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Thread: SB 400 build suggestions

  1. #11
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    I've had the good fortune to build dozens of 400 SBC based engines over the years. Your stock 4 bolt main block will serve you well as long as the core shift is low as they had some trouble with that. I'd sonic test it on the thrust sides of the cylinders and watch for it being more than .200 or so wall thickness. The 4 bolt blocks will do fine as long as you keep the compression down below the 11.00-1.0 range and the power below 500 hp. After that and things start to move around a bit. If either of those are planned higher I'd go with a 2 bolt block converted to 4 bolt splayed caps. In that configuration I've successfully ran up as high as 13.00-1.0 and 600 hp. Beyond that and cylinder troubles can and do happen. As far as heads are concerned I'd look at AFR's stuff, around the 200cc range CNC ported if your budget allows. As for as the cam is concerned I'd look at a hydraulic roller from either Comp Cams or Erson. Understand yourself what your looking for in drivability and give them a call. Good rods and pistons are very reasonable priced these days Wiseco pistons and Callies rods will serve you well. With balancing being required I'd look seriously into buying a rotating assembly meaning crank rods and pistons already balanced. I just finished a 408 LS with my son and we had tons of fun and he learned a lot. Good luck enjoy your build!
    Quote Originally Posted by Eds56 View Post
    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. #12
    Registered Member Eds56's Avatar
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    Quote Originally Posted by Bluegrass Trifive View Post
    Good rods and pistons are very reasonable priced these days Wiseco pistons and Callies rods will serve you well. With balancing being required I'd look seriously into buying a rotating assembly
    Thank You for the input, What are your thoughts on standard rod length VS. bumping it up to 5.7"?
    Also, for my situation....would stroking the crank to 3.875 really make that much of a difference.....other than a lighter wallet?

    If my block, crank & rods do NOT check out ok at the machine shop, then i'll look into a rotating assembly....just have to see what it yields first.

  3. #13
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    Rod length is not a really big factor. The biggest thing is that a long rod shortens the piston and gives you a lighter assembly - but not by much. Too long on the rod and the piston pin is up in the oil ring groove and that requires some special parts. Stick with simple on this. If you replace the rods, slightly long is the way to go to keep it simple.

    The 3.875 stroke gets you about 14 cubic inches - and about 15-20 hp with most combinations. And more expense, along with potential clearance problems (which can be solved with the right parts).

  4. #14
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    I would stick with a stock stroke and concentrate on cylinder heads is $$$$ are a factor.

  5. #15
    Registered Member Maddog's Avatar
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    I would never keep the stock rods, 5.7" a must do with stock crank.

  6. #16
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    Quote Originally Posted by Eds56 View Post
    Thank You for the input, What are your thoughts on standard rod length VS. bumping it up to 5.7"?
    Also, for my situation....would stroking the crank to 3.875 really make that much of a difference.....other than a lighter wallet?

    If my block, crank & rods do NOT check out ok at the machine shop, then i'll look into a rotating assembly....just have to see what it yields first.
    That's a little bit of a complicated question to answer. The assumption is that you'll buy a set of pistons regardless of the direction you choose to go and bore the block .030 over as 400s typically need it if they have very many miles. In rare cases you might get lucky and make a .005 over. Now you look at the rods, I would for sure change the rod bolts with ARP bolts and resize them, (I'd use a set of 5.700" rods since you're buying pistons anyway) but now you have $200-$250 in a set of pressed pin rods. You can buy a set of Callies I Beams for about $550. Next is the crank, new pistons means rebalance anyway and if you need to grind the crank in my area that's $150 plus $ 200 to balance. A new Scat or K1 4340 Crank is about $700. It's been a few months since I bought a small block rotating assy but the last one I bought cost about $1800 balanced and the Wiseco pistons came with good rings. If you went that route I'd consider the 3.875 stroke and 6" rods as the cost of the rotating assy is the same but... you have to clearance the block and get a small base circle cam to clear the rods, not a big deal. So you can save some $ and use the stock stuff you have if it checks out ok, or spend a little more and make some improvements. If I could only do one or the other I'd spend my money on the heads and cam.

  7. #17
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    Like everyone has said, get your block checked out first and go from there. On a stock 400 block, I don't think I'd worry about changing the crank stroke and I wouldn't worry about the 4 vs 2 bolt deal...you're not looking to wind it up so it doesn't matter. I'd use the stock crank if it checks out too...going to a 3.875 stroke will not only cost you more, but you'll need to clearance the block, and you might need a special oil pan to clear the counter weights...I did (I have a 420 Dart SHP SBC). You're not looking to wind it high so I'd put in a set of decent I beam rods and hyper pistons...there's no reason to go with forged unless you plan to wind it high or apply forced induction/nitrous (or you plan to do a lot of towing with it...which seems unlikely). Keep in mind that the LS7 Corvette motor used hyper pistons...yeah...it makes 505HP SAE net (likely 600HP gross, maybe a bit more) and your 400 SBC won't come close to that power level. Use some high quality bearings and be done with it. If you don't plan to turn more than 5500 RPM...there's no reason to build a crazy bottom end.

    Put your money into heads and the valvetrain. If you really want to max it out, buy a new intake too. That's where you'll make a lot of power. I wouldn't run anything less than a 195/200cc head even on a street-only 400 SBC...a single plane intake like the one you have won't hurt you on the street with that many cubes either so your current manifold, while not the best, is a decent choice if you're looking to save a couple hundred bucks. Read here one intakes: http://www.hotrod.com/articles/19-si...-intakes-test/

    Heads: I'd look at a set of AFR 195's set up for a hyd roller/flat tappet or a set of Profiler 195's (Jeg's brand heads are the same as Profiler's btw). The 200cc Dart SHP heads aren't a bad choice either, but they'd be third behind the others I suggested (they're also cheaper). I think you could easily run 10.5:1 compression with the right cam and heads on the street with 93 octane at sea level. I wouldn't even hesitate to run 10:1 with newer heads. I'm running 11.3:1 on 91 octane at high altitude, btw. Cam...I'd convert to a hyd roller, but that's some extra coin (probably a solid $700 over a new flat tappet cam/lifters) so that's a choice you have to make depending on your budget. A hyd roller will make more power everywhere in the RPM range than an equal flat tappet...but they cost more to install on an old block so that's the trade-off. In the end, the power is in the heads more than anywhere else so spend your coin there.

    You could make an easy 450 HP (gross) with a mild build in my opinion using the right parts. Also...you'll likely roast your stock rear end with a motor like this so plan ahead.

  8. #18
    Registered Member Eds56's Avatar
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    WoW!!! a lot of good info to take in, THANKS

    I think for my situation, assuming the Bottom half checks out ok, i would be better off putting any "extra" money available into the Heads / Roller Cam area, instead of worrying with stroking crank, 6" rod and all the block clearance issues.

    Anyways, I suspect there should be a "noticeable" power difference between current 30over 327 double hump headed engine changing to 30over 400 w/5.7 rods, roller cam, alum. heads engine, so maybe that'll hold me off for awhile.

    I do THANK all of YOU for the input and esp. the specifics to detail.

    More to come, after i drop parts off at machine shop.

  9. #19
    Registered Member Eds56's Avatar
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    One more Question related to new Alum. head choice-- Angled or Straight plug heads?? ---- Currently running Patriot H8055 headers with my double hump heads.

  10. #20
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    Straight plug to reap the real benefits of an angle plug you need dome pistons.

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