Boat not running good? HELP

PROBLEM SOLVED

First of all thanks for all the help. Problem turned out to be a simple one, two of the wires on the distributor where switched. I looked at the manual on this site and got the correct firing order. So it ran "ok", but will terribly backfire under fast acceleration.

So after pulling my hair out, it was an easy fix.
thanks

Hate to revive this thread, but still not fixed. I advanced the timing and while that certainly helped, (backfiring wasnt as bad), it still backfires under hard acceleration.

Someone said the "power valve", could that be causing my problems? I never did replace it after taking it to the lake and having it backfire pretty bad. Where is it on the carb? How hard to replace?

thanks
Jason

Appreciate the fast advice, I know the basics of an engine, but not a lot of the finer points.

But, I am learning. Sounds like I need a timing light.

Thank you,
Jason

Jason, I apologize if I am about to tell you what you may already know, don't be insulted. I am going to try to answer your question the best I can.

The distributor rotor makes one complete revolution for every two revolutons of the crankshaft. Therefore one complete rotation of the distributor would represent 720 degress of crankshaft rotation. If your distributor were positioned to fire the spark plug when the piston reached the exact top of the cylinder following the compression stroke, the ignition timing would be said to set at zero degrees or more commmonly, "Top Dead Center". Since fuel takes time to burn engines perform best if the fuel is ignited slightly before the piston reaches top dead center or "BTDC". Typical timing specs call for the spark plug to fire 6 to 10 crankshaft degrees BTDC during engine idle. Since the distributor spins half the speed of the crankshaft one degree of distributor movement will represent two degrees of crankshaft rotation.

Yes, 1 degree of timing change will be a very small movement of the distributor. You do not have to lift and turn, just turn. The adjustment is so sensitive that just tightening down the distributor clamp can change the setting.

You will see friendly arguments on this forum about setting your timing by "ear" versus using a timing light. My advise is to buy a cheap timing light, set your timing to spec (probably somewhere between 6 to 10 degrees BTDC - someone on this forum will know the spec for your engine), and recheck it after you tighten down the distributor clamp.

I hope this helps.


By the way, you can remove your distributor cap, bump your engine and see which way the distributor rotor turns. If you adjust your distributor by turning it in the opposite direction of that rotation you will be advancing your timing.

Also do you just turn the distrubutor, or do you lift up and turn?

Sorry,
Jason

ultrahots wrote: Does the boat start hard ? This would also be a cause of timing beeing to far advanced.

I concur entirely

ultrahots wrote: If it pops out of the carb the timing is too far advanced.

Nope, retarded. Perhaps when grossly advanced. I know its counter-intuitive, but that popping is sysmtom of being not quite bTDC enough. Its quite repeatable

Thanks for your help, it makes sense that would be the problem after thinking about it. I am going to advance it a notch and test her out.

Jason

Jason wrote: UPDATE So I think it rules out the timing, because it runs strong, but just not if you hammer it.

Uhm, nope. Timing. If your accel pump is in good working order and has no delay, timing is highly suspect.

<darth voice on> I find your faith in your mechanic disturbing <darth voice off>

I put some new plugs in her, and ran it on the hose last night. It purred like a kitten at idle (as it did before),and I carefully brought her up to 3000 for a just a few secs and she sounded great, no sputtering or backfiring up any kind.

I am going to lake test her tonight and cross my fingers.

Thanks for advice

The mechanic said he adjusted the timing after the electronic igntion install. He adjusted with a timing light at idle.

He said he was 99% sure the plugs where bad after I told him how it acted. He also said I could turn the distrbutor, one notch to the left if still not running perfect.

Does turning it to the left advance it or, or just the opposite.

Also just to make sure I got the plug wires in the correct order, is the distrubutor marked in anyway? The intake manifold, is marked with numbers write above the cylinders.

thanks

thanks

Jason:

Timing lights are dirt cheap. Go to the auto parts store and pick one up for under $30.00.

Yes, change the plugs. Did you put in a new distributer or just the ignition module? You will have to time it again either way. Since the engine has been coughing through the carb you will need to replace the power valve in the carb also. Located on the interior side of the primary meatering block. A cheap fix. Also you may want to open the gap on the plugs to 35 to 40. I have mine at 35. Sounds like your timing is off. Check the fire order also if you changed the cap or the plug wires. The order will be on the valve cover or refer to the past posts. I'm guessing that you have a ford 351 with a lt hand rotation. The rotor will turn counter clockwise. Rotate the engine around so it's firing on tdc #1. To find this pull the #1 plug out and you will feel the air push on your finger. That will be your #1 plug wire on the cap and then go left from their. Check the springs in the base of the distributer also. Could of unhooked one in the process of the ignition. If you have the pertronix check the notes on the balast resistor and coil. I have the mallory ylm554cv with a mallory 3440 epoxy coil. It will run good, just work out the kinks. Work from the known to the unknown. Happy motoring!