View Full Version : Timing???
08-18-2008, 06:03 PM
Ok, I've been through this around 100 times. My boat ('91 Maristar 240SC w/454) cranks fine when I drop her off the trailer. In fact, I would go so far as to say perfect. But after she warms up and runs for a while, it drags and is REALLY hard to turnover. I've even burnt up a battery pulling too many amps trying to start it before. It isn't the starter, I've had it tested (twice). I know that as these older carbuerated engines warm up, they advance in timing a few degrees. Is it possible that this advanced timing would cause hard starting when the engine is warm? If so, should I look at retarding the timing a degree or two? I really hate to fool around with a 17-year old engine with 1250 hours that runs like a top. I mean literally runs perfect. I even had the MC mechanic at our local shop ask me what I did to keep a boat that old running so well. I just said, "I love her every chance I get....:D"
The timing won't advance unless the distributor it turned or a component's value drifts in an electronic ignition. The advance springs and weights may need to be looked at, though. If the weights are sticky (which I could see happening when it gets hot), they may stay where they were when the motor was at higher RPM. Idle the motor for a minute after a hard run and see if that makes any difference.
08-18-2008, 07:33 PM
mine did the same thing, and I replaced the positive and neg cables and solved the problem. Been working fine for a year or better......same exact symptoms as yours, up to and including the battery!
08-20-2008, 03:57 PM
I normally do idle it down before turning it off. Actually I don't run it all that hard to begin with. I will try to make sure I let it cool down at idle a little while before killing just to see if that will do it. I don't have electronic ignition and I don't think the distributor is moving. You think I should have a pro take a look at the ignition system?
I have so far replaced the battery, but not the cables. Cables appear to be good, but it sounds like putting some new ones on may not be a bad idea. I'll try to make it to winter for that, but I'll definitely try it.
Any other ideas or thoughts are certainly welcomed.
If you have points, make sure the little wedge that rides on the distributor cam hasn't worn down too far. When that wears, the dwell angle decreases and the spark intensity drops. I've never measured how far the timing changed when I replaced points but this is about the only thing that I know of that would affect timing/spark, over time. If you don't plan to get rid of points completely, look on the link below. I bought one at either Sears or AutoZone and it works fine. I also have a multi-meter but that kind is harder to find.
It's easy- set the meter to the number of cylinders, get the gap close and adjust the points.
08-20-2008, 05:40 PM
Awesome...Thanks. Another afternoon or weekend project.
About the only tools you should need are a slotted screwdriver (flat blade), 9/16" wrench for the distributor hold-down bolt, feeler gauge, timing light and tach/dwell meter. With those, it should take a lot less than an afternoon.
08-21-2008, 01:06 PM
Cool. Thanks. I may have to come back with more questions once I dive into it....
08-21-2008, 01:17 PM
Watch the timing w/ a good timing light as you rev the engine, and watch it as you drop the rpms also. Your timing should advance smoothly with rpm increase and drop back smoothly when going back to idle. If it jumps around radically on the decel portion of the test (according to the marks) then you could have slop in the timing chain and gears, which would result in an intermittent slow crank situation when hot (over-advanced at shut-off). Should not vary much more than 3 deg. I believe.
Generally, the engine (once it starts with a chain issue) will run like crap until you shut it off, then a restart it may run fine. It seems like an intermittent problem.
08-24-2008, 05:09 PM
The engine always runs perfectly. Only problem is that it hard starts every now and then. It's almost like high compression. It's just really hard to turn over. After that, she runs absolutely perfect.
08-24-2008, 05:21 PM
Take the battery out and have it checked!
08-24-2008, 05:39 PM
Probably just terminal, wire or ground connection problems, but maybe a look at the exhaust manifolds for leakage into your cylinders should not be discounted.