GT Tune Up #2. - Opel Motorsports Club
Contents
1. Thick Gasket the top of the manifold and the bottom of the carburetor to prevent common Opel vacuum leaks Other gaskets such as the Weber fiber gasket are too thin to seal properly or repel heat and the qp Opel plastic gasket restricts the 36mm barrel of the Weber Installation without gasket sealer or with zm improper gaskets will allow vacuum leaks to form over time These leaks will make tuning the Weber ij Heat Shield carb more difficult due to the resulting excessively lean condition Note Lean conditions raise internal cylinder head temperatures which can crack the exhaust manifold S lt Thin Heat Note In warm climates installation of the Opel Aluminum Heat Shield will help shield the Shield Gasket carburetor from the exhaust manifold heat This heat can cause a vapor lock condition making the vehicle more difficult to restart Note The heat shield requires an additional Thin mount gasket Intake Manifold rn The Intake Manifold uses studs with two thread pitches 1 25mm pitch into the manifold and 1 0 pitch for the carburetor mounting nut The smooth portion of the stud helps to prevent vacuum leaks Factory Bulletins suggest the installed height of the studs to be 1 1 2 above q the manifold surface Original Carburetor Mounting Nuts sized 13mm Note Many owners mount extra washers on the intake manifold studs to reduce the number2. of wrench turns required to tighten the carb mount nuts Using a stubby less than 3 1 2 long open end 13mm wrench also helps greatly in this tight access area Check the for vacuum leaks where the manifold seals to the cylinder head as well as for loose manifold 15mm mounting bolts Repair as needed Make sure that the 4 central 15mm mounting bolts use the 5 32 thick washers with the thinner 1 16 washers on 2 end bolts Additional intake manifold hardware includes the brake booster tree fitting connecting to the brake booster vacuum hose This fittings threads should be wrapped with Teflon tape to prevent vacuum leaks Note Check for leaking or cracked vacuum hoses and replace accordingly before you can correctly adjust the idle mixture and the idle speed www opelclub com 6 2006 Electric Choke Loosen ring to adjust Weber 32 36 Carburetor Adjustment Weber Carburetor Adjustment Procedure iy 8a Idle Jet l l amp Screw Mount 1 First perform the various engine tests amp adjustments g w Mou Compression Points Timing Vacuum etc 4 2 Clean Carburetor with carburetor cleaner spraying down the main throats of the carburetor with running engine at Idle Speed Screw a fast idle to prevent stalling 3b Idle Mixture 3 Carefully remove the Idle Jet 3a and the Mixture Screw cea 3b Clean the jet and screw using the carburetor cleaner are as well as the carburetor pas
3. New Full Memberships receive A year of b monthly print issues of OMC newsletter The Blitz a roster of club members an OMC decal and a window emblem Members can also participate in local OMC chapter activities held all over the USA OMC Newsletters THE BLITZ Print version black white Online in color OMC Activities amp Annual Meeting Opel Motorsport Club is the longest established Opel club in the U S A Members travel great distances to attend the OMC Annual Meeting a mid Summer gathering and display of classic and restored Opels Benefits of membership also include information from other Opel owners on the maintenance and improvement of their Opel s and the ability to contact fellow members on their common interests Opel Motorsport Club funds help maintain our website with helpful Opel information at www opelclub com OMC s peer reviewed technical information helps owners avoid common and costly errors on Opel repair jobs OMC is officially recognized by the Opel factory of Russelsheim Germany and OMC SOLO IT racing activities are also sanctioned by the SCCA Sports Car Club of America for racing nationwide in the USA Full U S Membership 45 00 Includes bi monthly b w print issues of The Blitz postage amp benefits listed above Online O nly Member 20 00 Includes downloadable Acrobat pdf version of The Blitz for home color printing To Join Send your name amp address
