Coughing 307Q dual engines(both)

Author Message   bill heffron New member Username: shldbfshnnotfxn Post Number: 1 Registered: 05-2008 Posted on Sunday, May 11, 2008 - 02:34 am:    I just don't understand it. pulled the boat out last year and had a slight cough coming from the carb on the starboard engine when under load over 1500rpm or so. port motor ran great. asked the storage yard if they would do a compression check over the winter on both motors and install new plugs, wires, caps and rotors. they confirmed adequate compression on all cylinders and installed all said parts except rotors. dropped the boat in this morning excited like a kid on christmas morning. dreaming of jumping steelheads on the end of my line all the way to St. joseph from chicago. then we had to cab it to the next harbor where the boat was stored. showed up to find that we needed a new battery, no big deal we were prepared and had 2 new ones with us. then starboard didn't start. took a look to find the coil wire not plugged in. plugged it in and motor coughing out carb like crazy. tried port with the same problem. of course you're probably thinking "timing" like we were. so we tied to a dock to straighten out the timing and we'd be off. I tell you, I tried everything. found 2 new rotors in boat and installed them. tried adjusting dist. in very small increments from one end to the other. confirmed wiring correct.(which was a bit of a challenge.) the only thing that was fishy, was that the number1 cylinder was at top right on the port side dist. and it was the second point down from the top left on the starb.(figured standard install would have been mirror image.) oh yeah, these are converted hei from the points system. and I couldn't find a mark on the balancer when trying to use timing light.(1972 motors) Should they be marked for top dead center for #1 on stock installs for this year? with that aside, I was able to get the motors to run a little bit better in the high r's but coughing under idle and having very little response.(bogging down when raising throttle, taking time to raise r's, very little power.) so on I went into the fuel system. changed fuel filters, adjusted carbs air idle. at this point, we were able to tell that the gas was really old and smelled like turpentine, or kerosene. we pulled the carbs for rebuild, and are going to pump out the gas tanks and install the reblt carbs when we return. I've never had fuel system problems with symptoms of coughing out the carbs before, but then again I'm used to land vehicles where I can retard the timing and all is good. anyone have these symptoms before? I'm stumped!   Mark Campbell New member Username: wheelsnkeels Post Number: 3 Registered: 10-2007 Posted on Sunday, May 11, 2008 - 04:54 pm:    Here is the manual to check you firing orders   bill heffron New member Username: shldbfshnnotfxn Post Number: 2 Registered: 05-2008 Posted on Sunday, May 11, 2008 - 05:30 pm:    thanx for the reply, you url didn't pop up, but I managed to find it on another post. the firing order was accurate, but some mechanic had the #8 piston marked as #1 on the cap. I noticed this when reading the manual and saw that the number one was top left on both motors. he thought that it was bottom right. nonetheless, the firing orders were correct, but that explains why I couldn't see the potmark on the flywheel.lol but as far as the firing order, I took notes of what was there and it checks out ok with the diagram in the manual. I'll dial the timing in this weekend, but I still believe I'm pretty close. I don't think that the marina used fuel stabalizer when storing the boat due to the smell of the gas. the port motor ran fine last season. seeing that both motors are now having the same problem, and that the fuel seems bad, I'm defintely thinking that it has to do with the bad fuel or tarnished carbs. anyone else have this coughing problem when splashing in a boat w/old fuel? I've got a video of what it is doing, but I can't upload a vid as an attachment here.   Mark Campbell Member Username: wheelsnkeels Post Number: 4 Registered: 10-2007 Posted on Sunday, May 11, 2008 - 08:44 pm:    When I resurected my 350Q's from a 5 year layup I used a high concentration of Sea Foam available at Napa. It's one of those wonder chemicals that is an upper cylinder lube for our older engines. ( to replce the lead) while it also stabilizes the fuel and removes moisture. I highly reccomend it, I use it regularly with the unleaded fuel as a valve lubricant. Sorry the attatchment turned out to be too large to post at this site. I am glad you where able to find it! Good luck this weekend.   Jonny Peters Member Username: knightime72 Post Number: 8 Registered: 04-2008 Posted on Friday, May 23, 2008 - 08:10 am:    I had the same coughing problem when I had old fuel for my Ford 302... I pulled the carb and found that it was clogged horribly (it's amazing that the motor would even start). After a rebuild and fresh fuel, my problem was solved.

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