just wanted to know what Idel speed are people running? stock/custom?

got mine down to 50rpm sounded like a V8 till things started to fall off! put the foot down and flames came out of the carby and then stalled! poor datto

Idle speed of 500 might be possible on a 4 cylinder. It's possible on a v8 or v12 or a single cylinder steam engine with a massive flywheel..



50rpm. Sheesh. I can't believe that.

how did you get it to idle at 50? and how did you measure it?

500 yeh, ive had my thou down around there somewhere when cold... it fouled the plugs up tho

750 is the optimum idle for a new small 4cyl carby engine.

just adjust the mixture untill you get the smoothest idle, then slowly bring the idle speed down too. Make sure its running as smooth as it can and not trying to stall because its too low. And no it doesnt sound like a V8... it sounds like a pooly tuned 4pot!

mine hunts at around 900rpm but is great at 1000rpm. hats by my tacho anyway. still revs to 6500 but had to 7000 with L series su's with no issues.

50rpm per a cly

got 1... 2... 3... different tachos and they were all reading 200rpm then I tried the electrical way and it was jumping from 45 to 55rpm per a cly

but now i've got it to 500rpm the lowest I can get it with out thing falling off

With a stock camshaft, go for 600 rpm for quietness and smoothness. Emission-controlled A12s are generally spec'd for 750 rpm. Much higher, and you are getting out of the idle band of the carburetor.

Compare with Tune-Up Specs. Somebody should add the Australia-market specs to the page.

Mine would sometimes idle at almost zero. Who knows what would cause it, but you could clearly hear each cylinder fire. Pop, pop, 1 , 3, 4, 2.
I would let it idle like this for a while cause it was weird and sounded cool. Didn't notice that the oil pressure was at almost zero, too.
Letting it run like this may have been the cause of 3 cam lobes getting rubbed off. I'm not sure if it was a coincidence or not but I do know that I don't let it ever idle this low anymore.

Normally, my A12 idles at around 1500rpm.