Test Tank/Ignition Testing?

quinnf

Seaman Apprentice
Joined
Aug 27, 2003
Messages
35
So just how big is this test tank the manual keeps yapping about? <br /><br />I'd really like to be able to run my 120 V4 up to 5500 rpm with a test wheel to check ignition timing, but my plastic trash can would be shredded in an instant :confused: . Is there a way to do so without hanging over the transom at 40 knots?
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: Test Tank/Ignition Testing?

Mako171.... You can blow up to a couple thousand on the type test tank you're speaking of.<br /><br />However, you do not need to run the engine as the manual states. The timing can be checked and set as follows.<br /><br />(Timing At Cranking Speed 4°)<br />The full spark advance can be adjusted without have the engine running at near full throttle as follows. <br /><br />To set the timing on that engine, have the s/plugs out, and have the throttle at full, set that timer base under the flywheel tight against the rubber stop on the end of the full spark timer advance stop screw (wire it against that stop if necessary). <br /><br />Rig a spark tester and have the spark gap set to 7/16". Hook up the timing light to the #1 plug wire. Crank the engine over and set the spark advance to 4° less than what the engine calls for. <br /><br />I don't know the full spark advance setting your engine calls for, but to pick a figure, say your engine calls for 28°, set the timing at 24°. The reasoning for the 4° difference is that when the engine is actually running, due to the nature of the solid state ignition componets, the engine gains the extra 4°. <br /><br />If you set the engine to its true setting at cranking speed, when running it will advance beyond its limit by 4° which will set up pre-ignition causing guaranteed piston damage! You don't want that to take place. <br /><br />No need to be concerned about the idle timing as that will take care of itself. The main concern is the full advance setting. <br /><br />Be sure to use your own engines spark advance settings, not the one I picked out of the air here in my notes. Good luck.......
 

quinnf

Seaman Apprentice
Joined
Aug 27, 2003
Messages
35
Re: Test Tank/Ignition Testing?

Joe, <br /><br />I'll give it a try this weekend. Manual states 18 BTDC. So I gather I should time it for 14. Beats the heck out of hanging over the transom with a timing light at 40 knots!<br /><br />Thanks for the info.
 

clanton

Rear Admiral
Joined
Jul 9, 2001
Messages
4,876
Re: Test Tank/Ignition Testing?

I not real sure about this , you need factory manual. The info I have says this engine has Quick Start, and if you use Joe method the total advance timing will be off at least 4/8 degrees. The idle is seperate adjustment and is set at 8 degrees ATDC. Final check of timing should be at wide open throttle and 5000 rpms. A cold engine at cranking rpm is in Quick Start mode, for 5 seconds and until engine is up to 96 degrees F,or over 1100 rpms which advances the timing about 6/8 degrees. After the 5 seconds and 96 degrees F the timing will shift to normal (run) timing settings.
 

alcan

Commander
Joined
Dec 14, 2001
Messages
2,505
Re: Test Tank/Ignition Testing?

Hi Mako<br />To solve the problem of the high speed test tank for larger engines. I find a boat ramp in the off hours works great. Some times this means I am out there at 11:00 pm. Of course you will need to make your choice of ramps wisely.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: Test Tank/Ignition Testing?

Clanton is correct. It had slipped my mind about the "Quick Start" feature. That feature would need to be disabled in order to use the 4° timing procedure that I mentioned.
 
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