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Triple Carb - Manifold Hose - Plug or Bypass? Fuel Level?


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I am embarking on the rocky road of installing Triple Webers on my US TR6.

So far I have the Weber DCOE40s, Bastuck Inlet Manifold and Exhaust Extractor Manifold.

I have also read a huge amount of contributions on this Forum (many thanks). However one thing I cannot find is, what to do with the Original Carburettor Manifold Heater Pipe? Shall I Plug it or put in a bypass pipe?

Also, looking at the Kieth Franck white paper on tuning Webers, I did not realise how critical, setting up the fuel level is! His method of removing the main jets and putting in an optical fuel level gauge, while the car is running, seems very risky, anybody tried it? would you not get an accurate measurement while the engine is not running? 

 

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I think what I did is pretty typical. I blocked the port in the thermostat housing with another temp sender (I recently learned that a spark plug also fits... ) And I used a PI version of the solid line from the water pump housing to the heater. The PI version does not have the extra T in it.

Stan

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You can measure the height quite safety with the engine running. All you are doing is removing the jet cover and extracting one of the main jets. As the main jet is not being used at idle this has no effect on the engine idling. You can then measure the distance from the top of the hole for the main jet to the petrol surface with a micrometer and a torch. Should be 25mm +/- 1mm, however mine run best around 28mm. 
If your running an electric fuel pump you can just remove a main jet from the three carbs, turn on the ignition so the pump tops up the fuel, then switch of the ignition and measure the height.

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  • 2 weeks later...

Thanks Guys,

I haven't run her up as yet and am going to operate on the mechanical fuel pump to start with.

I can pump fuel into the carbs manually and check fuel level without the engine running, see how that goes and then check it when (if) I get it running.

I'll keep you posted on how that compares.

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  • 1 month later...

Update

I wish I had bought new carbs!

I cleaned the starter valves but mixed them up without realising how critical it is to keep them to their original orifices. Had 2 of the little s**s leaking fuel - on different carbs!  As I have capped of the choke mechanisms, I made up some PTFE rings to seal the starter valves off. Now running much better and am now able to get the slow running mixture close enough to get me to a rolling road.

The tickover is very high and the best I've achieved is about 1200rpm! The electronic ignition is set at tickover at 4deg ATDC set with a strobe. With an extractor manifold and triple webers on a Bastuck inlet manifold, I think I've changed the characteristics of the engine enough to experiment with the Ignition Timing. Any ideas out there?

 

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On 11/4/2020 at 10:15 PM, unclepete said:

Update

I wish I had bought new carbs!

I cleaned the starter valves but mixed them up without realising how critical it is to keep them to their original orifices. Had 2 of the little s**s leaking fuel - on different carbs!  As I have capped of the choke mechanisms, I made up some PTFE rings to seal the starter valves off. Now running much better and am now able to get the slow running mixture close enough to get me to a rolling road.

The tickover is very high and the best I've achieved is about 1200rpm! The electronic ignition is set at tickover at 4deg ATDC set with a strobe. With an extractor manifold and triple webers on a Bastuck inlet manifold, I think I've changed the characteristics of the engine enough to experiment with the Ignition Timing. Any ideas out there?

 

4atdc ??? Should be 11btdc

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30 at 5000 rpm

Pete i had problems with the Bastuck manifold. More manufacturing issues . Also the 3 connecting rods were poor /useless /****.

Cannot help with the jetting as i have 3 x 45s and full race engine.

Im near by so could pop around to cast an eye over yours or you come here. Keeping 2m apart of corse 

Roy

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On 9/25/2020 at 11:57 PM, foster461 said:

Re the fuel level, you are correct that this is critical and you need to start there or everything else will get thrown off. I have never set float height with the engine running but I also dont have one of those sighting gizmos. Tom Fremont does though.

I have set the fuel level height using a clear plastic tube from a WD40 tin!

Take out the main jet, drop in the tube and mark the tube at shoulder of the carb, lick finger and stick over end of tube, lift out carefully and see the fuel level, mark before you take your finger off and measure - Simples!

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