Tuning issues

[Hellfighter334]

Hi guys.  GREAT SITE WITH TONS OF INFO by the way.

Just picked up an 84 American Skier with Commander 351.  Ingniter conversion.  The guy I bought it from put an Edelbrock 1405 on it (I know, not marine and I will be changing it soon).  I still have the 2 barrel.  Stock intake.  Plugs gaped at .40 and I set timing at 6 BTDC. (not sure where I should set timing with these mods?)  I've adjusted air/fuel mixture and she runs great on the trailer.  My problem is she won't run under load.  I've searched and searched and tried everything I've read on here.  I'm lost.  Boat sat for quite a while before I got her.  I've put about a half tank through her just trying to get her going.  And then topped her back off with high octane.  Any suggestions.  Gotta be a carb issue right?  Timing wrong?  Thanks for any help.

[Hellfighter334]

Alright how bout if we start with timing.  Should I time it at 6 btdc or bump it up to 8 or 10 with electronic conversion and plugs gapped at .40?

[RonT]

The manual calls for 6 deg. BTDC I usually ran 8 deg. (power-timing usually ended around 9 but I would stick with Next check to be sure the timing is actually advancing when reved, a simple timing lite will show movement, a deluxe one will show how much advance. The manual calls for Autolite ARF 32M plugs gapped at .032-.036 replacing the points for electronic ign, does not change this.
Next i would accelerate under load (in the water) while the motor box & spark arrester are off & looking down the carb to see if the accelerator pumps are squirting (this is where I would have my brother looking just in case she backfires)  this takes 2 people to do safely. 

[Midskier]

won;t run under load - good bet the the ignition is not advancing - pull the cap and ignitor plate - see if the flyweights are free or rusted in place 6-8 btdc is a good place to start for base timing on a Ford

Dan T

[backfoot100]

Good things to check as detailed by everyone else.
Another thing to do is set the idle mixture screws for highest vacuum (with gauge) or highest RPM. Then adjust idle RPM to 600. However, do this on the water warmed up, idling and in gear. That provides a "loaded" idle setting.
Then make sure the accelerator pump lever doesn't have any slop to the pump cam. You should have a shot of fuel from the pump nozzles in the carb throat with the slightest throttle movement or you'll get an off-idle stumble.



 

[Hellfighter334]

Thanks for all the info guys.  Took it out on the river last weekend camping.  Ran well off and on.  What it would do is run up river (always right now..lol)  then I'd stop and float.  Then wouldn't start until it was completely cooled down.  I pulled the distributor cap and the weights seemed to move freely but that doesn't necessarily mean they aren't sticking.  But guess what I found on Ebay.  New springs.  Have no idea if they are the right ones cause I couldn't find a part number for the old ones but I'm gonna try them out tomorrow. 

[Hellfighter334]

Old springs

[RonT]

Your symptoms do not lead toward dist. adv. springs. If the engine is running fine at all rpm ranges, starts & stops normal, accelerates normal but only has a re-start problem after a lengthy "heat-soak" I would look at the fuel system for vaper lock, extreme flooding (look down the carb throats after shutting down & see if gas continues to dribble into the engine. The only ignition area that comes to mind from heat-soaking is a overheating coil.

[Midskier]

sob

2nd time typing this one so it will be more brief

questions call me

3-23 issue way different than 3-4 issue

you can check timing with it in the water or on the trailer
since you have mechanical advance it will advance with rpm increase
so start it run to temp get you light set up
note base timing , rev it if you should see it advance - back to idle timing should return to 6-8
if does it's doing its job

who installed the ignitor?
is the red wire from ignitor going to + terminal on coil?
do you have a purple wire going to the electric choke on the carb?
if so remove red from coil all other wires remain, attach red to purple @ carb
purple is +12v when key switch is in RUN or START position
ignitor requires min +8v to function
which you may have when cold or while under way
however you may be under +8v @ the coil when hot
commanders have a ballast resistor WIRE - not an actual porcelain resistor
common on PCM or Indmar. if original this ballast resistor wire is wrapped up in the wire harness
near the starboard exhaust manifold - when it gets hotter it increases in resistance decreasing voltage
to the + side of the coil - if your ignitor is terminated there it may exhibit the symptom you described so move it to a switched +12v source

so what to do with the ballast resistor wire ? -
1. leave it alone
2. shorten it
3. remove it and replace standard stranded wire
4. remove it and replace with porcelain ballast resistor

the ballast resistor is in the circuit to save the points - which you don't have anymore


good luck

Dan T

more brief lol

could be one more issue - but that's a guarded secret

[Hellfighter334]

Thanks a lot guys.  Didn't think about vapor lock.  I'll do some research on that before I ask any dumb a$$ questions.

