255 Mercury Timing

50 merc

50 merc

Member
Hi guys I am a newbie on this site and have just purchased a 50 Merc. I was wondering if anyone could help with the timing proceedure?
 
I would guess just timing.You may want to use a timing light.I don,t use a light ,turn it till it runs the best and starts good.
 
I used a timing light last night and adjusted the timing to the 0 degree mark on the pulley and then added about two degreese. I took the merc out for a spin and it just laid down and misfired and no acceleration after about 1500rpm. when I first checked the timing it was advanced almost 1/4 of the pulley. I just want to know if there is some kind of quircky proceedure I don't know about before I jump into the distributor. The car was running pretty good before I touched it.

Andy
 
The mark on the pulley is not 0 degrees TDC. Ford preset the timing mark for us at 2 or 4 degrees (I forget which) BTDC. I usually set at about 1/4 inch before the mark.
 
Are wanting to test the timing with a light are set the timing, if setting it you need to go to number one plug on the passengers side, set the pointer at the little dot make sure your valves are down you can look inside number one if you see any one of the valves up you not on tdc you need to turn 180, once this is set go to your rotor button find the number one wire on you cap sometimes its mark number one, then pull or insert the shaft down into the hole feeling far the gears it will fall in, The way i check is make sure the holding ledge on the distributor is setting all the down and the rotor button is Aline with number one on the cap, once this is all done then go over the firing order in a clockwise rotation, then fire her up and set the timing like Andy said i use a timing light with 4 degrees setting on the light so i line up the marks no guessing thanks AL
 
Your point dwell could be way off (low dwell will result in advanced timing). Check or set the dwell to 27 degrees, then readjust the timing to the bump on the pulley, which is 2 degrees BTDC, not 0. An additional 2 degrees can usually be added if overall performance is satifactory with the gas you are using.

Checking the distributor vacuum diaphragm operation is important as this is a loadomatic, or vacuum-only advance system, with no centrifical or mechanical advance.

If you are a serious about your Mercury, purchasing a '49-'51 Lincoln/Mercury shop manual would be a wise move. :)
 
Make sure and disconnect the vacuum advance and plug the vacuum line first. Then check and set the timing. Right at the dot or just a scootch in front of it (left) of it. Then hook the advance back up and set your idle speed.
Just a bit of additional info. If you will get in the distributor and tighten the advance springs (you can turn the post on one end of each spring to the tightest the spring will get) This will slow the advance down a bit and helps the motor run better. It works on mine and has for years.
Check your carb bowl for crud if you are still running bad. I took the top off the carb and poured out some white, milky crud mixed with the gas. Cleaned the jets and blew everything out. This was after a complete carb clean and kit just a couple of months ago. It made a world of difference in how the motor runs.
 
I have owned this car for three weeks now and I have always wanted a 49 or 50 Merc with the original flat head, So now I have one and have to learn about the flathead. I have several other cars including a 54 Monarch Lucerne Canadian car a 62 Kustom canadian Pontiac 2 dr hard top and some others. I have orderd a carb kit from Macs hope to be here in a couple of days. I know there is carb isues related to the accelerator pump. When I adjusted the timing I did have the vacum line removed and I plugged it before I started. I did not notice any vacum or very little at idle. When I hooked it back up and accelerated the throttle the timing only advanced a couple of degreese. That was around 2200rpm and it started to miss fire and lay down. I noticed the points have been changed recently as has the cap and rotor. I will check the dwell tonight I guess I should have done that first. Just a side note the carb is a 885 Holley side draft 4 bolt to the intake.

Thanks Andy
 
dont take it for granted the mark on the pully and the pointer on the engine are absolutly correct, either one can be off by a 1/4", use the marks to get the engine started, then take the car out for a run, either on the hiway or on a long hard up hiil pull, advance the dist till it pings then back it off till it doesnt ping, seat of the pants timing but it seems the best way, once you find the sweet spot check where it is with a timing lite,then mark it on your crank pully so you will know where to to time it the next time, use a good grade of fuel to reduce pinging
 
Thanks for that. I am running Shell premium fuel. In Canada it is the only fuel to claim there is no ethanol in it. At least for now anyway. I am realy starting to think there is something else going on, I am going to check the dwell before I re check it.

