Hey Guys

I have upped my boost again (now hits 15psi regularly - 17max) and have run into a new problem.
It would seem that Fuel is pooling somewhere in the system at idle. After a good run if you let it idle (at 950rpm) for a minute or so, then just crack the throttle a tiny bit, it has a rich bog AFR off chart black smoke. If you hit the throttle a bit harder from idle to say 1/4 open, its not such an issue. If you increase the idle to 1200 it also seems to be less of an issue. (guessing the charge is staying suspended better with more air speed)
Intake (from carb to sc12) is just a bit shorter than Bens kit and is pretty level (not uphill). It is short but very icy. Normal idle AFR starts at around 14:1 but does gradually increase to 12.5:1 as the blower heats up at idle.

Just wondering if anyone else has encountered this suspected fuel pooling issue at idle before? I don't like the idea of idling at 1200 but may be my only choice. I might also try hooking up the Vac advance to give me some more idle advance. (Currently at 20Deg BTDC at 950rpm - Have never had the vac advanced hooked up in the past but in testing it seems to add an extra 20deg advance)
I have seen some of the longer intakes water heated with some copper pipe bent around it plumbed to the heater coolant line but mine is short so probably of little help and the fuel may be pooling somewhere else in the system anyway.

PS - reducing the boost back is not an option

cheers
Rick

_________________
1310 SC 1969 Morris Deluxe - 15psi boost
1293 1968 Morris Deluxe Miglia - 45 Weber
HSV Maloo Z Series - Comp Cam - 300rwkw
Ford DF LTD - 5Ltr

Not an authority at all here , but I think the short intake and no gradient for run on fuel to drain back will mean pooling will occur ( as you have already worked out.

If you haven't seen this thread it may help , and or Graham on that thread would be a very good contact

https://www.theminiforum.co.uk/forums/topic/289202-supercharger-kits/

What carb was it?

_________________

Cheers guys. I have seen a few of grahams posts over the years. That link didn't work for me but I will do a manual search to investigate. The Carb is a HSR42 Mikuni with custom profiled needle. Below is an old pic of the engine bay. (Has since been tidied up a bit, alloy radiator added, better catch can etc). Pulsar Dizzy, MSD boost retard, Bosch MEC717 coil.

Link works now cheers.

_________________
1310 SC 1969 Morris Deluxe - 15psi boost
1293 1968 Morris Deluxe Miglia - 45 Weber
HSV Maloo Z Series - Comp Cam - 300rwkw
Ford DF LTD - 5Ltr

Hey Guys - just an update.

The current fix - have upped my idle timing to 30 Deg advanced and increased idle speed to 1200rpm.

It seems to like this timing and it is also producing bit more vac. Coupled with the increase tickover, the fuel is staying suspended in the charge better at idle.

Ultimately, I think that I will design a new intake manifold out of stainless with some downhill built in. I have enough room to factor in about 6mm fall over the 220mm intake pipe. (Mild steel exhaust pipe 40mm at the moment)

HSR 42 specs - Might help someone
Idle – 22.5
Pump – 100 (1mm drilled)
Main – 300 (Gives me 10.5-11:1 at WOT)
Needle 98 Profiled
3 Psi fuel pressure

Bosch MEC717 Coil – Soon to upgrade to HEC715
MSD Boost Retard - 1.5psi retard per pound of boost over 5PSI
0.6mm plug gap


Cheers
Rick

_________________
1310 SC 1969 Morris Deluxe - 15psi boost
1293 1968 Morris Deluxe Miglia - 45 Weber
HSV Maloo Z Series - Comp Cam - 300rwkw
Ford DF LTD - 5Ltr