I just purchased a 454 motor that was just rebuilt fot my 70 chevelle.The block casting is #3999289/heads#336781.Iwas told it was a 73 two bolt block.After dissasembly the motor is in great shape but appears to be stock with a .040 bore.The pistons are flat tops with two valve recesses and the heads I think are 110cc.I calculated the compression ratio with a .020 head gasket to be around 8.5:1.I would like to add a aluminum dualplane intake and headders but dont have a clue how to select a camshaft.The car has a muncie M-20 with 3.31 posi rear and 14
" tires.I would like it to have low and mid range torque with that lumpy idle we all like.This car will mostly be driven on the street so I can't loose all my vacuum because of my power brakes.What kind of horsepower can I expect out of this block without raising the compression at this point.Also will the dualplane manifold let me use my cowl induction hood?Any info will be greatly appreciated.Thanks Guys Great Web Site

An Edelbrock Performer intake will work with the cowl induction air cleaner..I have one on my car,fits fine.You'll need a nice mellow cam..forget about a rumpity rump idle with your low compression..you'll need something in 210-220 duration @ .50,.515 lift or so ,ground on a 110 or 112 LSA..your compression is 8.0 to 1 if you're lucky.You'll need short duration as I mentioned to build cylinder pressure to make up for your low compression.Your 781 heads (great casting # BTW graemlins/thumbsup.gif ) are more like 118 CC's +,and good luck finding a .020 BBC head gasket.Bottom line-not a terror,but a great street motor with a 4 speed,3.31's,and the right cam to build cylinder pressure.

Just use .022" steel shim headgaskets to up her CR. a schosh..

pdq67

Flat tops and 781s= graemlins/sad.gif , don't go with a performance cam, the engine will be a dog.

U could try and locate a set of closed chamber heads for the motor would bump compression to 9 to 1 or so and still run pump gas no problem. Would make a big difference when a mild 268-280 range duration (210-225@050) and 500-530 lift cam is used with the performer intake( for cowl hood) and a 750-780cfm vacuum carb, headers and good exhaust system. If U keep the 781's run a 260-270 range duration and something in 480-510 lift, but the smaller cam will not get U the slight chop in the idle. I have a crane thats 222/234@050 with 529/525 lift rpm range 2200-5200 and with 9.5 comp has a nice choppy sound at 900rpm idle. A cam in the range of 280 duration and 520 will give U the idle U want, Rpm range will be 2200-2500 to 5200-5500.

Thanks guy's for the great info.I'd hate to spend the money for pistons or new heads because the motor was just rebuilt (why throw good parts away).As for the performance I'll take your advice on the cam selection and stay mild(haven't got any bad info on this site )My other question is with the higher lift cam can I use the stock dual valve springs and what height can you go before they have to be changed.The bottom end is a two bolt with a forged crank.I read that you can go up to around 600 hp with a 2bolt.
From the info on the block,pistons and heads it is a 1973 270hp block.Any improvements at this point would be great because I only paid $500 for the complete motor carb to pan.Thanks again for all the help (all the duration and lift #'s give me a headache)

As long as the lift stays at .515 or less,stock springs are fine.I've lived by that quite a few times with stock 454's and 402's and never had a problem.

The cam I was running would be great for that engine. It was a 276/286 UD which is now a Lunati grind.

More top-end than 276, still works all power accessories. Good for 454 to 502, lope at idle. Power 1200 to 5800. 276 286 221 230 0.515 0.515 0.303 0.303 112 106 5 BTDC 36 ABDC 53 BBDC 3 BTDC 302A6LUN

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