I have not adjusted the carb on my restored 54 3100. As best i call recall, the way i use to do it was hook up the dwell meter, get the points set correctly. Follow this with a timing light check and then adjust the air mixture screw on the carb to get the best rpm at idle. then adjust the idle to the desired level. Can you give me info on the points setting, dwell, timing and starting setting for the mixture screw? Finally, what's the rpm when idling with the engine warm? thanks,
Basic Tune Up I'll make a WAG and assume were talking about a 216/235/261 here... Adjust the valves _first_ ! I know you think they're fine but the tight valves I find in every single truck I work on tells me that unless you personally adjust them , they're wrong in a way that makes proper tuning impossible . So , valves adjusted ? good . nowthen : set the dwell to 33° , I like to run the engine on the starter with the spark plugs removed and adjust the dwell as it's cranking so as to get the most accuarate reading.... Or just gap the points to .016" , use a wire gauge if you have one floating 'round your toolbox . Check all the spark plugs for proper gap , they must be .035" to have a really smooth idle , plugs get dropped and bounced around in shipping so never trust " pre-gapped " sales pitches . BTW : use a round gauge , it's far more accurate . Start the engine and let it warm up fully , then adjust the ignition timing to ball on pointer dead nuts , at or below , 500 RPM . A few different ways to adjust the carby , as you mentioned , twiddle the mixture screw gently and slowly until you reach the best idle then back it out 1/8 a turn more , then finally , re-adjust the idle speed as needed using the throttle stop screw . If you have a vacuum gauge , connect it to the port below the carby , on the intake manifold and watch it as you twiddle the mixture screw , adjust to the highest -steady- idle , no twitching nor ' floating ' allowed ! . The actual amount of vacuum varies in each engine , it can be as low as 13" or as high as 21" (that's a LOT) the main thing is : it's steady ~ if it twitches no matter what , you have a tight valve , too much timing advance or maybe a burned valve . if the vacuum reading ' floats ' but the engine stays pretty much at the same idle speed , you have a vacuum leak , usually between the intake manifold & the cylinder head . I hope this helps .
Nate is right on about valve adjustment. My truck seemed to run fine when I bought it, but when I checked the valves they were all way too tight. I can hear the valves "purring" now that I've adjusted them.
A Noisy Valve Is A HAPPY Valve ! When correctly adjusted , the 216/235/261 should sound like Grammaw's Singer sewing machine.... Mucho lateral play in the rockershaft is acceptable as long as you're getting oil out the weep holes in the tops of the rockers , you'll be fine . Failure to do frequent hot oil changes , esp. back when all oils were parrafin based , caused many internal oiling passages to glog up , leading to serious , rapid wear of the rockers & shafts . If you do not see oil bubbling up out of the tiny weep hole in the center of your rockers @ fast idle (remove oil filler cap) you have a serious problem that needs rectifieng right away . Often , simply doing a hot oil change with synthetic oils will get the clogs dissolved in a couple hundred miles... Adjust those valves ! NOW ! then once or twice a year . Is there a way to post the tune up info as a sticky ? .
