Sometimes the components of a freshly rebuild engine need time to get to know each other before all is good. Kind of like cooking chili; good chili needs to simmer for at least two days, and will still get better after it is reheated a few times. An engine is the same. All of the new components fighting each other create friction and heat, and require a somewhat richer mixture until all components become friends
Jon
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
When you're used to driving new cars that are hermetically sealed and soundproof and bump proof, I'm sure it does!
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
My truck’s 228 engine idle is really really bad. It don’t have more than 10-15 miles on it since a complete overhaul but something else has to be my problem.
It was idling quite decent when I put the first 10-15 miles on it.
What has changed since it was idling well:
1- I got stranded and found the fuel pump was full of debris. After cleaning it out, all was well again.
2- Wouldn’t start, found the pump was not delivering fuel to the carb. Replaced the pump and still no fuel.
3- found the fuel outlet/peacock at the tank and that end of the fuel line was plugged with debris. Cleaned petcock out but I punched a hole through the rusty fuel line while trying to clean it out. Looked in tank and it was full of junk.
4- Bought a brand new tank, petcock and fuel line. Rebuilt carburetor at the same time and installed new inline filter.
5- started up and took a short drive without any issue.
6- moved across the country from Illinois to North Carolina with truck in covered trailer.
7- while driving around new house from trailer to back yard it died.
8- pulled truck to garage with tractor. Replaced distributor cap, rotor, plugs and wires, as well as points and condenser.
9- ran good, took a very short drive to neighbors house. Started running very rough, was lucky to jack the throttle just right to keep it from dying before getting it back in garage.
10- reset the points. Started up fine but suddenly started running rough again while backing out of garage.
11- i have a very difficult time trying to get points set just right. Decided to get a pertronix. It has a lobe sensing igniter rather than the old style with magnets in the rotor. Also installed 1.5 ohm pertronix coil.
12- started ok but has rough idle. A local “expert” came over and helped identify a bad plug. Installed a new set of plugs gapped to .035.
13- still idles very rough. Smoothes out when carb is partially blocked with my hand. Took carb apart and cleaned with carb cleaner spray can and blew out everything with compressed air.
14- idled better but not good or anywhere close to like it used to. Repeated the cleaning process. Spent more time and cleaner this time. Not much help.
15- disassembled carb again and boiled the castings in water with dawn soap. A definite improvement this time but engine still hunts for a steady rpm.
16- started to go for a drive but very rough running suddenly came back.
At this point I probably need new carb gaskets but my problems seem to coincide with the pertronix install. I keep wondering if the lobe sensor is erratic.
I’m going nuts since I can’t drive my truck but I’m not sure what to try next.
My truck’s 228 engine idle is really really bad. It don’t have more than 10-15 miles on it since a complete overhaul but something else has to be my problem.
It was idling quite decent when I put the first 10-15 miles on it.
What has changed since it was idling well:
1- I got stranded and found the fuel pump was full of debris. After cleaning it out, all was well again.
2- Wouldn’t start, found the pump was not delivering fuel to the carb. Replaced the pump and still no fuel. What kind of pump? New or rebuilt original? I had two Chinese POS fuel pumps fail. One last a few hundred miles, the other wouldn't pump a drop straight out of the box. I had the original pump rebuilt and haven't had any problems since.
3- found the fuel outlet/peacock at the tank and that end of the fuel line was plugged with debris. Cleaned petcock out but I punched a hole through the rusty fuel line while trying to clean it out. Looked in tank and it was full of junk.
4- Bought a brand new tank, petcock and fuel line. Rebuilt carburetor at the same time and installed new inline filter.
5- started up and took a short drive without any issue.
6- moved across the country from Illinois to North Carolina with truck in covered trailer.
7- while driving around new house from trailer to back yard it died.
8- pulled truck to garage with tractor. Replaced distributor cap, rotor, plugs and wires, as well as points and condenser. What condenser? New ones are CRAP!!! Had new NGK fail in about 1000 mile. Get one of Jon Goodman's 200,000 hr condensers. See sticky at top of electrical forum.
9- ran good, took a very short drive to neighbors house. Started running very rough, was lucky to jack the throttle just right to keep it from dying before getting it back in garage.
10- reset the points. Started up fine but suddenly started running rough again while backing out of garage.
11- i have a very difficult time trying to get points set just right. Decided to get a pertronix. It has a lobe sensing igniter rather than the old style with magnets in the rotor. Also installed 1.5 ohm pertronix coil. Setting points on an AD truck is one of the easiest point sets to gap. What problem are you having? Pertonix is crap.
12- started ok but has rough idle. A local “expert” came over and helped identify a bad plug. Installed a new set of plugs gapped to .035.
13- still idles very rough. Smoothes out when carb is partially blocked with my hand. Took carb apart and cleaned with carb cleaner spray can and blew out everything with compressed air. Smoohing out when blocked with your hand may indicate a lean mixture
14- idled better but not good or anywhere close to like it used to. Repeated the cleaning process. Spent more time and cleaner this time. Not much help.
15- disassembled carb again and boiled the castings in water with dawn soap. A definite improvement this time but engine still hunts for a steady rpm. Have you checked for vacuum leaks? Don't forget both ends of the windshield wiper hose.
16- started to go for a drive but very rough running suddenly came back.
At this point I probably need new carb gaskets but my problems seem to coincide with the pertronix install. I keep wondering if the lobe sensor is erratic. Weren't you having the same problems with the breaker point ignition? I'd re-install the breaker points and start from the beginning with a methodical process of elimination on all systems.
I’m going nuts since I can’t drive my truck but I’m not sure what to try next.
I think you've thrown a lot of variables into the mix, especially with the Pertronix. If the engine is capable of running smoothly, it will do so with breaker points. Once you get it running smoothly with breaker point ignition, then you can consider changing to HEI or whatever.
