Hi all,

This is my first ever post after many years of viewing the site and I'm hoping someone can assist me. I apologise about the length of the post, but it’s about as concisely as I can describe my situation. Hopefully some of you find it interesting!

I'm looking for an alternative carburettor/inlet manifold set up for my a12. For some years, I've been running a weber 32/36 DGV using an adaptor to connect to the stock inlet manifold. Certainly nothing unusual. The motor has been rebuilt in the last few years and has a mild cam. I also have set of custom headers. The motor has been dyno tuned fairly successfully to provide a good amount of top end poke.

However, a problem I have been plagued with for some time is a distinct hesitation off idle or from low speed. I'm fairly certain that I've successfully diagnosed the problem to be a lack of heat supply to the underside of the inlet manifold as the original 'hot box' heat source was obviously removed when the headers were installed. I’ve recently installed an air/fuel ratio gauge which clearly identifies an extreme lean condition coinciding with engine hesitation. I can be fairly certain the carby is not malfunctioning, and in particular, I can confirm the accelerator pump to be spot on which I know would be an otherwise likely source of problem in this regard. What is particularly annoying, is that there is no hesitation when the engine is cold and the choke is on. In fact, the car is at its most responsive in this state, and it’s frustrating that drivability worsens as the engine warms up.

In an attempt to recreate the hot box effect, I’ve fabricated a water heated hot box that bolts to the underside of inlet manifold. Engine coolant now flows through new hot box and is in direct contact with the fins on underside of manifold. To my delight, this improved engine drivability significantly. Understandably though, it did not solve the problem completely, and I’m guessing it is due to the cooler temperature of the coolant (80-90 degrees depending on thermostat) compared to exhaust gases.

Anyway, as I can’t easily provide any more heat to inlet manifold (I do not want to use heat risers from headers for a number of reasons) I thought the next option would be to use a side draught carb. The theory being that the mixture will not lean out from having to make a right angle bend as it passes from the carb to the manifold.

So, my question is: what side draught carburetor/inlet manifold combination is most readily available and also reasonably cheap? I guess fuel injection would be another option, but I know least about this method of induction.


That’s all I’ve got to say for now. I hope someone can help!

Cheers,

Stu