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Engine bogs down past 2,100 RPMS

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joesoboti
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Engine bogs down past 2,100 RPMS

Post by joesoboti » Sat Aug 11, 2018 4:42 pm

MCL 175 timing is spot on, idles smoothly at 500 RPMs, under load accelerates smoothly and steadily up to 2,100. Past that it seems to bog down and choke through 2,700. It will not go past 2,700. Without load, the engine will rev all the way up smoothly. Carbs have been synchronized with a pressure gauge. Any thoughts?
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Re: Engine bogs down past 2,100 RPMS

Post by mbigpops » Sat Aug 11, 2018 8:21 pm

Timing. I have the same issue with my KL.

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Re: Engine bogs down past 2,100 RPMS

Post by cc-woodboats » Mon Aug 13, 2018 8:17 am

sounds like either fuel delivery issue or lack of spark at higher load&speed.

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Re: Engine bogs down past 2,100 RPMS

Post by krrs » Mon Aug 13, 2018 11:06 am

If still running points in the distributor, make sure the condenser is screwed down tight, making a good gound.

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Re: Engine bogs down past 2,100 RPMS

Post by joesoboti » Mon Aug 13, 2018 11:18 am

Thanks, fuel pump pressure is my bet as well. I'm working on checking that out, not an easy thing to do. As for distributor, its been upgraded to Petronics.

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Re: Engine bogs down past 2,100 RPMS

Post by davidvn » Mon Aug 13, 2018 10:45 pm

Joe drain back both of your carburetors through the main jet plug which is on the back of the carburetor pointing about 45°. You’ve had this problem before and one of your carburetors more than likely has dirt in the main jet

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Re: Engine bogs down past 2,100 RPMS

Post by joesoboti » Tue Aug 14, 2018 3:36 pm

Thanks David.

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Re: Engine bogs down past 2,100 RPMS

Post by jfrprops » Tue Aug 14, 2018 7:23 pm

you say you have petronics….but if you left a coil resistor inline....and it has burn through....those are the symptoms?????

John in Va.
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Re: Engine bogs down past 2,100 RPMS

Post by tkhersom » Wed Aug 15, 2018 6:22 am

Interesting thread!
I am having a similar problem with an MCL and I have changed to Pertronix ignition. I have been expecting fuel delivery was my problem.
John where do I look for this coil resistor? Should it be removed or replaced?
Thanks guys! :D
Troy in ANE - Former President CCABC

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Re: Engine bogs down past 2,100 RPMS

Post by jfrprops » Wed Aug 15, 2018 8:37 am

The coil resistor on older engines is always located near the coil....it is a white ceramic deal about 3 inches long and 1/2 wide and across.....inside it is a coil of wire ( visible on the open back side of the ceramic deal) that acts to reduce the high voltage of starting from burning out the points and etc....but I think it is not needed with electronic ignition...though it may have been left in the circuit and if so when if fails it overloads and leads to the problem mentioned. When you try to accelerate it messes up the ignition....not a likely scenario...but possible and one I have run into more than a few times. You can usually tell if the resistor is broken by looking for burned out place on the wire coil inside it....if that is compromised you are toast).
John in Va
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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Re: Engine bogs down past 2,100 RPMS

Post by mbigpops » Wed Aug 15, 2018 9:15 am

In this unrestored engine photo it is the white vertical item to the right of the coil. No longer needed with Pertronix.

Mark
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Re: Engine bogs down past 2,100 RPMS

Post by tkhersom » Wed Aug 15, 2018 9:54 am

Thanks guys!

I will look next time I run Yorktown.
Troy in ANE - Former President CCABC

1957 CC 21' Continental "Yorktown" (Mom's boat)
https://www.chris-craft.org/boats/22625/
1985 Formula 242LS "Gottago"
1991 Formula 36PC "Band Aids"

Life Is Too Short To Own An Ugly Boat

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Re: Engine bogs down past 2,100 RPMS

Post by joesoboti » Wed Aug 15, 2018 10:13 am

Thanks John, I do not have one of those.

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Re: Engine bogs down past 2,100 RPMS

Post by joesoboti » Wed Aug 15, 2018 8:21 pm

Thanks everyone. I think we have a handle on it. Combination of timing and dirty fuel. Running much better now, up to 2.900 rpms under load.

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Re: Engine bogs down past 2,100 RPMS

Post by Badger85 » Thu Aug 16, 2018 2:31 pm

Initially your post indicated timing had been checked and was "spot on"- easy enough to do on an MCL as there is a timing mark. So how was it off? Spark advance not working properly?

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Re: Engine bogs down past 2,100 RPMS

Post by joesoboti » Fri Aug 17, 2018 6:40 am

The initial timing was done using the plug closest to the flywheel as #1 when in my case it is actually the plug closest to the transmission. Also, there was dirt in the carbs, which I have drained. I noticed some water as well.

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Re: Engine bogs down past 2,100 RPMS

Post by tkhersom » Fri Aug 17, 2018 7:03 am

I'm surprised it ran at all timed to #6.
Troy in ANE - Former President CCABC

1957 CC 21' Continental "Yorktown" (Mom's boat)
https://www.chris-craft.org/boats/22625/
1985 Formula 242LS "Gottago"
1991 Formula 36PC "Band Aids"

Life Is Too Short To Own An Ugly Boat

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Re: Engine bogs down past 2,100 RPMS

Post by drrot » Fri Aug 17, 2018 8:13 am

Actually with a 153624 firing order 1 and 6 are 180 degrees apart so the timing mark would light either way.
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Re: Engine bogs down past 2,100 RPMS

Post by mbigpops » Fri Aug 17, 2018 8:55 am

Timing is everything
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Re: Engine bogs down past 2,100 RPMS

Post by davidvn » Fri Aug 17, 2018 11:29 pm

<t>Hi Joe which cylinder you pick as number one is somewhat arbitrary so long as you follow the proper firing order. If you think of the aft end of your engine as actually the front of your engine if it were in a car then the Aft cylinder would be number one. As for your timing the best thing to do is to power time the engine while you’re on your way. If you turn your distributor counter clockwise you’re advancing the timing and may pick up more RPM. You must be careful that the engine doesn’t ping. If there are only two of you in the boat when you do this retard the timing a little bit more as if you have more people in the boat you’ll have more load on the engine and the engine may be inclined to ping if the timing is too far advanced. Glad removing the dirt from the carburetors helped</t>

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Re: Engine bogs down past 2,100 RPMS

Post by joesoboti » Sat Aug 18, 2018 7:10 am

Thanks David. Yes, that makes sense. The engine is still not getting past 2,700. Full throttle, 2,700 is the max. I also notice a lot of valve/lifter noise at the higher RPMs.

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Re: Engine bogs down past 2,100 RPMS

Post by krrs » Sat Aug 18, 2018 1:44 pm

On a properly adjusted valve train there should be a "very slight" clatter at rpm, hardly noticeable. Pull the covers and have a look for any damage before it leads to something worse.

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Re: Engine bogs down past 2,100 RPMS

Post by davidvn » Sun Aug 19, 2018 9:55 pm

Joe I’m concerned that’s not valvetrain noise that it’s pinging at high rpm you’ve got my cell why dont you give me a call Monday

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Re: Engine bogs down past 2,100 RPMS

Post by krrs » Mon Aug 20, 2018 9:11 am

Please let us know how this turns out. A lot of us, myself included, could use this for future trouble shooting.

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