Classic Winnebagos & Vintage RVs

Hello,

I'm not sure if my secondaries have ever opened up under acceleration while driving. The carb has run fine for me and the only thing I ever did was renew the heater coil assembly for the choke unit that releases the fast idle.

Can you guys hear your secondaries open up while driving when you mash the gas peddle?

Should I be able to hear it with the engine cover on?

I think once I drove it around with the Dog House cover off and really didn't hear the deep roar when the secondarys open up.

Where is a good place to look if mine are not opening?

Thanks,

Steve

Oh, yes.  On my Holiday Rambler, when the secondaries open you can definitely hear it.  Or you can just look at the gas gauge and watch the needle move to the left.  Seriously, there is a distinct sound when the gas guzzling parts become active, even with the dog house on.  You can also tell a big difference when the fan is on or not.  You could just take the dog house off and the air cleaner off and drive around and just look at the carb.  You will see whether the secondaries are open or not.   
Dan

Thanks Dan,

I'm sure I did that once, run around with the Dog House off. I never heard the secondarys open up ever. I don't feel comfortable doing it with the air filter off. BTW, our RV's are allot alike but mine is shorter. It is a 33 or a 30 footer.

I've looked at the carburetor linkage a few times but I have no idea where to start.

It seems to run OK on 2 barrels just would be nice to hear the other 2 cut in. I guess I will need to read up on it some.

Steve

You've got me wondering now.  I am going to have to do the dog house off thing.

If your not sure you have a 33 or 30 foot model, look on your rigs side, aside from my having the original dealer sticker, mine has a decal on it's side that says "Imperial 28".

I hear the secondaries kick in when going up hill... if I am pushing her, which yes for the gas needle heading left LOL... 
Tina

I have only "noticed" mine opening once and that was going up a very steep hill. I never floor it tho, I TRY not to open them up, because then I'd be getting like 1/2 mpg

Now I'm wondering how long it would take the gas tank to go from half to a quarter if mine worked.

I'd bet money that mine does not open nor has it ever since I have owned it, but so far it pulls OK and on long steep roads I just downshift since it only will go so fast anyway and watch the following car line get longer.

Steve

Be brave.....pull the dog house....pull the aircleaner....let engine warm up for a few minutes......hammer the throttle to the floor for a quick second...look to see if the secondaries open.

I will have to rethink my previous answer.  I asked a friend of mine who owns a 1990 Champion LaSalle about how loud his engine was in the cockpit.  He said it was relatively quiet and that he couldn't tell when the secondaries opened up nor when the engine fan kicked on.  I guess I need more insulation in mine. 

Edelbrock on 440 though... I never "heard" them kick in, even flooring it to climb mountains and, a 440 in a '74 Winnebago with stock engine shroud is a LOUD beast.

Quote from: HandyDan on July 16, 2013, 07:08 PM
I will have to rethink my previous answer.  I asked a friend of mine who owns a 1990 Champion LaSalle about how loud his engine was in the cockpit.  He said it was relatively quiet and that he couldn't tell when the secondaries opened up nor when the engine fan kicked on.  I guess I need more insulation in mine. 

They must all be quite different, my fan is VERY loud, much louder than when the secondaries open up for sure.

I have know problem hearing my quads kick.Sounds a little like a sick fog horn. I just have a hard time taking turns listening to the exhaust manifold Leak, the secondaries kicking in, the fan motor noise,and looking in the rear view for parts falling off or a stream of lord knows what following me. :)

On some Q-jet carbs if not most if you lightly floor it the rears will not open up at times. Generally you'll have to punch it to get them to open. This can be due to the rear linkage has a leg - or foot if you call it on the out side of the linkage, this keeps the back barrels from just opening up every time you go past 1/2 throttle not punching the gas pedal like your going to pass someone. It can be removed, but for the performance aspect you will suffer more in the fuel economy.

ML You may have a siezed fan clutch and the fan is runnung full on all the time  Check with engine cold/cool and not running can you easily rotate the fan blades by hand (engine OFF) If not its frozen and the fan clutch needs replaced   Frank

my fan doesnt run all the time, I hear it kick on every single time. Sometimes I think it doesnt come on often enough tho.

Oh yeah, sounds like it's going to suck the dog house in. :)clap

I can definitely hear mine kick in on the 440. No mistaking it.

On my 440, no.  Definitely could not hear them kick in.  Seems like maybe you can, maybe you can't.  It all depens on your RV, your carb, and how good you can distinguish the sounds.

Here is a video showing kind of what happens on a carb with vacuum secondaries. Holley type act much the same. Secondaries dont run off engine vacuum, they respond to venturi velocity (At least holley type do).

http://www.youtube.com/watch?v=nRK9n4NQvOA

blipping the throttle while out of gear probably isnt going to get them to activate. You will have to really rage on it to be able to actually hear them...like pushing it up a hill... and there will probably be a lot going on at this point you will REALLY have to be good at differentiating sounds...

Now there is a whole lot of good Quadrajet info, To take some of the myestery out of them ! Frank

QuoteI will have to rethink my previous answer.  I asked a friend of mine who owns a 1990 Champion LaSalle about how loud his engine was in the cockpit.  He said it was relatively quiet and that he couldn't tell when the secondaries opened up nor when the engine fan kicked on.  I guess I need more insulation in mine.

Go back and ask him if he has a 1989 or 1990 P30 Chassis.

1989 = Quadrajet
1990 = TBI (no such thing as secondaries)

Dave

oh heck ya you can hear them kick in... good amount of rumble in addition to it all... add on the Banks torque tubes... and it then sounds like you have a pack of Harley's along for the ride.

Stole my thunder Dave.

 Hm? I see what you did there.......... N:(

That video was funkaliscious!!!

Quote from: maxximuss on July 17, 2013, 09:34 AM
On some Q-jet carbs if not most if you lightly floor it the rears will not open up at times. Generally you'll have to punch it to get them to open. This can be due to the rear linkage has a leg - or foot if you call it on the out side of the linkage, this keeps the back barrels from just opening up every time you go past 1/2 throttle not punching the gas pedal like your going to pass someone. It can be removed, but for the performance aspect you will suffer more in the fuel economy.

On a properly adjusted quadrajet that lock would be released after warm up. That lock should on keep the back barrels closed until the choke has released if the pull off is correct. The throttle plate will open when you push down on the pedal BUT, the top butter flys may not. Depends on the setting, they can be adjusted to open as early as you want. To early and you will get a big bog. The rear butter flys on a holley carb has a diaphragm and spring that can be tuned, the quad just has a spring that can be adjusted as necessary. most box store rebuilts have too much spring pressure, keeping the rear butter flys closed too long. Last thing you want is the BOG on a heavy vehicle like a MH.


http://www.youtube.com/watch?v=JrQBCLdyDC8