I have a 1972 B20 E in my 1967 122s with a weber carb.. I have been trying to set the electric choke on it and I think I have it working pretty good now after watching a few You Tube vids on setting it.. It seems to be running very well but when I come down a long hill ,about a half mile or so geared down with no throttle it seems to buck and stumble for a bit when I start going up another hill at the bottom ,, down one hill and up another right away.. The new temp. gauge I put in reads about 180 degrees or so and I am wondering if I put in a hotter thermostat if it would help.. I do a have a new 195 degree one in my box of junk but would that be too hot ??.. The outside temp will be in the 90 s this week.. Thanks in advance

A ‘72 B20 with FI would be a B20F. B20E models were 70 and 71.

Did your comment add anything to the post? Correcting him really does nothing to answer/resolve the question.

I have to say the car is running much better now as I have leaned out the electric choke,, turned it counter clock wise.. Yesterday after I leaned it out a bit it was perfect going back up he hill ,,no misses,, no kicking,, but it was not starting as nice as before. Today I turned the choke a very little bit clock wise and it started very well, went the hill from my place very well with no kicking and missing... Test drove to my son`s place and it ran great,, come down the big hill and up the other and it ran perfect.. Maybe it was just a case of fine tuning the choke. I was told this B20 E engine came out of a 1800 sports car.. Thanks for everyone`s help !!

Maybe the hot weather is making me grumpy but I need to point out that if any post in this thread was useless--it wasn't the post that informed the OP of the correct designation for his motor. This information could guide him in any future service or repairs. I'd find it useful to know that my "F" model has a lower compression ratio than the "E" and could probably run fine on regular grade gas rather than premium and a quick kick for power would be to shave the head to "E" specs. - Dave

I don't think I would suspect either the thermostat or icing. Icing usually in cool humid conditions but under hood temps at 90º in Ca unlikely to be in that area. If you fitted this as a complete new kit it's known that the jetting is often slightly adrift for some cars. IPD used to, may still do, offer a jet kit so you could tweak the jetting. You paid a deposit and got your money back less the cost of the jets you kept. I would check the floats and needles for free movement. Floats might stick low as you go down hill giving very little gas when you come back on the throttle. You say it is an E engine, what distributer are you running? There may also be issues there.

Thank you everyone for all the suggestions.. Our son moved to a new house that is up this hill and I drive that road a few times a day as we have been helping him move etc. and my wife has a big garden there as well so I have been test driving the volvo alot since putting in the frost plugs.. We are in a hot dry spell here possibly 37 C today so not sure about carb ice..I had the car parked for 4 years prior to working on the frost plugs but it did run fine before but I never took that hill either.... Everything is the same as it was before I took the intake manifold and exhaust manifold off,, hoses,, distributor etc. although I may not have the throttle linkage just right.. I have thought about the float as well .. On this hill I gear down to 2nd and 3rd to save the brakes as the speed limit in town is 50 kph.. Yesterday I did give it a little some gas coming down the hill and that may have helped.. About a week ago it really acted up and and I stopped and adjusted the linkage and that helped a lot so I obviously had it wrong.. I have tried to find some pictures of the linkage to see the proper adjustment.. One think to add,, I can go up that bloody hill in 4 th gear and the car runs great..The torque of the B20 engine is amazing compared to the B18 I had in my old 1963 122s

Sounds like a classic case of "carburetor icing" to me. Ice can actually form in the venturi, especially during high humidity & even with ambient temperatures in the 80's or 90's. Small aircraft engines have "carb heat" to prevent it during landing & take-off. It usually happens during a decent to land when the engine is throttled back, not producing much power, so the engine cools off enough to allow the venturi to ice up. That's why you always land with carb heat on. Several years back I owned a Toyota which did it occasionally.

Carb ice is possible I suppose.. I also had the intake manifold off as I replaced some frost plugs and possibly I do not have the throttle linkage back the way it was as well.. I used to use the carb heat on my old Cessna when descending..Thank goodness the Cessna didn`t act up like my volvo when applying power again.. lol

I have some experience with aftermarket carb systems and also think icing is the problem. You need 2 things for that -- are the intake manifold coolant tubes connected? -- in from the cover plate near the front of the head and returned to the line to the water pump (the heater hose attached to the metal tube under the manifold). The other thing you need is hot air from around the exhaust manifold. Older SAAB 99's and 900 models had a nice outlet with a built in metal strap to get attached to an exhaust runner. Some hot air tubing and foil covering part of the air filter. I haven't seen any aftermarket air filter housings that have provision for heated air but Pintos and Vegas used a Holley version of the Weber 32/36 with provision for that. -- Dave BTW - the electric choke on the Weber will come off to quickly in cold weather -- for the winter I install an ignition resistor to cut the voltage.

I actually recently converted my '79 244 from fuel-injection to a Holley (Pinto) carburetor. It runs great but I haven't put many miles on it yet. Luckily no carb icing so far. And no provision for heated air on my home made air filter.