John S Posted January 15 Share Posted January 15 Does anyone have any pictures or can they tell me which carburetor base gasket is the correct one for a 350 4 bbl. I have three pictured they are all 1/4 inch thick. John S Quote Link to comment Share on other sites More sharing options...
Dtret Posted January 15 Share Posted January 15 They are all correct. It’s what you’re planning for the engine is where the difference comes in. Intake, carb? 1 Quote Link to comment Share on other sites More sharing options...
John S Posted January 16 Author Share Posted January 16 No modifications in the works. Just trying to figure out an issue. I can back out the idle screw all the way and the engine will keep idling at 850 RPM. Pulled the carburetor check to make sure the throttle plates were fully closing and they were, nothing was in a bind. I had a slight hangup when releasing the throttle with the accelerator pump I replaced that operate smoother still same issue. At Idle the engine has 20 inches of vacuum. If I pull a vacuum line off the carburetor, the idle will increase, idle mixture screws are backed out to where it idles the best. I believe they are a little over 2 1/2 turns out. Maybe it’s nothing just thought that by backing out the idle stop screw the engine RPM would decrease until it quit running. Quote Link to comment Share on other sites More sharing options...
1970mcss Posted January 16 Share Posted January 16 Did you pull the distributor? Did you check the timing? Quote Link to comment Share on other sites More sharing options...
John S Posted January 16 Author Share Posted January 16 8 minutes ago, 1970mcss said: Did you pull the distributor? Did you check the timing? No did not pull the distributor. Timing is unchanged. 1 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted January 16 Share Posted January 16 Check to see if the throttle arm, where the idle screw touches is not hitting the body of the carb. Sometimes people bent the arm. If this is the case, bend/ tweak the arm to let the carb ldle lower. Also disconnect the throttle cable from the arm to see if the cable isn't adjusted too short. Not letting the idle come down. 2 1/2 turns out on a Rochester is where 99% of them like being adjusted to and disconnecting a vacuum line will cause the idle to go higher due to a lean condition being created. 1 Quote Link to comment Share on other sites More sharing options...
John S Posted January 16 Author Share Posted January 16 Thanks yes, I checked all of that. I disconnected The cable, pushed on the throttle arm to try to close it more. Everything moves freely. I guess the good thing is that it idles at 850 RPM instead of 1500 RPM. To double check that I have to use another tachometer. The tachometer in the gauge panel is 250 to 300 RPM off at idle 400 RPM off over 2500 RPM. If I close the choke or put my hand over the carburetor, the engine will quit, so I don’t think I have a big vacuum leak. Quote Link to comment Share on other sites More sharing options...
1970mcss Posted January 16 Share Posted January 16 John, I remember years ago I had a 71 Corvette with a 350 4 speed that had a high idle. I worked at a Chevrolet dealership in the parts room when I was just starting out. One of our mechanics told me that there was a carbon build up under the intake manifold. I first thought he was pulling my leg because I was young and I won't say stupid, but he insisted. So, I took the intake off the car one weekend, drilled out the plate under the intake and sure enough there was a big chuck of carbon. I pulled the carbon out, screwed the plate back on and put it back together and the car ran perfect. I'm not sure that's what you have going on but maybe someone else can confirm. I hope you figure it out. Quote Link to comment Share on other sites More sharing options...
John S Posted January 30 Author Share Posted January 30 My throttle cable can connect to three different holes on the carburetor. Does anyone have a picture or could tell me which one is the proper hole to connect the throttle cable to it is a 350 4 barrel with a four speed. Right now it is hooked up to the farthest forward hole. That is the way it was since I bought the car. Quote Link to comment Share on other sites More sharing options...
stangeba Posted January 30 Share Posted January 30 This is my 71 350 Automatic with speed control added by me. I would say the top hole? After you do attach it, make sure you get WOT (Wide Open Throttle) 3 Quote Link to comment Share on other sites More sharing options...
John S Posted January 30 Author Share Posted January 30 November 2020. Canuck posted a picture of his carburetor on a thread. His carb number is one off from mine. Mine is 7040203. His is 7040202 and his throttle is hooked to the top right hole, so I’m going to assume mine should be the same. And yes, make sure to verify closed throttle, wide open throttle, and smooth operation of the cable. Thanks. 2 Quote Link to comment Share on other sites More sharing options...
John S Posted February 2 Author Share Posted February 2 It’s surprising what happens when the throttle cable is connected in the proper position. The car idles. I’m able to use the original style throttle return spring. Even with simple issues. Everyone here is very helpful. You can see the throttle cable that was on the car that the sleeve had to be cut since the geometry was off. It would hang up if I didn’t cut part of that sleeve off. The new cable on the carburetor is the way it supposed to be. Thanks Bruce for the picture. 3 Quote Link to comment Share on other sites More sharing options...
stangeba Posted February 2 Share Posted February 2 And now you do get WOT!! Everyone needs WOT!!! 3 Quote Link to comment Share on other sites More sharing options...
John S Posted February 2 Author Share Posted February 2 Yes, I do. I checked it visually with someone pressing on the accelerator pedal and it’s almost 70° here today so I took it out for a carbon blast on a county Road and did a quarter-mile run. Runs fine. 2 Quote Link to comment Share on other sites More sharing options...
Canuck Posted February 8 Share Posted February 8 Here’s mine Quote Link to comment Share on other sites More sharing options...
John S Posted February 8 Author Share Posted February 8 16 hours ago, Canuck said: Here’s mine I believe that is the picture I used as a reference. My carburetor had the ball stud on the front hole. That’s where it was always connected. Now it’s right and works as it should. Thank you for the pictures. 1 Quote Link to comment Share on other sites More sharing options...
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