1275 crank problem.

Side valve, 803, 948, 1098., 1275 and Vizard mods

Re: 1275 crank problem.

Postby Gman 63 » Sat Jan 05, 2019 8:23 pm

It does look similar, not the same though.

2018-06-13_20.30.01.jpg


Could this be my problem?
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Re: 1275 crank problem.

Postby MM » Sun Jan 06, 2019 2:12 pm

I suspect you have a standard 1098cc Minor crank pulley fitted. Looking at my 1275 Midget engine, the crank pulley has approx. 1/2" of solid metal protruding from the front of the 'V' that the fan belt sits in, which I guess acts as a crank vibration damper.

A similar one is pictured below:
Image

Also, you need to ensure the crankcase breathing setup is correct for your engine - I notice your rocker cover has a pipe that seems to just ventilate to atmosphere; normally those would be fed into the back of the carb crankcase breathing tubes, or direct to the back of the air filter housing.
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Re: 1275 crank problem.

Postby woodywoodchipper » Sun Jan 06, 2019 3:12 pm

you have a standard pulley, you need the damped pulley.?

As MM says you need to sort the engine breather, you should be running on negative pressure,

also do you know if flywheel is balanced to crank, as it will have been modified if running a mog clutch setup
Image

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Re: 1275 crank problem.

Postby Gman 63 » Tue Jan 08, 2019 4:18 pm

The beather pipe on the rocker does return to the carb. (Just not on this picture) the flywheel, crank, clutch plate were all ballanced together.
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Re: 1275 crank problem.

Postby MM » Tue Jan 08, 2019 9:33 pm

That's all well and good, but you ideally should fit the correct crank damper (front lowest pulley) suitable for a 1275cc engine - they are quite a bit heftier than the 1098cc Minor pressed steel item.
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Re: 1275 crank problem.

Postby Gman 63 » Wed Jan 09, 2019 1:10 pm

Ill definatly be doing that just as soon as i can source one. Not confident it will resolve my issue though.
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Re: 1275 crank problem.

Postby MM » Wed Jan 09, 2019 4:29 pm

Have you established what has happened this time around to cause the knock?
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Re: 1275 crank problem.

Postby Gman 63 » Thu Jan 10, 2019 4:34 pm

Unfortunately not. Once i heard the knock i threw my toys out of the pram and put the car in the garage. Its been there since (2months or so) im ready to sort it out now, just wanted some advice on where to start and what to look for. The only thing i can think is that the bearings are not getting oil. It was knocking instantly, didnt wear into it. Unfortunately like i said, i has a new oil pump and all the oil ways are confirmed as clear. Oil pressure is high though. This could be my cheap oil pressure gauge or a blockage maybe.

I think at this point ill just be pulling the engine out again. As much as i dont want to.

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Re: 1275 crank problem.

Postby MM » Fri Jan 11, 2019 11:24 pm

I would check the basics again before pulling the engine apart; I had a Fiat twin cam Minor that I could have sworn had blown its head gasket, so got fed up with it and left it in the garage for months, only to find it was quite a simple carb/timing issue causing the (overheating) problem.
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