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Fuel System
  • Suggested articles, sometimes including step-by-step procedures, are indicated with orange colored text. You can also submit YOUR Opel TechTips, for consideration by the Editor of the OMC Blitz, to: joinomc@opelclub.com
  • Most 1.9 liter Opels require replacement of the aftermarket Weber 32/36 DGAV/DGEV (Series 33B) for the original Solex 32DIDTA carburetor for reliable performance. (Always check used Webers at the throttle shaft bushing, to make sure it is not worn-out). Additional steps include sealing the vacuum system for leaks (including installation of the "thick" carburetor mount gasket with sealer such as Permatex "High Tack"), isolating the fuel hose from contact with hot surfaces, and lean-setting carburetor fuel mixture, for trouble-free performance. Mechanical fuel pumps on 1.9 engines require a spacer plate for installation, and installing a fuel pressure regulator (set to 4 psi) also helps.

HOW to Order: Reprints of Individual OMC Blitz issues, can be ordered by mail from the OMC Treasurer (3824 Franklin Ave, La Crescenta CA 91214) for $2.00 each (cost includes postage). This offer is subject to availability.

Nov - Dec 2008

Original Opel GT air filter system (1 page) Click to download
Weber carb air filter options (1 page)

June 2004

GT Gas Tank Venting (Hoses), 1 page (illustrated)
Photos illustrate corrent vent hose routing from the GT fuel tank, including the 1973 GT fuel tank (which has an additional fitting). Changing these hoses (frequently rotted after 30 years of vapor exposure) will help rid the interior of gasoline fumes after a fill-up.

April 2004

Adjusting Weber Carb Choke, 2 pages
Replies to inquiry from Roger, describe troubleshooting and installation methods, to solve a "hard starting" problem on a GT with a Weber carburetor. Includes note to connect the electric choke wire to the fusebox (not the ignition coil!), correct adjustment procedures for the choke plates and the fast idle setting screw.

Dec 2003

Adjusting the Solex, 1 page
In case of poor acceleration, throttle stop adjustment procedure is provided, to set for operation of accelerator pump diaphragm.

Dec 2003

Vapor Lock Cures, 1 page
Otto B. describes how covering the metal fuel hose in front of the engine (using common wire loom plastic insulation) isolated fuel in the line from the heat blowing back off of the radiator, solving his vapor lock problem.

Nov 2003

Non-Acceleration in Rainstorm, 1 page
Bill H. relates that sudden non-acceleration in a rainstorm was caused by water in fuel, and a bottle of gas dryer fixed it.

July 2003

Cold Air Induction System for Weber, 1 page (illustrated)
"Texas Tom" customizes weber air filter adaptor system with a Jam Engineering Weber Adaptor #3-009 coupled to K&N filter.

April 2003

Fuel lines, 1 page
John S. warning, to check engine area fuel lines to avoid leaks.

April 2003

Weber 32/36 bogging down, 1 page
Similar solution to 6/2000 tip, re: checking internal venturi tubes to make sure they are correctly seated.

April 2003

Weber 38DGAS jetting, 1page
General notes re: Weber jetting, and specific sizes for a 2.4 liter engine.

April 2003

GT Vapor Canister with a Weber, 1 page
Notes you also should connect vapor hoses to the vapor cannister (sits next to the battery on 19701973 GT's) to avoid fumes entering the interior from the fresh air vent by way of the engine compartment.

Nov 2002

GT Fuel Tank Internal Sock Removal, 1/2 page
Otto B. lists 13-step procedure of use of 1/4" sheet metal "cutter" and a "flexible fingers" tool, to reach in and remove this (often-clogged) filter.

Mar 2002

Removing the Fuel Sock in a GT Fuel Tank, 1 page (illustrated)
Otto B. describes a custom tool and procedure, to remove this internal filter, which over time can clog the fuel tank output hose.

Nov 2001

Dual Webers in a GT, 3 pages (illustrated)
Illustrates areas for cutting and sheet metal replacement, to install dual DCOE Weber carburetors in a GT and retain the heater function. Requires custom sheet metal fabrication, rerouting of heater hose and replacement of the stock GT heater fan with a fan from a Manta/Ascona. (Reprinted article originally from August 1985 Blitz). Throttle linkage installation with illustrations in October 1985 article.

Sept 2001

K & N Air Filter Part Numbers, 1 page
GT type #E-2340, Manta/Ascona type #E-2780

July 2001

Weber 40DFAV & 38DGAS/32-36DGEV Setup Tips, 1 page
First section concerns the larger 40DFAV/DFEV carb, which contributor Charles G. installed to replicate its higher performance (noted by BMW 2002 owners. Second section includes general notes about using engine response to mixture screw settings to determine jet sizes.

June 2001

Improving Gas Mileage, 1 page
Bob L. suggests a combination of well-tuned 38BGAS Weber carb, ported intake, mild lift camshaft, roller rocker arms, Sprint/FI exhaust manifold, 2" exhaust system, GETRAG 5-speed transmission on high-compression motor for 28-32+ highway mpg.

