1958 Mark 78 backfiring when starting

[technostingray]

Re: 1958 Mark 78 backfiring when starting

Well, if I might hijack this thread, we had our dockbuster out for the shakedown cruise and it was a great success. Used all the fuel we could afford for the day and stayed on plane for over an hour. had a peeing good time. What can you tell me about boat speedometers. All we have left is the tube that runs to the back of the boat...... <br />Mark, don't slap out what little brains you have left.

 

[heybaylor]

Re: 1958 Mark 78 backfiring when starting

the speedo works as a "bourdon tube" type instrument<br />I/E a coiled tube usually of brass.<br />as pressure of any kind is applied it tries to "straighten"<br />the bottom of the tube is hooked to a chain<br />and pulls on usually a chain <br />that is hooked to a gear ..than the gear rotates...<br />that gear is moving the "pointer" of the instrument that is is attached to.<br />"hence" the pressure applied to the "bourden tube " reflects ......what ever it is calibrated to ..speed , and or pressure...<br />In a short :::::<br />the water pressure that the "pitot tube see's "<br /> by being placed in water usually on the transom,just barely in the water at speed .<br />that pressure is then transfered to the speedometer by the usually small plastic hose. <br />the pitot tube is not the hose ..<br />It is the device that is in the water , airstream if you are in a airplane.<br />Now just how was that watch made?? or did you just ask for the time ???<br />lol

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

Congratulation on a concise if not clear explanation of the mechanics of the auqua speedometer. With my new found rank and a dollar (maybe I had better make that two dollars) I can get a cup of coffee in most any cafe.

 

[heybaylor]

Re: 1958 Mark 78 backfiring when starting

techno , read the edited version I was deep into the JD last night <br />I would buy you a cup of coffee , ,dont even need the 2 bucks..

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

No, No Hey, It is Mark that has the Mark, I have the 700E. Mine runs, his won't. His speedometer would work if he could get the engine not to backfire. I can go fast, just don't know how fast I am going. Thanks for the offer of the coffee. I would much prefer a Coffee Royale. I spied a bottle of Gentleman Jack at the local Discount Druggist for less than 20 bucks so I brought it home to compate it to Makers Mark. Conclusion: It can only get so good, after that it only costs more money. <br />New pick up or GPS??????????? Decisions, Decisions Decisions, where will I throw my money away next?

 

[heybaylor]

Re: 1958 Mark 78 backfiring when starting

hmm, pick-up is around 20-25 $$ <br />Gps ..even the handheld is better than $100.00<br />down side ..gps is accurate....water speedo is not ..<br />but the water usually errs on the hi-side ..<br />now do you want to spend less, and impress your friends? , or be accurate,and dis-appointed with no $$ left for the "finer" things in life

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

Sounds like a no-brainer to me. Of course if you can afford 18 year old liquor maybe that is not an issue. Back to your previously scheduled program. Will Mark solve the backfiring problem? Is 18 year old scotch smoother than (more intoxicating) than, 8 year old bourbon? Where can glennfick d (or whatever that was) be found in America (Estados Unidos de Republico Mexico)??? STAY TUNED.

 

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

Well guys, I'll be heading to the lake for a week, so probably no post on progress. Not unless the resort lets me use their computer...Maybe some JD black might work.

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

You are probably still at the lake, but didn't want to see this buried to deep. Let us know how you came out. You might even try a Thread Merger..... Only administors may perfom this function. Is this like the five second rule?

 

[gwmark78]

Re: 1958 Mark 78 backfiring when starting

Back from the lake- great weather and just nice to take a week off.<br />I did finally get the mark 78 to run on all 6 cyl. But I'm not confident I found the exact problem. To make it short:<br />Put on the adaptor plate I forgot,cap,rotor,side#2 coil lead-no fire on #2 set of points. So what's going on? I get fire holding it to ground,but install it into the cap and no fire. Check continuity between brush and secondary lead in and is sporadic when pushing in and out on brush. Clean again inside of brush contact area and spring, put on rotor, clamp a piece of alum foil 1/2" from rotor contact and have my son hold the brush and turn over, ( we disconnected #1 coil) he gets a good jolt and we have fire to the foil. Put on the old cap, screw in 1 extra spare lead into #3 and hold to ground- have fire. Do the same with #2 and 6- have fire. Install the new cap which is still all wired up and now we have fire on all 6. It sure would appear that the problem is in the spring/brush/housing. I'm going to put in a new spring and brush if I can find it, I know the housing is not avaliable. We ran about 18 gal of fuel thru it and other than a carb tweaking, it ran well! Thanks for all the help and interest everbody!

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

Good news Mark, Did I hear you to say that a new dist cap was one-hundred twenty dollars? Parts sources that is the name of the game. Not to mention those oportunist setting on things they can't even use. Are you into water skiing, if so I have a few questions over on the outboard not engine topic. As you can see I am now techtoosweeto. Long story. Don't go there <br />Maybe you should post over on the good news board..

 

[technostingray]

Re: 1958 Mark 78 backfiring when starting

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