Thread: engine still misses over 2600 rpm

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I can control what tank the gas is feeding from with a valve. I will shut the valve off on the engine that is running bad then they both will be getting gas from the same tank and filter. This should eliminate the tank & filter, bad gas out of the picture. If it's not this than, I guess I need to check fuel pump & carb.
thanks

Hello All:

I had a chance to work on the engine today. Here is the results. First I changed the fuel filter, didn't help. Next I switched the carbs between the engine, set the timing back a little and to my surprize she ran pretty good, I would say she runs better now at mid to high than low(2000 & below). Can still hear a little popping out the exhaust. I will keep trying things to get her perfect. One thing that comes to mind is this engine is the oppsite rotation engine and I have always heard they run the worse.

Thanks Denny I really appreciate you helping me out on this engine.
When I switched the carbs shouldn't the problem have followed the carb? The engine I switched it to still runs just fine.
How do you check the pressure?
If the float is wrong, how do check for this?
Thanks again.

hello . not trying to but in, but maybe you have a mecanical problem if you changed the carbs and the same problem did'nt go away,i think that i would start looking at the heads and the valve springs. maybe to tight and maybe still to much timming. how old is the gas that you are running thru the engine? if it's old then maybe the valves are sticking in the guides and giving you this problem,and even if it's not old now, has it ever been and you ran the engine? did you check the advance in the dist and see if it's working right? let us know

You might want to check the distributors mechanical advance mechanism. You could have a broken spring.

hello all:
Went out in the boat today. I would have to say the problem is now 2000 rpm's & below. Runs good at high speed. She cough back in carb some. Can hear popping out the exhaust & missing at low speed. The last time I had a low speed miss was a crack in the distributor cap. Do you guys think it could be plugs or in distributor, it's a mallory single point distributor. If it was a broken spring wouldn't she miss at high speed too?
thanks guys

hey guy. now you say that the engine is running ok at the top and the idle is bad, sounds like things have changed from the top to the bottom. just a thought, when was the timming chain checked in the engine that is running bad?seems like you changed the timmimg and things moved to the bottom as being the problem. check the timming as follows- put the engine at top dead center(timming marks lined up at the crank) remove the dist cap and turn the engine untill the rotor starts to move.(opp way then the way you went when you set it to o deg's) when you see the rotor move STOP and look at the amount of degree's the engine moved. that will give you an idea of how far much slop their is in the chain, and let us know good luck dave

Hey Dave thanks for the reply. This is a new long I was told. If it is a new long block, is slop in chain still an issue? I don't know if the problem moved because I could always hear it popping at 2000 rpm's & below but I guess I didn't feel it miss like it's doing now.

hi guy. if the engine is fairly fresh then the timming chain prob isn't an issue. imo i think that you still have a problem with the timming and or the cam, maybe you can take the valve covers off again(i know it's getting old) and turn the engine over and watch the rockers to see if the cam is flat or going flat.maybe the cam isn't in time? the one thing that is for sure is that you have the engine firing and the valves are still open slightly, giving you that popping. how did you adjust the valves while it was running? and how much did you turn the nuts down?try resetting the timming to 0 deg and make sure that the vac adv is not connected when you set it. try not running the vac adv at all and see what happens. make sure that you check to see if you have a vac leak any where in the intake area. double check to see that you don't have ant valve springs broken or weak. again does the valve springs have any shims under them? and are they new springs? keep us posted, some one will be able to help you i'm sure. dave

Hi Dave:
The engine is 3 years old less than 100 hours. The marine engine has no valcumn advance. I adjusted the valves while running. Tighten the valve 1/2 turn past zero lash. Not sure about shims under the valves & I don't think the shop replaced any springs when the head was done.
Why would I want to set timing at zero deg?

thanks
leonard

hi. if you set the timming to 0 deg's and then see if the engine runs any better, maybe that will tell you something about what's going on. did the engine sit for any time with gas in it? and was it serviced at the end of the year? and by setting the timming to 0, it may tell you about the adv in the dist. set the points to 17 and the dwell to 28-32 degree's.

Hey guys thanks for the replys. I winterize the engine with marvel mistery oil. Gas is fresh. Engine runs good at idle. Misses when running at about 1000rpm's to around 2200rpm's, that's when I hear the popping.
I will check if popping when cold and change timinig & point setting the next day light time I have.
thanks
leonard

"set the points to 17 and the dwell to 28-32 degree's."

You might want to clear this up, lest you confuse your readers.

sorry, set the points to 17 thousands with the points on the high lobe of the dist shaft. if you have a tach and dwell the set the points to 28-32 degree's with the meter. negitive wire of the coil and ground. using the dwell meter is the best way to get the best reading. hope this is what you need.

Hello Guys:

It's been a while. I got change to work on the engine this weekend. Set the timing at 0 and the point gap at 17. This made no difference at around 2000-2600, she still missed. Also had less top end, advanced the timing a little and top end picked back up again. When I set the point gap to 17, I checked the dwell and it was only around 22 not 28-32 as you said. My distributor cap has no windows to set while running. She feels as if she fires on some cylinder than not firing, at 2000-2600. She really has me baffled.