1968 65hp Carb. Question

[GLPmike]

Hello,

Our old motor is running strong on our project boat after many months of restoration. But, we have a question on rebuilding the carb. We ordered the carb. Kit Rl436959 and should receive it soon.

Our gas milage could be better. 5 gallons in about an hours running time with two adults and two teens. Topped out at 26mph with this load and 32mph with one adult only.

Carb. Appears to be running rich and we are leaving a healthy rainbow trail. We are having problems starting the engine even after it's been run for a bit.

Other than replacing the gaskets and seals contained in the kit is there anything else we can do with the carb to reduce the fuel loss and help resolve the trouble starting issues?

Thanks,
mike

 

[jtexas]

Re: 1968 65hp Carb. Question

Is your fuel burn rate increasing, or it's been like that since you got it? 5 gallons per hour at full throttle seems pretty reasonable. but the rainbow trail.....

The fuel pump on your motor...does it bolt directly to the manifold, or does it have a pulse line (3rd hose)? Reason for my question is, the pumps with a pulse line dribble fuel out a hole on the back of the housing if the diaphram gets punctured, which will cause an oil slick around your transom. It could also account for hard warm starts, as some fuel drains down the pulse line flooding the motor.

the hull -- is that a 15 foot tri-hull? if so, I'd say 32mph is pretty darn good

Sorry I don't have an answer to your specific question -- installing the carb kits is about all I know to do.....

 

[GLPmike]

Re: 1968 65hp Carb. Question

Thanks for the reply.

This was the first time we had a chance to take it out for a decent run.

I am waiting for the carb rebuild kit to arrive in the mail. Hopefully, this solves some of the problems with the old float and leaky gaskets.

Yes. It's a 16' tri-hull and according to our GPS we hit 32 with just one adult aboard.

The motor has excellent compression for it's age and I replaced the entire ignition system on it along with rebuilding the entire lower unit.

We also replaced the transom and floor.

 

[Andy in NY]

Re: 1968 65hp Carb. Question

Thanks for the reply.

This was the first time we had a chance to take it out for a decent run.

I am waiting for the carb rebuild kit to arrive in the mail. Hopefully, this solves some of the problems with the old float and leaky gaskets.

Yes. It's a 16' tri-hull and according to our GPS we hit 32 with just one adult aboard.

The motor has excellent compression for it's age and I replaced the entire ignition system on it along with rebuilding the entire lower unit.

We also replaced the transom and floor.

if the floats are out of adjustment it will cause a rainbow trail too and excessive fuel consumption as well.

im having the same problems too... on land with muffs i get lots of unburnt gas/oil in the prop. mine is a 74 50 hp.

 

[F_R]

Re: 1968 65hp Carb. Question

GLP, you might as well face reality. That motor is a far cry from being fuel efficient. 5 GPH really isn't too bad. Because it is inefficient, a lot of gas is wasted. In fact it is drained off on purpose. Those drains empty into the exhaust housing and end up in the water. Of course you see a rainbow. Always has and always will be. If it runs well and is adjusted as good as you can get it, that is the best you can do.

EDIT: You cannot stop the discharge, but you can ease your concience and lessen the impact on the environment. Use Penzoil 100% Synthetic Outboard TCW-3 oil. Get it in gallon jugs at Wal-Mart. You may have to look around for it--last time I bought some it was on the car oil shelves Duh!!

Anyhoo, it smokes less and is bio-degradeable. Mix it at 50:1 ratio

 

[GLPmike]

Re: 1968 65hp Carb. Question

Thanks for oil tip F.R. Sounds like it's a little easier on the wallet as well.

Yeah. Looks like we will rebuild it with the kit and just leave it at that I guess.

Thanks