Help with 406 sbc build

General engine tech -- Drag Racing to Circle Track

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johnny5
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Re: Help with 406 sbc build

Post by johnny5 »

But I'm still trying to make the best average power up to around 6000 rpm with a hft camshaft on pump gas
F-BIRD'88
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Re: Help with 406 sbc build

Post by F-BIRD'88 »

You don't want to open those chambers up to the 400 gasket fire ring.. You seem incompetent in these areas. Leave it alone. The fire ring is bigger than the bores are.
There are lots of areas in a sbc combustion chamber that can be deshrouded to increase flow.
The 170 cc as cast heads can be ported to create great flow and velocity. (178-185cc finished volume)
The rod beams need no work. The rid big ends need to be checked. As long as the rods are straight and the big end is in spec they are fine.
If you use a garden hose to spray a water stream thru the ports you will see where the air flow pattern is on a sbc.
johnny5
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Re: Help with 406 sbc build

Post by johnny5 »

Opening up towards the fire ring ,on these 200cc heads,increases flow at every lift. Yes, I am extremely incompetent at cylinder head porting, don't own a flow bench. That's why I am just blending and polishing things . Circle track racing with stock rods always shown increases in time before cracks appear on beam with polishing alone and about 10 more races with polishing and shot peen. The last time I had small dart heads on a chassis dyno with a 350 sbc with stock bottom end you could feel them nose over early. They mustered 300 whp with big tires think it had a 1106 summit cam dyno'd with a dual quad and a team g single plane 650cfm carb fun times can't remember which out powered what, made 500 whp with 250 shot.
johnny5
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Re: Help with 406 sbc build

Post by johnny5 »

F-BIRD'88 wrote: Mon Feb 14, 2022 6:00 pm You don't want to open those chambers up to the 400 gasket fire ring.. You seem incompetent in these areas. Leave it alone. The fire ring is bigger than the bores are.
There are lots of areas in a sbc combustion chamber that can be deshrouded to increase flow.
The 170 cc as cast heads can be ported to create great flow and velocity. (178-185cc finished volume)
The rod beams need no work. The rid big ends need to be checked. As long as the rods are straight and the big end is in spec they are fine.
If you use a garden hose to spray a water stream thru the ports you will see where the air flow pattern is on a sbc.
Ok, I'll see what I can find on what 170cc heads need to flow, and see if I feel comfortable doing it. I just feel like those things with a small cam,are going to beat the rods o.o.r. and the bearings out of it in no time, then nose over once I start having fun.
F-BIRD'88
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Re: Help with 406 sbc build

Post by F-BIRD'88 »

When ported with 2.02's (178cc finished port size)
245cfm @.500". 230's @.400". 160-180 cfm ex would be very decent to the purpose. The whole port needs to be done but the finished port size is not maxxed.
1205 gasket size is plenty.
A single plane intake is a big mistake on this.
johnny5
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Re: Help with 406 sbc build

Post by johnny5 »

What cam would you recommend?
Bigchief632
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Re: Help with 406 sbc build

Post by Bigchief632 »

I recently did a 396 sbc with those DNA heads, Erson shelf hydraulic roller, made 553hp at 6400 and 509 ftlbs at 4600 or so. It had a single plane intake on it also. OTB Holley Strip dominator, still made over 500 ftlbs with a pretty flat tq curve. However, in your truck, a air gap would be better, and you'd want a little less cam shaft. I did some porting, and installed 2.055 intake valves, and redid the valve job to the heads. I have another engine going on the dyno soon, with the DNA heads also. A little more sporty 406. Should make over 600. The heads are ported more, and have a 2.055 intake valve in them also. I would use those heads.
Maximum power using simple logic and common sense
johnny5
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Re: Help with 406 sbc build

Post by johnny5 »

Looking for a balance rotating assembly for my 406 . Had the local machine shop do my heads and don't trust them to do any work for me. So I'm looking for a rotation assembly that's balanced and most likely won't need anymore work. This engine will probably make around 400 hp and never see over 5500 6000 rpm. What have you guys had luck with?
lefty o
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Re: Help with 406 sbc build

Post by lefty o »

for a mild motor, id not put too much thought into, just pick up some scat parts.
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