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Re: digest #430 Sat Nov 16 02:35:01 MST 1996

Subject: Re: digest #430 Sat Nov 16 02:35:01 MST 1996
From: Stuart Bollen <>
Date: Sat, 16 Nov 1996 12:15:28 -0500 (EST)
At 10:11 AM 11/16/96 -0500, you wrote:
>> "Carl Musson wrote
>> Subject: TR3/4 Carbs
>> My 3 has a '4 engine in it (about ct39000)
>> I am going to rebuild a set of carbs over the winter, and wonder
>> 1) which is standard for that motor (SU or Zeniths)
>> 2) which gives better performance (SU or Zeniths)
>> 3) which is easier to maintain
>> 4) which is easier to rebuild
>>- '58 TR3A
>Firstly don't dispair that you have the TR4 engine inside your TR3 , 
>there is no real difference in the block other than for the TR4 block 
>having 87mm size pistons & sleeves and a breather cap over the breather 
>hole near the bottom left rear of the motor (which can easily be punched 
>out if you ever overhaul the motor).
>My advice about the carbs.... Go with the 1 3/4" HSU's which were 
>original on the car. They are also about the simplest carb ever made and 
>require no maintenance unless they ever gum up.
> As for rebuilding get yourself the Haynes "owners workshop manual" for 
>SU carburators. It's very detailed and easy to follow even for a 
>relative novice. The HSU carb only has two adjustments to it, the 
>throttle screw and the jet nut which raises or lowers the height of the 
>jet. The closest thing you can compare the SU's to is a toilet bowl, the 
>fuel bowl fills up and the fuel "flushes" through the carb, with the jet 
>needle, piston and throttle disk adjusting the air/fuel mix. The thing 
>to watch out for is air leaks which are caused by worn throttle bushings 
>and deep scratches on the piston chambers which will impead performance. 
>Buy yourself a proper overhaul kit and it's probably a good idea to 
>change your needle, jet, and float needle once your overhauling. If the 
>throttle bushings are worn you'll have to order a new throttleshaft & 
>bushing kit. 
>As for performance, most will swear by these carbs.
>Good Luck
>Barry Shefner
>59 TR3A OTS 57675
>As an aside , the TR4 engine uses different engine mounts according to a
friend who put one in his TR3.

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