Have you inspected your distributor? Perhaps the shaft is wobbling.
You say that the truck idles bad. What happens when you step on it on the road? Does it run well at speed and only falls apart at idle? While idling in the driveway, what happens when you goose the throttle? Does it bog? Does it work ok? What happens when you gradually increase rpm?
I would also perform a compression test on all cylinders.
Last edited by Otto Skorzeny; 12/06/20227:30 PM.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
Since the problem presents itself with both breaker point and Pertronix ignition, it's probably not a spark problem.
Congratulations on moving to the Sunny South from the freezy azz frozen North.
Last edited by Otto Skorzeny; 12/06/20227:32 PM.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
Thanks. Intake and carb vacuum ports are plugged, can’t find any leaks. Mechanical pump is airtex brand. Point gap changes when the hold down screw is tightened so it takes a lot of messing around to get it right. When it throttles up it will go but it wants to die when I let off the pedal. I’ll check out the 200,000 mile condenser and get a new set of points. I just hate to mess with the ignition if my carb is the problem. How do you identify and correct a lean condition?
There's an idle mixture screw somewhere on the side of the carburetor. I'm not familiar with Zenith carburetors so I can't tell you more than that. They're all pretty similar, though.
Have you checked the fuel pump pressure? If the pump is putting out too high pressure, it may overtop the bowl and flood the engine. That would mean it's too rich rather than too lean. Airtex is a horrible brand, by the way. I had two Airtex pumps fail on my Cadillac because the inlet and outlet valves were not staked at the factory. They popped out of their seats. I had 2 or 3 Airtex brand pumps fail on my F-100 in just a couple months of use because the diaphragm tore. Friends have had similar experiences.
Is the Pertronix still installed?
What is the status of the dizzy? Is it new? Was it rebuilt? Is it 70 years old and worn out? Check to see if the shaft wobbles at all if you try to move it by hand.
Last edited by Otto Skorzeny; 12/06/20227:46 PM.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
Pertronix is still in but I’ll swap back to mechanical next. Afterwards I’ll check the other things. I am venting today more than anything. I’m just so darned frustrated after all of the $ and effort so far. On the brighter side I’m freshly retired and have the time!
After one fuel pump failed and the new one wouldn't pump a drop straight out of the box, I began thinking that the cam lobe was wiped. After all a brand new pump should pump gas shouldn't it?
New doesn't mean anything anymore.
After I installed working fuel pump (rebuilt original), I still had trouble. It turned out to be debris in the carb keeping the needle off the seat. After that was cleared up, it's been running like a top.
I only suggest reinstalling the points because A) the truck was known to run properly with them installed, B) it removes the variables associated with the Pertronix system.
Once things are set up "by the book", it's easier to zero in on the problem.
Do you have a timing light? What do you have the timing set at?
Last edited by Otto Skorzeny; 12/06/20228:07 PM.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
I have a timing light and experimented with different timing. Manual says set to u|c but I’ve tried advance and retard. I could possibly have a restriction in the upper idle passage in the carb base. I can see light through the bottom passage but the upper is not a straight shot from above so you can’t tell visually. Current plan is to boil the castings again and get points and condenser reinstalled. Thanks.
Good. My suspicion is that there is a small piece of debris/rust still in one of the orifices of the carburetor. See if you can get a little piece of floral wire or other very small rod or wire to run through various holes.
Even if you can't see straight through a hole with right angles, you should be able to see light if you put a little flashlight up to one end.
What's the story on the carb? I'm not familiar with Zenith on stovebolts.
Everything I've learned about stovebolt carbs from this site is that the Carter YF is preferred over the Rochester B and that almost no one uses the Carter W-1 or whatever it was called.
Last edited by Otto Skorzeny; 12/07/20221:02 AM.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
Is your vacuum advance hooked up and working? Are you checking the timing with it connected or disconnected?
What's the fuel line pressure?
Have you checked the fuel pump flow? Disconnect it at the carb and put the hose in a bottle and see if you get good flow while cranking for a few seconds...should give you a few ounces pretty quick.
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
Chevrolet factory installed carbs were Rochester, GMC used Zenith.
I don’t think my fuel pump is the problem but I have another one and am planning to pick up a pressure gauge and tee today if the auto parts store has them.
My vacuum advance works but I can manually turn the distributor to vary timing which speeds up or slows down RPM and the issue remains.
My vacuum gauge readings can’t be trusted but the needle jumps up and down in concert with the surging RPM.
I forgot you were working on a GMC instead of a Chevy.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
I did get a set of points and sent a PM to Jon about buying one of the 300,000 hour condensers.
Make sure the newpoints set has a flat spring-steel spring and not just a brass spring (both is OK). Had this happen here on Stovebolt a few months ago and I personally troubleshot one over the phone 6 years or so back. Engine idles fine. But as RPM increases dwell decreases (points are starting to float) and by 1500 RPM or so the points are not closed long enough to allow the coil to generate a good spark.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
That sounds good. You should probably go back there and buy another set or two.
What brand are they sold under? Anything on the box indicating where they are made?
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
Standard Motor Products still seem to be decent quality for the most part. Funny thing is that Standard's "T-Series" is their so-called economy line.
I'll take Hecho en Mexico any day over Chinese crap!
Last edited by Otto Skorzeny; 12/07/20229:18 PM.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
50gmc253 Why don't you carefully look down your carb throat with it surging and see if it's flooding over a little. At idle shouldn't see any liquid fuel. Maybe one of your float tanks (if you have two) is leaky and heavy with fuel in it.Or float setting may be a little high.
I received the rebuild kit from carbking. It even includes screws. I’ll find some fine wire to use on the upper idle port in the base when I take it apart again for another round of super-cleaning.