4. on intake manifold Opel CIH Distributor 1970 73 type vacuum canister shown Internal Shaft amp Rotor rotates clockwise when engine turns Correct 1TDC To view the camshaft dowel pin either remove the valve cover or remove the triangular plate held with three 10mm bolts on front of the cylinder head Use a flashlight and consider the angle from which you are viewing to determine correct 6 0 clock position of the camshaft sprocket 1A Camshaft Dowel Pin at 6 o clock bottom and Flywheel ball mark 1B lines up with pin To view the window where the flywheel ball becomes visible look below the manifold near the oil pressure sender unit until the ball rotates into place when the crank pulley on the front of the engine is turned with a 19mm wrench preferably done with the spark plugs removed 1C 1D Because Opel didn t put a timing mark on the lower crank pulley until 1975 and later European models the marks on the front of the timing cover won t help you 4 TDC Cam dowel pin at 12 o clock Also ball mark on edge aligns through center of sprocket not just vertically with slot in support plate 4 TDC is correct for Opel engine assembly but then the crank pulley needs to be rotated 360 degrees one full turn to line up cam sprocket for correct timing at 1 TDC Avoid This Common Mistake when assembling an Opel engine A common error is when Opel eng
5. depress the brake pedal Notes A Booster Hose to Booster Use a proper reinforced air hose Do NOT use ordinary heater hose it will collapse under vacuum Note The Booster Check Valve is originally located within 10 inches of the intake manifold fitting The Brake Booster Hos B Integral PCV Fitting for engine via the small valve cover hole You may use regular vacuum hose for this fiting Note The Integral PCV fitting was relocated to back side of manifold on the 1973 74 engines for a port to operate the 1973 74 EGR valve C Manifold Vacuum to Distributor Retard Port on distributor Hose Inlet amp Master CyEnder 7 r 7 Poster Hass j heck Vahe D Manifold Vacuum for the Automatic Transmission Modulator Arrow k one way air towards maaifold White end towards Booster when vehicle is equipped with an automatic transmission only Y After locating and repairing any and all vacuum leaks readjust carburetor idle mixture and idle speed as necessary www opelclub com 6 2006 OPEL MOTORSPORTS CLUB OMC is an independent US based auto club that specializes in German made 1968 1975 Opels OMC was founded in 1980 by Opel enthusiasts who wanted to share information and promote their marque in motorsports A newsletter was established to promote Opel events report OpeFrelated news provide technical tips discuss vehicle upgrades and give members a free place to advertise
6. with check money order payable to Opel Motorsports Club by mail to OMC Treasurer 3824 Franklin Street La Crescenta CA 91214 1607 OR Send 47 for Full US Membership or 22 for Online Membership via PayPal to JomOMC opelclub com International Members Please Add 10 for Full Membership to cover additional postage costs
7. Opel CIH Ignition System The Opel ignition timing is designed to be set at TDC Top Dead Center Adjustments are made to the point gap 018 on most and operation is checked at idle with a dwell Meter Dwell is to be set to 50 degrees or 2 degrees This test is to be performed with the distributor vacuum hoses disconnected and plugged Lower Front Crank Pulle i Can be rotated clockwise Firing Order is 1 3 4 2 with a 19mm wrench on bolt to align timing marks 1 How to Verify 1 TDC Camshaft Sprocket Timing Generally if an engine ran without backfiring prior to a tune up it can be presumed the timing marks are probably in alignment If the engine doesn t run or backfires on cranking or is low on power then there is a chance it may be caused by cam timing being off To inspect timing marks for 1 TDC alignment the camshaft dowel pin needs to be in the lowercenter 6 o clock position 1A at the same time that the small ball marker on the flywheel is lined up with the pin in a window on the lower passenger side rear of engine 1B Note this is not how to align the cam timing but it is how to verify if you are aligned for 1 cylinder firing position Cam timing is always done on 4 TDC see below Opel 1 9 Engine Firing Order Vacuum Advance Connected by larger hose to ported vacuum outlet on carburetor base Vacuum Retard Connected by smaller hose to port on brake booster tree fitting
