1975 135 HP Timing Issue

I followed the posted 'substitute' WOT timing protocols and found that my current setting was around 18-19 (+ the 4 factor = 22-23). I wanted to retard the timing to 16 (equals 20 as per manual) but I ran out of adjustment possibilities (only about two turns left) and could not change the timing much. I got it down about two units to around 18, so now my timing is theoretically set at 22 degrees.

This is still two degrees advanced past what it should be. Would it even run when set 4 degrees past the recommended setting as it was?

Before I started messing with this motor it ran fine on the upper end, I just had major starting and idling issues. Another clue: When trying to do a link and sync following the manual last weekend, I was setting the idle rpm to get 5 degrees BTDC, so I could line up my cam. But all I would get was about 0 degrees at a normal idle rpm. Increasing the idle did not change this much (1-2 degrees BTDC). I don't have a tach so I don't know how high I went up on my rpms but it was quite high (and I did have the motor submerged).

I read that having the timing advanced is not good for the motor and mine seemed to be set about 4-5 degress past where it should be. Both high and low readings were off by about the same amount.

Re: 1975 135 HP Timing Issue

Something is wrong here. Did you check the timing pointer before starting?

Re: 1975 135 HP Timing Issue

HighTrim said:

Something is wrong here. Did you check the timing pointer before starting?

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I don't have the special tool to do so. Is there another way to confirm the pointer setting?

Re: 1975 135 HP Timing Issue

The special tool can be made, I have heard of a few methods on this forum, such as using an old spark plug with the guts torn out and a rod fastened in to the correct length. Also ask around and see if you can locally rent the tool.

If you do get one, the first thing you will need to do is pull the plugs out.

Then temporarily set the timing pointer half way in its adjustment slot. Install a piston stop tool in number 1 cylinder. Turn the flywheel clockwise until the piston contacts the end of the tool. Adjust the tool to 12* TDC and lock it.

Mark a line on the rim of the flywheel adjacent to the timing pointer. Now turn the flywheel CCW until the piston hits the stop tool. Mark a line on edge of flywheel opposite pointer.

Using a measuring tape, measure halfway between the two marks. Mark this "mid point." If the mid point line and the cast in TDC mark on the flywheel are the same, the timing pointer is correct. If not you will need to turn the flywheel to align the mid point mark with pointer (hold flywheel in this position.) Loosen pointer adjustment screw and move pointer to align with cast in TDC mark on flywheel. Tighten screw.

Now check the timing with a timing gun.

Re: 1975 135 HP Timing Issue

Forget about the 4 degree fudge factor - it's not accurate for the PP4 ignition system on your 135. Where it fires at cranking speed will be nearly identical to what you'll see at 5000rpm. If you want to be conservative, subtract 2-3 degrees total from the recommended WOT advance.

Re: 1975 135 HP Timing Issue

ledgefinder said:

Forget about the 4 degree fudge factor - it's not accurate for the PP4 ignition system on your 135. Where it fires at cranking speed will be nearly identical to what you'll see at 5000rpm. If you want to be conservative, subtract 2-3 degrees total from the recommended WOT advance.

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Thank you for that tidbit of info. I think I will set it back where it was for now until I can figure out what to do next on that issue. What do you know about the timing at idle? Any ideas on why the timing would not retard to -5 at a reasonable idle speed?

Re: 1975 135 HP Timing Issue

I set the WOT timing forward a few degrees, almost back to where it was. I bought a tach so I can know exactly what my rpm's are and so I can perform the linkage and timing setup properly (not just guessing at the rpm's). I performed all this while the motor was submerged just about up to the ventilation plate (all I could do with the tub I had).

After adjusting the linkage, adjusting the cam yoke a turn or two, and confirming the timing and idle, I developed a new problem. This occured as I was doing th aobve procedures and before I set my idle high enough. With the warm-up lever up partially to let the engine warm up (go figure ) I notice that every time I dropped the idle below about 700, the engine just shut off. Move the lever up a little bit and no difference, but there was a fine line that I would pass where the engine would run fine. Drop below that and it would just die. Be right on the 'line' and it would surge from zero to 700 rpm. Not sure what that meant. After i raised my idle to just under 700, the set screw it is now almost all the way in (only a few more turns to go), the engine runs fine and starts easily now but that is just in the tub of water in my driveway. I still don't know what it will do once I get it in the water. Right now winds are 30-40 with 50mph gusts so I don't think it's going to get wet today I still have to find out if the engine will run at full throttle or die as it was doing before this whole mess started.

But I am worried about the run / don't run threshold I was experiencing.
Is this a red flag??