Atomic 4 Slow forward

Jeff Gallo · #1 06-14-2001

I own a 1979 C&C 29 with the original atomic 4 engine. The engine has always run great up till now.
Neutral & reverse has all the power in the world however when in forward the top 2/3 of the throttle is flat. The RPM just stay flat and the engine feels strained. Saltwater Exhaust is flowing great, new plugs, points, condenser. I have noticed that the clear inline fuel filter before the elctric fuel pump is never completely filled more than half way. This RPM is just not cutting it in a 5 knot current. HELP!!!Thanks.

JohnYates · #2 06-14-2001

Make certain that the prop is clean. It only takes a small amount of fouling to really de-power the A4. I had a similar experience last summer and did a quick haul to clean the prop. I was amazed how little fouling was on the prop. After cleaning and relaunch, it felt as though the motor was new.

RichH · #3 06-14-2001

Agree with the fouled prop.
However, if this doesnt clear the problem..... Check the following:
1. dirt in the emulsion tube in the carburator.
2. The very beginnings of a blown head gasket. If you have closed loop freshwater system you can get some specialized dye from an automotive speed shop to check for excess CO/CO2 in the cooling water. Obviously, if your raw water cooled this wont work.

EscapeArtist · #4 06-15-2001

You may have something wrapped on the prop shaft. Put on the mask and snorkel and have a look.

gerardw · #5 07-10-2001

The atomic 4 on the Morgan 28 I purchased had a similar problem on the survey sea trial. My surveyor said it was pretty common and usually caused by the flyweight mechanism in the bottom of the distributor seizing up. I''m not sure if that was actually the cause since the shipyard/broker took care of the problem before delivery.

armarine · #6 07-11-2001

If it works good in reverse, it''s possible that you could have something around the prop, also check your transmission, may be slipping in fwd.