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MCL Baulky At Slow Speeds

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evansjw44
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MCL Baulky At Slow Speeds

Post by evansjw44 » Fri Aug 29, 2014 7:04 pm

I' helping a friend sort out issues with the MCL in his 1956 Express Cruiser. It does just fine over 1500 revs but just refuses to idle or run slow like it should. I cleaned one carb of all the junk inside and redid some fuel lines. It behaves like it has a vacuum like but where is the question? Blocking off the PVC doesn't help. The distributor mechanical advance needs some work but I'm at a loss. It surges and just runs really rough.

Throttle plates have been synchronized. It responds similarly to both carb idle adjustments. Just not well.

Is there some possibility there's a hole in the exhaust manifold where the intake passes through? How about a head gasket?
Jim Evans

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offshorespars
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Re: MCL Baulky At Slow Speeds

Post by offshorespars » Tue Sep 02, 2014 6:30 am

Jim:

Since no one else has replied I will tell you an experienced I had this spring with my KLC. The symptoms are very similar. I have owned my boat for 4 years and in the first year a local engine mechanic convinced me to change my existing small diameter distributor that has points and condenser to a larger diameter distributor with Petronix ignition. The motor has been running great ever since. But for a boat show this past summer I decided to go back to the original distributor in an effort to stay original. The engine ran fine above about 1300rpm. Very smooth. Below 1300 it would barely run. Missed constantly and stalled frequently if run below 700rpm. After the show I went back to the Petronix ignition and the motor runs great. The timing was set correctly for both distributors. The points and condenser are new for the small distributor. The only explanation that makes sense in my case is the Petronix ignition.

Mike
1978 30' CC Sportsman
1948 22' CC Sportsman

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evansjw44
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Re: MCL Baulky At Slow Speeds

Post by evansjw44 » Tue Sep 02, 2014 10:21 am

Thanks for your input. The distributor is definately messed up. I don't really see changing to Pertronix as a solution as these old things ran fine on points and condenser ignition. However, a high resistance ground connection could be issue, cam wear or shaft bushings, or messed up advance mechanism.

We'll have to look at those. I only had a five minute check of the distributor and the advance mechanism is definately messed up. Its rusty and dirty inside under the breaker plate. I suppose that if the advance is too much for idle it would indeed be baulky.

My advice to my friend will be to get the distributor rebuilt.
Jim Evans

knotty48
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Re: MCL Baulky At Slow Speeds

Post by knotty48 » Tue Sep 02, 2014 5:09 pm

This is a very interesting topic and surprised that more people have not chimed in. I have a KFL that has been completely rebuilt even the distributor and carbs and I just cannot get it to idle smooth. I know others have had our same problem and would love to hear from them. My engine runs good 1000RPM's up and it will idle down to 700-800 and does not cut off but sure idles rough. I sometimes think it could be a vacuum leak but not sure where to start (PVC, intake / exhaust gasket??). I will check compression this weekend again along with running a leakage test on each cylinder.
All comments welcome...

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mfine
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Re: MCL Baulky At Slow Speeds

Post by mfine » Tue Sep 02, 2014 7:52 pm

Get something that smokes and move it around until you find where the smoke is getting sucked in.

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