Idle speed in an E32???

[Chris Knudsen]

My E32 has the atomic 4 and it runs beautifully. I don't have a tach but my idle doesn't seem high to me. But when my boat is in gear at idle it is cruising at about 4 knots. This just seems too fast to me. I am passing most of the power boats in the no wake zone. At 1/4 throttle I have reached hull speed of 6-7 knots. I am just wondering what the lowest speed other people are able to do with their boats. I would love to get mine down to about 2 knots but I don't think I can adjust the idle down any more.

 

[Rocinante33]

Just turn the idle down until it sounds like it is about to stall and then turn the screw back in the other direction 1/4 to 1/2 turn and that should be good if the engine is running well otherwise. 4 knots seems way too much to me. It must be tough getting in and out of the slip. On the Moyer website they can probably give a recommended idle speed.

 

[Chris Knudsen]

I have adjusted the idle down as low as it will go. I have also adjusted the idle air screw as well. The idle doesn't sound high to me but without a tach I can't confirm that. It just purrs like a kitten. I was just curious what speed others were getting at idle. I am very blessed and have a straight shot into my slip so it is no big deal.

 

[Gregoryulrich]

How did you adjust the idle air screw, that is, are you sure the mixture is adjusted properly? Most engines should idle around 750-800 rpm at idle. I haven't checked the Moyer site to confirm the A4 idle so take that with a grain of salt. A tach/dwell meter isn't too expensive and you should have one in your quiver if you're doing your own engine maintenance, which you should.

Mixture should be adjusted with the engine warm. Turn the mixture screw clockwise gently all the way until it stops then back it out 1 to 1 1/2 turns. Turn the engine on and give it a quarter turn counter clockwise and give the engine a minute to adjust and settle down. Did the idle rise? If so give it another quarter turn counter clockwise. Did it rise again? Repeat until the idle stops rising and then give it a quarter to a half turn clockwise to enrichen it a bit.

Engine idle should be adjusted only after after proper mixture has been achieved. If the mixture's not right you may be running a high idle to compensate for a bad mixture.

 

[Gregoryulrich]

On my E-27 I can maintain about 2 knots at idle.

 

[Chris Knudsen]

H
Mixture should be adjusted with the engine warm. Turn the mixture screw clockwise gently all the way until it stops then back it out 1 to 1 1/2 turns. Turn the engine on and give it a quarter turn counter clockwise and give the engine a minute to adjust and settle down. Did the idle rise? If so give it another quarter turn counter clockwise. Did it rise again? Repeat until the idle stops rising and then give it a quarter to a half turn clockwise to enrichen it a bit.

Engine idle should be adjusted only after after proper mixture has been achieved. If the mixture's not right you may be running a high idle to compensate for a bad mixture.

I used the above method to adjust my idle. It seems to me to be low enough. Moyer says that idle should be in the 600-700 range. I bought a new tach this spring however it didn't work correctly. I have a new one on backorder. I am sure that will answer some questions.

 

[Chris Knudsen]

My tach came in today. So it turns out that I was idling high at around 1,100 rpm. I was able to adjust it down to about 900 RPM but couldn't get it any lower. Looks like I have some work to do. I have a spare carb so I may do a full rebuild/upgrade on that and then install it.

 

[Bill Sanborn]

A4 idle

It sounds like your throttle cable is mounted to far forward on its mounting bracket. The throttle cable jacket is mounted onto a bracket somewhere aft of the carb. Try moving the jacket slightly aft in the mounting bracket. This should change the "adjustment range" of the throttle adjustment at the carb. You should be able to reduce idle far enough to kill the engine.

FWIW the idle mixture adjustment on the A4 carb is an air adjustment, not fuel. When turned clockwise it reduces the airflow thru an air orifice which makes the mixture richer and vice versa. It should only be adjusted when the throttle plate is fully closed thereby only affecting idle speed. It is adjusted for max rpm at idle only. Make sure when the throttle is fully aft that the throttle plate in the carb is fully closed.

The std carb does not have a fuel mixture adjustment unless you have added Moyers hi-speed adjustment which is on the bottom of the carb and is adjusted for max rpm only at cruising speed. This is worth buying/adding, you can lean out the mixture at cruising speed increasing the mpg appreciably.

Both the hi and lo speed jets in the standard carb are fixed.

You can make both of these adjustment by ear but a tach is nice.

I learned all of this because my e29 was moving too fast to troll low and slow for the big salmon.