RPM Airgap?

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scamp340

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Sudbury, Ontario, Canada
I am running a 73 Scamp with a 70 340. A good street/strip package. Fully rebuilt motor 30 over with purple stripe cam, 3000 stall converter, 3:91 gears, Holley 650 carb. Stock fresh heads, no real tricks. The car wieghs 3600 lbs with me in it. I am currently using a Holley Street Dominator intake. I am thinking of switching to an RPM Airgap.

Does anyone know what I could expect? I drive the car sparingly, just for cruising and showing, and a couple of times a year to race in street trim with street tires, driven to the track which is 80 miles away. It now runs high 8.70's in the 1/8 mile with a 60 ft of about 1.97.

I should also mention that I've been running this motor for about 25 years, so all of the rework was done then. It probably has about 15k on it.
 
I just switch from that intake on a 318 with 360 heads to a RPM non air gap with keeping the exhaust intake heat open on both intakes. I feel the motor is more enjoyable to drive that way even if I lose 10hp. I have no heat related problems either.

Well heres my take. The idle smooth out, even cold. Low rpm power is better but it did seem a bit softer on top-6000 rpms. My overall power is better but with your 3000 stall speed, I have 1800 but 3.91 gears too.

I am using a 750dp, I know dual planes like big carbs so that 650 might be a bit small too but for your intake now its prefect.

I would leave it alone...you could try it. My gas mileage went from 9 mpg to 10mpg with the RPM. And it does idle better in gear but again I have a lower stall speed than yours
 
I have a Air Gap on my 360 and love it although I nothing to compare it too since I rebuilt the motor using a different cam and ported heads. My first combination was the same 360 with unported heads and a smaller old style cam (lots of duration and not alot of lift) and a Torker intake. It runs tremendously better now. When I was looking to buy the new intake I searched out all the info I could on the different intakes and from what I gathered the Holley intake you have is a decent piece. The Air Gap is probably the best street intake you can buy. It has real good fuel distribution and top end power near that of a single plane. Some other intakes have poor distribution so some cylinders run lean while others run rich. I don't know how much you'll gain by switching. I'd guess an improvement but how much is hard to say if it's worth the time and money to switch.

BTW: Mine is no more cold natured than it was with the old combination which had an exhaust crossover.
 
You'll notice more bottom end torque with the RPM and a great top end. The air gap takes a few min.'s to warm up when it gets cool out. Much like a big block needs some time.
 
I will also mention that at the moment I am using my 650 carb with a Profrom main body, and Quick Fuel Technology metering blocks for the four corner idle set up. This should give me more cfm. As well I have the heat crossovers completely filled in with high heat silocone. Therefore I am not using any heat crossover.

Thanks members for the input thus far.
 
Oh wow, I notice you live in that place you lose your car and drivers license for driving 50 kpm over the speed limit--thats 30 mph-guys :eek:ops: Some of us would be in trouble over there--but then you have those great ladies to have fun with :D so I guess it evens out.

I change my mind, where you live, you most likely take your time getting around. The rpm gives a nice strong idle, its smoother down low, as for the top end, I don't think you spend much time at 6500 rpms--me I hit 6000 maybe waaay to often.

It took me a few hours to swap, did it 2 weeks ago when we had that mini warm up--boy is it cold today. I am keeping mine.
 
I got one on the Duster. 340, 727 auto. I had a stock intake
on the engine when I got it. Big difference. Go for it. You'll
have the low end torque and better throttle response.
 
The Eddy Air Gap is, of course, designed for a square-bore carb, whereas the Eddy Performer is spread-bore. I never liked the way my built 360 ran with a Eddy Performer RPM and a square-bore carb. It seemed like it had poor fuel distribution. But I really like the way it runs with the spread-bore Performer and a big ThermoQuad. Never understood why Eddy never made the Air Gap in spread-bore.
 
Number 1 Eddy does not sell a spread bore carb, the performer is a factory replacement intake, so it has it.

On my RPM non air gap, theres lots of metal around the base. With the intake off I guess it could be grounded out around for a spread bore carb. Just need a high speed grinder. Need to trace the spread bore gasket and cut out to it and go down a ways to smooth it out. Only need to go like a 1/2 inch out on each side and I would say 1 inch down.

Sometimes in this hobbie you need to make things work for you. Look what NASCAR does to these new cars. Factory makes it front wheel drive-they swap it over to rear wheel drive :p
 
Dodge freak, lay a T-Q gasket on top of the RPM and you'll get the picture of what can and can not be done so easy.
 
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