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Mallory Unilite
Hello everyone,
I went to the "technic control". In France we have to do every 2 years to be allowed to drive the cars on the street. Was successfull with 0 default, but I had to play with the mixture screws to get the minimum CO at the exaust which is 4.5 CO max to pass this "test" and get the stamp.
I have a "Mallory Unilite" distributor without any vaccum capsule, not easy to get on idle those 4.5 of CO. I'm thinking to change this distributor with one equipped with a vaccum. Any ideas? And why some distributors have vaccum and some others not?
Thanks for any advice,
There are a lot of people that think they will get better street performance without a vacuum advance. Vacuum advance, and a vacuum secondary carb, are usually better performing on the street, where you will have changing driving conditions, like stop lights and traffic.
There are many options for a replacement distributor. Is your car allowed to have upgrades? Or are you required to keep it as close as possible to how it came from the factory?
Electronic ignition is one of the best upgrades we can do to these older cars.
If you have the budget, MSD is a really good product. However, a stock Ford distributor, with an MSD box is a good option, as well as a new Ford distributor, and a Ford ignition module.
If you are only driving on the street, the Ford Distributor, with either ignition module, will help with cold starts, better idling, and better acceleration. Neither are very hard to wire up.
I don't think the addition of a vacuum advance will make any difference in CO emissions at idle primarily because if hooked to a ported vacuum source it will not be providing any advance at idle. In general I don't think timing has much effect on CO emissions but I could be wrong about that. I know a lean idle generally reduces CO emissions.

I suppose that if the idle were lean enough there may be a benefit to having a vacuum advance hooked to full manifold vacuum to provide additional timing at idle which would theoretically help in igniting the lean mixture.

Why not just keep doing what you are doing and play with the mixture screws to pass the test and then put it back to where it runs best?

If you are really concerned about emissions put a catalytic converter(s) on.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.
Here is my ignition system from Mallory.
Of course i'm concerned like everybody about emission but not at the point to install a catalytic.
I'm pretty sure that a vaccum capsule can help to the advance at idle and can reduce the Co emission. It went up to 9.5 at idle, which is good for high comsuption and bad for my wallet and for me when I drive cause the smell is very bad and not good for health.
Can I keep Mallory coil and change only the distributor? Or better to change the complete ignition equipment?
CO emissions go down with a lean mixture. HC emissions go down with less advance. NO2 emissions decrease with cooler combustion temperature (richer mixture or reduced compression). This is why car companies in the 70s and 80s struggled to reduce emissions and produced cars with lower compression, less initial advance, retarded cam timing, less power and less efficiency. The power and gas mileage of these cars was awful. You might try optimizing the carburetor calibration, make sure the wires are all good (ohms per foot measurement), and the plugs are the correct heat range and not gas or oil fouled. Opening the plug gap.010-.015 may help some (larger flame kernel and more complete combustion). The coil you have will be able to deal with the additional gap if the wires and plugs are good. Assuming your distributor is working properly, changing to one with a vacuum advance should not reduce emissions but would likely increase light load cruising mileage. Too much light load advance can be a very bad thing so, if you use a vacuum advance, make sure you check maximum advance. Good luck on your project. Chuck
The spark plugs are new, Denso T16PR-U, were ACDelco R45TS before, air filter is new, wires are all new.
I need a vaccum gauge which is on the way. And about that, my distributor doesn't have any vaccum advance capsule, so how should I do with the timing gun?
Yesterday I set the ignition at idle with 6°, I will today try on the road to check how does it runs.
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