I try to get my two Stromberg carbs balanced in air flow by listening to sound with plastic tube. But when sound seems equal, the surface temperature on front and rear exhaust headers is significantly different. For example, 150C and 200C when measured at same spot on two central headers.
My questions
Is this temperature method misleading or not significant?
2 Or could it be due to different air fuel ratios from two carbs with equal air flow?
Or is my plastic tube method inaccurate and I need to buy manometer type flow meter?
Hi Phillip,
I’ve not used the temperature technique since I have triple SU’s but here are my thoughts. Yes it could be different AF ratios as that needs to be set at the same time and often one changes the other so it is a repeated process. Your hearing must be a lot better than mine with using the hose technique, I use a ‘snail’ type airflow meter and have found it to be better than the synchronizer (floater in a straw) type and the results seem a bit more reproducible to me. Lastly make sure the rubber diaphragms are up to snuff as they tend to crack with age/use. YMMV
Cheers,
LLynn
Yes but with the crossover manifold working it will either mix or swap. Balancing with a hose works well. You have the air flow balanced but not the mixture.
I suppose it could but it also could also indicate poor firing or balancing. And you’d have to do it reasonably quickly before the latent heat in the adjacent ports blend across.
Personally, and FWIW which is as much as you paid for it, I would balance the airflow then stick in a new set of plugs, take the car for a run and then read the plugs.
Or just do the piston lift test and know how they run. Lift the pistons by 1-2 mm and if the idle speeds up it’s rich - if it drops it’s lean and if there is little change, up and down and then settling, it’s alright.