old chrysler air-cooled 3.5hp motor

[Squeakit]

Just bought an old motor for 5 bux for something to tinker with. It's a Chrysler 3.5hp air-cooled unit that looks like it came over on the Ark. It's a Model 303, Ser#3666. Anyone ever hear of an air-cooled Chrysler OB? Anyone know the year of this thing? Looks like the water intake is a bent tube coming out of the exhaust opening right behind the prop. Gas tank is teardrop shape. Rest of it looks like a lawnmower engine. Be fun to get it running. Any info would be much appreciated. Thanks.

 

[rickdb1boat]

Re: old chrysler air-cooled 3.5hp motor

Hi Squeakit<br />About all I can tell you is the year, but it sounds like a fun project.<br /><br />303-04 3,5HP 1968-69

 

[JB]

Re: old chrysler air-cooled 3.5hp motor

Hi, Squeakit.<br /><br />The Chrysler line was originally West Bend.<br /><br />Your engine was probably based on the West Bend general purpose 580 2 stroke.<br /><br />Use a 16:1 mix with chainsaw oil, not TCW-3.<br /><br />Good luck.

 

[Squeakit]

Re: old chrysler air-cooled 3.5hp motor

Thanks, guys for your prompt replies. One more question - does this motor have a water pump &impeller or is the water blown up to the exhaust by the force of the prop? I pulled the powerhead and blew out the water tube which seems clear, but I don't want to disassemble the lower end looking for a waterpump if there isn't one. Thanks.

 

[alcan]

Re: old chrysler air-cooled 3.5hp motor

Hi Squeakit <br />Your mod303 is 1969 model. I agree with Rick and JB. There is no water pump in the L/U. Cooling water for the exhaust is just scooped up the tube when under way. The problem I find with most of these West-Bend,sears,gamefisher,ted williams,Chrysler and many other names for the same motor is the lower units are shot. So you may want to check this.

 

[scotiany]

Re: old chrysler air-cooled 3.5hp motor

The point gap is.020 and spark plug gap is .030. The recommended spark plug is the Champion H8J. The fuel-oil ratio is 16 to 1. The lower unit requires "Texaco Outboard Gear Oil EP-90" or equilivant. Marine white or automotive white gasoline is recommended-I assume that means unleaded gas.

 

[Squeakit]

Re: old chrysler air-cooled 3.5hp motor

Thanks for the additional info,guys. Yesterday I worked all day on this old motor and today I took it out on the lake. BOY IS IT LOUD! Sounds like a cross between a Lawnboy and an old WWII aircraft but it actually ran and pushed my 12ft aluminum boat at a reasonable speed (3.5hp isn't much). Basically all I did was clean the points, flush out the carb & gas tank, flush out the lower unit which had sand in it & nothing else, and repair a hole in the gas tank. The water tube works well and there was a good spray coming out of the little holes in the lower leg. Why aren't these scooper tubes used on more OB's? No impeller probs. Its a little cranky, and it clanks and farts and sounds like it's going to self-destruct at any moment, but it works! What did these things sell for when new? Probably not much. After riding around with my old 5.5 Evinrude this engine seems pretty primitive.

 

[DaveDomingo]

Re: old chrysler air-cooled 3.5hp motor

Hey, I just got one of these, too.

In the water, it starts fine, but after a second or two it starts to sputter and has very low RPMs, even with the throttle all the way up. Forward motion aggravates the problem.

The seller said use a 40:1 ratio with high-octane gas from the gas station and normal 2-stroke oil, so I did. In this thread, people are saying 16:1 and chainsaw oil. Those are two big differences! Does my problem seem consistent with having too much fuel and too little oil?

This little motor will be perfect for my Mariner 4 if I can get it to run correctly and reliably. Thanks in advance for your help!

 

[Frank Acampora]

Re: old chrysler air-cooled 3.5hp motor

Yes, dave, the correct ratio is 16 to 1 because these engines have plain bearings. The oil should be chainsaw oil because the engine is air cooled. the water only cools the exhaust downtube so you don't burn yourself on it. and yes, too little oil can cause slow running as you described. Use regular gas High octane has additives which MAY be harmful to the engine and it simply wastes money--but, of course, with the amount of gas that engine uses, wasted money is simply not a problem.

 

[DaveDomingo]

Re: old chrysler air-cooled 3.5hp motor

Frank, I can't thank you enough for this advice.

Is it safe to simply drain the tank, fill with the correct stuff, and run it?

 

[Frank Acampora]

Re: old chrysler air-cooled 3.5hp motor

You can do that or you can simply add more oil to the existing fuel and burn it. One tank of premium will not hurt anything.

 

[DaveDomingo]

Re: old chrysler air-cooled 3.5hp motor

Frank: Again, thank you! Invaluable advice.

 

[WIMUSKY]

Re: old chrysler air-cooled 3.5hp motor

This thread is 11 years old. Dave, please start your own thread with questions... Thanks
WIMUSKY

 

[DaveDomingo]

Re: old chrysler air-cooled 3.5hp motor

Too late -- my question was answered here! But will do that next time. Thanks for the coaching.

 

[pecheux]

Re: old chrysler air-cooled 3.5hp motor

Dave: I owned one of these (West Ben) and used TCW3 oil .... = and it cooked. So listen to JB and Frank's advice and use chainsaw or lawn mower 2 cycle oil made for air cooled engines W(ink)