June 2001

Adapting the Stock GT Air Cleaner to Fit a Weber, 1 page (illustrated)
Revisits topic covered in 6/99 & 12/00 Blitz, with new photos.

April 2001

Solex Carb troubleshooting, 1 page
Suggestion to bend float tab to raise float (if carb continually dumps gas), or just to replace Solex with a Weber carb.

April 2001

Weber 32/36 Carb Troubleshooting, 2 pages
Bob L. provides detailed procedure to determine correct carb jet sizes, in this case on a "double pumper" 32/36 carb.

Dec 2000

Weber Adaptor for GT Air Cleaner, 1 page
Condensed version of 6/1999 Blitz tech tip.

July 2000

Weber Carb runs rich, stumbles on acceleration, 1 page
Suggestions consider float bowl setting, need to install a fuel pressure regulator, checking the internal venturi brass tube slots point down, also using a vacuum gauge.

July 2000

Weber 32/36 Carb Lean Idle Adjustment, 1 page (illustrated)
Reprint of (generic non-Opel) Weber carb tuning procedure.

Aug 1999

Repairing & modifying GT gas caps, 1 page (illustration)
Update to Feb 1997 article includes dimension of machined internal locking bar to replace original spring-actuated internal tang fitting.

Jul 1999

GT fuel tank safety (factory impact design), 1 page
Reply in response to question of the safety of a rear impact collision upon the GT fuel tank, states that although there have been horrific crashes over the years, the GT fuel tank system is located in a more protected position high in the chassis, and is designed to "break away" and not necessarily rupture.

Jun 1999

Weber carburetor Model ID and Air Cleaner modification, 1 page
Wayne T. lists Opel 1.9 downdraft Webers: 32/36 DGEV, 32/36 DGAV, or 32/36 DGV, and describes in detail modifications to fit the stock GT air cleaner system on top of the Weber carb.

Mar 1999

Gas cap vs. Ignition key blanks, 1 page
Multipart discussion on application and sources of code OP11/OP19 key blanks for early and late model GT's.

Jan 1999

Service Manual reprint: Repairing the Solex carburetor, 5 pages (illustrated)
Reprint of carburetor text and illustrations from 1973 Opel Service Manual, including stock Solex 32/32DIDTA disassembly and overhaul procedures.

Jan 1999

Solex carburetor: Vacuum Hoses and Throttle Stop Screw, 1 page
Brief explanation of Solex carb hose connection from float bowl vent to 1970-72 evaporative cannister system, and distributor vacuum advance.

Aug 1998

Carburetor vacuum leak fix, 1 page
Describes Jim F.'s Weber 32/36 carb installation problem, and  how to repair the vacuum leak with installation of a thick base gasket and proper Permatex Hi-Tack gasket sealer. Also discusses the option of re-installing the stock aluminum heat shield, and the desireability of installing the original Opel intake manifold studs. Also covers John M's suggestion of replacing the intake/exhaust manifold gasket and the thick brake booster vacuum hose. Diagnosis tip from Andrew L. (spraying carb cleaner along the base of the carb when running, and listening for idle speed change).

May 1998

Repairing a accelerator pedal mechanism; 1/2 page (illustrated)
Elliott B. suggests repair or replacement, of gas pedal underside roll pin.

May 1998

Dangers of MMT gasoline additives in older cars; 1/3 page
Reprinted article.

Nov 1997

Simplifying Weber Carb Mounting; 1 page
Wayne T. suggests installing replacement metric studs on the intake manifold, that have the same thread size but are 1/2" shorter (or, 1" total from manifold surface to top of stud) to make it easier to install Weber.

Feb 1997

How to repair & re-key a GT gas cap; 2 pages
Wayne T. provides extensive detail on disassembly and internal modifications to the stock GT gas cap. A particular size of fiber ring, use of propane torch, and some patience is required,  and parts from extra gas cap(s) would also help.

Oct 1996

Reformulated gasolines; 3 pages
Reprinted article explains the possibility that newer reformulated gasolines may internally corrode rubber fittings in the fuel system (ie fuel pump and carburetor diaphragms). Conclusion is, impact is likely minimal on Opels.

Dec 1995

Opel 1.9 Fuel System (Solex & Weber carburetor notes & adjustments); 2 pages (illustrated)
Explains various solutions Opel owners have found to malfunctioning original Solex 32 DIDTA carburetors, including custom rebuilds and factory tuning procedures.

Dec 1995

"Solution: Weber (Carburetor)"; 1 page (illustrated)
Weber DGAV/DGEV 32/36 carburetor and other fuel system tech tips, includes illustrations of "lean mixture" setting techniques and float levels. Illustration also of the early 1970's "Holley-Weber" as the Pinto carburetor sometimes installed on Opels, that you should avoid using, as it uses "progression slots" that cause the engine to run lean (and hot).

