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235 rough running
#1289872 Tue Dec 04 2018 07:39 PM
Joined: Jun 2015
Posts: 293
I
Shop Shark
Been driving my 41 around a lot and it’s been dependable and great but all the sudden it’s running real rough like chugging almost and hard to start, the only way it starts and runs is if I make the choke sit about half open/closed took the spark plugs out and they don’t look terrible but they probably have about 10-15000 miles on em at least, I thought bad gas but ran fuel line into a can and acted the same
Yesterday I wasn’t getting fire out of my coil so I changed it to an old one I had and it worked but still running crappy . points look fine, anyone got an idea?


Stovebolter -- the Next Generation
(I'm 20)

1941 Chevy 1/2-ton pickup
"Lucy"
In the Stovebolt Gallery
More pix on Photobucket

1967 Ford Mustang - "Sally"
Re: 235 rough running
Ian Ring #1289878 Tue Dec 04 2018 08:31 PM
Joined: Jan 2014
Posts: 1,374
J
Shop Shark
Mine ran like that (only run with partial choke) when I first got it running. Advancing the timing corrected it.

Re: 235 rough running
Ian Ring #1289887 Tue Dec 04 2018 10:58 PM
Joined: Apr 2007
Posts: 797
L
Shop Shark
I would do a standard tune-up. You are at or beyond the recommended life of your spark plugs. If you haven't changed points and condensor since the plugs were changed you are past the recommended life of those as well. Even if the points look good you need to check the points gap (dwell) anyway. Finally, check the timing as suggested by JW51,
Let us know how it runs after the tune-up and we will come with more suggestions if it doesn't help.
Kent


1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
1947 Diamond T Model 509
1951 Chevy 1/2 ton
1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix
Re: 235 rough running
Ian Ring #1289931 Wed Dec 05 2018 05:43 AM
Joined: Jun 2015
Posts: 293
I
Shop Shark
I probably need to do plugs and stuff soon anyway but it was point gap, they had worn and there wasn’t really a gap anymore so I adjusted them , they’ve not got as many miles on them as the plugs but still. While everything is a year or less old I drive her a lottttt.
Thanks for the suggestions


Stovebolter -- the Next Generation
(I'm 20)

1941 Chevy 1/2-ton pickup
"Lucy"
In the Stovebolt Gallery
More pix on Photobucket

1967 Ford Mustang - "Sally"
Re: 235 rough running
Ian Ring #1290024 Thu Dec 06 2018 01:08 AM
Joined: Mar 2010
Posts: 9,449
5
Master Gabster
You need new points. The part which has warn, leaving little gap, is the plastic part which rides on the distributor cam. You need to use grease on that plastic piece. I tiny dab will do it.

Re: 235 rough running
Ian Ring #1290047 Thu Dec 06 2018 03:28 AM
Joined: Feb 2004
Posts: 21,240
H
Boltergeist
At a cruise speed of 2,000 RPM, those points are cycling 3,000 times a minute. If you manage to get 10K miles on a set of points, that's pretty good. Since electronic ignition has been around for 40+ years, people tend to forget just how short point life can be.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: 235 rough running
Hotrod Lincoln #1290724 Wed Dec 12 2018 01:09 AM
Joined: Jun 2011
Posts: 31
G
Wrench Fetcher
Originally Posted by Hotrod Lincoln
At a cruise speed of 2,000 RPM, those points are cycling 3,000 times a minute. If you manage to get 10K miles on a set of points, that's pretty good. Since electronic ignition has been around for 40+ years, people tend to forget just how short point life can be.
Jerry

I am a bit confused (not at all unusual), Jerry. I am assuming you mean the number of times the points open and close (i.e. one cycle = one open/close of points) so there would be 6,000 cycles per minute for an engine turning over 2,000 RPM, right? I figure a 4 cycle engine = two complete revolutions for all six cylinders to fire one time so that equals 1,000 firings per minute times six cylinders = 6,000. Or am I missing what you were saying if so you had better use small words to explain to me...

Agree 10k is decent mileage for a set of points - especially as many of us will be driving a limited number of miles so the time period will be longer than in a daily driver.

Re: 235 rough running
Ian Ring #1290731 Wed Dec 12 2018 01:59 AM
Joined: Feb 2004
Posts: 21,240
H
Boltergeist
The points open and close once every time a cylinder fires. A 4-stroke engine takes two turns to complete the cycle, and the distributor turns 1/2 crankshaft speed. Since a 6 cylinder engine must fire three cylinders per revolution of the crankshaft, at a crank speed of 2,000, the distributor is turning 1,000 RPM, firing 3 cylinders per turn of the crankshaft. that's 3,000 point cycles per minute, right? (or 180,000 per hour!)

OOPS I can't count! You're right - - - -it is 6,000 sparks per minute- - - -360,000 per hour! That's several MILLION cycles of the points in a 10K mile average lifespan.
Jerry



The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: 235 rough running
Ian Ring #1291636 Tue Dec 18 2018 06:25 PM
Joined: Jun 2012
Posts: 1,729
S
Shop Shark
Might help if you have a Dwell meter. Set the point gap. Set the timing(initial setting) start. use the dwell meter(it can tell if the point gap is not optimal) If all is working(sort of) then use a local hill to fine tune the timing. Up the hill and no "ping"? then advance a bit. Repeat until it "pings". Then retard a bit.Timing is done. Dwell is done. Now for the other things that cause rough run. Set the valve train(one tight valve will cause it to be rough) Use a vacuum gage to check the idle mix. Set to max vacuum. Mix is done. With valves set. Timing set, and Dwell set. Check the plugs. One bad plug will cause rough.After all that( I know,it is a process) You are left with a few possible bad actors. Condenser, they do go bad(just not often). Bad cap/rotor(carbon in the cap is not your friend). You can clean the cap. You can clean the rotor. The air gap is critical. Use care and see if that helps. Things left, none are fun to get to or fix, Mechanical advance. Rust and sticky are the bad actors. Vacuum advance, leaky? Change it. Not leaking? Let it be. You have to pull the dizzy to fix those two things. Then you get to start all over from the beginning(I did say these are not fun, right?) That is about it. Some one here will tell on me if I left anything out.


Steve H

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