Anybody go from performer to an rpm air gap

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On a 430ish horse 360 with a 275HL, there was almost no difference between an air gap and a performer 318/360. The performer was cleaned up at the port openings, but, it wasn't matched to the head.

Each had a 1" open spacer and 750 DP carbs.
 
crackedback said:
On a 430ish horse 360 with a 275HL, there was almost no difference between an air gap and a performer 318/360. The performer was cleaned up at the port openings, but, it wasn't matched to the head.

Each had a 1" open spacer and 750 DP carbs.
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I thought I have heard several story's along the same lines that there would be no noticeable difference.
 
Plenum depth,is loosely connected with overlap. If you run,a dual.plane. Cylinder runner size,paramount.......
 
The most common problem on all intakes which all overlook is port match not gasket match per say. Intakes ports are usually ported as per the gasket per side . But it is left bank to right bank that every one over looks. Scribe a line on the top of each intake port separator using a straight edge on the gasket side. Doing this will show you where th web between the two ports are after the intake is set in place. These lines should match centered with the valve cover bolt holes which are centered in the ports.

Wait until you all see how far off some of your intakes are. This is corrected by splitting the difference from side to side by moving the intake front or back. One reason after market intakes do not have the pin holes drilled. after you locate your intake put your pins back in an reset the intake back on in the corrected location .

At this time tap down on the intake ends leaving a marks where the pin goes and then drill them. This intake will always set where it is best aligned on that motor now. Once this position is found you can now port match the intake front or back to the corrected gasket location. This procedure means a lot when it comes to balancing cylinder charge at higher RPM's. which if not correct will throw the motor into a static vibration and cause power loss.

I shift my car at 8500 and it will climb to the end of a 10,000 recall tach. My Indy intake and heads were off almost an 1/8 of an inch. One reason a good sheet metal intake is built on the motor and heads it is to be used on. I learned this trick and others from Mike Dunn through Roland leong. AKA " Hawaian Punch" years back. Works for me.

This is why everyone has a different choice of intake and what works best for them . Some of the same intakes that are perfect on some motors but are way out on others. One intake two motors. two different locations. A used ported intake on one motor may not even come close to sealing on another.

When buying a older or used intake make sure it is virgin and never touched in the ports.

Now its time for you all to kick in with your neg. replys why this doesn't apply to you because your intake is already on and your car is perfect. But to some this may be helpful. "Happy Easter" Steve
 
Oldmanmopar said:
it is left bank to right bank that every one over looks. Scribe a line on the top of each intake port separator using a straight edge on the gasket side. Doing this will show you where th web between the two ports are after the intake is set in place. These lines should match centered with the valve cover bolt holes which are centered in the ports.
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No trash talk coming from this direction. Awesome info!

Equally as kick *** as the Hawaiian Punch shirtless track snapshot. You've got a new fan.

This thread has convinced me to look really closely at port alignment on my project, before buttoning everything together. Firing up the Thanks button.

Also, I'm not entirely sure about this, but it's been mentioned that port matching on the skinny side of the head and intake runner, where the pushrod relief sits isn't worth it? It makes sense to me, if you think about how the pushrod creates a dead spot right there. Has anybody found any conclusive evidence of port matching the pushrod side vs not?

I'm definitely going to center the intake up on my engine and at the very least, get rid of inconsistancies in the castings, per runner at the corners, etc. I'm not terribly interested in port matching, per se, as much as I am getting the runners looking the same.

As for the original post, I'm sort of lost on the Air Gap. I think the idea of getting a cold charge is fantastic, but if you're up in RPM, I agree that a single plane may be for you, if you're looking for top end. I'm sort of convinced that the Air Gap is a stepping stone between a traditional dual plane and a single and I'm also convinced that it would help more on an engine that runs warm, than one running at 195-200. If it runs a dual plane without any air temp issues, an Air Gap wouldn't do a lot.

Also, if a single plane isn't what you're looking for, hitting the secondary side of the plenum divider wall at the carb with a window can help balance. I can't remember if the Air Gap has this already. I know the LD340 does.
 