Timing is between 6-8 and advances normally on acceleration and returns to normal.  My rpm's seem high when I'm running though.  At about 30 mph I'm running like 4500 rpm's.  Is that normal for these boats?  I've got a 12x13 prop too.
 
My + ignitor wire does go to the + coil.  I didn't know about the resistor wire though.  Good to know.  There are 3 wires on my + coil and 2 on my - coil.  My choke is a manual so that isn't an option.  I'll try to find another source though. 

FYI it ran pretty good the last couple days.  Started right up every time.  Although it doesn't seem very efficient on gas. 

Thanks again for all the responses.   

[Midskier]

it's not vapor lock - if your fuel in the carb bowls mysteriously vaporizes most likely you have a leak and the fuel is running into the intake

30 mph @ 4500 rpm really ?  1 - use gps for speedo 2 - use digital tach from your timing light
if its propped any where close to stock either 13 x13 or 13x 12 3 blade nibral sans cast prop
you'll be turning about 1 mph per 100 rpm / 30 mph = 3000 rpm give or take a couple hundred rpm
if it is in fact only pull 30 mph @ 4500 rpm with a stock or near stock prop you have major trans slippage

good luck

Dan T

[backfoot100]

Timing is between 6-8 and advances normally on acceleration and returns to normal.  My rpm's seem high when I'm running though.  At about 30 mph I'm running like 4500 rpm's.  Is that normal for these boats?  I've got a 12x13 prop too.
 
Although it doesn't seem very efficient on gas. 

Thanks again for all the responses.

A little late to this party, but if you didn't flip flop the prop numbers that is not even close to the right prop. A 12" prop would explain why you're revving so high and not going anywhere. Get a 13x12 or 13x13 like Ron said. I got one of each I could sell you if you're interested.

If you're really worried about using gas then maybe you shouldn't even be owning a boat...LOL. They burn a lot of fuel but if you're turning that many RPM and not getting the speed, that's also sucking a lot more gas than it should be.

[Hellfighter334]

Funny about the gas thing .  But my 454 jet sucks less gas it seems.  Anyway....

New speedo installed and now I have the opposite problem.  Revs to 4000 no problem in neutral but in gear doing 40 it reads around 2000.  Im not sure its hooked up right though.  Ron there was a grey wire on the old tach that I can't figure out where it goes.  Every time I attach it to anything on the tach it kills the motor.  My dumb ass didn't pay attention to where I removed it from.  It goes to the port side harness which goes to the rear of the boat.  All gauges and lights work.  Any ideas?

[backfoot100]

Funny about the gas thing .  But my 454 jet sucks less gas it seems.  Anyway....

New speedo installed and now I have the opposite problem.  Revs to 4000 no problem in neutral but in gear doing 40 it reads around 2000.  Im not sure its hooked up right though.  Ron there was a grey wire on the old tach that I can't figure out where it goes.  Every time I attach it to anything on the tach it kills the motor.  My dumb ass didn't pay attention to where I removed it from.  It goes to the port side harness which goes to the rear of the boat.  All gauges and lights work.  Any ideas?

So did you replace the tach or the speedo? I'm confused. You replaced the speedo you say but you're talking about the tach.
Gray wire is a signal lead for the tach. It should be coming from the coil. You should also make sure the tach is set for 8 cylinder. There should be a switch or a jumper on the back of it to designate 8 cyl.

[Mike Harry]

FIRST thing you should do is download GPS on your (or your kids) smartphone and get a GPS speed on those speedo's ................ unless you have upgraded them to gps speedos that is