Dec 1995

Opel 4-barrel Holley manifold project history, 1 page
Excerpts of the old C&R Small Cars' "Opel USA" newsletter from, the 1980's, which describes the progress in adapting the 390CFM 4-barrel Holley carb to to the Opel. (The prototype never went into production).

April 1994

"There's Life in the Old Solex Yet," 2 pages
Nick W. describes his attempts to tune a stock Solex 32DIDTA  carburetor on a 1971 GT, including the need for a water manometer (setting 1" to 7" water at 600rpm idle speed), the process of locating and fixing vacuum leaks (including replacing hose ends and brake booster seals), and finally fixing a rich idle condition by installing a fuel pressure gauge (set to 3.5 psi) on the fuel hose to the carb.

March 1989

Used Weber 32/36 Inspection Note, 1 page
Note suggests inspecting the primary throttle shaft on a used Weber 32/36 carb for looseness (typical wear point, indicates it is worn out) before buying.

Oct 1988

How to Install Two Webers and Keep Your Heater; 12 pages (illustrations)
Reprint of earlier October 1985 article.

Sept 1988

Smog-Legal Weber Carb Idle Jet Replacement Info/Ad; 1 page
On the "smog legal" Weber 32/36 DGAV/DGEV (Series 33B1) Carb, the side-mounted electric idle jet solenoid can be replaced with a more reliable non-electric mount for the idle jet.

June 1987

Weber "Smog-Legal" Carburetor Installation Tips; 1 page
Notes on Weber 32/36 installation, including the need to obtain an air filter adaptor (when original air cleaner is retained) and mounting adjustment for clearance under the hood.

June 1987

Dual Weber Carburetor Installation & Manifold Bolts; 2 pages

Sept 1986

Opel Factory Service Bulletin (Carburetor Gasket Kit); 1 page
Reprint of FSB #75-I-07 (9/30/1975) listing new universal Opel carb kit #9293775 with gaskets and o-rings, but species that older kits (with accelerator pump diaphragm and needle/seat assemblies) are: #830353 (1968-72 GT), #830359 (1970-73 GT's with automatic trans), #830362 (1973 Opels except GT), #830365 (1973 GT manual trans), #830368 (all 1974 Opels).

Aug 1986

GT Fuel Tank Metal Hose Fitting, Replacement Part; 1 page (diagram)
Blaine S. describes the Aeroquip #FCM 2116 adapter for the GT fuel tank fitting, and adapters to the standard -06 fuel hose. Specs for the fuel tank threading is listed as 12mm x 1.5 thread. Note: This application requires an internal "crush sleeve" to seal properly.

Feb 1986

Getting the Lead Out, 4 pages
Reprint from BMW newsletter on the subject of driving a pre-1975 vehicle with unleaded gasoline. Conclusion is that damage to exhaust valve seats is minimal when a quality unleaded gas is used (such as 89 octane), with best results from avoiding gasoline which contains methanol and from installing hardened exhaust valve seats when rebuilding a pre-1975 cylinder head.

Nov 1985

Dual Weber Kit Throttle Cable Installation Tips; 2 pages (illus)
Roger L. suggests using a throttle cable from a Manta/Ascona, instead of the cable that was (formerly) supplied with Weber carb kits, with a custom bracket (illustrated), and throttle return springs from a MGB.

Oct 1985

How to Install Two Webers, Revisited; 2 pages (illustration)
Adds detail of throttle cable and linkage illustrations to Aug 1985 article.

Sept 1985

Dual Weber Article Replies (Letters); 2 pages
Repiles include suggestions of using compact Weiand air filters, and upgrade to a 2-inch exhaust system.

Aug 1985

How to Install Two Webers and Keep Your Heater; 8 pages (illustrations)
Ilustrates areas for cutting and sheet metal replacement, to install dual DCOE Weber carburetors in a GT and retain the heater function. Requires custom sheet metal fabrication, rerouting of heater hose and replacement of the stock GT heater fan with a fan from a Manta/Ascona. (See also Sept/October 1985 replies. Reprinted in November 2001).

April 1985

Lo-Tech (Carburetor Settings & "Dieseling" Tips); 2 pages
Stu W. describes possible dieseling causes: Low octane gasoline, low idle speed (he suggests 1000 rpms), installing 160 degree thermostat, and internal engine carbon buildup (use can of GM Top Engine cleaner to remove).

Feb 1985

Solex Carburetor Rebuilding; 5 pages (illustrations)
Includes assembly, cleaning and tuning procedures, with exploded views of Solex 32DIDTA (1.9) carburetor. Specifications by model include: 1969-1970 1.9 liter engine carbs have 117.5 primary jets, 155 secondary jets, 120 primary high speed air jets and 80 secondary high speed air jets, and primary g50 idle jets and secondary g75 idle jets. 1971 GT main jet sizes are 115 primary and 155 secondary (manual trans) and 112.5 and 130 (auto trans); GT high speed air jets are 120 primary and either 100 secondary (manual trans) or 150 (auto trans). Idle jets are g47.5. GT tag numbers are #3441549 (manual trans) and #3441550 (auto trans).

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