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.
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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.Comment
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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.Comment
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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.Comment
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Straight plug to reap the real benefits of an angle plug you need dome pistons.Comment
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Most good aftermarket heads have a raised exhaust port. Having angle plugs heads help with spark plugs...I would do it.Comment
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Over the years I have seen angle plug heads cause as many issues with wires as they solve. To bad OP is so far away I have a std bore 400 block of the 509 casting varity with a std crank I would love to trade for a small journal 327.Last edited by markm; 09-26-2016, 09:52 AM.Comment
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A lot depends on the headers. I had some fuelie heads on this motor first and didn't have an issue at all. Went to a AFR's with straight plug and had issues. New setup has angle and much betterComment
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I really try to avoid things like discussing header fitment. I have a set of Hedmen headers on a BBC Camaro that were the envy of my Ford driving friends. Then I installed ARP head bolts, first trip to grinder, then Canfield alum heads with raised EX ports, my header fitment is no longer the envy of the neighborhood.
Additionally, on 55-57 cars especially their are dozens of motor mount setups stock, forward even some setback all of these factors can effect header fitment.Last edited by markm; 09-26-2016, 03:18 PM.Comment
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There's usually a way. Angled plugs on factory heads are not a problem at all with most headers, in fact they have better clearance most of the time than straight plugs. Many of the aftermarket heads move them farther and this becomes a challenge.Comment
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I'd check with the mfg myself. I've never had a problem with angle plugs with my Doug's headers...they are a bit tight in spots though. Don't be surprised if you have to run heat sleeves of some type to keep the boots from melting. The worst two plugs to change are on the passenger side...if you leave the battery on the firewall that is.Comment
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