'76 Euro 308GTB carb exhaust gas analyser points

All eight of the points on my low mileage car can be removed easily so no problem there. I'd like to make up a set of adapters so that I can connect my analyser to each pipe in turn to adjust the idle mixture a bit more accurately than by ear. The rear (accessible) bank are easy to deal with and I've made up a set of four brass M6 adapters that I can push the analyser pipe onto. The front bank is much more difficult as they're only accessible from underneath the car and I don't fancy standing in the pit as it fills up with CO! They are a larger thread (M12 I think) and at all angles so need a different approach.

My idea is to make up a set of screw in adapters, each with a length of 1/4" copper tube pushed in and brought out to the side of the car to avoid CO poisoning and very hot pipes.

An old thread suggested that rubber hose could be used but the pipes are far too hot and the pipe melts in seconds. I dare say the hot tube would lead to a false CO reading as well as all the sulphur coming off the rubber.

Has anyone done this successfully or have pictures of the standard Ferrari kit to copy. I think an old thread may have had pictures but they were lost in the big Ferrarichat file loss of a a few years ago.

And, yes, I have read Birdman's excellent tutorial on carb synching but always have a problem with getting the idle mixture adjustment just right.

Thanks

Paul

 

Hi Shaun

thank you, that's very interesting and informative. My car, being Euro spec, doesn't have the permanent connections. My manifolds are different to your US spec car and the front bank pipes each have an M12 hole plugged with a brass bolt on the underside or vertical face. They are really difficult to get at and can only be accessed from a pit or a lift. The rears are similar but with an M6 hole and are much more accessible from above.

Having seen your photos, I'm going to fabricate a similar arrangement that can readily be fitted for tuning and then removed afterwards.

We don't have such strict emission regulations on old cars as you seem to have in the US. At the annual inspection (known as an MoT) they measure and advise the hydrocarbons and CO etc but cannot fail the car - yet! Pre 1993, for the time being, you can get way with almost anything.

Thanks again

Paul