Choke pulloff too strong?
Thread Starter
Pro
Joined: Nov 2008
Posts: 542
Likes: 3
From: Bloomfield Hills MI
Choke pulloff too strong?
I'm having a problem with my choke. My carb was rebuilt by The Carb Shop and when I first installed it, the choke worked great - depress the pedal before starting, choke engaged, start up, car idles at about 1100 rpm, after a minute or less, a blip of the throttle and it disengaged - perfect!
OK, so I fixed a major vacuum leak I was having through the incorrect carb gasket. Now the choke pulloff seems to be so strong, that it 'pulls' the choke open on a cold start. It pulls so hard on the weighted arm that it forces the choke open.
Is there some adjustment I am missing? As mentioned before, it worked great before I removed the carb.
It's a 1970 Quadrajet on 454 bb car with the divorced choke setup (coil on intake).
I had a good search on here with no luck, apart from references to Lars paper. That choke pulloff is so strong!
Anyone?
OK, so I fixed a major vacuum leak I was having through the incorrect carb gasket. Now the choke pulloff seems to be so strong, that it 'pulls' the choke open on a cold start. It pulls so hard on the weighted arm that it forces the choke open.
Is there some adjustment I am missing? As mentioned before, it worked great before I removed the carb.
It's a 1970 Quadrajet on 454 bb car with the divorced choke setup (coil on intake).
I had a good search on here with no luck, apart from references to Lars paper. That choke pulloff is so strong!
Anyone?
Race Director
Joined: Dec 2004
Posts: 15,009
Likes: 2
That is the job of the pulloff....to open the choke slightly so the engine will have some air upon start up. You should adjust it to have the choke flap open about an 1/8th inch. That is something that should have been set at the manufacturer.
Tech Contributor
Joined: Aug 1999
Posts: 14,375
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
The choke pulloff should pull the choke open 1/4" immediately upon cold start as measured from the forward lower edge of the choke to the airhorn wall. It should be forceful.
Choke setup and adjustment procedure, including pulloff adjustment, is outlined in detail in my Q-Jet Setup Paper, available from me by e-mail request:
V8FastCars@msn.com
Lars
Choke setup and adjustment procedure, including pulloff adjustment, is outlined in detail in my Q-Jet Setup Paper, available from me by e-mail request:
V8FastCars@msn.com
Lars
Thread Starter
Pro
Joined: Nov 2008
Posts: 542
Likes: 3
From: Bloomfield Hills MI
Thanks Lars - appreciate the feedback. It is indeed forceful and appears to pull more than 1/4". I'm trying to figure out what changed from when I removed the carb.
I'm sending you an email for that paper - thanks for the offer.
I'm sending you an email for that paper - thanks for the offer.
Tech Contributor
Joined: Aug 1999
Posts: 14,375
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
Use a 1/4" drill bit to measure the pulloff amount.
Take a long piece of vacuum hose and attach it to the pulloff. Stick the other end of the hose in your mouth and suck on it to contract the pulloff. Crack the throttle open and fully close the choke using the choke lever that the divorced choke rod attaches to. Apply light pressure to the choke plate to simulate the force of the airflow trying to open the choke. Measure the opening amount with the drill. Bend the pulloff contact arm so that you achieve the 1/4" dimension.
It's not possible for this adjustment to change once it's set. Chances are that the adjustment has not changed: You changed your mixture by fixing your other problem.
Lars
Take a long piece of vacuum hose and attach it to the pulloff. Stick the other end of the hose in your mouth and suck on it to contract the pulloff. Crack the throttle open and fully close the choke using the choke lever that the divorced choke rod attaches to. Apply light pressure to the choke plate to simulate the force of the airflow trying to open the choke. Measure the opening amount with the drill. Bend the pulloff contact arm so that you achieve the 1/4" dimension.
It's not possible for this adjustment to change once it's set. Chances are that the adjustment has not changed: You changed your mixture by fixing your other problem.
Lars
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
You need to re-adjust the whole carburetor from start to finish. The fast idle settings, the minimum idle settings, the curb idle settings and the fuel mixture settings.
cc
BTW, you should probably check the timing also.
Thread Starter
Pro
Joined: Nov 2008
Posts: 542
Likes: 3
From: Bloomfield Hills MI
Well, one thing that changed is the vacuum. You fixed "a major vacuum leak" which affects air to fuel ratio and the strength of the vacuum available at the carburetor which is the primary force that it runs off of.
You need to re-adjust the whole carburetor from start to finish. The fast idle settings, the minimum idle settings, the curb idle settings and the fuel mixture settings.
cc
BTW, you should probably check the timing also.
You need to re-adjust the whole carburetor from start to finish. The fast idle settings, the minimum idle settings, the curb idle settings and the fuel mixture settings.
cc
BTW, you should probably check the timing also.
Thanks, however for the comments.
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Thread Starter
Pro
Joined: Nov 2008
Posts: 542
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From: Bloomfield Hills MI
