Hi All,

just thought I'd put this out there to see what feedback is given and to confirm I seem to be on track...also understanding that a dyno is required for finer tuning...

I installed brand new Empi HMPX 44's on Wednesday, after checking the jetting and floats. I stopped playing with them on Wednesday and again today as it appears apparent that the idle jets are too small (50) and of course nobody in Darwin can help me. Rather than buying shitloads of jets i've purchased a set of jet drills to sort the problem out.

No matter what mixture is set (even the best idle) the car pops and surges around 1500-2500 then the car takes off revving easily to 4000rpm and wanting to go further (noting i'm running the engine in and don't want to over rev it just yet). I note that when I pull up the car almost stalls, which to me suggests the car may be running to rich up high possibly?

My plan is to up the idle jets to 55 and give it a go. Should this fail I'll try 60 as a last resort (there is no 57 in the drill set I've ordered).

For your info the carbs currently have in them;
choke: 36
aux venturi: 4.5
main jet: 155
emulsion tube: F11
air corrector jet: 175
idle jet: 0.50
accellerator pump jet with exhaust orifice: 55
needle valve: 1.75

And for those wanting to know engine specs;
Fully flowed and clearanced RIMCO case
CB performance MAXI 3 full flow pump - blueprinted
CB performance lightweight lifters
Scat 1.25:1 4340 pro comp ratio rockers
CB performance 2242 camshaft (294 intake duration)
CB performance Magnum 8640 chromoly straight cut gear set
New Steve Timms ported and cc'd 043 heads, 40x35 valves, ported, chromoly retainers, stainless valves, dual springs (to run 8:1 static compression) - Click here Heads
Match ported intake manifolds
CB 69mm welded crankshaft with 8 dowels, balanced
Scat 4340 chromoly I beam rods with ARP bolts
12lb german forged flywheel, 8 dowelled.
Gene berg deep sump extension (1.5 lt extra oil approx)
Aircooled net 6160 alloy pushrods
New Mahle A's P&B that have been balanced
Webber 5lb electric fuel pump
All new engine tin
1 5/8 hpc coated merged slip fit header
Black fatboy (for initial use - custom one to be fabricated)
Kennedy 1700lb pressure plate
Bosch 009 with compufire module
MSD 6AL ignition and MSD blaster 2 coil
Scat billet serpantine pulley kit

Any advise appreciated.


[ Edited on 28-4-2007 by reub-revhead ]

Based on some reasearch I'll be installing 55 idle jets, 200 airs and installing a fuel regulator to be sure I'm only getting 3lb fuel pressure to the carbs.

and maybe a fuel regulator?

nick

"No matter what mixture is set (even the best idle)"

If you can achieve "best idle" then your idle jets are right
ie if your revs pick up when adjusting the mixture screws then things are fine.

have you balanced these with a sync tool??

have you pulled and checked the plugs.??

Sounds more like balancing or air leaks to me

Also some good info here

http://waitresses.servebeer.com:81/vwpage/hpmx/hpmx.htm 

Sounds like a vacuum leak of sorts plus idles should be at least 55's. Otherwise that is a bit on the lean side. A fuel pressure regulator would also be a nice addition as I've seen these pumps have a fit and pump more pressure than they are supposed to!! Chased that one for a long time till i replaced the pump and problem solved!!

way too fat start 130 main 175 air check your idle jets arnt blocked only takes tiny peice of grit to block these jets (screwe your mixture screws in one at atime no variation youve found the blocked one unscrew the jet watch out for the oring on the holder somtimes fall off blow it out with air lube the o ring and refit dont forget to re adjust your air mixtures

my kadrons are doing the same thing ,im thinking its running rich too in the low revs pop splutter then its smooth

This is what Stan suggest for our 1916 with Webbers 44's idfs

Emulsion F11
Main 140
Air Correction 175
Pilots 50

On the bottom of his note he has 1 1/2 idle pilots 55
not sure what this means.

Thanks for the continued input everyone....

I've finally got some reasonable tune in the car.

I had to go to 60 idles as it was leaning out on 55 idle jets, guessing cam overlap adds the need to richen up down low.
I'll be playing with the carbs a little more over the weekend as i've got a wide band air fuel meter to hook up to the car.

Currently it's running 155 mains (which I'm sure can be reduced to 140/145's and 175 air correctors with F11 emulsions.

I also got rid of the hideous sound from the fat boy resonator by installing a 2 1/2" lukey muffler. Sounds great now! Alot more of a daily driver as I can hear myself think......