Qualcast 43s just dies when hot!

[mowerman]

Hi folks,

Finally got the parts together for this mower. Even a new electronic ignition unit, fired up 2nd time. Only problem is, when the mower gets hot it suddenly cuts out. There is no spark from the existing plug or a new one.

When it has 5 mins to cool down, it is possible to start it again. The earth cable from the ignition unit is well shielded and the HT lead looks fine and has adequate insulation around it from when it leaves the ignition unit and passes by the metal plate on the engine block.

Any clues please? Thanks in advance.

Simon

[Clive.]

Hello Simon,
There was once an issue with early engines with ref routing of the earth lead..but I think that lead to a visible chaffe and I think was back when the first electronic unit appeared on A98 engine on the DL models pre S.
The suppressor caps, HT lead to plug top, could last for years but also they could perhaps fail internally.?? although I don't remember many doing so relative to the regular dropping to bits of the older open clip type.! Then there can also be a situation where the suppressor has been removed from the HT lead many times such that the wire has degraded leaving suppressor only screwed into insulation with the spark having to jump at that point. Or if the first screwing in of the suppressor to lead missed the centre...similar.?
I think though that the lead would have been integral with the new electronic unit...and thus be new.?

Two types of ignition were used on engines on Punch 43S...Dellorto carb A114 engines had early type whilst later Tillotson? carb types had a new type.

There was a period during the time of the first ignition type, Dellorto carb, that the plug gap was changed to a massive 40 thou inch to try to improve running....but then I was told a few years ago on another forum that this later changed back to the original 25 thou and a new recommended plug from the NGK range was advised....I was long out the mower world by then though....

The spark definitely goes.??..and its not a sticking valve, loose seat, air lock in fuel feed.??

All of the above is ref A114 engine on Punch 43S on the chassis derived from the old Super Colt/Super Punch

Clive.

[mowerman]

Hi Clive,

Thanks again for your input here. I believe the HT lead is screwed in at both ends (plug and ECU) so I can try a new lead and report back. The ECU is from the Dellorto carb 35s model. On a slightly different note, I want to adjust the clutch for the blades to stop turning at tick over. The engine settles nicely but the blades still rotate albeit slowly. I have seen 2 types of clutch, one can be adjusted with screws and the other fixed tension with only springs. This being the non adjuster http://www.ebaying.toucansurf.com/Mowers/Clutch.JPG & this being the adjustable http://www.ebaying.toucansurf.com/Mowers/Clutch1.JPG. Any clues as to which one is on a orange & green Suffolk Punch 4* engine pos 1963 please?

Thanks in advance.

[Clive.]

Hello,
This one http://www.ebaying.toucansurf.com/Mowers/Clutch.JPG would be similar to the 43S.
The 43S would have an alloy clutch backplate and a pressed steel drum....the one in the photo is from a 1969 to mid to late 1970s Super Colt or Super Punch. It has a machined cast "iron" backplate and a machined drum. The chassis of your 43S was a widened version of these mowers.
The cast alloy clutch backplate and pressed steel drum on 43S was a much poorer construction than the machined type shown...and the alloy backplate used on 30/35/43DL and S tended to work loose on the engine shaft.

The other adjustable spring tension clutch shown is from an earlier mower model using a totally different chassis design. I can't make out the size of it.....
The Colt 12" and Punch 14" used a small adjustable unit and the Punch 17" used a larger unit.

Lots of minor faults can cause the clutch to continue to drive. Misalignment of engine to drum drive shaft. Over tightening of cutting cylinder without correct chain adjustment leading to a dead tight chain and drum shaft pulled out line. Under tightening of cylinder leading to a too free spinning "windmilling" cylinder. Dry bushes, etc.
The shoes can become stuck on the pivot pins and thus not return correctly and or the pins can wear and cast shoes break at the pivot. Springs can become damaged. Linings can become loose or come off. Pins can become loose in backplate. etc

**Cautionary note; Only run the mower fully assembled and thus shoes fully covered by the drum.
(If run with shoes exposed the shoes would fly out terminally damaging return springs, the shoes could break away causing serious injury or worse.......)
Also old clutch linings, like brake linings, may contain asbestos.

