My Latest Carburetor (q-jet guys will get a kck out of this)

[Oldsmoletick]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

That it is, lol, even if the helping eyes can't actually see exactly what's going on.

 

[Bonnewagon]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

Glad it worked. Just remember that on a Q-jet, just because the secondary throttle is opened, doesn't mean the motor is ready for it. If you look at the throttle linkage, the secondaries don't begin to open until the primaries are at about 3/4 open. Then they both finish opening together, and the air valve opens in concert with the secondary throttle .You want those primaries wailing so when the secondaries open, the motor is hungry for it. Keeping the air valve slightly tight is key to a proper transition, as you found out.

 

[Oldsmoletick]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

This is the type of info I wouldn't get on an amc/jeep forum, lol 8) .

 

[Dugan]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

Ive had my experience with holleys and I feel im able to tune them very easily, maybe its just me. My brother has a stock qjet on his 80 trans am 301 motor and its a dog, cannot get the secondaries to open and I have no background with these carbs. Any idea why the secondaries wont open?

 

[Oldsmoletick]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

There's a few things to check, as you've probably read, we were mentioning air valve spring tension, starting at 3/4 of a turn from zero is a place to start (worked well for my I-6). When you push down on the flaps, can you watch the secondary hanger raise up? If not, your cam that lifts the hanger may have deteriorated, I noticed that with a few of my parts carbs. Next, is your pull off working correctly? There's a couple different types, some have one pull of diaphram for both choke and secondary, and some have separate ones. If your choke pull off is not working correctly, there is a little tab that prevents the secondary throttle plate from opening (it's a little arm that locks against the little pin on the throttle shaft). I usually omitt this piece, as long as you know better than to wail on your car from start up, it won't harm anything not having it there. Look at these few things, cycle the throttle to see if the secondary plate is actually opening (engine cold you will have to hold that little arm away from the stop pin). Other than that, as long as they aren't corroded closed (seen that too, lol) they should work if all that is in check.

 

[Bonnewagon]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

Dugan, I had an 80' Firebird with the "W" 4 barrel 301 also and banged my head against the wall forever trying to get some performance out of it. The problem wasn't the motor, or carb, it was the dead-dog 2:41 rear gears! They wouldn't let the motor work worth a damn. I finally swapped in a 2 barrel Dualjet and the motor loved it because it was a better match for the dead rear. Then the car was a pleasure to drive. Several years later I fell into a 2:56 posi rear and that helped a little more. More recently I had an 81' Malibu wagon and after I pulled the Pontiac 400 out because of the price of gas, I put another Dualjet equipped 301 in for work car duty. The 3:23 rear in that car let the 301 breath so well I put the Q-jet back on and kept it like that. So my advice is to look at your rear gears, and if they suck, upgrade.

 

[Oldsmoletick]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

hmmm, that gets me thinking bonnewagon, I'm running a 33 inch tire, with 3.55 gears, which is roughly as bad of ratio as a 25 inch tire with 2.41 gears. I wonder, for sh*ts and giggles, if I throw on a set of stock tires this thing may wake up dramatically? stock would about a 27-28 inch tire, which would drop the ratio about to the equivalent of a 25 inch with a 3.23. I never realized gears could play hell with engine perfomance as far as the carburetors function is concerned. Maybe a re-gear will be in order for the jeep, lol.

 

[pontiacgp]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

Your tunnel has the cut out for the transfer case shifter. Is it not a 4x4 any longer?

 

[Oldsmoletick]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

?? Are you looking at when I had it gutted? I had to remove the t-case shifter to clean it, along with the trans shifter, they were both full of mouse presents, lol nasty, . The jeep is still 4wd though, interior is all disinfected, cleaned and installed now :lol: (minus a carpet).

 

[Bonnewagon]

Re: My Latest Carburetor (q-jet guys will get a kck out of t

Oldsmoletick, ever ride a bicycle up a big hill? Being in the wrong gear makes you feel a hundred years old, right? Same with the car. A lot of performance issues can be traced to the rear gears not letting the motor flex it's muscle. Sadly, starting in the early 70's GM installed dead gears for these reasons: grams-of-pollutants-per-mile, and C.A.F.E., which is Corporate Average Fuel Economy. So a 2:29 geared car in high gear on the open highway got the most fuel economy and polluted the least with performance not even a consideration. That is why you saw the Saginaw manual trans eventually get a 3:50 first gear, to knock down those 2:41 rear gears. Then came overdrive transmissions which basically did the same but used 3:42 rears in the "performance" cars for some much needed relief. Huge tires affect things as you noted. Ever wonder why the racers use 4:11's and up? Besides for great acceleration, those big slicks affect the ratio, especially at high speed as they grow in diameter, effectively changing the ratio even more.