EMPI HPMX Guide

EMPI HPMX Carburetors. Performance, reliability and race proven. EMPI HPMX carburetors offer ultimate engine tuning with total air and fuel metering and adjustment. The EMPI HPMX series have separate idle and main circuits featuring changeable air and fuel jets. Intake air is metered by changeable venturies, and the accelerator pump is adjustable for maximum acceleration. Jets, gaskets and repair parts are readily available. All our kits are pre- jetted for most VW engines. Choose the appropriate size carburetor for your application. Cams, heads, valve sizes and other factors will determine which carburetor set up works best. At the end of the day though, when in doubt, go larger as venturis and jets can all be changed to make a larger carb suit a smaller engine as needed. (When a future engine modification is planned, size-up now!)

Part#	Description	Idle Jets	Main Jets	Air Corrector Jets	Accelerator Pump Jets	Emulsion Tubes	Venturis	Pump Exhaust Valve
47-1010-0	EMPI HPMX 40mm - Dual	.52mm	.130mm	.170mm	.50mm	F11	28mm	.55mm
47-1012-0	EMPI HPMX 44mm - Dual	.55mm	.135mm	.200m	.50mm	F11	36mm	.55mm
47-1010-2	EMPI HPMX 40mm - Single	.60mm	.135mm	.160m	.50mm	F11	28mm	.35mm
47-1012-2	EMPI HPMX 44mm - Single	.60mm	.140mm	.160mm	.55mm	F11	30mm	.35mm
All carburetors come with a 2.00mm Float Bowl Needle Valve.

Carburetors are jetted for smooth operation.

Float levels checked and set at the factory.

Carburetors are bench tested and run.

DESIGNED FOR TUNABILITY

HPMX carburetors are based on the famed Weber IDF and as such feature all their benefits and interchangeability. If it fits on an IDF, it will fit the HPMX.

LESS IS MORE

Brand new Gen 4.0 HPMX carburetors feature a cast-in enrichment plate block off. This upgrade eliminates the bolt on block of plate for additional clearance end. Less parts, less gaskets, more performance!

IMPROVED PERFORMANCE & RELIABILITY

Brand new Gen 4.0 HPMX carburetors feature extended idle jet vent tubes. This upgrade virtually eliminates clogged idle jets. All HPMX single and dual kits have this update installed, AT NO EXTRA COST. *Type 3 kits do not have the vents due to a lack of engine compartment clearance.

SINGLE OR DUAL CARBURETOR - SET FOR SUCCESS

40 and 44 HPMX carburetors intended for use in single carb applications have an idle hole drilled in the butterflies to ensure a smooth idle.

Why choose an EMPI HPMX carburetor over a Weber IDF?

Don't get us wrong, we're suckers for performance and when it comes to VW engines and performance carburetors, few will argue with the quality and performance that comes with the Weber name. That being said, there are better Weber versions than others with the Italian versions being the more preferred. So when EMPI decided to take on the task of reproducing one of the most popular VW performance carburetors they went to the best and made it better. They started with a 44 IDF carburetor as a base for the casting for both the 40HMPX and the 44HPMX carburetors. Some of the first improvements was updated circuitry and profiled throttle shafts to flow better right out of the box compared to the Weber.

Now on their 4th generation, having made improvements along the way the HMPX carbs now feature a cast in enrichment plate block off, a vacuum port and extended idle jet tubes to help eliminate clogged idle jets. So, why choose an HPMX Carburetor? Because it works just as well, if not better than a IDF carburetor, it's less expensive, and all the components, jets, gaskets and parts are all interchangeable with the IDF. Why pay more for less?!

These are common tuning guidelines the VW Industry has used for decades. You'll find some suppliers, builders and tuners choose different components as they see fit...the code is more of what you call guidelines than actual rules, so to speak. EMPI supplies the carburetors with jetting they have found to work well for their recommended applications. Use these charts to further fine tune your carubetors as needed.

	Idle Jets	Main Jets	Air Corrector Jets	Accelerator Pump Jets	Emulsion Tubes	Venturis	Pump Exhaust Valve
40 HPMX Single Carb Jetting & Weber IDF 40mm
1500-1600cc	.55mm	1.25mm	1.75mm	.55mm	F-11	28mm	.00mm
1600-1835cc	.60mm	1.35mm	1.60mm	.60mm	F-11	28mm	.00mm
1835-2000cc	.60mm	1.55mm	1.60mm	.60mm	F-11	30mm	.00mm

	Idle Jets	Main Jets	Air Corrector Jets	Accelerator Pump Jets	Emulsion Tubes	Venturis	Pump Exhaust Valve
40 HPMX Dual Carb Jetting & Dual Weber IDF 40mm
1500-1600cc	.52mm	1.15mm	2.00mm	.50mm	F-11	28mm	.55mm
1600-1835cc	.55mm	1.25mm	2.00mm	.50mm	F-11	28mm	.55mm
1835-2000cc	.55mm	1.35mm	2.00mm	.50mm	F-11	28mm	.55mm
2000-2235cc	.60mm	1.45mm	2.00mm	.50mm	F-11	28mm	.55mm

	Idle Jets	Main Jets	Air Corrector Jets	Accelerator Pump Jets	Emulsion Tubes	Venturis	Pump Exhaust Valve
44 HPMX Single Carb Jetting & Weber IDF 44mm
1500-1600cc	.60mm	1.60mm	1.75mm	.80mm	F-11	34mm	.00mm
1600-1835cc	.60mm	1.65mm	1.75mm	.80mm	F-11	34mm	.00mm
1835-2000cc	.60mm	1.60mm	1.65mm	.80mm	F-11	36mm	.00mm
2000-2235cc	.60mm	1.70mm	1.65mm	.80mm	F-11	36mm	.00mm

	Idle Jets	Main Jets	Air Corrector Jets	Accelerator Pump Jets	Emulsion Tubes	Venturis	Pump Exhaust Valve
44 HPMX Dual Carb Jetting & Dual Weber IDF 44mm
1500-1600cc	.60mm	1.45mm	2.00mm	.50mm	F-11	36mm	.55mm
1600-1835cc	.60mm	1.50mm	2.00mm	.50mm	F-11	36mm	.55mm
1835-2000cc	.60mm	1.55mm	2.00mm	.50mm	F-11	36mm	.55mm
2000-2235cc	.60mm	1.60mm	2.00mm	.50mm	F-11	36mm	.55mm

Note the operational range for each component:
Idle Jet - Idle - 2500 RPM
Main Jet - 2500 - 4500 RPM
Air Correction Jet - 3500 RPM and up

Note when tuning a car you want to make sure that there are no vacuum leaks, the valves are adjusted properly, the timing is set correctly and you have fresh spark plugs and most importantly the carburetors (if you are running duals) are synced. When tuning, make sure to drive the car at steady RPM ranges. Accelerating from a stop to full throttle and back to a stop, getting snapping, popping and back-firing along the way tells you nothing about which circuit on the carburetor needs to be tuned. Drive with a smooth foot, at various RPMs and make note of any issues, at what RPM, along the way. Popping indicates a lean condition - meaning you need more fuel or less air. At higher RPM this would tell us a larger main jet or perhaps a smaller air jet is needed.

**Every HPMX carburotor has two of each component listed above with the exception of the Pump Exhaust Valve and they should be the same size. For each barrel. You don't want one idle jet at .45 and another at .50 or so on. This is the case for all two barrel carburetors with isolated plenums. Meaning, one barrel feeds only one or two cylinders, on a 4 cylinder engine.