BenPerfected

I would check for a broken valve spring. Moroso sells a spring pressure checker for less than $100.

BLOWN85

Ok. Took out the boat lastnight to do some testing. For some reason I think that it is an electrical issue. I ohmed all of the plug wires to start and noticed that plug wire off of the #7 hole was abit higher then the rest of the wires but plug seems to be burning the same as all the others. I had a new msd coil so I gave it a shot....seemed to run a touch better. Checked plugs and still lean. Jetted up 4 sizes on the pri/sec. to 78/88 and it ran worse but the plugs had good color to them (light brown). I am now thinking that it has to be electrical. I gave it more fuel which is what it indicated that it wanted and ran worse which brings me to the conclusion that something electrical is going on in either the box or the boost retard box. I am going to switch out MSd boxes and throw the boost retard box out and set the timing at 30 degs. and see what happens. I am also going to pull the valve covers of and check for a broken spring. I will let you guys know if this solves the problem. Thanks for all the input!

Panther

I've run into problems where the ignition wires were arcing and causing a pop in the carb on the top end.... One time it was the wires, the second time it was a coil....

thought for sure it was either leaning out, springs or valve job at the time but it actually had nothing to do with with any of that.....

Go figure...

RumRunner

A few thoughts:

With dual carburetors in the HP Range you're making there is no need to use anything larger than .110" N&S assembly.

You can "Read" spark plugs even with todays fuels, plugs, and good ignition systems, however you have to know what you're looking for. I do this on a weekly basis at race tracks around the country.

Usually an ignition related problem will happen at a specific RPM each time. If changing the amount of fuel made the engine run worse, but didn't change the problem split the difference and go down 2 sizes to be safe. If the problem changed when you changed the coil you should look at the ignition system.

First thing I would do would be to lock out your timing, and remove the retard box. They have been known to cause issues from time to time. When you run the boat next set up to run "Heavy" drag your tabs, and tuck your drive so the engine has a lot of load on it. When you get to the RPM that is having the problem back the throttle off to just below the RPM when it's happening. Now free the boat up with the drive and tabs. If the problem is fuel related the amount of load will make a difference, but if it's ignition related it should happen at the same RPM again.

BLOWN85

RumRunner. I think you have narrowed down my problem. The "pop" is at the same rpm every time no matter if I am trimmed up or dragging tab. I am pulling out the retard box tonight when I get home from work. I also have an extra ig.box I may swap out to see if that solves the problem. Going to run a load test on the batteries as well. I have run 84 on gps with this issue. I cant wait to see what she'll do once I get this all sorted out!

RumRunner

If it were me I'd pull out the retard box, and run it that way. Set up your second ignition box so you can swap them while you're out on the water.

BLOWN85

I can do that as well. One other question for ya. What kind of resistance should you see on a good set of wires like Taylor or MSD? I ohm'd mine and the seem to be high.

RumRunner

It depends on the wires, check with the manufactures. They should be able to give a ± range for their different series, and lengths.

blue thunder

My taylor spirolpro wires made both tachs go crazy when they got to 400-800 ohms. I was suprised with thier limited life. I did not have any popping though.