I currently am running a 434 with a super victor intake and a Holley 830 cfm carb in my 1989 vette with a 6 spd, 3.75 gears. I am using the AFR 210 competition heads(1103) which flow 312cfm @ .700 lift. My camshaft is a solid roller 245 251 @ .050 .630 lift on a 112 lsa. I was looking at going to a solid roller 248 254 @ .050 .640 lift on a 110 lsa because I would like to get some more top end power. My concern was how much the heads could flow. Is it a waist of time adding more cam? Are the heads maxed out? I have not had the car on a dyno, but I can feel it running out of power before it hits 5500 rpm.
I run the car in a half mile shoot out and run through the traps in 5th gear @ 6100 rpm doing 161 mph. I would like to move the power band up a bit so I don't have to use 6th gear. I don't really want to buy new heads...

Any advice would be great,

 

A 434 can use alot more cylinder head than the 210's. If you want more top end I would think about AFR 227's or 235's. You might need a little more cam also. My 450 has 235's, and I would have gone with the AFR 245's if they were available when I upgraded the heads.

 

Given your limitation with the heads, I'd get ahold of Chris Straub. He's definitely an industry insider!! If you provide him your head flow #s, rpm range desired and other vehicle specifics, he can spec out a cam to meet your needs. With the right info he can tailor your powerband to your liking where an off the shelf cam is at best an educated guess. P.M. me if you'd like his info.

 

A built 434 ci sbc should pull up to 7,000 RPM's plus easily in high gear running flat out for 1/2 mile or more.

Like TPI Jim said, it likely could stand more air flow in & out of the engine.

A 434 ci sbc could easily use cylinder heads that flow 350 to 400 CFM + @ 28 inches of water depression.

A port design with high velocity numbers from .300" lift & up is important too.

Its more than just having huge holes feeding air in & out.

Means nothing without high velocity flow numbers to match engine Cubic Size & intended RPM power band operating range to match the cars final overall gearing, car setup, and driving- racing style & needs.

TPI Jim can help you I am sure with a matched set of AFR's to best suite your current needs.

BR

 

I don't know what the seat timing (duration) numbers on those 2 cams are but judging from the @50 numbers you need A LOT more camshaft than either of those you have listed.

BTW adding only 3* of intake duration@.050 is likely NO change in powerband espc when you cut the LSA down 2* on a cam that is already way too small for the engine (unless you like the 2500-5500RPM powerband).

The old style 1103 AFR 210's are not optimal for a 430+inch motor but they will work fine to about 650HP.

It's not a waste of time adding duration on the cam because it changes the power band. With the proper camshaft even on a 434 it will pull to 7000rpm.

If you go to a bigger cam - Say something like 296/306@.020 and 268/272@.050 on 110LSA screwed in on 106ICL you would move your HP peak up to about 6800RPM with those heads and induction system. It'll pull to 7000 or so before power drops.

I'm buying my cams from Mike Jones or Bullet (who also owns all of the Ultradyne masters).

Now with a set of the new AFR 235's HP will also peak at about 6800RPM but instead of 650HP it''ll be about 700HP (if the motor has any compression) and have an additional 200RPM of over rev on the top end of the powerband over the 210's.

A few other things are holding you back like that 830 Holley.... I'm guessing since you specified it's "830" that you have that annular booster thing Holley trys to sell to pavement late model racers.... If your stuck with a 4150 base you need to buy a HP950 or call somebody like C&S, Braswell, BLP ect and get something that will run. Your killing 30HP running that POS annular discharge carb on a big motor.

Last but not least - A 2925 Super Victor out of the box is hurting you. It could be 50HP stronger in the right porters hands. I'm not joking either. My little 383 gained 40RWHP just from porting the intake manifold.... 3 people really know their beans about porting that intake. Bryce at DR J's, Denny at JDS Induction and Larry Meaux. There are many other good head porters in the US but those 3 know specifically what's up 100% with fixing the 2925 and those are the only 3 I'd pay to touch one.

If you have any trouble locating anything from the info I gave you, please send me a PM and I'll give you their contact info.
Will

 

Thanks for all of your input, If money grew on trees I would put a bigger head on it. I would be perfectly happy with the motor if I could just get the peak power to occur around the 6000 - 6200 rpm range..