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Discussion Starter · #1 ·
I have aquired a standard bore '71 402 LS3 motor with the #3993820 heads. It needs some freshing up, so I'm going to rebuild it. I know these aren't the greatest heads for maximum power but I am building it to go in my '71 Chevelle wagon. It won't necessarily be daily driven, but it will see a lot more street and highway miles than your average show or track type of car. My question is, this being my first big block chevy build, what should I do to make it a good driver with good low end power and torque? Should I just leave it basicly stock and add a better cam and intake? I'm not expecting great MPGs but I don't want it to be too low (I have a '69 Firebird with a 428HO that still gets about 12MPGs and, if possible, I'd like this to get alittle better). I plan on backing it with a built 700R4 overdrive so I can't go to big on power anyway as the transmission is only good to around 500 ft lbs of torque supposedly. Any suggestions would be greatly apreciated as, like I stated previously, this is my first big block chevy build. Thanks again.

-Paul
 

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nothing wrong with those heads at all. decent valve job and a little pocket porting and you're good to go.

IMO the best single thing you can do is convert to a roller cam. Instantly bypass all the BS with lobes going flat and problems with having to run the right oil and all that jazz. Have a serious look at the usual suspect vendors for pricing on this stuff and make a decision. Pretty much everything else revolves around that.
 

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Use these pistons with those heads....just over 9.5 with the 820 heads.
Pistons:
Sealed Power #844-L2242F60
396ci Aluminum Closed Chamber Stock-Type Piston, .060'' Overbore
Piston Bore: 4.154''
Piston Top: 38.3cc Dome
Pressed Pin
Comp Ratio: 10.58:1 w/109.4cc Heads
Ring Grooves: 5/64'', 5/64'', 3/16''

The 820 heads flow well for a milder big block. Use a cam designed for torque....the cams at the "top of the list" rather than the bottom of the page.
Everything else you have will be good to go...intake, q-jet carb and stock exhaust manifolds....headers would be overkill.

jim
 

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Discussion Starter · #4 ·
Thanks for the reply. That's pretty much what I was thinking with the porting and the torque type cam. I'll check those pistons out too. Thanks again, guys. -Paul
 
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