Triumph Repair: 76 Spit vacuum retard

Question
Hi,
  how important is the vacuum retard? i installed a weber downdraft and it says it is not used in this installation and to block off the input to the carb,my question is can the car run properly with it disconnected,it certainly hasn't made my car into the daily driver that the Weber retailer said it would do.Car seems worse and worse for starting but once warm i get a fairly even idle at about 1000rpm but hesitation when you first put your foot down and also when you change down and put your foot back on the gas it will almost backfire but actually does the brap brap noise before smoothing out again,if you put your foot down for full acceleration it is not bad has quite a bit of nip to it,been fighting problems for over a year now and nobody seems to be able to diagnose what's going on,went to a carb place yesterday and found out it is vacuum retard,he said there is nothing he is prepared to do until i find a way to connect the hose up to the manifold as there is no facility for retard system on carb and he says it is definitely needed to run the car properly,i'm a bit confused because the weber instructions don't clarify what to do with the hose after blocking vacuum advance input.
 Hope you can help,Thanks,Barry

Answer
Hi Barry,
You can't blame the carburetor nor the vacuum unit until you have someone who is skilled at tuning a engine that has been altered. ANY time you alter an engine in any way you change the carburetion, ignition advance, ignition advance curve necessary to make the engine run well. It is very rare that you can just put a different carburetor and intake manifold on an engine and just fire it up and expect it to run great. Especially when you eliminate the advance system.

You need to find a shop in your area that builds and tunes race engines. Even a shop that has a distributor machine may have the know-how to tune your engine. They will probably insist on first running a compression test and start from there. Any shop with a Dyno will know how to correct the problem.

Generally, all vacuum retard units operate on straight manifold vacuum and all vacuum advance units operate on "Ported" vacuum (vacuum off of a carburetor flange that only has vacuum when the throttle is open) Emission control forced on the factories made them put all kinds of devices in the system like thermal control of the vacuum and vacuum delay valves etc. All of this greatly affected the performance of the engine.

Don't just take it to any repair shop. Do some research first and find a shop that knows racing engines, they usually understand the theory and can work with a altered engine.

Howard