funny idle problem

[flymaster]

1997 3.0LX I have a weird problem when I take my engine cover off my rpms will drrop to 1000 when I put it back on it will go up to 1200/1330 rpms.
I needed to replace the module on my distribtor this year so I did the works plugs,cap,rotor,wires,all fuel filters, new fuel pump. I reset the timmig by the book
jumped distribtor and set 8 degrees past top dead center. So while I was at it I decided to rebuilt merc carb new acclorater pump needle and seat float with proper drop and lift preset all screws to book specs. Put it in the water pumped some fuel in carb it started right up with one turn of key. I have adjusted everthing I can and what book says to do swivil barrel on cable. But I can't figure out this problem with engine idle with the cover on the idle goes up off it goes down. I am a back yard mecanhic I know my way around an engine.
Jack

 

[alldodge]

1997 3.0LX I have a weird problem when I take my engine cover off my rpms will drrop to 1000 when I put it back on it will go up to 1200/1330 rpms.
I needed to replace the module on my distribtor this year so I did the works plugs,cap,rotor,wires,all fuel filters, new fuel pump. I reset the timmig by the book
jumped distribtor and set 8 degrees past top dead center. So while I was at it I decided to rebuilt merc carb new acclorater pump needle and seat float with proper drop and lift preset all screws to book specs. Put it in the water pumped some fuel in carb it started right up with one turn of key. I have adjusted everthing I can and what book says to do swivil barrel on cable. But I can't figure out this problem with engine idle with the cover on the idle goes up off it goes down. I am a back yard mecanhic I know my way around an engine.
Jack

8 degrees past TDC to me means 8 ATDC, your engine should be 8 before or BTDC if you have points or DDIS ignition. If you have EST ignition it should be at 1 BTDC. As for the idle change it would appear the flame arrestor is coming in contact with the throttle linkage. Is the flame arrester clean?

 

[airshot]

Yep , something is coming in contact with your linkage when the cover is installed or removed. Nothing else that I know of could cause a throttle change.

 

[flymaster]

I did mean 1 degree BTDC sorry. I forgot to mention that the boat runs great with the cover on or off. I did clean the spark arrestor with choke spay
and let it dry. possible time for a new one it dose rattle a lot. I will try today but right now it is pouring out
thanks for the input.