Hi, I have recently fitted a single HPMX to my 1976, 1600 Beetle. I have tuned it as best I can by ear and a carb syncrometer. But it still has a couple of flat spots, and it is using a fair amount of extra fuel.
I have an electric fuel pump fitted, and an electronic ignition kit.
Just wanting an idea of the next step in fine tuning the carb. Dyno? Different jets? Better manifold?
Good luck dude... I had some once, tried everything to tune the flat spots out, and got rid of them for some second hand italian webbers after which it never ran better...
Maybe I'm just a gumbie, who knows.
Reub
What jets do you have in it now??
idles?
mains?
vents?
emulsions?
BTW - i have Dells and never been happier
Personally i wouldnt use HPMX
No experience - all word of mouth
soory - just noticd it was a single
Good luck!!
Futue te ipsum!!!
Need to know more about current setup, as above, and what size engine etc.. I've seen manufacturing faults with these carbs so lots of basics need to be checked too.
Where are you, maybe we can recommend a good repairer.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Adrian from Powertune (Victoria Rd, Gladesville, Sydney) was talking about these a while back. He's got a rebuilding technique for these to bring them up to italian/spanish standards.
EMPI junk
Without bagging what Adrian does - and jake raby uses them as well
I have had several people work on them and one of the main problems is the porous material they are made of
The fuel drains "through" them
How would you bring this up to Italian standards???
Futue te ipsum!!!
Bizarre wrote:The fuel drains "through" them
I had a set where this was an issue, after removing the venturi's the casting was obviously cracked, not visible at firs but with dye-check...... all becomes obvious.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
It is a standard 1600 dual port. Only other mod is set of headers. Something I have noticed a few times is that the manifold gets really COLD. Condensation even on the outside of it!
Below is the jetting guide for the 40 HPMX's as they come from EMPI.
40mm HPMX
Single
V = Venturies 28mm
A-V = Auxilery Venturies 4.5
M-J = Main Jet 1.30
E-T = Emulsion Tube F7
A-C = Air Corrector 1.60
I-J = Idle Jet .55
P-J = Pump Jet .50
P-E = Pump Exhaust .55
N-V = Needle Valve 1.75
Weber IDF
chokes; Main jet ; emulsion tube; air corrector; idle jet; pump jet; needle valve;
single IDF40
1600-1835cc; 28(weber idf36=30); 145; F11; 165; 60; 50;
Dunno if i agree - but it might help you
Taken from here
http://cgi3.ebay.com/ws/eBayISAPI.dll?ViewUserPage&userid=alfa1750Futue te ipsum!!!
Futue te ipsum!!!
Mave you manifold preheat? Maybe warm air intake could be rigged up easily to test.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
I have managed to sort it out mostly. I bought some new jets. I found mine was fitted with 135 main jets and 60 idle jets. With a bit of experimenting I have found 125 main jets and 65 idle jets to be working best, for my car. You must, of course, make sure your spark plugs are in good condition, and also that your timing is set for optimal performance.
