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Old November 21st, 2011, 02:26 PM   #1
85toy4runner
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Default need advice with newly purchased small block

hoping for some advice... long story short, got a call from a buddy said he got a built 350 and equally built th350 trans from his grandpa for sale for $400... went and looked and sure as hell it was a fresh never fired small block chevy. looking a little close i noticed the cyl heads were aftermarket (and also new as the rest of the engine was as it turns out),upon getting it home and pulling the heads and running some numbers heres what i ended up with... 1511 casting 1971 400cid, fresh .030 bore (making it a 406cid) new forged flat tops, new bearings through out, new cam, heads are world sportsmans with 200cc runners and 54cc chambers, stainless valves, roller rockers, double row timing set, hv oil pump, stainless long tube headers ( i believe they are 2 inch primarys), and a fresh rebuilt th350 built to handle the engine.. now where i need some help is, im needing an intake and wondering what anyone thinks might work well with this engine. ive got my eye on a team g but i dont know if thats too much or?? i should also mention i will be using a 4 speed manual behind this... i was thinking also maybe a performer rpm but i dont think the ports will be large enough to match the heads... any knowledge as to if this is true or not would be really helpful.. also wondering what the compression might be with forged flat tops ( they have fairly deep valve reliefs) and the 54cc chambers.. also any advice on how i can id the cam and maybe what kinda roundabout horsepower numbers i can look forward to from this build.... any advice greatly appreciated, and sorry i dont know much more about this, he didnt have a clue what he had and for $400 i couldnt turn it down
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Old November 21st, 2011, 03:30 PM   #2
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Flat-tops and 54cc chambers should give you somewhere in the neighborhood of 12:1

Hopefully, it has a huge cam with plenty of overlap to cut down on your static compression ratio. I'd go wit an air gap single-plane intake and an 850 cfm carb and expect about 500 or so h.p.
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Old November 21st, 2011, 03:37 PM   #3
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I love the perfomer rpm air gap,I've seen huge performence increases by getting rid of a big open plane intake,on most small blocks.I guess it depends on what you putting the motor in,are you going to be in the upper rpm range of your motor most of the time?maybe you want a team G,victor,or strip dominator.If you will be doing anything more then racing,I like the rpm air gap.
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Old November 21st, 2011, 03:39 PM   #4
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Your freind is either not very smart,or a great freind.thats a hell of a deal.
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Old November 22nd, 2011, 06:13 AM   #5
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Sounds like a nice find. Sportsman II heads came in either a 64 or a 72 chamber (most that I have measured are bigger than advertised). I doubt they could even go to 54 with angle milling. How do you know they are 54? Best thing to do would be to remove a head so you can see exactly what you have. Do the pistons have 2 or 4 valve reliefs? I would also remove the cam so you can hopefully get a part number off it and seee what you have there as well. If the headers are 2" sell them and get some
1 5/8" or 1 3/4", 2" is way to big, it will be way down on tq.

The air-gap would be a great intake for this motor, depending on how much cam and compression you have it should be just over 400 hp.
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Old November 22nd, 2011, 06:43 AM   #6
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Unless there's some kind of adapters included (to adapt to a hooker/stahl/spread port pattern), there's no way they are 2" primary tube header anyway.
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Old November 26th, 2011, 08:36 AM   #7
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Sounds like you scored a sweet deal. If you are unfamiliar with small block 400 then you need to look into the crank to see if it is the stock unbalanced (ie externally balanced needing a special damper and flywheel or flexplate) or an aftermarket internally balanced crank. Did the heads have the small steam holes between each pair of cylinders to match the block?

You may also want to check the stroke since it was common to destroke a 400 with a 350 crank and special main bearing inserts (or a custom ground crank)

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