ig they put on a 600 cfm holly replacing a 750

 

what would be a good air fuel ratio max was 12.4 average 11.6

 

12.4 and average 11.6... hmmm... that sounds great, my 355 vortec had 12.8:1 peak.

 

should i get a bigger carb has a 600 holly was thinking of getting a holly 670

 

Naah, you want to know what I would do?

 

what would u do i dont know anything about carbs im 20 years old

 

I would make sure it truly doesn't need an overbore and take it apart and make sure its a 383 crank. Your piston is a 1.560" stock type press fit piston with 5cc reliefs. Either your quench clearance is wrong or you got excess blowby with worn out cylinders in the block. Or its not a 383 If your block's deck is 9.025" stock actually can vary greatly, and your using a .040" gasket, yuk. If you have a 9.0" deck or decked to piston tops with a .039" compressed thickness gasket= AWESOME. But 64cc heads and 5cc piston and .039" gasket don't equal 9.5:1 compression not on a 3.75" stroke crank engine. It equals 10.99:1 on a 377 and 10.27:1 on a 350. A 327 its 9.66:1 and a 305 its 9.12:1. Dig into that 5" of paper work you got and give us the actual engine build specs. If its a 327, 220 hp to the wheels aint too far off. And your cam has a 112 lobe that explains it's 500 rpm idle. I would have thought it to be your valve springs, yet you said it revs to 6000 rpm on dyno with a 600cfm carb right?- sounds like a 327 vortec to me with 9.5:1 compression maybe? It could be, I would check the internals, check deck height to piston at highest point in each corner of block I would check the difference to see if its decked or not. And if its decked level with pistons all I would do is stick a comp cams XR276HR roller cam in it. It must be a roller block maybe? I would hate to think someone told you a 305 was a 383? That is what usually comes with a t5 manual trans later fbody. Wonder if it was a roller TPI 305 with a T5 engine? Oh well I can only speculate without accurate and certain information. If heads are bone dry stock an XR276HR would be an undertaking as it would require the fire be worked out of the heads. I believe a Throttle body 305 would put out 190-195 rear wheel hp and 240 to 260 lb ft. TQ. And a TPI 305 220HP and 280 up to 300 TQ. A 327 Vortec would make for a screaming engine probably hp
starting where your torque left off. Maybe your head just needs screw in studs? Was the engine experiencing any valve float during dyno? Probably, I would look into it. I am going to stick with valve float due to valve springs right now because that is all I can conclude at this point. Also the studs if they are press fit could be pulling out. Just machine the heads for the right springs and screw in studs use valve covers a little taller and use narrow body self guiding roller rocker arms and throw in that XR276HR COMP cam. Note if its a 305 forget that cam it won't even use the lift not even with the mighty vortec heads on.
I know, give us the block id tag . And the head casting number and we can get that stuff figured up. Your engine may have nothing wrong with it 220 to the wheels is a good driver car I had a 350 with only 190 in a camaro before I built it. Your engine could be 300 plus hp I am sure all the guys here can help figure this out. Maybe its the rear end ratio or transmission/ torque convertor worn out who knows but for a cammed otherwise stock engine it has good hp I am concerned about the tq you said it was 240 well again a bone stock cammed engine with wrong valve springs maybe? It sounded fine though please don't take anything I'm saying insulting many people even that have big money builds are shocked at the lower than thought output on real world chassis dynos I saw a 12 second pontiac claim 500hp and made actual 360 rear wheel so there ya go. dyno's vary tracks vary engines vary I bet your car is a fun peppy car the way it is right now. it really is good output for a say stock showroom flow 90's F bird v8 or something.

 

it has +5 cc pistons and has screw in studs and has comp cams valve springs and retains and all that stuff up top use to have a 750 holly now has a 600 has a 2400 b and m stall also has richmand 373 gears going to get the block id tag this weekend started needs shiming grinds a lil paper work says its a 350 block also says 5.7lg, sgi, k243, 14093638, v1130z23, bore 4 inch by 3.75. the pistons i said the type but the number on them r stl-h345np w 4 inch bore. and the push rods r 5/16, 7.050 length, 4340 chrome, .080 wall. ok in the heads roller rockers comp cam 1001-16, 1.5 ratio, keepers comp cam 611-16, retainers 740-16, springs 986-16 they said compression might be under 10.1 i dont htink they checked it

 

and its a 79 camaro so idk where your getting 90s show rooms?

 

and im not gonna tear it apart if anything il either have a shop rebuild it right to over 400 hp or might just get a crate 383 with over 400 hp found a few for 5 grand