1975 75hp...about to take a hammer to it!

[everhart57]

I still can't figure this thing out. I'm new to boating but I have automotive background so I'm not totally out of my element. I have intermittent starting issues based on what I believe is the battery going dead. When started I can't find the screw to adjust the idle so I need to know that first. I need to know where the mixture screws are as well. I have read posts and looked at pics and I still can't see it so here are some pics and I hope someone might identify it for me. Then I'll hopefully adjust that and minimize the rest of the questions I havehttp://s692.photobucket.com/albums/vv286/everhart57/?action=postupload

 

[SweeperForce]

Re: 1975 75hp...about to take a hammer to it!

First I'd start with clean and tight connections including tight terminals on the battery. Make sure it has a fully charge too. After that test your starter selonoid then your starter itself. My engine is a 150 horse but as a guide these might be helpful.

Idle screw



Mixture screw should be on the carb



If you plan on doing alot of your own maintenance I suggest a Clymer shop manual. There are only about $35 and well worth every penny.

Tom

 

[SweeperForce]

Re: 1975 75hp...about to take a hammer to it!

I found a better picture on the carb.



Tom

 

[Frank Acampora]

Re: 1975 75hp...about to take a hammer to it!

Idle stop screw is on the bottom of the timing tower (stainless rod that links carbs and distributor) and is used to adjust idle to 700-750RPM in forward gear, in the water.

These engines are different than automotive and will not tolerate a lean condition at all. So, when you do adjust the mixture on the carbs, be certain that the screws are not set too lean. See my post on synchronizing carbs and timing.

These engines also differ from autos in that they are old school: Your 75 will either have points or a pre-amp in the distributor. They are powered from the ignition switch. The blue wire MUST be attached to the "I" terminal on the switch so no power is delivered when the engine is off. If it is attached to the "B" terminal, then the battery will be gradually drained.

 

[everhart57]

Re: 1975 75hp...about to take a hammer to it!

okay so I do have the blue wire attached to the i terminal but I think power might be draining anyway. I used an automotive ignition and this is what I did. I have red to battery, blue to ign, yellow to solenoid and up until yesterday I had a choke button wired to the batt, when we got home I moved the choke button to the accessory terminal as it occured to me that it may have been draining the battery, do you think that was it? Also if that's the idle screw, which I believed it was, I have adjusted that all over the place to no avail. I'm going to go out and take some more pics of the engine though because I swear I have looked all over the carbs specifically for something that looks like that mixture screw and haven't seen it but I'm going to look again. I'll post again in a few mins. Thanks for all the help though.

 

[everhart57]

Re: 1975 75hp...about to take a hammer to it!

also...with the idle screw, when you screw it in the idle should go up? or is it the other way around.... that might help huh...

 

[everhart57]

Re: 1975 75hp...about to take a hammer to it!

Okay so these are maybe better pictures of my carbs (well the top one mainly) I don't see a mixture screw on there in the place that all the pictures you guys have... any thoughts?

 

[Frank Acampora]

Re: 1975 75hp...about to take a hammer to it!

OK! Lets start with a couple of basics.

To start these engines, on a cold start, you must pull out the silver knob on the control box and push the handle as far forward as it will go. This is fast idle cold start position. Many of these engines will not start at all if not in this position most will take excessive cranking. You also must hold the choke button while cranking. Choke is not automatic and will release when you release the button.

You may possibly not be draining the battery. There is a neutral interlock switch on the side of the engine opposite the starter, down below the bottom carb. It is a brown micro-switch with a white button. The shift linkage pushes in the button when the engine is in neutral. If the button is not depressed, no voltage goes to the solenoid and the engine will not crank. Because of slop in the cables, sometimes when the control handle is in neutral, the switch is not depressed and the engine will not crank. Jiggle the handle to center the shift and depress the button.

In the front of the white air box attached to the three carbs there are three holes. they may be filled with rubber plugs. You pull the black rubber plugs and reach in the holes with a long fine flat blade screwdriver to adjust the low speed needles. Search and read my post on Synchronizing carbs and timing BEFORE you monkey around with the carbs.

 

[everhart57]

Re: 1975 75hp...about to take a hammer to it!

ok....so I know about the nuetral switch already (the guy who sold me the motor thankfully told me about that) What is does is different....it acts like its going to crank but just doesnt have enough power... but that was rememdied at this point by a new battery... I have had the boat started and running already and the motor sounds strong... the problem I had this last time (that it wasn't doing before battery and starter change).... It started perfect and I was hopeful but as we were going accross the lake it started to hiccup at WOT...I thought it would clear up with running it. When I stopped for a min to relax it didn't want to start back up. It would turn over but not start. finally got it started and about half way back and it started dying.... I tried to adjust idle since it has had problems idling since I got it but that didn't help anything. finally it just wouldn't even turn over but luckily someone towed us in. I took the battery to autozone and it tested bad. Got a new battery and now it turns over fine but I'm concerned since I can't start it at home (no rabbit ears) that it's going to die due to idle issues or something. Could all of that have been caused by the battery? and those rubber plugs? that's how you adjust mixture? wow I might need a mechanic LOL. Also, for adjusting the idle....screw the screw in for higher speed? or out? thanks for all your help..... Oh, and I have read the post on syncing carbs but since I can't find the screw I have been unable to apply it... Thats why I was asking...