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Lee reed

Bike Carbs And Brake Servo

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i am nearly finished fitting the bike carbs to my pinto, however the last job to consider and not the least important is the vacuum for my servo. Will tapping into just one of the four inlet tubes create enough vacuum and i have been reading how this messes with the engine when heavy breaking??. has anyone used an electric pump to get the vacuum? What have you guys done ??

again thanks for any answers

 

Lee

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Hi Lee,

I dont use a servo. Just after you trousers go brown, you realise that you dont need one as it`ll still stop dead, just takes

a bit of getting used to.

Tiger do a different push rod that apparently is a much more effective braking mod.

 

Andi

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doing some reading on other sites it seems ok to have the dizzy off one tube and the servo off another tube and leave the other two tubes (so none are linked). the thing is they were not talking about a pinto engine so unless i hear otherwise I will run with this.

thanks for your comment Andy but the car has the pedal box with the servo fitted so would like to leave it there to be honest.I used to have an MG Midget that had a 1700 X Flow and Type 9 box and no servo, I never got used to those brakes no mater what pads I tried.

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Hi Lee , I have a 1.8 pinto in my 2b running on bike carbs. I have the dizzy taped onto one manifold pipe and the servo taped onto another pipe, brakes all work ok.

Cheers Neil.

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Tapping a single inlet runner for dizzy gives pulsing at low revs and unstable timing. A better way to do it is to tap all four runners and pipe them to a plenum vacuum chamber. You can then use the dizzy vacuum advance from this chamber. Or disconnect it altogether and fix the dizzy baseplate.

 

Nigel

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my bike carbed pinto had 1 take off pipe on number1 it ran great and fueled perfect on the dyno, would only cause issue if your servo was knackered

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many thanks all for your help. I will do as Neil has and if I have problems with the dizzy I will fix it and blank the hole. I do have a non vacuum dizzy from an injection sierra but I dont think it will wire up to my current ignition so may be look out for an injection module and then the vacuum issue for dizzy is gone.

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servo on on runner is fine mount the connector vertical so any excess fuel does not run down the pipe. also move the in line one way valve closer to the manifold, this allows the rest of the pipe to act as a small reservoir.

before going to megajolt ing. to smooth out pulses to the vac adv i used a very small fuel filter as a reservoir with a small carb jet inset.

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all done, runs a dream. I connected the dizzy straight to the first tube with no chamber and it seams to tick over smoothly so far and revs very freely. thanks all for your words of advise.

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Tapping a single inlet runner for dizzy gives pulsing at low revs and unstable timing. A better way to do it is to tap all four runners and pipe them to a plenum vacuum chamber. You can then use the dizzy vacuum advance from this chamber. Or disconnect it altogether and fix the dizzy baseplate.

 

Nigel

 

Do you mean something like this:

http://danstengineering.co.uk/index.php?route=product/product&path=59_89&product_id=121

 

Tap holes into the manifold attach balance bar, then use a t-piece to split the 1m vacuum hose between the dizzy and the brake servo?

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