will cap/mag removal affect timing?

[mred 2436]

hi folks! i just came into possession of a 1956 mark 30 turbo four. i have no spark at any of the four wires, so i'm getting ready to get into the mag, and see if it may be a points or cap problem. what i need to know is when i pull these off, is anything going to fall out/jump out, and will i effect the timing any in there? this is the first merc i have ever touched, so i am absolutely clueless as to what's in there! the motor is extremely clean, and compression tests were all an even 107 psi with no pressure bleed down after 15 minutes of waiting on each cylinder.

 

[Chinewalker]

Re: will cap/mag removal affect timing?

Hi Mred,<br /> As long as you're not messing around up top with the timing belt, you shouldn't mess up the timing of the magneto. It has a driveshaft with a flat on one side so it will only go back on one way. <br /> When removing the magneto, you may want to scribe some marks on the various stamped steel pieces that actuate the carburetors from the magneto tower. <br /> To remove the magneto, remove those steel pieces, then remove the four bolts (should be 7/16" head bolts), then start with the wiggling, twisting, and occasional cursing to get the magneto out. You may have to try different positions of the shift linkage to get the room you need. Once free of the tower, remove the ground strap from one of the lower cover screws. Also, remove the kill switch wire from the post on the side of the mag, and remove the spark plug wire anchors from the side of the exhaust cover.<br /> Once out of the motor and on your bench, remove the rotor cap (plug wires coming out of it, held on by two screws). Be careful prying, as it is a bakelite type plastic and is brittle. Next, remove the rotor - again taking care with any prying. Next, remove the magneto cover (four screws). Clean and gap the points (.008"). If you suspect the condenser, a small engine shop should be able to test it for you.<br /> To bench test the mag, ground the mag housing against a bench vice, then hold the copper tang from the vice about 1/2". Spin the splined rotor clockwise (looking down). You should get a good blue spark to jump that gap. Second test: reassemble the mag, still on the bench. Place the plugs in the vice, ground the mag body against the vice and spin again. All four plugs should fire, one at a time.<br /> You really should get that '65 and prior manual from Grubb's (www.oldmercs.com) which has a really good section on setting up the old 4-cylinder mags.<br /> Good luck!<br />- Scott

 

[mred 2436]

Re: will cap/mag removal affect timing?

hey! great!! big THANX scott!! if everything checks out ok on this motor, i will get that manual. parts for this one are a bit expensive, so i wanna try and at least get a little sign of life out of it, before i invest any real money. i already got burn't once for about 300 bucks on an old motor before, cause i did not do my homework!

 

[rodbolt]

Re: will cap/mag removal affect timing?

hello<br /> wow <br /> Chinewalker<br /> I wish I had known that test method some years back.<br /> I just gave the wires to my ex and said hold these and the spun the mag.<br /> maybe thats why she is an ex . by the way she jumped I figgued good blue spark about 5KV or so <br /> sounds like yall have this one sewed up. just be very careful with some of the bakelite stuff. some of it is NLA.<br /> good luck and keep posting

 

[Chinewalker]

Re: will cap/mag removal affect timing?

Hi Rodbolt,<br /> I had a similar test method - except I borrowed one of my little brothers. At least they were little back then... Funny, I only got about one good test out of each of them...<br />- Scott

 

[mred 2436]

Re: will cap/mag removal affect timing?

ok scott, i got the mag out without any hassles, however, going in looks like will test my knowledge of speaking in tongues! pulled the cap. a bit crusty on the tips, but otherwise clean. same for the rotor. points appear to be good and the gap was ok. however, the bench test failed to produce a spark, so i got brave, and tried it on my hand! nothing! not even a tingle! <br />is there anything else i can do before i check the balance in my savings account?

 

[Chinewalker]

Re: will cap/mag removal affect timing?

Hi Mred,<br /> When you say the points are clean, how did you determine that? Try running some 400 or 600 grit wet/dry sandpaper through them - cut a strip about 1/2" wide and double it over on itself. After that, run a piece of index card dipped in carb cleaner or lacquer thinner through the points. Clean points are key. If everything else looks good, then I would suspect the condenser (a good small engine shop can test it for you). Coils generally go bad when they have a crack in them that allows them to arc out. I've rarely seen a bad coil that didn't visibly show in some way.<br /> Also, you may want to remove the kill wire from the points just to eliminate that as a possible cause. It's the wire that runs from the small threaded post on the side of the housing to the points.<br /> For reassembly, you'll notice a small notch on one side of the small tube that comes down out of the base of the mag tower - that aligns with the flat side in the tower splines.<br /> Sounds like you're making progress! If you're a motor head who appreciates the sound of a high revving Japanese road bike, or a well tuned V8, you'll LOVE the sound of the old Merc 4-bangers. On a light hull your motor will absolutely sing... I have the racing version and have it propped at 7000 revs - absolute music!<br />- Scott

 

[mred 2436]

Re: will cap/mag removal affect timing?

scott i really appreciate your time on this! yeah i ran a piece of emery (800 grit) thru, and a match book cover, which came out clean after two passes. no signs of cracks, or arcing. i am curious as to the two hoses that were on this mag. one comes out of the distributor housing and goes to the front of the engine casing( where the operation tag is attached, left side) then another goes from the right side of the engine casing, to the bottom right side of the mag housing ( looking from the top, facing towards the front.) is this some kinda ventilation? or vaccuum advance? btw, i have a 350 small block in my chevy 2500, with a vortek intake and duals that crackle! me? a motor head?? naaaah!!!!

 

[mred 2436]

Re: will cap/mag removal affect timing?

chinewalker !! i had a revelation today!! i was on my lunch break at work...and was daydreamin' about a time when me and my dad was out fishin'. the motor wouldn't start, and i remembered him pulling off the fly wheel, and scraping the magnet and coil surfaces to get it to fire. so when i got home, i decided to delve deeper into the mag, and pulled out the coil. low and behold!! a fine layer of rust and dirt on the magnet surfaces and the coil! did a gentle wipe down with some emery cloth, inserted the coil, gave her a spin, and i got bit!! reinstalled the points and condenser and...snap! snap! snap! nice hot spark!! now...if i can get the cap and rotor to clean up decent, i'll try to fire it up. and aye aye cap'n! i'll get that manual now!!

 

[Chinewalker]

Re: will cap/mag removal affect timing?

Hi Mred,<br /> Sounds like you're making progress! Make sure those cap screws that hold the coil in place have the wire reinserted, as the coil screws can vibrate loose over time.<br /> Fuel system is next up. See if you can get it to run, then if you get that far, replace the waterpump impeller.<br />- Scott