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twin carb to single ?


allen
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Hi all i have recently joined the TSSC again after a 30 year gap, at that time i had a mk3 spitfire wish i still had it. i did have constant issues with the carbs. following an 18 month restoration of a 1200 Herald, I have bought a mk3 spitfire. I love it but again trouble with the carbs. they have been rebuilt by the previous owner, but the choke was sicking., Sorted this, then one of the needle vales kept sticking, now sorted. however i continue to have trouble with smooth running. 

To my question can i convert to a single carb set up, im not into power just want a nice running car that ticks over smoothly.

also should this car have a mechanical rev counter ?

Do i remember right, was it driven of the distributor, this one has no facility ?

 

All thoughts would be appreciated. 

 

Allen

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Hi Allen & welcome back! Yes, John Thomason looked at this about 20 years ago and he found that the so-called "log" manifold off the compact 1300 & 1500 saloons gave a little more torque for only a small loss of top-end power. Other benefits are fuel economy and ease of setting up - no balancing multiple carbs. Triumph it seems introduced this to give better fuel economy during the '71 fuel crisis and really did a great job of getting equal flow distribution between all 4 cylinders - something that single carb manifolds, especially "log" types, are not renown for. He preferred this type over the "cumberland sausage" manifold used on Heralds. Internally, it has clever little bumps to disrupt the flow so it goes equally down either port - 1 or 2 and 3 or 4. I'm putting one of these on my stroked 1500 engine for the Atlas and it should be fine for your 1300 engine too. You may need to do a bit of research to find the best needle for the carb.

 

Cheers, Richard

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John's work with a 1500 Spitfire is in Courier 216 Jun 1998 p.8 covers all the basics.  There was a follow-up article by Brett Dennis on the 1300 engine in Courier 221 November 1998 p. 24.

Buy your CD set from the Club shop !

 

Both had remarkable success, but I guess a Dolomite 1300 manifold with Dolomite SU carb would work well out of the box as the engine specs are similar.  

 

A 13/60 manifold with a Stromberg might need some fiddling with the needle spec for best results.

 

C.

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  • 2 weeks later...

Thanks for your thougbts been having trouble loging back into the forum.i seem to have it running well kn the twin carbs at the moment other than needle valve periodically sticking. Just brought new ones but going on two week holiday and trying to finish stuff of a work before i go. Thanks again for the replies.

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