Hey guys,

as some of you might have read on my other threads I'm trying to tune up my 400 SBC a little bit.

Here are the specs:
- 400 CUI SmallBlock Std. Bore
- 10.2:1 CR (75cc chambers, Flat Top Pistons)
- Ported 2.02/1.6 GM Heads (487x)
- Edelbrock Performer Manifold, Cam and 1405 Carb
- Headers 1.625 inch, 2,5 inch American Thunder Exhaust System (not tested yet, I'll finish installation tomorrow)
- TH350 w/ 2400 Stall Speed B&M
- 2.73 12 Bolt Posi rear

At the moment my engine isn't pulling very well above 4000 RPM, giving me bad quartermile times. People have suggested a few things and I will do what they told me:

I bought a new timing light and will check timing as soon as I have the Exhaust System connected to the headers. Hey, this is a residential area! :D

I'm trying to get a Holley 3310 750 Vac secondaries.

I'm planning on a bigger cam (XE268 or XE274) in the future.

But now to the question in the topic.
I just bought a RPM Air Gap Manifold, because the price was lowered more than 100 Dollars, maybe because it has a torn box. It's brand new, what a deal! graemlins/hurray.gif Now my question is whether to use it when I'm installing a new cam or to sell it on Ebay for a nice gain. Will it give me an improvement over the Performer? I don't want to go above 5,5-6k. I was wondering if the big displacement of the 400 would benefit from the use of the RPM (Air Gap) Design sooner (lower RPM) than a 350 for example?

So what do you say, stay with the Performer or go with the RPM Air Gap?

Here's a pic of my bargain:
http://www.abcnetworks.de/ebay/Bild168.jpg

BTW, how much taller is the Air Gap? I have a stock Malibu hood. :eek:

Olli

I bought an airgap for my 355 from a co-worker. His 70 chevelle convertible runs low 12 and high 11's with the air gap on his 383. It's best sixty foot was in the 1.6 range. He replaced it because he was going to use a large nitrous kit that required a single plain intake. I don't know if it helps with your decision making process but I have heard nothing but good things about it.

I've never used the standard Performer but my 350 is pretty happy with the air gap. And I have a stock hood on my 71 Sprint with the Edelbrock 1406 carb and an open element 14" dia. filter and it fits just fine.

Since you already have it, I would use it. (especially with the larger cam)

A VERY good, but generally over looked intake for a SB is the great old Holley 300-36, true high-rise dual plane!!

And the price is rigfht from Summit too...

I got a new one a while back for my little 283 motor I'm thinking about building that should see 8,000 rpm for the fun of it...

pdq67

Are you using a splash pan in the lifter valley? if not you might see a slight gain, since you're changing cams, I'd use the air gap just for the cool factor.

Not to get off topic but I think steeper gears would help out your e.t. more than anything.Now where can I get the ripped box discount?

i picked up .25 at the track going from a Weiand #8004 (basically the same thing as a Performer), to the regular RPM intake. no other changes at all. my motor was an 8.5 to 1 400sbc with an old GK 288/.480 cam, same size headers and exhaust, but i had a 3000 stall and 3.55 gears.
BTW, what cam are you running now?
i agree with the gear advice given in the previous post too. i would try and run at least a 3.31, preferably a 3.55 or 3.73 gear.
oh yeah, i had 487's on mine too.
i now have an air gap on my 406 and i love it. i wouldn't try another intake if someone gave it to me.

I'm running a performer cam. Most of the people said it's too small fr a 400. I wan't to go to a XE268 or XE274. What would you reccomend?
Yes, I know about the gears, that's one of many things I am planning on changing in the near future, see my other posts. I'll probably go with a 3.55.
I also just bought a 3310 Holley and I will install it with the air gap and the new cam somewhen early next year. It's winter now and I can't pull some timeslips anyways. Time to do some other tuning.
Thanks guys, I'll try the Air Gap!

Olli

did you cut out the divider in the plenum????
maybe thats why it was cheap...
shane

I believe thats the way it comes stock...atleast mine looks the same

Originally posted by ovelle:
did you cut out the divider in the plenum????
maybe thats why it was cheap...
shane No, they all come like this.

http://www.sallee-chevrolet.com/Edelbrock/images/7501small.jpg

i dont have a air gap but just a regular rpm
and my plenum isnt cut out....anybody know why????
shane

RPM (non-air-gap) don't have the plenum cut out. Only the Air Gaps have that.

So you didn't get ripped off or anything, all RPMs are like yours.

would it benefit going from a performer rpm to an rpm air-gap? if i go the vortec head route it would require a new intake and was wondering if it would help any.

I have one, its the 7501. Some guys route cables or fuel lines, etc. Through the gap, ive even heard of people putting ice in the gap at the strip to keep things cool. Couldnt make things any worse, thats for sure. I like mine...

You'll get kicked off either of our local tracks with ice on the intake after a warning,,,it leaks on the starting line when you launch.