Re: 1974 Sonett III - Installing a Manual Choke on a FoMoCo carbureto - Saab Sonett Bulletin Board -

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Re: 1974 Sonett III - Installing a Manual Choke on a FoMoCo carbureto

Posted by juanm [Email] (#201) [Profile/Gallery] (more from juanm) on Thu, 3 May 2018 05:26:51 Share Post by Email
In Reply to: Re: 1974 Sonett III - Installing a Manual Choke on a FoMoCo carbureto, Jim H, Mon, 23 Apr 2018 22:00:13
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Thank you for your comprehensive list of other issues to check. All VERY VERY good points. I have checked many of those (virtually all, I think) and replaced most of them. I have replaced points, cap, wires, condensor (as well as a non-functioning voltage regulator), the deceleration valve diaphragm,and all the gaskets and properly gapped the spark plugs. I replaced the air filters and all the hoses on the car including the ones to and from the automatic choke. I have taken the automatic choke apart and discovered that the lines within the automatic choke were plugged with debris. I cleaned all that out. In addition, I found that the piston in the automatic choke was frozen in place (took a lot to free that up but I did it). I have used a gallons (an exaggeration) of carburetor cleaner in a lot of areas. We have made numerous adjustments on the carburetor. I replaced the fuel pump too. Also replaced the starter. Lots of trial and error coupled with some basic logic and electrical tools, etc. A friend (well-experienced with carburetors and old cars and cars in general) and I worked on this for quite some time. We observed that it always came back to the choke (butterfly valve) not opening and closing properly. The car typically would start up quickly or fairly quickly but it would run at about 2,000 rpms and then start going up to as much as 3,000rpm (in cold, warm and hot weather conditions). I tried the push (or tap or kick or whatever) the accelerator to the floor quickly to try to get the choke to adjust to a normal position to result in the RPMs going down to about 900. Never happens. Sometimes the car starts out at about 1,500 rpms but again it starts to creep up over 2,000 and doesn't settle down. We have checked all the accelerator and choke linkages - all seem fine. Manually adjusting the choke works perfectly. I have read that many persons (even with the other alternate Sonett Carbs) have installed manual chokes. I did recently got photos from a guy in one the Facebook Sonett forums which was inspiring but was similar to what I had been creating. Then as I was going through my large library of Sonett books, articles and photos, I found what a great reference. It was a one-age article written and nicely illustrated by the dean of all things Sonett, Jack Ashcraft that appeared in a compilation Titled " Technical Information Maintenance Tips and Modifications The Saab Sonett 1956 - 1974" originally published in May, 1982 by the Minnesota Sonett Club, the Saab Clubs of North America, the New England Sonett Club and the Saab Sonett Club of Southern California. About a year ago, I purchased this publication through membership in either the Vintage Saab Club of North America or (sorry off-hand I don't recall which one). I am now in the final phase of the creation and installation of my manual choke (simple mechanisms cut from one small piece of steel from Home Depot and screws and washers), and if other things don't get in the way, What I am doing is similar (coincidental) to Ashcraft and the one other manual choke installation. I hope it is installed and fully functional in the next week. I will gladly post some photos once I know it is working properly.
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