What kind of increase in horsepower can I realistically expect on a 460 with an edelbrock performer rpm intake and cam topped with a holley 850 double pumper by replacing stock heads with these which are advertised as direct replacements for super cobra jet heads? I haven't built the engine yet - I'm a dreamer, and a planner - but I will have true dual exhaust the whole way back with headers feeding 3" pipes, no cat. converters, and flowmasters. I'm on a bit of a budget, and $1800 isn't exactly pocket change. Does anyone have any recommendation for good heads that may be cheaper? I like the weight reduction of aluminum. Thanks a lot for everyone's help.

Neal

 

>What kind of increase in horsepower can
>I realistically expect on a 460
>with an edelbrock performer rpm intake
>and cam topped with a holley
>850 double pumper by replacing stock
>heads with these which are advertised
>as direct replacements for super cobra
>jet heads? I haven't built
>the engine yet - I'm a
>dreamer, and a planner - but
>I will have true dual exhaust
>the whole way back with headers
>feeding 3" pipes, no cat. converters,
>and flowmasters. I'm on a
>bit of a budget, and $1800
>isn't exactly pocket change. Does
>anyone have any recommendation for good
>heads that may be cheaper?
>I like the weight reduction of
>aluminum. Thanks a lot for
>everyone's help.
> Neal
Neal, first off your Performer RPM manifold will not match with the SCJ heads, the port sizes are way bigger. Also you'll need a lot more cam to make use of the heads new breathablity...of course with more cam you need more compression, etc. If you have everything matched correctly expect to make a maximum of 600-625 HP with those heads.Those Cobra Jet heads will still be the limiting factor, they sign-off around 6,500 RPM. If you really want to "step-up" you need the "A460" heads, manifold, 1050 Dominator, etc. expect an easy 725 HP...I've spun a 514 to 7,600 RPM with no problems.

 

I appreciate the info. This will be a daily driver, and I'm on a 18 year old budget, so I need something that really moves when I hit the gas (got sideswiped recently in a Jeep because I didn't have the acceleration to get out of the way - it will never happen again), but I need something reliable that gets at least about 8 mpg and I can't afford to spend a fortune doing it. Should I just stick with the performer rpm kit or what? Are there better heads that cost less and would match this intake/cam or what? I'm basically looking for power in the 2000-6000rpm range. My only racing will be at the occasional redlight (gotta at least beat those new weak Z28s daddy bought his lil' unemployed rich boys). =) I'm basically new to this whole thing. My first car was a 90 mustang 5.0, but the engine was stock. I'm looking for 500-550hp if I can do it within my budget.

 

If your an 18 year old with that kinda power, dont forget to budget for tires. I was 18 once, and its amazing how many tires a 302 can go through!

Nathan

 

Actually, I'll be 19 in two weeks, but the mentality's still the same. In the 'stang, I really wasn't that bad on tires. I had a few can't see anything but tire smoke all around you burnouts, but I enjoyed hurting my gas mileage with quick acceleration a lot more than sitting still and smelling burnt rubber. Fun, fun, fun! I kinda wish I still had that car - convertible and all, but the insurance just killed me.

 

I figure from the way you're talking you've already got the 460. If so I have no idea why you're short on power, unless the engine is shot. If that's the case I would suggest a good stock rebuild with some head work (port matching), and an RV cam . I had a stock rebuilt 390/4 speed/3:08 rear that would outrun and out pull anything I've ever seen and it always got a solid 10 mpg - loaded or empty. Just my 2c.

Trail Rider