How can I tell if my outboards are opening on a six pack?

[Righty Tighty]

It is my understanding that the outboard carburetors do not open if you're revving in park in your driveway -- that is to say the engine needs a load placed on it. I remember reading somewhere that people will sometimes place a clip somewhere on the linkage and take the car out, then check the clip for movement.

That sounds like a nice and simple method, are there any other techniques you guys & gals use?

After I get the timing dialed in on this setup, I'm going to look at the outboards because I have a sneaky suspicion they may be hanging up. The throttle shafts are a tad rusty.

 

[toolmanmike]

A vacuum pump like Mityvac can check individual carb diaphragms. A vacuum gauge can check the source vacuum. Here's a good video to show you.

 

[Righty Tighty]

Thanks! I've watched just about all of Mr. Demes' videos on the six pack and forgot about the air compressor method.

 

[Dana]

If your neck isn’t stretched back over the backseat, then they are not opening

 

[Demonic]

Usually the back tires start smoking.

 

[Righty Tighty]

So, I know its a vacuum signal that operates the outboards, but is there a typical RPM range they start to open? If I remember correctly, I have the bare metal (unpainted) springs installed.

I know I need to get the timing figured out first, but this has been gnawing at my brain.

 

[Lefty71]

I wouldn't screw around with potentially sticking carbs..... pull them down and have them checked by a reputable shop, if you aren't the handy type.

 

[Daves69]

Mount a mini cam with a cell phone next to your tach?
such as......
USB Snake Inspection Camera, FANTRONICS USB C Borescope, Scope Camera with 8 LED Lights for (16.4ft) OTG Android Phone, Windows PC, MacBook: Amazon.com: Industrial & Scientific

 

[K.O. SWINGER]

So, I know its a vacuum signal that operates the outboards, but is there a typical RPM range they start to open? If I remember correctly, I have the bare metal (unpainted) springs installed.

I know I need to get the timing figured out first, but this has been gnawing at my brain.

There is going to be several factors that determine when the outboards come in. I use yellow springs which a factory springs I also use a fairly gnarly hydraulic cam but I guess to keep it fairly straightforward I would say generally at wide open throttle around 3,000 RPMs. The outboards butterflys need move freely.- the diaphragms will fail I've had to replace mine once. If you don't think you're outboards are coming in then they're definitely not. You would know.

 

[413]

Never remove the linkage from the outboards and run the car. If they open there will be no closing them. This linkage closes the carbs, the vacuum lines open them.

With engine off remove the return springs to the center carb and hold it wide open. Now open the outboards by hand and see if the operate smoothly and easily. They should, they’re will be a mild resistance from the springs inside the vacuum pods.

Easy way to tell, go run the car wide open for 5 seconds. Now un plug the vacuum hoses from the outboards and do the same run, is the car running slower now?

to add to Dana’s post, if you have to ask, they are not opening!

 

[Righty Tighty]

Never remove the linkage from the outboards and run the car. If they open there will be no closing them. This linkage closes the carbs, the vacuum lines open them.

With engine off remove the return springs to the center carb and hold it wide open. Now open the outboards by hand and see if the operate smoothly and easily. They should, they’re will be a mild resistance from the springs inside the vacuum pods.

Easy way to tell, go run the car wide open for 5 seconds. Now un plug the vacuum hoses from the outboards and do the same run, is the car running slower now?

to add to Dana’s post, if you have to ask, they are not opening!

Thanks!

I need to make sure my timing is good first, because without getting too off topic, I can’t run it full throttle (or even above 3400rpm) without it acting up. One theory is that it’s running lean, but I want to rule out timing/ignition first.

 

[ch1ll]

Easy peasy, get some vent whistles.

 

[Righty Tighty]

Vent whistles! Brilliant! Why didn’t I think of that?

 

[Righty Tighty]

There is going to be several factors that determine when the outboards come in. I use yellow springs which a factory springs I also use a fairly gnarly hydraulic cam but I guess to keep it fairly straightforward I would say generally at wide open throttle around 3,000 RPMs. The outboards butterflys need move freely.- the diaphragms will fail I've had to replace mine once. If you don't think you're outboards are coming in then they're definitely not. You would know.

Thanks. I replaced the diaphragms about 10 months ago after I rebuilt the carbs. What I didn't do when I had them apart was clean or replace the throttle shafts, and I'm thinking I should've.

I tried the test from Harold Demes' video, but I couldn't get too far, because I ended up with a mist of fuel spraying back out of the throat of the carb.

 

[Bewy]

Get a paper clip. Adjust the tension so that it grips the arm of the vac sec linkage arm; adjust so that clip just touches the underside of the vac sec unit. Drive car to actuate secs. If secs are opening, clip will be further down the arm.