of thing), and other stuff. I would like to take it down the 1/8 mile once or twice but nothing too hard.

I want a great sounding classic car that will have lots of power on lauch and will cruise nicely.

I looked at the heads and wrote the number off the heads down, but have not been able to find then on any database, so I will have to verify that this is the number on the heads: 3973488

Thank you for your replies on this.
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Old 12-08-2004, 08:04 AM
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I don't know what heads you have.

A Comp 280 would be nice for you. It will give a good sound and won't be too big for the 400ci even with an average set of heads...but you really need to know more about those heads to make a proper decision.

Intake runner cc

Combustion Chamber cc

Valve size.

If they are1.94s and 160cc runners/64cc run the 280/480"

if they are a 72 cc run a steel shim head gasket and the 280/480"

If they are 155cc intakes runners, port them or look for new heads.
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Old 12-08-2004, 08:09 AM
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I'll look again, maybe I wrote the number down wrong.

Most of the stock heads I have see for the 400 SBC in were 76cc heads.

I'll double check today and post back.

Thank you for your time helping me.
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