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Thread: SB 400 build suggestions

  1. #1
    Registered Member Eds56's Avatar
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    SB 400 build suggestions

    Hello All,

    My Son has been after me for awhile now for us to do a "father/son" engine build from my stock pile of parts, So I would like some feedback on what i have in mind....and or possible suggestions. The engine will likely go in my 56 at some point and as currently, will remain a weekend driver (No Drag Strip).... like a lot of others, i want all the POWER to the wheels i can get from red light to red light and still burn pump gas. As much as i really like the current 327.....I've always been told that MORE Cubic inches is the way to go.

    Looking for low RPM power....not pushing RPM's thru roof.

    400 small block (4 bolt main) bored 30 over ---- Also have same block standard bore too.
    Crank suggestions--?? thinking of having it stroked to 3.875 --- or should leave it?
    5.7" or 6.0" rods?
    Piston type?? (Hyp....Forg....flat....dome)
    Aluminum Heads -- Any specific recommendations, esp flow rate?? --Also-- I have a good set of #186 heads i could use, but was saving those to replace the old 461 double humps on the 327.
    Cam type & size
    Intake -- Have a Edlebrock Torker single plane.....but may replace it.
    Engine will run a 4-speed tranny & Current Rear End Ratio is 3:08 ...... but i also have 3:36 ---- 3.55-----3:73

    Yes, I know 400's have possible block issues and I understand to go with longer rods / crank combo will require machine work. And I have already looked at just buying a crate engine, or Rotating assembly, or even a short block and go from there.....BUT, that's not the direction i want to go at this time.


    Thanks,
    Ed

  2. #2
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    A local friend of mine who built a number of good running 400 SBCs actually prefers to start out with a late 400 two bolt block. The ones he likes have 509 cast in the side. The story goes they have thicker decks and more metal in main area. One of these with splayed mains is your ultimate stock based block. The early 4 bolts are your weakest design. 6.0 rods are the way to go. You have not given near enough info to recommend any camshaft.

  3. #3
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    To my knowledge markm is correct on the block - the 2 bolt with aftermarket caps is the preferred deal.

    As long as you use a 64cc head, there's no need for anything other than a flat top piston for a street engine - you will have plenty of compression.

    I would stay away from the short stock rods (5.55"), and there's no good reason to do anything other than a 5.7" or 6.0". No special machine work or parts required if you get pistons that match the rod length.

    A 186 or other double hump head is pretty small for a 400, it's going to respond a bunch to a bigger aluminum head.

    Given your description, there is not much reason to go for a big cam.

  4. #4
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    I am not sure you eve want a FT piston with a 64 CC head as that's pushing 11-1. I would look in to aftermarket Alum with 72-76 CC for pump gas.

  5. #5
    Registered Member chevynut's Avatar
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    Wow, the guy clearly says he wants to build a "weekend driver" engine with his "stock pile of parts", and that he knows "400's have possible block issues" and the first response is to suggest he use a different block. I'm sure his block is just fine for what he has in mind for the engine and all the bs about different blocks is irrelevant to his stated objectives.

    If it was me I'd go for as many cubic inches as you can get since what you really want to get from red light to red light is maximum low and mid-range torque. You're not going to rev the engine to 7000 RPM in that situation. If you need to get a crank anyhow, why not get a stroker? I'm not familiar with all the SBC heads out there but I'd consider your budget and get the best ones you can afford since heads are largely what determine airflow and more airflow makes more power.

    It's my understanding after going through the exercise myself that you really need to decide on every other aspect of your engine before you choose a cam, especially the heads. Don't get into the mode of believing that more duration is always better like some guys claim. More duration shifts the torque curve upward, which is not what you're looking for.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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  6. #6
    Registered Member JT56's Avatar
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    There is a huge difference from a 327 or 350 to a 400 sbc. This can be a slippery slope to go down...more power is addictive. Do you plan on keeping those gears?

  7. #7
    Registered Member JT56's Avatar
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    There is a huge difference from a 327 or 350 to a 400 sbc. This can be a slippery slope to go down...more power is addictive. Do you plan on keeping those gears? The 3.73 is the best for light to light in what you currently have. However with a manual transmission and the stock rearend...spinning is your friend! Dumping the clutch to many times and it wont hold up! I know you have said weekend driver. What are you plans? Cruise 50 miles from home or just go to the local hangouts?

  8. #8
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    A mild 400 with 9.5-1 CR, with some mid range alum heads, Performer RPM intake, and a .480 lift cam, decent street tires add some aggressive stoplight to stoplight driving will send a stock rear end to scrap pile.

  9. #9
    Registered Member Eds56's Avatar
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    Thank You to everyone for the suggestions, you have given me plenty to mull over. At the moment, i'm just looking to put some ideas to paper, then i'll have my block & crank checked out to verify they are as good as the "guy" said. Still looking at several Alum. heads......what flow rate would you recommend? ---- And regards to Pistons, Forged?? Hyper...? or cast??

    Not sure which car the engine will go in for sure, I have another 56 BA (4-door) that my son has hinted at reviving (A TON of WORK)....so, it will likely just replace the current 327. As for my driving habits..... mostly local cruise ins, drives out to mountains, 120+ mile weekend trips, just out enjoying the car, but it being a 4-speed, i like to FEEL the Power when taking out from a red light....you know....going thru the gears. then it's back down to a good cruise.

  10. #10
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    Unless you want a trans change too I would stick with 3.08 gears. I have a 4 speed Z28 with 3.42 gears and it talks to me at 75 mph. Forged is always better I have seen a few failures on the Hyper. A friend of mine owns a machine shop and he always recommends them if budget allows.

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