Q-Jet rebuild question

[Bill75]

I'm putting a rebuild kit in the Q-jet on my 75 and am using Doug Roe's book which I'm finding very good. I lifted the air horn assy. off and then the gasket and discoverd a part I could not find any reference to in the book. My NAPA kit does show it in the parts blowup as an "Aneroid Assy, (Spacer 1976)". It's screwed to the carb and has a long brass shaft that appears to seat in an orifice in the bottom of the carb. By the serial numbers the carb is for a 1976 car and is a California model (whatever the heck that means!). Can someone tell me what the function of that part is?? Wonder why it's not in the book?

Also I'm going to seal the primary and secondary fuel wells with epoxy while I'm at it. Is J-B Weld the best stuff to use for sealing against leaks, and does it stand up OK to gasoline?

Thanks,

Bill

 

[motorman]

I'm putting a rebuild kit in the Q-jet on my 75 and am using Doug Roe's book which I'm finding very good. I lifted the air horn assy. off and then the gasket and discoverd a part I could not find any reference to in the book. My NAPA kit does show it in the parts blowup as an "Aneroid Assy, (Spacer 1976)". It's screwed to the carb and has a long brass shaft that appears to seat in an orifice in the bottom of the carb. By the serial numbers the carb is for a 1976 car and is a California model (whatever the heck that means!). Can someone tell me what the function of that part is?? Wonder why it's not in the book?

Also I'm going to seal the primary and secondary fuel wells with epoxy while I'm at it. Is J-B Weld the best stuff to use for sealing against leaks, and does it stand up OK to gasoline?

Thanks,

Bill

the aneroid is used to change the mixture with altitude. DO NOT adjust the screw in the top of the aneroid or you will never get it back right. some carbs have it and some do not

 

[Bill75]

OK motorman, thanks. I won't touch it.

 

[pgtr]

Roughen up the surface and use the JB weld epoxy rather than straight epoxy. It should last longer AFAIK. I've got some carbs I rebuilt 10 years ago and was lazy and used regular (clear) epoxy - that glue job went soft and could be pulled off easily I recently noticed. Other thing that might beat JBWeld is the stuff sold here: www.carbdoctor.com though I have no personal experience.

Good luck!

 

[Bill75]

Q-Jet

Thanks for the reply pgtr, I was hoping someone would say that. I bought some and sealed the fuel wells, let it sit overnight and reassembled it last night. She fired up without a problem and this morning it fired right away.

For anyone interested, this was not much of a challange to do and most people would have no trouble rebuilding a carb that was in the condition mine was. The butterfly shafts weren't worn so that saved allot of grief. If you're careful about organizing you're work and follow the book, it's pretty easy.

Thanks for the link also, never knew they were out there.

Regards,

Bill

 

[Bill75]

Secondary Problem

Well, everything works fine except the secondaries won't cut in. So.............later today I'll be firing up the grill for some crow to eat!!!!!!!!!!!!

The engine runs fine except the secondary butterflies at the top of the carb will not open, I can't figure out how this thing works.
As soon as the engine is started a vacuum is pulled on the Front Vacuum Break Assy. which in turn pulls in the mechanism attached to it. The mechanism is attached to the secondary butterflies by a linkage arm which when pulled by the Break Assy, prevents the buttrerflies from opening. I can see this happening when the engine is cold but after warming up it seems like it should allow them to operate.

I temporarily disconnected the vacuum line to the Break assy and they work perfectly but as soon as I reconnect it the linkage arm pulls the secondary linkage closed.

I checked the diaphram on the Break assy just for the heck of it and it looks like it's OK, it holds a vacuum which indicates the diaphram is OK .

Although the carb performed poorly before the rebuild, the secondaries did open.

Help!!!!!!!

 

[motorman]

Well, everything works fine except the secondaries won't cut in. So.............later today I'll be firing up the grill for some crow to eat!!!!!!!!!!!!

The engine runs fine except the secondary butterflies at the top of the carb will not open, I can't figure out how this thing works.
As soon as the engine is started a vacuum is pulled on the Front Vacuum Break Assy. which in turn pulls in the mechanism attached to it. The mechanism is attached to the secondary butterflies by a linkage arm which when pulled by the Break Assy, prevents the buttrerflies from opening. I can see this happening when the engine is cold but after warming up it seems like it should allow them to operate.

I temporarily disconnected the vacuum line to the Break assy and they work perfectly but as soon as I reconnect it the linkage arm pulls the secondary linkage closed.

I checked the diaphram on the Break assy just for the heck of it and it looks like it's OK, it holds a vacuum which indicates the diaphram is OK .

Although the carb performed poorly before the rebuild, the secondaries did open.

Help!!!!!!!

the secondary will not open except under a load on the engine. when the engine is under load the vacuum to the choke pulloff will go away and the secondary air flap will open

 

[Bill75]

It won't open under load going down the road either motorman, not even the slightest amount. Sounds like a 2 barallel carb right to the floorboards!

 

[motorman]

It won't open under load going down the road either motorman, not even the slightest amount. Sounds like a 2 barallel carb right to the floorboards!

make sure that the choke is open all the way and the secondary butterfly lockout is not preventing the secondary butterfly from opening which of course will not allow the secondary air valve on top of the carb to open.

 

[Bill75]

OK, I'll go look it over

 

[Bill75]

Your comment made sense, I really looked the linkage over and worked it many times. Choke was opening correctly all the way and everything seemed in order. I retightened the carb hold down screws that were a little loose and took it for a ride and it worked perfectly. So whatever I did in that area fixed something. I hate these things that fix themselves, but it works every time. Maybe part of the linkage was caught on something and I freed it up somehow.

Now if only the engine underneath it had a little more HP, it could make use of the carb!!!

Thanks for taking the time to help me out motorman.

Best regards,

Bill