1. When I put my q-jet on my Edelbrock 2101 intake the secondaries will not open. I'm using the insulator/gasket that Lars supplied when he rebuilt the q-jet. Don't know the vendor.
The secondaries open fine when on bench. Must I use the Edelbrock gasket or should a Fel-pro gasket work??

2. When bolting the carb to the intake, the 71 AIM specifies a crisscross sequence in 2 stages. The first at 24 - 48 inch pounds and the second at 20 - 30 foot pounds. Seems high to me.
Is this torque value correct?

Thanks

 

1. Did you turn the carburetor upside down with the gasket and see if the secondaries hit the gasket.
2. Did you try loosely installing the carburetor and before tightening anything open the throttle wide open to center the carburetor on the intake?
3. I really doubt anybody uses a torque wrench when installing a carburetor, it should be "wrist" tight for lack of a better way to explain it. Do not put your forearm into it and the second figure is way wrong.

 

The '72 AIM shows this: (no clue what the "roll test" is)

 

I torque mine in three stages - 6ft lbs, 9 ft lbs and finally 12 ft lbs in criss cross fashion. No leaks, no warping.

 

Sorry, but 12 lbs sounds way to low for a 5/16th's bolt. 18-22 would be standard tourqe .
12 could come loose.

 

How about a pick of the intake. Are you making sure the secondaries prevention lever is moved. If yes pull the carb up and open the secondaries then slowly lower it until it hits and see why

 

1969 AIM is 10-15 ft lbs. I think its not so much about the standard range for a Grade 5 5/16th bolt (22 ft lbs), but rather the soft metal of the carb air horn, body and throttle plate that is the concern. Too much torque may damage the soft metal of the carb. But to your point, it is possible for the bolts to heat cycle and come loose, but I have yet to have that happen.

Sammy

 

Unless you want to do damage to the carb, tighten the hold down bolts only as tight as you can get them with a nut driver. 15 ft-lbs is WAY too much, and it will damage your carb. 22 ft/lbs will probably break the casting, and it will actually crush the float bowl over time. And use a flat washer under the bolt heads so you don't chew up and destroy the carb casting. GM got away with running the torque as high as 15 because these carbs were designed and intended to only last for 10-15 years. If the carb is destroyed in 15 years, who cares..? Throw it away. And throw away the car, too. Who wants a 15 year old Vette..?

For perspective, I did a demonstration during one of my Tuning for Beer Tours about how much torque is needed on the carb hold-down bolts to seal up the carb. I loosened all 4 carb bolts so they were only engaged into the manifold on a few threads - all the bolts were doing was holding the carb in position on the manifold - they were not clamping the carb down at all. When the engine started with the loose carb, engine vacuum pulled the carb down tightly onto the manifold, and it ran flawlessly. That's how much torque you need on those bolts.... (No, I'm not advocating running the car with the bolts loose. Just snug them down good with a 1/4" drive nut driver and you're good.) More Q-Jets end up in my trash can as a result of the owner over-torquing the forward hold-down bolts than any other cause.

Lars

 

Love it......
And take a look at the average Q-Jet where the bolt meets the casting up front........the tops are usually always chewed up by overtightening.....washers as stated are a MUST.

Jebby

 

I feel like a real dummy now. Of course it worked upside down.... because the secondaries prevention lever falls away from the stake. All is good now.
Thanks RR!!

 

So you are saying the choke was closed preventing secondary opening.

 

Yes....feeling like a real dumbass.

 

Everyone's done it. That's how we know...

 

I haven't done it, but that's only because I haven't had to install a carb yet. Hopefully when I get to that stage, I'l remember this and do it correctly!

Paul

 

Curious question Lars - for the air horn to body screws, is there a good torque value? I ask because the German Spec "Gudentight" is a relative thing to each person. Do you have a rule of thumb, maybe something like 15 inch lbs or something?

Thanks

Sammy