I can try to borrow my buddy's torker II and try it? And thanks for the info! Never thought about that stuff. The car to the seat if the pants on the street feels like its lacking high rpm power it has plenty of low end. I'm planning on testing it Friday night, play with timing and what not and see what it does then look into intakes and what not. I just was curious to see if the intake could be holding me back. I know advancing the cam "gets you out the home quicker" but is this holding it back from pulling hard in the higher rpms?
 
Steve - Thank you for the tip. I've put the gasket on the head and then on the intake assuming that the bolt holes would line it up. Well next time there will be scribe marks!

Dave - Yes. The LD340 has a notch in the plenum divider. And in the Direct Conection tips for drag racing, they had best results removing most of the divider and then depending on the carb, notching the carb's boosters. It doesn't say so in the reprint, but my assumption is this was for stock or super stock classes and because 3500-7000 rpm was the primary focus!
 
Good to know. I've always assumed that it was for static balance between runners @ high RPM, to gain cylinder sharing at high runner speeds.

Do you know what your distributor advance curve numbers look like, Sam? It would be nice to see what kind of advance you are getting at different RPM ranges. Stock springs don't give full advance until some unreasonable RPM, which could be killing top end, as well. What RPM does it start to taper off at?
 
Are we talking about a plain 'performer' or a Performer RPM? A plain ol' Performer is not a high rpm intake. Somone can correct me if they know different but the plain Performer is was not a aprt of the design program that turned out the RPMs.
A 'Performer RPM' ought to do some good at higher rpm if you are using a unmodified Performer. Whether to us the regular or air gap version depends on the temperature situations you're dealing with.

The orignal Torker was supposed to be sweet from 2500-6500 rpm. You should be able to find the recommended range for the II version, but likely its the same.

Sure its possible to be losing some in the exhaust or the timing. If you have a tach drive distributor, the curve in that is great for what you're doing. It has its drawbacks, but great for higher rpm consistancy and power.
 
It's a distributer that a buddy gave me. It has the lighter springs in it. Vac is plugged off. It's the regular performer
 
Dave. The unmodified notch is fairly small. You're probably right that it helps balance as the secondaries open. Pressure would certainly even out left to right, and one would expect some, but not a lot, of fuel-air sharing.

Attached is a picture (hopefully) of an LD-340 with the divider notch pretty much original. (Yes someone, not me, made the exterior into a stealth version).

You'll see the LD-340 design really looks nothing like Performer RPM. If I ever get the chance, I'd like to try the RPM as well as a Holley Street Dominator. I had the Holley on my last engine with a somewhat similar cam (but not quite) and I don't think it was any worse at idle and low rpm than the LD340. Take a look at those big runner entrances - my theory is that the LD340 was a good higher rpm dual plane and that's where its rep came from. My guess is that's why certain people say it is just as good as the Performer RPM - they're looking at high stall (3000 rpm) street-strip or strip use.
 

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Anybody seen a 3 barrel Holley lately. Look at the LD340 notch, it has to do with those carbs.

If the OP doesn't have a 1" open spacer under the carb, try one.

I wouldn't bother with a torker II if you want to make a change. Decent manifold but you're going to give up low end power. Get a performer RPM or an Air Gap and be done with it. You'll retain more low end with equal top end to most any single plane intake. Use a 1" spacer with either of those RPM intakes as well.
 
Mattax said:
Steve - Thank you for the tip. I've put the gasket on the head and then on the intake assuming that the bolt holes would line it up. Well next time there will be scribe marks!

Dave - Yes. The LD340 has a notch in the plenum divider. And in the Direct Conection tips for drag racing, they had best results removing most of the divider and then depending on the carb, notching the carb's boosters. It doesn't say so in the reprint, but my assumption is this was for stock or super stock classes and because 3500-7000 rpm was the primary focus!
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The notch between the sides on the LD340 was to allow use of the old Holley 3 barrel carbs that they were pushing as the latest greatest thing back then.(showing my age now) Of course most of you guys never heard of a 3 barrel and will probably never see one. A lot of mags back in the 70's urged people to cut the wall out between the 2 sides of the LD340 and it added a few rpm up top and killed off some of the low end torque. I wouldn't recommend it. They ended up coming out with better designs. The Performer RPM(whether airgap version or not) will outperform the standard performer pretty easily.
 
