1968 4hp Mcculloch air cooled S/N 82090-11

[Jeremy T]

Hello! I am new here and am seeking some advice. I have a 1968 4hp Mcculloch air cooled S/N 82090-11 that i got from a family member and it has been sitting for who knows how long. I cleaned out the gas tank and carb and installed a new fuel line. I installed a new spark plug and put fresh gas in mixed 50:1. I have a carb rebuild kit ordered from discount marine parts. The engine will start and idle but when you try to accelerate you will get what i think is a lean pop. Its not backfiring through the carb but making a popping sound at upper rpm's which causes the engine to die. It will idle as long as you want it to though. This engine also has what looks like advanced timing when you accelerate. Would a lean pop situation be solved by my carb rebuild kit that i have ordered or does this sound like an electrical issue? Thanks for any help.

 

[steelespike]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

Be sure the sync cam opens the carb as it should.
Set the High speed needle valve to 1 1/4 open from gently closed.

 

[Jeremy T]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

Be sure the sync cam opens the carb as it should.
Set the High speed needle valve to 1 1/4 open from gently closed.

Thanks for the responce. Just went out and checked it. everything operates smoothly and the carb opens with the sync cam.

 

[F_R]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

A high speed pop that causes it to die? I've been around for a long time, but that's a new one on me. I suppose it could be a fuel starvation situation, but that remains to be seen. Lean sneezing normally happens at idle speeds.

 

[Jeremy T]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

I received and installed the new carb kit this morning. Following instructions that were sent with the kit. The only difference is that it starts easier but still makes a popping sound when the timing is advanced to accelerate. If you set it to 3/4 or full throttle it will make the popping noise and will eventually die if you dont back it back down to idle. It seems to get worse when the timing is advanced. Im going to look for a puller to take off the flywheel. What should i expect when i get it apart. Are these engines complicated? Ive never worked on outboards before as you can probably tell.

 

[Jeremy T]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

The directions that came with carb said to not remove or adjust nozzle. I had already took the whole thing apart and cleaned it with carb cleaner. The nozzle installed back easily. Why does it say to not remove it? I could not see how any damage would have been done.

 

[steelespike]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

My after market manual says don't remove.If removed must be renewed with service part.
No indication why.
For the ignition::
Be sure the stator plate doesn't wobble that the plug wire isn't rubbed bare or shorting
Be sure the points are clean and adjusted at .020.Spark should be blue and have an audible snap.

 

[Jeremy T]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

OK i got around to making a video of this thing to help out showing what it is doing. After cleaning up the points and setting them to .20 it is starting easier than ever. Its just making the missing sounds when throttled up. I could not figure out how to upload a video here so i put it on youtube. Thanks you guys for the responses so far. The video can be viewed at http://www.youtube.com/watch?v=KP68R-qZWCc

 

[mrcrabs]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

my 2 cents, I would check the coil and high tension lead, sparkplug boot & any wire that may be moving when you advance the timing. it sounds like a dead short to me.

 

[Jeremy T]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

I am going to contact discount marine parts and order a new coil condenser and points. ill post another video once i get it put back together.

 

[Martin26UK]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

I purchased one of these outboards yesterday with a spare powerhead and carb + leg. On testing the complete outboard it was/is making the same sort of noise but doesn't respond well to the advancing. I replaced the coil and condenser with the one on the spare powerhead but I haven't got around to testing. I'll update within the next 8 hours.

Martin.

 

[Jeremy T]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

I purchased one of these outboards yesterday with a spare powerhead and carb + leg. On testing the complete outboard it was/is making the same sort of noise but doesn't respond well to the advancing. I replaced the coil and condenser with the one on the spare powerhead but I haven't got around to testing. I'll update within the next 8 hours.

Martin.

Ok yeah please update me on that. I still haven't ordered more parts but if that helps you any then im going to definitely order the stuff. Thanks

 

[Martin26UK]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

Well I cleaned the points and gapped. Tested this evening and it runs as it should. No more misfires. With a little tuning it should be perfect. (note: I'm not using the correct sparkplug).

 

[Jeremy T]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

Well I cleaned the points and gapped. Tested this evening and it runs as it should. No more misfires. With a little tuning it should be perfect. (note: I'm not using the correct sparkplug).

thanks for the update. Since ive already cleaned the points im going to order a new coil, condenser and points. If all that doesnt fix this thing ill have no idea what to do.

 

[mrcrabs]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

From the book,
High speed miss or intermittent spark

A. spark plug improperly gapped or dirty
B. loose, leaking or broken ignition wire
C. Breaker points (improper gap or dirty: worn cam or cam follower)
D. weak coil or condenser
E. Water in fuel
F. Leaking head gasket or exhaust cover gasket
G. Spark plug heat range incorrect
H. Engine improperly timed
I. Carbon or fouled combustion chambers
J. Magneto or distributor poorly grounded
K. Distributor oiler wick bad

 

[Martin26UK]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

I forgot to add that I reset the points at top dead with the advance in the middle. The ground from the previously fitted coil was actually bare wire, as if it never had a sheath on?


The plug that the outboard came with and is running with is a Champion L-87Y made in England. I have another plug that came with the spare powerhead that is a Chamipn J-14Y made in Canada (original?).

 

[Jeremy T]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

I just ordered a new coil, condenser, and points. It ran about $80 and i will have it in a couple days Ill shoot a video when im done and upload it on here. The guy told me to make sure when im finished to set plug gap to .35.

 

[mrcrabs]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

WOW $80 spent on a $50 dollar engine....from discount no less... :facepalm:

 

[Jeremy T]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

WOW $80 spent on a $50 dollar engine....from discount no less... :facepalm:

Yeah tell me about it. I was shocked because the carb kit was next to nothing. I guess they charge whatever they want because they bought out mcculloch when they went out of business. I about crapped my pants but i dont have the money to get another motor for now so im trying to fix what i have.

 

[mrcrabs]

Re: 1968 4hp Mcculloch air cooled S/N 82090-11

I have sworn never to buy from them...would rather row than pay there toll.

where abouts in kentuck are you from, i'm 30 miles from paducah ky.