cant get engine to idle below 2000rpm

[Ren]

engine is a rebuild and so are carbs but I cant get it to idle below 2000rpm.

solex carbs
912 block
s90 heads

idle screws are at the limit before they touch the throttle shaft rod bit so cant wind them out any more.

Plugs are NGK 6 HS and are brown in colour so mixture looks good.

Float level good
pump volume good.

[Dakota]

Hi
you may have an air leak or the distributor is hanging up with the timing too far advanced , make sure the bob weights are moving freely and the springs do something , whilst it is idling or not as the case may be try gently backing the timing back to a slightly retarded state as you do it you may find the idle falls right off suddenly or even try a different distibutor in it , what one do you have anyway? Bill

[Ren]

Dizzy is the correct 022 for an early 912 lump. Timing set at 3 degrees. Car idles very low when its first started then after 5 mins running goes up to 2000 and never settles down to 900.

[Hendrik Moulds]

It does sound like it could be an air leak to me.
I had the same type of problem on the '56 1600N in my PreA. Turned out the two rubber elbows behind the fan housing had split. You don't have these on your 912 engine before you look!

[Paul @ P R Services]

Bill is right.

Also check that your rotor arm is a correct fit and hasn't slipped sideways.
We have had a dodgy batch in the past.

P

[Ren]

So I took the carbs apart again last night and found nothing again. So this morning I tried the dizzy which I know is fine and as suggested I retarded the timing a tiny bit and bang. The idle took a massive dive. I have had to double check the timing and it was right.

Big thanks to all who gave advice.

She ticks over just right but runs terrible.