Desmc14 Posted June 2, 2023 Share Posted June 2, 2023 My 65 Riviera (401) is not shifting into 2nd - if it does it is at a higher than normal speed. I just had the carb rebuilt & installed... it was running rich and rough (plugs were all fouled due to too much gas) I'm pretty sure the cause was because the heat shield had worn through on the carb. So, I replaced it and the gasket from Best Offer Buick Parts... seems like it's running much better... but it won't shift - at least not easily. Did I miss something, knock a linkage or something that might contribute to this? Trans fluid is full and looks red... not burnt brown .... checked it while hot and car running.... I'm at the novice stage with respect to mechanical ability, so please bear with me..... Any ideas/suggestions are appreciated. The car has just under 80,000 original miles.. Trans has never been rebuilt. Our family are the original owners. Thanks for the help in advance. Regards, Bob ROA # 11459 Link to comment Share on other sites More sharing options...
1965rivgs Posted June 2, 2023 Share Posted June 2, 2023 Hi Bob, Sounds like the trans modulator or its vacuum source. The metal line on the passenger rear of the carb is the vacuum source. Be sure you connected the line when installing the carb and that it is tight. The metal line extends down to the modulator and there is a small rubber jumper hose from the metal line to the modulator. Make sure the rubber line is in good shape as these do fail. Probably a good idea to just go ahead and replace it. Tom Mooney 2 Link to comment Share on other sites More sharing options...
Desmc14 Posted June 2, 2023 Author Share Posted June 2, 2023 Thanks Tom.... that is exactly what it was. I forgot to connect that metal line. I just reconnected it and went for a quick ride... all good.. I appreciate the advice! Thanks so much! Enjoy the weekend! Bob 1 Link to comment Share on other sites More sharing options...
1965rivgs Posted June 2, 2023 Share Posted June 2, 2023 32 minutes ago, Desmc14 said: Thanks Tom.... that is exactly what it was. I forgot to connect that metal line. I just reconnected it and went for a quick ride... all good.. I appreciate the advice! Thanks so much! Enjoy the weekend! Bob I'll bet the engine runs better too! If you already adjusted timing/ mixture and idle speed you should go back over those adjustments. Tom 3 Link to comment Share on other sites More sharing options...
Desmc14 Posted June 2, 2023 Author Share Posted June 2, 2023 good advice - will do Thanks again! Link to comment Share on other sites More sharing options...
Desmc14 Posted June 5, 2023 Author Share Posted June 5, 2023 Tom two more questions... 1) What is the best spark plug for this 401 - I'm using AC Delco R43S plugs 2) have a look at this photo of the new spark plug - it only has about 120 miles on it. should it have this much carbon on it already? Thanks, Bob Link to comment Share on other sites More sharing options...
rocketraider Posted June 5, 2023 Share Posted June 5, 2023 43 is a colder heat range plug. Unless the car's getting some high speed runs or hard acceleration to burn off deposits once in a while, they're prone to both carbon and, in the day, lead fouling. I'd use a 44 range plug, or even a 45 if the engine will tolerate it without detonation. Link to comment Share on other sites More sharing options...
Desmc14 Posted June 5, 2023 Author Share Posted June 5, 2023 Thanks Glenn! Link to comment Share on other sites More sharing options...
1965rivgs Posted June 5, 2023 Share Posted June 5, 2023 5 hours ago, Desmc14 said: Thanks Glenn! I agree with Glenn, good advice. The plug color is good but you were running the engine with a substantial vacuum leak. correct? Tom Link to comment Share on other sites More sharing options...
NTX5467 Posted June 5, 2023 Share Posted June 5, 2023 That new plug looks fine to me. As long as it will stay that clean, no problems, regardless of the heat range. Personally, I'd rather have a heat range a bit cooler than hotter. As long as the plug burns clean, as in carb mixture "right" and no significant oil consumption. The beauty of the extended gap plug is that it will burn warmer at lower rpms, then the greater volume of air/fuel mixture at higher rpms will cool it down a bit, from what I've read. NTX5467 1 Link to comment Share on other sites More sharing options...
Desmc14 Posted June 6, 2023 Author Share Posted June 6, 2023 Vacuum leak for a short duration... 10 miles perhaps.. but I'll keep an eye on it.. likely needs an expert's touch to get the air/fuel screws set properly but for now it runs well. very little if any black smoke when I stomp on the gas... and the carburetor sounds great - can hear the 4bbl open up - like it really wants to go And I changed the oil.....should be good to go now. so far so good.. Thanks much! Link to comment Share on other sites More sharing options...
Desmc14 Posted June 6, 2023 Author Share Posted June 6, 2023 Wish we were able to get to Kalamazoo... I learn so much from speaking to Riv owners.. Have a great weekend to all those attending Link to comment Share on other sites More sharing options...
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