Timing

[marvin siebert]

will someone please show me how to adjust full spark advance stop on my 1977 mercury 175hp in conjunction with timing light on #1 cylinder? siebertms@aol.com thanx

[STV_Keith]

First, you have to make sure that that timing marks are lined up. We would take a dial indicator and put it in hole #1, then rotate the FW until we find TDC. Make sure the 0 mark lines up.
Once that is set, pull the plug wires off, but ground the #1 wire so it will trigger the light. Then push the advance arm to the stop and crank. The light should trigger at the appropriate degrees. If not, adjust the stop.
For the 2.5/2.4 Hi Perf motors, it's 26 or 27* if I remember correctly. They also idle at 0* +/- 2 degrees.

[Tom Brown]

8-10 degrees ATDC for primary pickup
15 degrees BTDC for max timing
I will second Keith's advice with regard to indexing TDC as my 1750 was out a bit and I've heard that it's not uncommon. Getting the timing right is really worthwhile.
You can use a black sharpie marker to mark TDC. It shows up fairly well on the bright red stock steel flywheel. I couldn't make the soapstone show up at all on the stock merc flyweel, hence the Sharpie. I marked TDC and then used an advance timing light.
-- Tom

[DUCKY]

Book says 8-10 degrees ATDC at idle, and only 15 degrees BTDC at WOT for that particular motor.
STV K's procedures are correct, but If you don't have the right dial indicator to check TDC, you can weld a 1" long 1/4" bolt to the end of a spark plug. Insert it in the number one hole and rotate the engine (softly, by hand only!) until the piston makes contact. Mark this location on your flywheel cover. Then rotate the engine the other direction until it stops, and mark that location on the cover (using the "0" or TDC line on your flywheel as the reference) Use a tape measure, and split the difference between the two marks. That WILL be TDC.
And when you go to check the timing, pull out all of the spark plugs, (except #1 of course) and ground their leads to the head bolts. DO NOT CRANK THE MOTOR WITH THE PLUG WIRES HANGING LOOSE!!!!!
Have fun!

[marvin siebert]

Thanks a bunch Ducky This verifys it Marvin