The V8 Owners Forum -

help
cant get my emissions down on hc

co is easy but hc is impossible at the moment

engine 4.6 camshaft unknown, weber 5oo carb ,mallory electronic dizzy twin exhausts 21/2 dia
in a westfield
i have a wide band lm1 for afr measurement and gas analyser for emissions.
i have tried different spark plug gaps 25 and 30 thou
different leads
adjusted timing back and forward
compression test all about 145 max was 150 lowest was 135
have tried a friends weber 500 from his 3.9 which gave lowest hc on quick test 600ppm
on my engine and gave 2400hc
engine also seems to be running very hot. but im not sure wether the plumbing is fully correct causing this .or i have a serious problem

what other factors cause high hc in exhaust gases.
aprt from weak misfire or to rich.
being to get well pissed off now

had some sucess today ,changrd the coil ht lead and bingo
hc droped down adjusted timing and got even better. now within tolerance

will play some more tomorrow

So there was a serious spark issue after all.

Sometimes its good to view the engine running in pitch dark. You can see any possible arcing/spark loss from HT equipment.