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Running Hot

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#1 Louisbaby


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Posted 21 November 2019 - 04:45 AM

Hi guys, so after many year I finally have the old girl up and running again. She is a blast to drive and every morning I take my kids to school in her.

But, and there is always a but... She runs very hot after driving for longer than 30 minutes or so. So here is what I have done/replaced before getting her to run again. New temp sender, new oil pressure sender, new thermostat 74 degree C, new plugs, oil filter, oil (serviced) new oil pump, new water pump, changed the standard air filter to the cone pancake type. Engine specs are 1275 with 20 thou over bore, Hs4 SU carb, stainless branch and free flow exhaust, standard cam, running on lead replacement fuel.

So something I'm concerned about, is when I trying to time her, I couldn't see the timing light reflection on the mark. So I'm wondering if the distributor drive gear is installed incorrectly. I did have the motor out to replace the gearbox at the start of the project, hence the gear might have shifted.

I have fitted an electronic fan on a switch for if I run her in traffic(which we have plenty here in Cape Town) but she never ever went past the halfway mark on the temp gauge during normal driving.

Has anybody got some direction for me please?
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#2 ChrisRuffell


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Posted 21 November 2019 - 07:06 AM

Have you flushed through the radiator? Might be a bit gummed up after a few years of sitting

#3 Rorf


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Posted 21 November 2019 - 07:40 AM

Hello Cape Town, give us a pic of the engine compartment showing the radiator and fan.


Over heating usually a dirty radiator or leaking head gasket or the fan cowling is missing. Possible too for the timing and fuel mixture being incorrect.

#4 johnR


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Posted 21 November 2019 - 01:30 PM

When I first put my car back on the road after some years there was quite a build-up of debris in the radiator which caused overheating - also the change from a standard to K&N? filter may leave the carburation running lean if not adjusted.

#5 Louisbaby


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Posted 22 November 2019 - 07:08 AM

Thanks for all the replies, let me start by saying that I made sure the radiator and engine block had been thoroughly cleaned before I reinstalled them. Secondly the radiator shroud was removed years ago, and it never gave me any problems before. I still have it in my garage, so I will happily reinstall that, which I probably should have done ages ago. But JohnR made me think about the running lean bit. I have adjusted the mixture, but my fear in that mid throttle range she leans out. Cause it's during me cruising at about 70/80 km/h that she gets hot. Can I change the needle? And if so, which one should I change it too? Or do I just screw the mixture open more to make it richer?

#6 Retroman


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Posted 25 November 2019 - 09:53 AM

Smart looking motor

As said above could be a bit lean

Have a look what needle its running




The minty lamb site is a good one to compare needles...though i did prefer it before it changed


It would be worth a needle change to see if you can improve it


Have you access to a colour tune / exhaust gas analyser or a rolling road ?

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