SAM67 said:
It's a distributer that a buddy gave me. It has the lighter springs in it. Vac is plugged off. It's the regular performer
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Well, even though we're discussing three things, pick one thing to change when you go into action!

Too many 'light' springs to even guess what's in yours. Measure the advance and see what you have. You can either put it on a distributor machine or you can measure it in the car using a timing light and tach.

Working alone, I find the easiest is to take the aircleaner off and use the throttle stop screw on the carb. To make it quicker, pre-number the sheet of paper from 16 degrees (or whatever the idle is) to 30. Crank in the idle stop screw just enough to move the advance 1 degree and write down the rpm. (or you could do every 2 degrees). When it starts to level off then just take it up to where you feel comfortable and write it down. In other words, if it starts to level off at 32 degrees and 2800 rpm I'll manual move the throttle up to and quickly note rpm and advance (if any). I try to get at least one read at in the low 3000 rpm range and another high 3 or 4000 rpm. You may see the advance back off a little when winging it to high rpm.

Now you'll have a baseline. If its really horrible, then maybe you'll want to start there instead of with the intake. On the other hand, even if you change nothing with the distributor timing for the moment, you'll know what the story is.
 
My fault for going a bit off subject on the intake runners. OP is using a 3800 rpm converter! Low rpm torque may not be useful or important for that setup. Might well be worth trying a Torker or maybe a more lower rpm friendly(?) single plane like old Holley Strip Dominator if price is right.
 
Ill see what I can do with the dist. Some guy set it up on a machine and put a curve kit in it when he had it. I think I got it at 34 at 3000rpms. Ill tinker with it Friday and see what happens. I'm hoping the car will hook up better
 
What's it got for timing at idle and at what RPM?

Just a guess. It should idle easily at 900rpm and have about 18-22* of timing. If it's a mopar distributor, hopefully it has the mallory style advance limiters.

I'm a total timing method hater... crappy way to set things up.
 
I prefer the whole curve, but for drag racing with a loose converter, the total method is simplest and focused on what is important for that purpose. 34 at 3k would be an OK starting point for that setup.
 
Mattax said:
I prefer the whole curve, but for drag racing with a loose converter, the total method is simplest and focused on what is important for that purpose. 34 at 3k would be an OK starting point for that setup.
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Total or Locked out?? Big Difference. So a guy has 5* initial at Idle and 34* total at 3K is fine?? I don't think so.
 
My 2 cents:

The intake comparison aar posted should answer your intake question. I compared a Holley Strip Dominator to a Weiand Stealth and the Holley was a bit faster BUT I have a LOT more gear, converter and cam duration. The Air-Gap should fit the bill. You can experiment with an open as well as 4-hole spacer. But simply fine-tuning the carb with jets, squirters and pump cams can yield noticable results IF you can get it to hook better. Are you simply spinning or wheel-hopping too?

I don't recall if you mentioned what's in the front suspension, but looser shocks and 6 cyl. torsion bars can help. Stiffer shocks in the back as well. The shackle spacer is a good idea. I got by with a 3/4" spacer.

But depending on the track, sometimes it's better to just add weight to the trunk - as long as it's done SAFELY and LEGALLY to help traction while you sort things out. I added almost 150lbs to an old bracket Challenger I had and the consistency improved quite a bit helping me win more.
 
building blocks... if the carb metering at idle is a pile o'crap, guess what, the rest of the metering needs to be compromised to get it right all the way up.

Insufficient initial timing causes those issues and a car with it set properly will outperform, especially 60' where it counts, one set crappy. Set initial where the starter or engine tells you and use that as a foundation to tailor the entire curve. Try a distributor in that engine with 30* of mechanical advance, but the total and where it all comes in is right, and see how well it runs! Like dog crap down low would be a good visual.

34 on an open chambered 360 with that cam would be the bottom of the timing range for me. Best thing to do is dial in more timing and see if it picks up MPH. Do that until it stops increasing.
 
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