Sbc 406 build

Discussion in 'Engine Topic' started by Obituary, Feb 21, 2019.

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Compression vs flow

  1. Engine runs better with flow

    7 vote(s)
    77.8%
  2. Engine runs better with compression

    2 vote(s)
    22.2%
  1. Obituary

    Obituary New Member

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    I had built a 406 small block Chevy back in 1999.It was going into my old high school car,1968 Camaro.Do to some events in life things were put on hold hoping that one day I would be able to finish restoring this car.Well thanks to the good lord that time has come.I had unwrapped the motor after 20 years and it looks just like the day I had built it.this motor was completely rebuilt back in 1999.With times changing and after market heads changing so much and more adorable I was wondering if I should replace these for 461 Camel humps I have on the motor now.This motor was never fired up.It’s A 406 Sbc .30 over with H-beam 5.7 rods and TRW forged flat top 4 valve relief pistons.Heads are 461 camel humps 62cc combustion chamber with stainless steel 202/160’s ported and gasket matched with steam holes.Cam is A Roller 294/302 Dur with 580/600 lift and 110 lobe with roller lifters.Cam was A kit that included the cam,lifters,springs,push rods ex ex.Victor jr manifold and A 850 DP carb.MSD ignishion system.Camaro has A 373 posi rear end and A 400 TH trans.I do have A muncie M20 4 speed sitting on the side :).I want this car to be A street beast,maybe take to the track once or twice but it will be A weekend warrior driving around town fishing for A mustang or corvette.With these HEADS Flowing around 160 compared to these after market aluminum heads flowing over 200 if swapping now would be A wise decision.I forgot what the compression would be with this set up.I would like to run pump gas (100 octane gas station up the street)if possible but willing to put octane boost if needed.QUESTION,if I swapped out these heads now,I would be sacrificing compression for flow.I was educated on compression being best way to make power/tork.The aluminum heads I see these days on the market that flow over 200 compared to these 160 camel humps.How much compression would I lose and flow would I gain over just swapping out heads.With this size cam,by bolting on aftermarket aluminum heads would the 406 fall flat on its face.I am not going to change the bottom of the motor and swap out pistons again since the motor it is ALL READY TOGETHER.So it comes down to compression VS flow.Should I swap out 62cc head that flows 160 for A aluminum 70cc that flow over 200 with the set up that I have now.Any insite on the matter would be greatly appreciate before I drop this motor in.
     

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  2. 1980RS

    1980RS Veteran Member

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    Here is what I would do with that combo, I would ditch the 461 heads and just get a set of Vortec heads. The Vortecs are light years ahead of the old castings. I would also get rid of the Vic Jr., either run a Super Victor or an Air Gap. I have seen guys at the track where i race have short blocks like yours running in the 11's with stock 062's or 906's. They just plain make more power. Downside is yup, hi octane fuel buy you will make more power.
     
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  3. Chevyforever

    Chevyforever Veteran Member

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    200 cc heads and 850 DP .... can you say soggy bottom end ? Stock vortecs will not handle .580 /.600 lift without spring/retainer and rocker arm upgrade. Also need to install screw in studs ...
     
  4. tom3

    tom3 Veteran Member

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    A 406 with flat tops would work really good with the 70cc heads that will handle that radical camshaft. Maybe get by with premium street gas too with that duration. Sure sounds like a fun project at this point!
     
  5. 1980RS

    1980RS Veteran Member

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    Not true with 200cc heads and an 850. My 406 ran it's best with the pair and was not soggy at all. You are right about needing to modifying the spring pockets and guide seals to make the Vortecs work, but it's not that much work.
     
  6. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    Those pistons with a .020 deck will put compression just over 11-1 with a 62cc head. Too much for pump gas.
    Swapping to a 70cc head drops compression down to ~ 10.25-1, which is right where you want it on a street motor.

    Those Camel Humps are WAY out of their depth with that cam. Just big flow restrictors that will make for an engine that does nothing well.
    A modern design aluminum head will support compression much better than those Camel humps (which were obsolete before I was born)

    Don't fear a 200cc head in an engine like this. Factory 396 big block heads are 253cc, no one calls that engine a torque dog.
     
  7. muscl car

    muscl car Veteran Member Lifetime Gold Member

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    I'm having a 406sbc built , it's based off of a Dart block , Dart Pro 1 227cc CNC heads and custom 600lift Hyd roller cam . Should easily make over 600hp on pump gas !!!
     
  8. tom3

    tom3 Veteran Member

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    Sure be interesting to put that combo on a dyno and see what it's doing at 4000 rpm though. When at "all systems go" I'd think there would be some serious numbers.
     
  9. nova75mike

    nova75mike Veteran Member

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    I think if you put a set of AFR 195 cc heads (65cc chamber) you'll have around 10.7:1. the combo of slightly lower compression and ALUMINUM heads will allow you to run your 100 octane pump gas easily. If the AFR heads are too pricey, there are other options out there (pro-filer, pro maxx, blue print, etc). 461 heads were great back in the day, but even an entry level aluminum head will put them to shame these days. I think with a good set of heads, you are looking at an easy 100 horse improvement.
     
  10. Obituary

    Obituary New Member

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    So first off dump the 850 carb and go with something more like A 750?
    Second off spending another $800
     

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