Ticking noise in carburetor after timing adjustment

"I started a thread last Octob

"I started a thread last October that I'm hopefully in the process of bringing to a close now. The link is here http://www.marineengine.com/discus/messages/12488/114866.shtml
My engine is an '85 OMC 3.0 liter. The basis of the problem was an inability to reach proper W.O.T. Bob recommended a full tune-up at the time, and after another season of sub-par boating at between 3600-4100 peak RPM, I finally did the entire tune-up today (new points, condenser, plugs, rotor, both fuel filters, and timing check.)
The plugs had little black spots on the electrodes when I took them out; my Clymer manual hinted this might be from overheating or improper timing. When I checked timing it was Way Off. The timing mark was well forward of the timing check plate. If I had to guess, it was somewhere in the mid to high 20 degrees BTDC at an idle. I adjusted it down to the manual-recommended 4 degrees BTDC, and this drastically slowed the idle and caused a faint ticking noise in the carburetor. I called a mechanic that I trust and he told me that I should set it at about 8 BTDC. This increased the idle RPM a bit; it runs more smoothly, but the ticking noise from the carb seems to still be there most of the time. It wasn't there when the timing was set at its previous location, but of course it now runs much better. Back on the lake, I was back in the 4200-4600 RPM range with higher speeds. Idle seems lower than it had been - possibly not a bad thing- but I don't know if I should worry about the ticking noise.
Any help would be greatly appreciated. Thanks in advance."

"I'd be looking for a vacu

"I'd be looking for a vacuum leak...one method is to use a propane torch (not lit) feeding a little propane around the manifold, carb base and listening for the idle to increase."

"I checked for a vacuum leak t

"I checked for a vacuum leak this morning with both a torch and carb cleaner. I concentrated on base and all visible gaskets of carb and also as much of the manifold gasket and areas of the manifold that were accessible. There was no change in engine performance throughout entire process. The ticking goes away when I bring it out of an idle, then it returns as the engine comes back to an idle - though not always immediately. After running at higher rpm's, it was quiet for a slight time but then ticking came back eventually - possibly after engine brought itself back to a SLIGHTLY slower idle. It runs smoothly and doesn't seem to be hesitating/missing like it was before the tune-up. Could I have missed something; should I be concerned about this. Thanks again."

"Some GM carburetors of that v

"Some GM carburetors of that vintage had electrical solenoids that "clicked" constantly at low speed. I remember that my 1982 with a 305 had such a carburetor. If your carb has 2 black wires coming out from the inside, it has the solenoid and the clicking is normal and if so, without the clicking, your engine will not function properly."

"Thanks Bob...I checked for th

"Thanks Bob...I checked for the two black wires and my carb doesn't have them. I think, based upon my Clymer manual that I may have a Rochester 2GC carburetor."

I suppose it could be an intak

I suppose it could be an intake valve sticking. A bit of sea foam in the oil or taking the valve cover off or listening with a stethoscope might help. a Stethoscope is a great tool to have around for this sort of thing.

I'll put some sea foam in

I'll put some sea foam in the oil first. How much should I add? I'm assuming that an additive might take some run time to work on the sticky valve if it's going to do the trick. How long should I let it run this way if no change is noticed before I take other measures?

"That's a judgement call o

"That's a judgement call only the boat owner can make... "if in doubt, check it out" is the old saying...I'd probably take the valve cover off and watch the valves at idle...resting your finger on the rocker you can feel the snap as the valve unsticks... but then I am always working on my boat over-investigating things... "if it works don't fix it" is the saying I always ignore"

"Thanks so much...you guys are

"Thanks so much...you guys are truly invaluable, and I appreciate your taking the time to answer all of my questions!"

"excellent reference for top e

"excellent reference for top end noise here too:
http://www.marinemechanic.com/site/page52.html"

"Excellent Information...Thank

"Excellent Information...Thanks again "