Thanks I realy appreciate all of the feed back from you folks

Andy
 
only advanced a couple of degrees? disconnect the vacuum line remove the dist cap move the dist plate to full advance hold put your finger over the the diaphragm vacuum connection and release the plate it should move back a little and hold till you take you finger off then return to full retard position, if it dont hold you need a new diaphragm. any small leak in the line from the carb to the dist will also cause a problem. lol Scotty
 
Try putting the timing back to where it was before you started. If it runs OK/better, the timing marks and the position of the plug wires are not in registry. Follow the procedure presented earlier in this thread to determine if the wires are in the right place relative to the timing marks. Good luck.
 
Thanks again guys I will check the position of the rotor when I am checking the dwell. Hey after all it is only 60years old and who knows how many hands have touched it. Funny thing is that it starts first bump of the starter button an sits there and idles nice with the timing marks in both positions go figure I will get to the bottom of it.

Cheers,
Andy
 
Thanks for all the help guys. The distributor was out 180but the previous owner just switched wires on the cap. The gap was set at over .020 now at .014, the vacuum advance did have a hole in the diaphragm. I had a spare so I installed it and tested it. I set the timing on the mark and added about 2 degrees of advance. The engine now sounds better and does not lay down and run limp. Although there is still a bit of a bog and there is not to much pep it does cruise not to bad at 60mph. I am sure the rest is the carb and I am waiting on parts.

Thanks to all :)

Andy
 
That .020" point gap resulted in a low dwell, or advanced timing. You really need to check and be sure of the point dwell in degrees vs just gapping the points to know the timing will be correct. Max stock timing should be 20-22 degrees around 3500 rpm. Be sure the ignition/timing is on the money before you do additional trouble-shooting, as the carburetor gets wrongly blamed for many engine performance issues.
Regular grade 87-88 gas is all you should need to run a stock flathead.
 
Yes, your Snap-on meter should work on 6 V + ground, as points/condensers are not voltage sensitive, just requires the leads to be switched. Connect the red lead to vehicle/battery ground, and black lead to the dist. side of the coil, and set the points to 27 degrees at idle. Both my tach/dwells are analog, and might be easier to use than digital equipment.
 
:cool: like i said in my other post, dont trust the timing marks at the pointer or on the crank pully, they can be off by as much as 20 degrees, if it runs good where its at now but still is not right, advance the timing a few more degrees, take it out on a hard pull, if it runs better and doesnt ping advance it another few degrees, do that till it pings and then back it off some, if it doesnt try to kick back when you start it and doesnt run hot your good,if it kicks back slow timing down another few degrees, make sure you mark the crank pully so you know where to set the timing next time
 
Ok so I checked the dwell and it is at 27 . I set the timing to 4 degrese advance, set the idle and the air fuel mixture. Took the car out and ran it at 65mph and it does seem to labour just a bit. I think now that I know where my base is I will try what you have suggested tonight on the way to the local cruise night. I feel it could use a touch more advance. I am deaf in one ear and the car has dual exhaust so listening for a ping might be difficult...lol

By the way this is a terific site and I am so happy I stumbled upon it

Thanks Guys
 
Re: 255 Mercury Timing
":cool: like i said in my other post, dont trust the timing marks at the pointer or on the crank pully, they can be off by as much as 20 degrees"


Ford1,
The only way the timing mark could be off on a late flathead is if the crank is twisted, or the pointer is obviously bent, because the front crank pulleys are just that-pulleys, made of either cast iron or welded sheet metal, that have no isolation, like most dampeners, and are keyed to the crank. But using an adjustable timing light would verify any timing mark discrepencies, and is something everyone that is serious about tuning should have in there tool box. :)
 
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