Pontiac 400 Question..... Have a 69 Pontiac 400, Motor just bored 0.030 over.... flat top pistons, I have edelbrock round port Aluminum heads they flow 320 cfm (2.11/1.77 valves), 2" primary tubes on headers headers reduced from 3.5 collector to 3" exhaust, 1.65 crane gold roller rockers.....I have the restrictive pushrods, melling high pressure oil pump, I have 2 option intakes... RPM or Victor... and I have a Com Cams R308 Roller Cam 262/262 duration 0.575/0.575 lift.... is this cam ok to make the power or a is a smaller duration needed? I have a 850 holley, but is that too much carb? looking to put the right combination together... This is in a 1972 Pontiac Ventura.... 350 TH streetfighter trans, Street/Strip 3600 stahl converter, 3.73 rear gear with 275/60 R15 drag radials.Thoughts on making the best race/street combination?
Welcome to the forum..A couple of questions here.What have you done to the bottom end rods/crank?Reason I ask that is the cam you mention is 3000-6700 RPM range. Stock bottom end I wouldn't take past 5800 at most and that's with a lot of re-work like sizing the rods, magnafluxing them and stress relieving, ARP rod bolts, balancing the crank to within 90-95% of zero and ARP bolts or studs for the mains. is your block 2 bolt or 4 bolt?What all has been done to the heads? They don't flow that much or have 1.77" exhaust valves from Edelbrock. You'll never ever need that much flow on the street unless you're running a monster 500+ cubic inch motor. At 5800 RPM a 406 (400+.030) would flow closer to 225 CFM.Is the flow mentioned intake only? What's the exhaust? Typically, the exhaust is restrictive and a dual pattern cam works best on a pontiac.I'd go with the RPM intake. It's better suited for street use and better sutied to your cam. The victor is basically race only and not much good for street use.Carb size depends on what RPM range you're looking at running in. But for a 400 @ 5800 RPM a 750 CFM is more than adequate. 850 is a bit over kill.Any more info you can give us on your set up?
ok our hp crazed friend how about a brief interrogation first.do you want mild moderate or rough idle?do you need vacuum for power brakes?do you want a drag car you can not take on the freeway, a freeway only car or something inbetween?as my 71 says a victor is not a great for the street but neither is a 308 roller cam, lol.
sounds like your going all out race with 320 cfm heads and that cam. you will need a good set of rods, light forged pistons, 4 bolt caps and a balanced job! i would also go with the victor intake and 850 carb. 4500 stall and some 4.11 or 4.30 gears!if it is a street car you need to start over with smaller heads,cam and carb you will be happier in the long run.if you stroke the motor you can get away with your heads,cam,stall and gears!
76 455/4spd TRANS AM69 GRAND PRIX 455/5SPD