GM 181 Rocker Arm Adjustment

[ASI Imperial]

Hello <br /><br />I am new to boating and Have purchased a 82 Asi Imperial 18 foot. As you could guess i have had to replace the head due to cracks in the spark plug holes.<br /><br />I have received the head back from the machine shop and torqed it to spec. I am having a hard time finding how to tighten the rocker arms down. cant find a spec or a how to. I know i have to adjust lash. I am used to having a set screw and feeler gauge to do this. There is only one nut and a half moon washer that sits under the nut.<br />The Motor is: MOTOR SERIAL# 5871803-MERCRUSIER 140 GM 181CI-3.0L<br />Can anyone help???????? Feeling really STUPID!!!<br /><br />Thanks!!!

 

[LubeDude]

Re: GM 181 Rocker Arm Adjustment

Tell us what engine it has. Maybe Im suppose to know by the name of the boat, but I dont!

 

[BMDODGE]

Re: GM 181 Rocker Arm Adjustment

 

[rattana]

Re: GM 181 Rocker Arm Adjustment

Remove the plugs and the distributor cap, turn over the engine until the rotor points to the #1 position if the cap was on. At this position both valves on #1 are closed. Turn the adjusting nut until all lash is removed. This position may be determined by checking pushrod side to side play. Turn the pushrod and at the same time adjust the nut very slowly. When movement is felt on the pushrod, turn the nut 1 full turn down. After adjustment to #1 has been completed, crank the engine until the distributor rotor points to #2 position. Repeat above procedure. Continue on with #3 and then #4. You should be good to go.

 

[LubeDude]

Re: GM 181 Rocker Arm Adjustment

Maybe if Id read the whole post Id have seen what I was looking for! Anyway Rattana covered it!

 

[ASI Imperial]

Re: GM 181 Rocker Arm Adjustment

Thanks alot! I will give it a go! Like I had said I am a new boater and loving every minute! Broken Knuckles and all!!!

 

[ASI Imperial]

Re: GM 181 Rocker Arm Adjustment

OH ANOTHER STUPID QUESTION! I THINK THE MOTOR IS LEFT TURN CAN YOU CONFIRM THIS? AND WILL IT MATTER WHEN I ADJUST THE ROCKER ARMS? <br /><br />THANKS!!!

 

[rattana]

Re: GM 181 Rocker Arm Adjustment

I can't confirm the rotation, maybe someone else knows better. You could look at the crankshaft end when turning it over. It won't affect the adjusting of the valves. I believe your firing order is 1-3-4-2

 

[ASI Imperial]

Re: GM 181 Rocker Arm Adjustment

Thanks You have been a great help! Will talk at ya all soon!!<br /><br />

 

[Bondo]

Re: GM 181 Rocker Arm Adjustment

Looking at the Front of the motor......<br />It turns Clockwise.....

 

[rkikenda]

Re: GM 181 Rocker Arm Adjustment

You can find the service manual for that engine at MercuryMarine <br /><br />If you need immediate information I can look up specs in my manual for my 2004 3.0L 135HP 181cc. Just let me know.

 

[Jdeagro]

Re: GM 181 Rocker Arm Adjustment

If the rocker arm is riding on a stud then the half moon washer is called a rocker arm ball and this is the bearing surface it rudes on. Bottom of ball should be very smooth.<br /><br />If the engines has hydraukic lifters then this adjsutment is done when the engine is running. At least that was the case when I was racing cards back in the 60's and 70's. The proceedure was simple - loosen the nut until the lifter clicked loudly, then tighten until is got quite plu 1/4 turn. If the lifters are solid the you use a feeler guage and we also did this while the engine was running. Admittedly a bit messy, but there was a company that made rocker arm covers with the top cut off so that the rocker arm were exposed but the oil did not splash over the engine. I do not know what the feeler guage thickness was but I think it was about .003". In any event I doubt that you have solid lifters anyway.

 

[ASI Imperial]

Re: GM 181 Rocker Arm Adjustment

could we all reply to the running adjustment comment. I have never done this. I am sure they are hydrolic lifters. If anyone knows more please share! I apprciate all the responses! It helps and will save me lost of time!

 

[djvan]

Re: GM 181 Rocker Arm Adjustment

I've done car engines both ways, both seem to work all right. The engine running option might be a little quicker but probably a whole lot messier. Check your manual and do what it says would be the safe approach.<br /><br />DougV>

 

[rkikenda]

Re: GM 181 Rocker Arm Adjustment

They are hydraulic lifters. I just re-built my engine and had to adjust the rocker arms. The best way is to follow the steps in the service manual, but I just went one by one slowly cranking engine until I saw that the pushrod was in the down position. Then the manual says that you should tighten 3/4 down from zero lash. I then proceeded to the next rocker arm and repeated the process. Everything runs great and no rattling. It is easier if you know the sequence spelled out in the manual so that you can do multiple rockers at one position. Let me know and I can fax you a copy of the manual pages that tell how to do it.

 

[Jdeagro]

Re: GM 181 Rocker Arm Adjustment

The idea behind adjusting the rocker arms when the engine is running is that it insures that they are filled (pumped up). It can be messy for sure. Given that I am an old dude this info is dated.

 

[FreeBeeTony]

Re: GM 181 Rocker Arm Adjustment

I like the "running" method myself. I tried to make this adjustment according to the manual, and when I started the motor it was very labored. The rockers were too tight! The "running" method is a bit messy, but alot easier. IMHO

 

[ASI Imperial]

Re: GM 181 Rocker Arm Adjustment

I would like to try the running method. Is there anything out there to reduce the mess? I was thinking of buying a used valve cover like the one i have and cutting the top out of it. Does anyone think this will work? <br /><br />Thanks for the help!!!!!

 

[Fishermark]

Re: GM 181 Rocker Arm Adjustment

Cutting the top off an old cover is what most car guys do. I assume it will work on yours. (I do the static methaod myself - engine not running. It works fine for me).

 

[wheels4]

Re: GM 181 Rocker Arm Adjustment

Yes you can use an old valve cover but there is nothing wrong with doing it the way Rattana described above.Ive done this on alot of engines and never had a problem.Much easier and a whole lot cleaner.Either way will work though.Good Luck!