Hot & Steamy

Singles, twins and fours.
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simon.holyfield
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Re: Hot & Steamy

Postby simon.holyfield » Tue May 08, 2018 2:22 pm

Richard Kal wrote:Hmmm.... when I reach the stage of engine assembly for my 4G, think I will machine an extended Tufnol spacer, with a couple of fins included.


Watch out for the distributor! The main reason that I had not fitted my Tufnol spacer yet was that initially I had the distributor the wrong way around - with the square 'condenser bulge' forward. This reduces the space available for the carburetter/spacer combination.

You'll see from my picture that there is very little room for the spacer before the carburetter hits the distributor, even with the bulge facing to the rear. You can extend the studs, and I may have to do that, but of course you need some space to get the carburetter off.
cheers

Simes

'51 Square Four, Masquerading D3 Bantam, '58 Huntmaster, '42 W/NG, http://ariel-square-four.blogspot.com

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simon.holyfield
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Re: Hot & Steamy

Postby simon.holyfield » Mon May 21, 2018 6:41 pm

I've finally fitted the phenolic spacer - a 3 mm thick one, details here:

http://ariel-square-four.blogspot.co.uk ... ation.html

Preliminary results show that it is pretty effective. Warming the bike up after the work, at rest, reveals the following temperature readings with the engine running:

  • 162 C on the fins near No.2 spark plug
  • 107 C on the inlet manifold flange - near the offside carburetter stud
  • 39 C on the carburetter flange, 1/2" from the 107 C measuring point but on the other side of the phenolic spacer. That's a 68 C differential across the spacer.
  • 22 C on the float bowl.
Whilst this looks encouraging, we must remember that this is a result of conducted and radiated energy - any convected heat is going upward towards the tank, not rearward toward the carburetter ; a 10 minute warm up is not a valid representation of 25 miles in a 25 C ambient at 70 mph, and we are not at full operating temperature yet.

But it's encouraging nonetheless.
cheers

Simes

'51 Square Four, Masquerading D3 Bantam, '58 Huntmaster, '42 W/NG, http://ariel-square-four.blogspot.com

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paul.jameson
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Re: Hot & Steamy

Postby paul.jameson » Mon May 21, 2018 9:08 pm

When the bike gets really hot, such as when standing in traffic on a hot day, the most effective cooling mechanism seems to be evaporation of the petrol in the carb. So in these circumstances, I stop the engine when stationary and restart when I can move again. The great benefit of the Square is its ease of starting - provided that it is set up correctly.
Paul Jameson
36 4G, 37 VH, 53 ex ISDT KHA (project), 54 KH(A), 54 4G Mk IV (project), Healey 1000/4 (project)
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser.

MARK.WALSH
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Re: Hot & Steamy

Postby MARK.WALSH » Sun Jun 03, 2018 10:55 pm

I agree with Paul
I have a tufnol spacer fitted and it does help keep the temperature down whilst on the move, but when in traffic at a standstill the carb gets loads of heat radiating from the engine. dynamo and oil tank. Switching the engine off isn't a bad idea and it will swing to life quickly when you need to get going again.(although onlookers always think you've broken down)
One thing the spacer wont cure is petrol boiling in the fuel line after a trip on a hot day - so leave the tap on for a couple of minutes at the end of a run.
Seems to me that any temperature in the 23degrees + region and the motor will get hot and bothered sooner or later. Nice crisp autumn days of about 12 degrees and the bike flies along, oil pressure is good and hesitation/flat spots minimal.
I went to a classic bike function today at Higham in Kent where the bike was well behaved on its 20 mile journey through slow moderate traffic in the medway towns, but the heat coming off the motor when I arrived at the venue is something else!

all the best
Mark


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