1972 OMC 60HP Help

kamikaze · #1 04-15-2012, 04:39 PM

Hey guys I need some help.

I have a 1972 60hp OMC three cycle that surges like it not getting enough gas at high speed (4200 - and above) but the primer bulb is solid and squeezing backs no difference. Motor is making good power all along - just feels like it leans out at high speed. If you run it a lower speeds no problem. Here what I've done to the motor to date.

Compression is 130 in all three holes.
Rebuilt carbs
Replace fuel pump/and gas lines
New CDI amplifier
New points
New plugs
Checked timing/TDC and there all good.

One additional problem I noticed to day is at low speed the (1000 - 1200 rpm) the tach will occasionally spin the needle right around the dia making a 360 rotation before it settles back on correct RPM. Not sure if this some other problem or perhaps related to the issue I'm having at speed?

Any suggestions/ideas....

THEFERMANATOR · #2 04-15-2012, 05:49 PM

Are you sure you got the float levels set correctly? Sure sounds like one running out of fuel from your description. Or it could be a bad fuel pump dumping fuel into the engine.

kamikaze · #3 04-15-2012, 08:55 PM

Ferm

Thinking about running with the air silencer off and using my hand to determine if its fuel related for sure by choking each carb individually and perhaps I'll be able to narrow down which one it having the issue at the same time.

I'm pretty sure the float levels are good but I'll pull and verify. Not like I haven't had them off five or six times already.

Kamikaze

phatdaddy · #4 04-16-2012, 07:11 AM

anytime i had a wacky tach, stator gave trouble later on.

THEFERMANATOR · #5 04-16-2012, 10:39 AM

Quote:

Originally Posted by kamikaze

Ferm

Thinking about running with the air silencer off and using my hand to determine if its fuel related for sure by choking each carb individually and perhaps I'll be able to narrow down which one it having the issue at the same time.

I'm pretty sure the float levels are good but I'll pull and verify. Not like I haven't had them off five or six times already.

Kamikaze

Running with the air box off is a good way to melt a piston. Most people don't realize it, but the air box is there to restrict the airflow coming into the carbs to fatten the fuel mixture out. Take the airbox cover off and they will scream, for a few minutes before a piston melts down.

kamikaze · #6 04-17-2012, 11:00 AM

Well its the lower carb. However, its not a high speed jet, float level for seat issue, so go figure. I'm going to look for a replacement and give that a shot.