Chrysler 75hp, need direction.

[Nordin]

Measured the gap at the block for the timing rod at my 1975 Chrysler 75Hp.
I have the Magna Power I system with electronic distributor (optic diod eye instead of points).
The gap is almost 1/2 in (12,3 mm metric).

 

[Tapphouse]

I numbered the teeth 1-97 CCW just as a reference point, on that sticker if fires one line left of 32*. Where on the sticker do I want plug #1 to be firing?

 

[Nordin]

As it is to the left of 32 drg right now it is more then 32 drg. Maybe 33-34 dgr.
Retard it to 30 dgr or something around there 29-28 dgr.
Try from there.
The gap between the timing rod would be about 1/2 in at 28-30 dgr.

 

[Tapphouse]

Ok I’ll try it.
Do you know on the sticker what marks would be 28*-30*? As it only shows roughly 5 lines between 32*-TDC on the sticker.
Also the tab is it just a reference point? Or does the notch mean something more?
Thanks a million Nordin.

 

[Tapphouse]

So after redoing “link and sync” and at full throttle I’m having trouble getting plug one to spark much less than 32*. The gap in the distributor block is 1/4” I would need more to get it to go more right.

 

[Tapphouse]

I’m clearly missing something here or there is an issue with the position of flywheel/distributor.
At WOT and 1/2” gap it’s at like 33*-34*. If I turn the plastic block on distributor all the way closing the gap it’s just under 32*-31* at WOT.
If my math is right it should be 8 teeth left of TDC for desired timing. 9 teeth is best I can get with 1/4” gap puts me at 32* WOT.
How important is the gap on the plastic distributor block?

 

[Nordin]

If you do not got the timing retarded when adjusting the timing rod there are something wrong.
Check the zero setting of the distributor.
Make sure with a screw driver that the top plug is at TDC and check it compered to the sticker. Is the sticker at TDC when the top piston is at TDC.

 

[Tapphouse]

I do get some retard when the gap closes. Not as much as I thot I would. Most I can get is one line right of 32* mark on sticker.
It’s at 1/4” gap now and on 8 teeth left of TDC which is roughly 30* if I did the math right.
TDC is set with screwdriver in top CYL and distributor pulley is lined up to the edge of flywheel.
The two things that have me confused is the plastic block gap (1/4”) and the fact I can’t go less than 30* without completely closing the gap.

 

[Tapphouse]

I read in another post you replied to, the guy had a 100hp Chrysler outboard with a possible sheared flywheel key. His wouldn’t start tho.
Do you think this is possible for mine?

 

[Nordin]

Well you can check the flywheel key to be sure, but as the sticker 0-mark lines up with timing plate mark at TDC I do not think it is shared.
I would suggest you to start it and check how it perform now.
30 dgr is in my opinion better than 33-34 dgr BTDC you had before.

 

[Nordin]

The gap at the timing rod block at my 1975 75Hp Chrysler is about 3/8 in (9,5 mm metric) at 30 dgr BTDC.

 

[Tapphouse]

Thank you for all your help. It will be a few days before I can test it. Really appreciate it, Talk soon.

 

[Tapphouse]

hi,
I pulled boat into driveway and put on the muffs. It would not start at all unless in neutral and throttle all the way forward.
Once in this position it will start first crank every time, but will not idle. It will stall out immediately.
I’m thinking RPM and air/fuel screws need to be dialled in better. But just to confirm and rule out anything I missed………what is the plug wire order from bottom of the distributor? Looking DOWN FROM THE TOP i have under adjustment block plug#1 plug#2 then plug#3 in clockwise rotation, is this correct?

 

[Nordin]

Yes, firing order correct.
You says it would not start unless in neutral and throttle all way forward.
If I do not missunderstand you it sounds right if the idle screw at timing tower is not adjusted right.
Maybe the throttle butterflies not open up at all when you throttle all way back. The idle screw maybe need to screw in (CW) to limit the throttle going back to far making the engine not to idle.
Since it is in neutral the interlock arm at the shift rod will limit the timing tower to fast idle and that is not so much move for the throttle cam at the throttle rod.

 

[Tapphouse]

Be a few days, but I will check and set the rpm’s on the water. I think it’s set too low now since the timing has been changed. Also the air/fuel screws need adjustment.
Anything else you can think of I may need to know? Talk soon.
Thanks!

 

[Nordin]

Set air/fuel mixture screws 1 1/4-1,5 turn out from seated.
Start the engine and warm it up.
Follow Frank A.s link and sync at top of this site.
Check and adjust the throttle pick up point adjustment as Frank A.
Dial in the carbs air/fuel mixture screw and set the idle RPM to about 1200
if you do it with muffs in drive way, 700-800 RPM in water and in gear.

 

[Tapphouse]

Hi, when setting air/fuel screws……. Do I move all 3 evenly at the same time? Or each one individually? I would think each individually to set each carb, no?

 

[Nordin]

Set all air/fuel screws at 1 1/4,note the setting.
Start the engine and warm it up.
Start to turn the first (top) slowly 1/8 of a turn CCW, let the engine adapt the new setting (about 10-15 sec). Continue with this until it start to act up from to rich mixture.
Note the setting and turn the screw back to the start setting (1 1/4).
Than do the same procedure by turning the screw 1/8 CW until it start to act up from to lean mixture. Note the setting.
Set the screw in the middle of this two settings.
Do the same procedure for the other two carbs.
I think you will end up with a setting for all carbs at nearly the same spot.
For myself I set them all at the same spot, about 1 1/4-1 1/2.
You will not see any different in performance at high speed, but you will see it at idle.
As past Frank A said, DO NOT SET THE MIXTURE SCREWS LESS THAN 1 TURN OUT FROM SEATED.
The idling will be better with screws set less than 1 turn out from seated, BUT it can end up with melted pistons as the low speed circuit in these carbs is working at high speed too.

 

[topgun3690]

For myself I set them all at the same spot, about 1 1/4-1 1/2.

I ended up doing the same......set them all at 1 1/4......runs great at that setting so didn't see any reason to mess with it further. Had it not run well at that setting, would have done like Frank A. suggested. And I know for sure they're not set below 1 turn out from seated......