steven 123 Posted December 5, 2019 Share Posted December 5, 2019 does anyone know the tune up specs for a 27 Chrysler model 50 flat head 4 cylinder ? Link to comment Share on other sites More sharing options...
Spinneyhill Posted December 6, 2019 Share Posted December 6, 2019 Maybe.... 1 Link to comment Share on other sites More sharing options...
steven 123 Posted December 6, 2019 Author Share Posted December 6, 2019 spinneyhill….thanks for the great and detailed info....it helps a lot......the car starts a lot easier and sounds better but I can see a backfire thru the card when I increase then decrease the rpm....I know it has the wrong carb on it it has a tillitson jr5a replacement could this be it ? Link to comment Share on other sites More sharing options...
carbking Posted December 7, 2019 Share Posted December 7, 2019 Really easy to say the Tillotson JR is the issue , but in this case it probably is not. A backfire through the carburetor occurs when: (A) a cylinder is firing AND (B) an intake valve is open A compression test might turn up a lazy or burned valve. The ignition timing might be off. Rare, but on well-worn engines with a timing chain, possible that the chain slipped a link. Jon. 1 Link to comment Share on other sites More sharing options...
m-mman Posted December 7, 2019 Share Posted December 7, 2019 (edited) Dont forget about the condenser. . . . . 😉 Two cars recently (brand new parts) and finally I discovered bad condensers based on the backfire symptoms. It was grounding intermittently turning the spark on & off. Edited December 7, 2019 by m-mman (see edit history) Link to comment Share on other sites More sharing options...
JACK M Posted December 7, 2019 Share Posted December 7, 2019 I will agree that a condenser will make an engine do funny things. But I don't see that a condenser could cause a real back fire thru the carb. Cough and sputter yes, fire off fuel in a muffler, (a real back fire) yes. I also agree that in order to actually (literally) "back fire thru the carburetor" there needs to be a path. unless the timing is way off the intake valve will be closed when the distributor tells the offending spark plug to fire. A burned valve or other reason that wont let a valve seal would allow that path to the carburetor. With all that said I still would try a different condenser, they are easy, as is a compression or leak down test. Link to comment Share on other sites More sharing options...
Guest Posted December 7, 2019 Share Posted December 7, 2019 3 hours ago, JACK M said: Cough and sputter yes, fire off fuel in a muffler, (a real back fire) yes. Fire off fuel in the muffler is in fact an "after fire". By definition a back fire is a fire that fires back through the carb. Nomenclature, nomenclature, nomenclature common usage does not make an "after fire" a backfire, all it does is confuse people that are trying to help solve a problem. Link to comment Share on other sites More sharing options...
TerryB Posted December 8, 2019 Share Posted December 8, 2019 Had a problem like this one time that turned out to be an arcing path in the distributor cap.. Link to comment Share on other sites More sharing options...
JACK M Posted December 8, 2019 Share Posted December 8, 2019 Sorry if I don't use the correct nomenclature. I home schooled myself. No intention of confusing anyone. Just trying to help. It could indeed be a distributor cap arcing causing flame in the carburetor. Which begs the question, Does it have all new tune up parts installed? including cap and wires? So steven, when you say you can see a backfire. Is it popping? You make it sound like it does it when backing off. Has this car been parked for some extended time? Did it run right before? Or did it just start doing this? Did you perform a compression test? Or even better a leak down? I may not know the right nomenclature but I am pretty good at troubleshooting. 1 Link to comment Share on other sites More sharing options...
steven 123 Posted December 9, 2019 Author Share Posted December 9, 2019 I have a new cap ,rotor points and condenser in it ,plugs were new but dirty and I cleaned them wires looked new ,when I got the car it was on the wrong firing order...thanks to spinneyhill I reset the points , plugs and corrected firing order adjusted carb.....I noticed rotor was off by about 1/2 turn reset my manual lever to full retard loosened and turned the distributor to #1 and tightened....this engine at 30 degrees out side started better than any car I have worked on...it is could natured but when warmed up is great...when I manually rev up engine the deaccelerate rapidly can see back fire from carb.....does seem low on power in 3rd gear....have orderd an adaptor for my compression tested so I can check it any other ideas ? Link to comment Share on other sites More sharing options...
trini Posted December 10, 2019 Share Posted December 10, 2019 A cracked cap will misfire at all times whether at idle or fast speed and the sparks will be noticeable in the dark. . Not through the carb. CARB KING is right on. Bad condenser will cause intermittent misfiring and sometimes blow the distributor cap off. An automatic advance unit with a busted diaphram will allow gas into the distributor , ignite and blow the cap off. This is irrelevant to the subject but I like to let others know. I have seen drivers using Quick Start to dope carburetors resulting in big blazes. I once doped a G M diesel engine on a shunt tractor . The engine fired but ran backwards emptying the oil sump, and oil spewing through the exhaust. I knocked out the fuel line quickly. Link to comment Share on other sites More sharing options...
steven 123 Posted December 10, 2019 Author Share Posted December 10, 2019 I also do not believe in starting fluid that's why I am thinking timing, I ran the engine in the closed garage and did see the flame out of the carb I set the timing by putting a rod on the piston top and cranked it to #1 cylinder....since had had the control to full retard when setting I thought maybe I should have set it to full advance before setting the timing Link to comment Share on other sites More sharing options...
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