1958 Mark 78 backfiring when starting

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

I think I remember being tossed a hot condenser in my younger days!

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

That must have been a shocking experience...... <br />This starting to sound like a who dunnit movie......... the period is sticking now, back to the dishwasher.

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

Hope we see a glowing report of your holiday on the lake.

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

Boing. How did the weekend go, Mark? If you don't mind me "axeing"?

 

[Clams Canino]

Re: 1958 Mark 78 backfiring when starting

Usually the condenser will return to normal after an overvoltage experience. Unless continually abused over and over and over.<br /><br />-W

 

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

Well my weekend was good, but my success with the old '78 was not so good. Changed the cap-no change. Changed the condensers-no change. Took top cowl off and checked timing-ok. Removed distributer- cleaned points again, re aligned #2 set of points and spent 2hrs with the dwell and sync plate and have the dwell and 60 degree phasing right on. Now it does not backfire, but starting and running on cylinders 1,4,5. Ok,the #1 set of points fires those cylinders, #2 set fires 6,2,3. So I think my phasing is still out, off again with the dist and check it all out. I was off about 2 degrees, so I made sure I was right on the marks this time. Put all back on and still no spark on 6,2,3. My wife said enough for the weekend and so I went to the neighbors and drank wine.

 

[heybaylor]

Re: 1958 Mark 78 backfiring when starting

Did you swap coils ???and or load resisters.

 

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

Hello heybaylor,<br />No, I did not-my mindset was it must be in the 90 degree dwell and 60 phasing because It came off the backfiring( had spark on all 6) after messing wirh the points but now spark on only #1 set. The merc manual says #2 must fire EXACTLY 60 degrees after #1 set of points. I do not think I can get it any closer using the dwell and sync plate. Just before I read your post I was writing down my next moves:<br />#1. Check/swap resistors<br />#2. Check/swap coils ( I did put new coils in 2 yrs ago)<br />#3. I'm out of moves

 

[heybaylor]

Re: 1958 Mark 78 backfiring when starting

exactly 60 degrees is what the pistons are from each other. But even if they were not (points) set exactly..the thing would still run and have spark to plugs..<br /><br />I would chase the "spark problem " ,<br /><br />And then try to get close to the 60 degrees apart on the points..thats the "fine tuning "<br /><br />dwell is set for max coil saturation...but if it is off a little it still would fire .<br /><br />with a battery/coil ignition ..you should be able to manually (dist in hand ) make and break the points of either set and get a coil spark from matching coil..<br />Hang in there ..Your # 3 aint a option

 

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

Hello heybaylor,<br />I thought it should work (fire) pretty darn good with my setup on the points as they are now. So, on to chase the spark.. manually check the points for spark, if no spark on #2, it has to be the resistor(#2) or from #2 coil to the cap right? Assuming I have power to the resistor from #2 coil which I did check. Thanks again.

 

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

Forgot to ask- If I do have a bad resistor, is there a off the shelf newer type that is compatible. I don't think this one is available anymore. thanks

 

[heybaylor]

Re: 1958 Mark 78 backfiring when starting

dunno about the resister ..57 chev otta work .<br />dont forget to check the actual wiring for breaks <br /><br />simple circuit ,power to the coil , 6 volts or so<br />from the resistor ..when you hit the start key that 6 is by-passed ,and full 12 (battery to the coil) ( jumpered off the solenoid )..from the coil to the points ..6 , or 12 volts to the points<br /><br />then the points break ,( with rotation of the dist cam) drop's the primary in the coil ..bang!!! secondary fires the plug wire..<br />if it is hooked to the dist cap ..out it goes to whatever plug terminal the rotor is lined up with ..Hang in there ..you will find the problem

 

[Clams Canino]

Re: 1958 Mark 78 backfiring when starting

Are both carbon brushes installed correctly in the cap??<br /><br />-W

 

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

Heybaylor,<br />I'm heading to the lake in a couple of hrs so I will be checking the whole ignition system as you have indicated...I wish I had a satellite connection up there. thanks<br />Clams,<br />I believe both carbon brushes are installed ok. the one thing I did notice-on the new cap, the center(#1 coil) high tension terminal does not have a good exposed brass contact for the spring to contact. But I do have spark on that terminal. The side terminal(#2 coil) brush I did not remove-so I will check. Thanks

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

Hey, this is getting better than Matinee serial. I can't wait for the next installment.

 

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

It gets better...drive 220 miles and find out I forgot the plastic distributor housing adaptor, so could not put cap on to try. Checked both resistors-ok,manually ck spark on points-ok, check fire at #2 coil secondary-ok,check fire on #2 coil wire arcing to ground-no fire. Pulled carbon brush-spring and contact in housing both dirty and corroded, cleaned both and installed..now we have fire but no way to test. Dogs!

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

There will be days like than, then it gets worse. Sounds as though you have found the seat of your trouble. What happened to the old cap? Rays' rule number one, never throw the old part away until you have the problem fixed.

 

[heybaylor]

Re: 1958 Mark 78 backfiring when starting

"fire in the hole " !!<br />Now we are getting somewhere ..<br /><br />why is my forehead flat ???<br /><br />ans: from slapping it everytime I forgot something. <br /><br />dont forget ...never ,never ,give up

 

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

Techno'<br />I did not pitch that $120.00 cap-that goes in the parts bin or ebay! It was the adaptor that the cap mounts to that I left at home...in my mindless state.<br />Heybaylor, I've got red marks all over my head..I just hope the bugger runs like never before when I go next weekend.<br />Thanks guys

 

[heybaylor]

Re: 1958 Mark 78 backfiring when starting

dont forget the "celebration wine "