edelbrock combo question

[Guest 83supaZ]

are the edelbrock 1406 600cfm performer carb and 7101 performer rpm intake a good combo on a stock (stock for now) 305 that will eventually be bored .40" w/new cam etc.. or once i bore it will i have to up to around 650cfm?

[Guest Magnum Rockwilder]

It's a great combo for a 305, or any mild smallblock. You can pick up about 25hp in the top eng by using a single plane manifold instead, but you'll lose about 25 lb/ft of torque in the low end. It depends on what gearing and converter you plan to use and what type of feel you like; effortless low end grunt, or screaming top end.

 

You won't need to upgrade the carb when you overbore to a 312ci. A 600 is fine for anything under around 400hp.

 

However, I'd like to recommend that you buy an build a 350 instead of a 305. It'll cost the same and you'll get a LOT more results. I have a friend with two built up 80's Camaros... one with a .060 over 305 (315ci), and one with a .030 over 350 (355ci). They both have equivalent parts as far as cams, heads, headers, intake, etc, only the 305 is 11.5:1 CR and the 350 is only 9.5:1. The car with the 305 runs low 14's at 100mph in the 1/4 mile, and the car with the 350 runs high 12's at 110mph.

 

You're lucky to get 250whp out of a typical bolt-on 305, not to mention you can run a lot wilder cam in a 350 without losing vaccum and idle quality. AND the 305 will need to spin 7000rpm to get the same power that a 350 can put out at 500-1000rpm less. A bigger motor will also retain more low end torque that would normally be lost when you use a big cam and single plane manifold.

 

I could go on.

[Guest 83supaZ]

so with the RPM manifold i'll have more torque? which is better in 1/4 mile or 1/8 mile runs correct?

[Guest Magnum Rockwilder]

The RPM has a little more torque in the low rpm range, under 4000rpm, and the Torker II has more HP in the upper rpm, above 4000rpm. If you use a typical Z rear end ratio, like a 3.90, the Torker II would be faster because the engine is in the upper rpm range during the whole 1/4 mile run. If you had a tall rear gear like 3.23 or 2.73, the RPM might be faster because the low end torque would help the car get off the line.

 

With a 3.90 gear, build for power between 4000-6500 rpm. The car is light enough and the rear gear low enough that you won't miss the lost low end torque.

[Guest rick458]

Magnum how does a Edelbrock 600 cfmfair against a 625 cfm Road Demon?

 

also for a 305 with a Performer RPM Intake, and possible a comp cam 240H

12-300-4 cam. 8.5/1 cr

 

Chevy Impala 4900 lbs 2.73 with a 350 thm

[Guest Magnum Rockwilder]

The Road Demon is a great carb. Which one you choose is simply a matter of budget and which one you or whoever will tune it is more familiar with.

 

As for the cam, it depends on your goal.

 

If you want an economical motor that's basically a hair more powerful than stock, the 240h is a good choice. If you want a little more top end power with no loss of bottom end or gas mileage, the 252H is your cam. Then there's the 260H... it will have well over 300TQ from off-idle up to 4500rpm, and it'll pull to 5500rpm easily. You'll lose a few mpg, but it'll still be very streetable.

 

The 268H will start to get noticeable as far as idle sound, but it's still pretty mild and you won't need a stall converter. That's about as big as I'd go with a 305 in such a heavy car with tall gears.

 

You won't lose any low end with the 268, but you'll only gain about 10hp on the top end over the 260, so you have to decide if it's worth the loss of idle quality and gas mileage.

 

If you choose a 240 or 252, install it retarded 4º, and if you choose a 260 or 268, install it 4º advanced.

 

Personally, I'd go with the 260H 4º advanced with small headers, a 600cfm carb, and an RPM manifold. That'll put you around 275hp/325TQ and will pull all the way from idle to about 5500rpm with 2.73's. A 700r4 would be a good move if you want to regain the 3-4 mpg you'll lose.

 

Whichever cam you get, use small tube headers and free flowing mufflers. Big headers will kill a 305's low end.

[Guest rick458]

Thanks for the reply, good info there