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Hello all,
Building a SBC 406 and was wondering about an intake manifold. The compression is 10.2:1, edelbrock performer rpm aluminum heads, ported and polished, Doug Herbert hydraulic roller cam; int-230 exh-235 @.50 525/540 lift with 1.5 ratio roller rocker arms (I am using 1.6 roller rockers). Wanting to run this on the street/strip and am wondering if my weiand team g manifold will work??? Heard many different views but all 50/50.

ANY IDEAS???
 

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Discussion Starter #3
Not sure on deck height but c, ompressed thickness of gasket is .48, they're the felpro marine 400 gaskets with steam holes
 

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I do not know how far along you are on this engine but if the deck is stock with that gasket your quench area is going to be .073" with .040" - .045" optimum. The tight quench allow more timing, will give a better burn, produce more power and get better fuel economy. The larger quench distance will be prone to detonation no matter where the timing is set and rob you of power.
Building a 400 small block is way different than any other sb or BB I have ever built. The head gaskets available for the 350 block allow the quench to be correct without machining the block. The 400 head gasket choices are not very good. Because of this I chose to cut the deck on mine to achieve a .005" height and run a .039" compressed gasket for a .044" quench. My static compression is 10.53:1 and the dynamic is 8.77:1, a little on the high side but the engine still runs fine on pump gas. The bottom end is stock and dished pistons were used. All the bolts are ARP with studs on the main caps. Built for the street it performs well and fuel usage ranges from 14 - 19 mpg. This winter it will be run down the quarter mile just to see what it will do in street trim.

As far as the intake, the power band is from 2800 - 7200 rpm's. This will be great for top end power but will have very little bottom end torque needed for street use. What transmission and rear gearing will be used?

To get the most performance from any build all factors of the car need to be considered and work together. The engine build, transmission choice, rear gear ratio, suspension and weight of car all need to be factored in to get optimum performance for the type of use the car will see.

Here is an article you might find helpful, the quench portion is towards the bottom.

Pump Gas Secrets
 

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Discussion Starter #7
After checking my parts, I used the felpro headgaskets Fel-Pro Q17031 that have a compressed thickness of .039". Reading the article it was saying that most felpro gaskets with thise compressed thickness will put me in the quench numbers. Will running the team g manifold be sufficient with my engine?
 

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If your block is not cut the deck height is .025" + the gasket at .039" = .064". Not trying to tell you what to do, but advising what should be done. You have purchased or going to purchase a good cam and decent heads to improve performance, cutting corners on machine work will leave you a bit disappointed with the results.
On the intake, it is a mid to high range intake. If this will be driven mostly on the street it will not make power until in 2500 - 3000 rpms range. Your cam makes power in the same rpm range so it is matched to the intake. Just need to build the car to be in that rpm range most of the time.
 

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RPM Airgap would make better power down low and provide good performance to 6500 rpms.
 

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Philip,

I've never done a 400sb. Are you saying that even with aftermarket pistons, they are down .025 in the hole? I didn't see any mention of pistons/rods used by the op. But that just seems odd to me.

Reducing that to .005" will raise the compression quite a lot.

I do agree that quench is important, but it needs to be considered up front so the correct chamber size can be chosen to meet the desired CR. Nothing you don't know.

Ron
 

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Ron all the GM small blocks have an .025" deck height. It varies with machining tolerances but that is the design spec.
GM used thin steel head gaskets to keep the quench tight on production motors, there are none available for the 400 engine.Thinnest I could find was .039" compressed.
In my engine the stock rods and crank were used necessitating the need for the block decking. Mine was built 10 years ago so I am not familiar with the after market parts available now, if there is a piston or piston rod combination to raise the piston to zero with the stock deck height it would be achieve the same result.
Compression ratio varies greatly, as you know, with piston and head choices. I run a 12.5cc dished piston and a 65 cc chamber head. It nets me a little over 10.5:1 static, with the cam choice it gives a dynamic of 8.77:1 but still runs fine on pump premium without any detonation issues. I like the dished pistons, keeps the charge centered in the combustion chamber and allowed for the use of a small chambered head.

There are many combinations rod lengths, combustion chambers size and piston configuration that will work well but all will need to keep the quench tight to gain optimum power.

I had a friend with a 70 Corvette, LT1 engine. It had a lot of miles on it and needed refreshed. When assembling I advised he use the same thickness gasket GM had in it when it was torn down. He did not feel that the difference between the steel shim gasket and the .039" was enough to make a difference. To get it to run without detonation he had to set the timing was so far retarded that it had no power. I helped him install a pair of GM replacement head gaskets and it ran well again. This was in 1980 when the gas was much better than it is now.
 

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Philip,

Thanks, I appreciate the explanation.
This is what I get for venturing into LS land. The LS1 has the pistons .007" out of the hole, stock.

Ron
 

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I've had mine for just a little over a year, so no expert. But they sure respond to improvements using the stock short block. If you chose to keep the electronics and learn how to tune it, going back to carbs and distributors will be hard!

Ron
 

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since youre running small heads on a 400 cube engine, an RPM intake will work best with it... team-g isnt that good a single plane anyway.
 
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