Regards,
Clive.

[mowerman]

Thanks again Clive,

Good point on the Asbestos.
My 1963 12" Suffolk is indeed way better made than the 35s, it stands out a mile. Those machines were made when quality came before price and Britain was "Great".

Thanks again, greatly appreciated.

simon.

[Clive.]

Thanks again Clive,

Good point on the Asbestos.
My 1963 12" Suffolk is indeed way better made than the 35s, it stands out a mile. Those machines were made when quality came before price and Britain was "Great".

Thanks again, greatly appreciated.

simon.

Asbestos is one thing...but I do always worry about the clutch fly out situation....hence the main cautionary note.

The older mowers were exported all over the world. The older version of this forum was once nearly overtaken by mower enquiries a few years ago Name a country and there was an enquiry from there..as local support for the type was disappearing.
Some of these mowers had specific variations to suit regulations in a specific country and slightly different names in some countries.
Perhaps the Punch name could have been misread.? Punch to drink, Punch on the nose, Hammer and Punch, Suffolk Punch a draught Horse..
So I think Super Colt became Super 12" and Super Punch became Super 14". I think in Australia the Suffolk Punch 17" may have been the Qualcast Admiral.??

On the cowling of the cast iron engines of the Super Colt/Punch there are two holes on the side near the carb'. This one puzzled me until I saw I think a German? export mower ..the holes were used to locate a proper stop switch rather than earth strip to plug top.
I think a European export model of 1970s Super Colt/Punch used a toothed belt rather than a chain drive. I think this idea came in on UK models later only at the very end of that chassis type on the last S.

So you have plenty of variations to collect..

Clive.

[mowerman]

Hi Clive,

is there any info on testing the ECU on the 43s? please? Still have this problem of the mower sparking sometimes then not. I recently cut the lawn, stopped the mower, took it to the front lawn and it would not start / spark again. Had fresh petrol in that day.

[Clive.]

Sorry, I have no info' on a test for the ignition unit.

Did you try the 40 thou spark plug gap.?...that was a prescribed fix for Dellorto carb engines way back when these were a lot newer.??

Also I was reading recently an article that discussed about the porcelain insulation section of the central electrode of plugs no longer being glazed and thus suffering from ingrained insulator and thus failing in some older applications.
http://www.gsparkplug.com/shop/fouling- ... on-vs-ngk/

What spark plug are you using.?

Way back when I was in the mower world I felt that the then new Champion J8C was not as good in Suffolk/Qualcast/Atco engines as the good old J8 had been. However J17LM seemed to give ok results.....


I never did remember the plug that was advised to me by a member of a now defunct mower forum a couple of years ago. I really questioned the posting at the time as I reckoned that the suggested plug had an extend electrode..and I feared it fouling something.!!....however the poster assured me that he was current in the mower trade...and by then I was not .... So I bowed to his up to date knowledge and it could just be that the extended nose plug was in an effort to place the spark in a more advantageous position.?? but have never checked this for myself so I express some caution here..

Not being very helpful here though ...as I can't remember what the NGK plug was.

What plug do local Qualcast/Atco mower agents recommend to you these days.??

Clive.

[mowerman]

Hi Clive,

well, this is really about the ignition unit as the spark has gone. I have tried 2 plugs and adjusted the gap, J8C & J17LM . I am going to get a new HT lead and try that but it seems like when the engine is hot, this occurs albeit not on a regular basis. I then test the plug on another (35s) and it works Just bear with me, I'll report back and hopefully / eventually, there will be a remedy. Thanks again g=for your advice

[Ian in Cumbria]

I think you said you had bought a new ignition unit. I would say not to assume that it is OK just because it is new. I know nothing at all about these units, but I do know a bit about old vehicle ignition, and one of the classic symptoms of a worn out magneto is its ability to spark when cold but not when hot. I think I'd be inclined to go back to the supplier of your ignition unit, speak to him and get another replacement unit. Chances of 2 being faulty are slim. It would at worst eliminate it as the problem.

Regards

Ian