8. System Operation ree Air Fuel Mixture The Opel Vacuum Solution flyer originally printed in the January ee ay from Carburetor 1996 OMC Blitz newsletter is one of the most widely distributed OMC ATTA Tech Tips This page will help to update the 1 9L engine tune up The Opel 1 9L engine draws the carburetors fuel air mixture through the intake manifold round the bend into the cylinder head past the valves into the combustion chamber Ported Vacuum advances the ignition timing via the distributor vacuum advance and the Manifold Vacuum retards the timing via the Vacuum Advance at idle Manifold vacuum also operates the Brake Booster ventilates the Crank Case and on automatic transmissions operates the Vacuum Modulator Therefore it s important to test and identify any vacuum leak sources Mixture goes Round the bend Diagnosis isn t difficult Typical symptoms include Hesitation Stumble or Surge pattern of acceleration and an inability to idle smoothly below about 1100 RPM The engine may idle smoothly at higher than normal idle speeds such as 1300 to 1800 RPM A loss of engine torque may also be noted If you can turn the Idle Mixture Screw IN all the way without the engine stalling you most likely have the idle speed rpm screw set too high possibly indicating that you have a vacuum leak somewhere Testing for a Vacuum Leak at the Intake Manifold Use a can of common Carburetor Cleaner Insert an
9. d aim the long red straw nozzle at the gasket between the cylinder head and intake manifold and spray a short stream of carb cleaner If the engine begins idling faster smoother stops misfiring or decreases rpm you have found the location of a vacuum leak This same procedure can be used to test the carburetor base gasket amp carb throttle shaft area to check the brake booster fitting hose check valve and fitting as well as the master cylinder to brake booster seal and the booster itself Manifold Check for vacuum leaks at gasket surfaces Testing for a Leak in the Vacuum Hoses Integral PCV Fitting located on 1973 amp 74 manifolds Once you know there is no vacuum leak at the intake manifold gaskets or at the brake booster fitting then test the a vacuum hoses while the engine is idling Pull each hose A a A one by one and place your finger over its exposed port If the i KS bse a engine speed goes faster that hose or fitting is leaking somewhere AB Typical 68 72 Brake Booster and Hose Disconnect the if booster hose from the manifold and plug to test If the engine idles better that hose may be T itting on manifold should leaking You also want to check test the booster check valve inlet a Fee ehe d eded fitting and seal as well as the master cylinder to booster O ring A with Teflon tape Note Another symptom ofa leaking booster is when an idling engine dies as you
10. e Key On 12V source on the fuse box NOT to the ignition coil facing the engine and older 1970 s versions are the DGV series 5A Used Webers Always check the throttle shaft on a used Weber for up and down play at the ball nut An excessively worn throttle shaft bushing indicates a high mileage carburetor and often coincides with a vacuum leak at the shaft which causes problems with tuning and idling Weber Throttle Linkage installation sequence Illustrated Below On anew Weber remove the Weber throttle shaft nut amp replace it with the Solex Ball Nut Also inspect the throttle linkage between the gas pedal and carburetor including the firewall mounted grommets lubrication of linkage ball connectors Linkage Bracket Ball Mus Tirone Litkage od i oT ay Par 4 E z i f Note Fully depress gas pedal and j Weber Model and check for full carburetor operation a R Series Markings to Carturatar If not Adjust the throttle shaft on P Seen on lower cde the drivers side until carburetor P faci W acing the engine Linkage Lock Spring opens fully under full throttle a a Carburetor Thick Base Gasket and optional Heat Shield with Thin Gasket Install a Thick base gasket to properly seal the carburetor to the manifold or heat shield if equipped Use a high quality gasket sealer such as Permatex High Tack on all surfaces between l lt
11. for a flat surface or pitting In most tune ups standard procedure is to just replace the point set and condenser altogether 3 Assemble new point set in place apply high revolution ignition grease on the rubbing surfaces of the dis tributor shaft occasionally this comes in a capsule with the ignition point set 4 Rotate engine with a 19mm wrench on the crankshaft pulley bolt or by engaging 2nd gear and pushing the car backwards until the rubbing block of the point set rests easily upon the top of a shaft lobe 5 Use a feeler gauge of 018 thousands of an inch to set a gap between the contact surfaces then snug the hold down screw 6 To check the accuracy of the setting Install the distributor rotor cap and wires 7 Then place the car in neutral gear or park gear with brake on then connect Dwell Meter to the negative terminal of the ignition coil and a ground a valve cover bolt is a good location for a ground 8 Start the vehicle and read the setting on the Dwell Meter Results The needle or gauge should read at a steady 50 degrees and shouldn t vary more than 2 degrees ie lower than 48 or more than 52 even when accelerating the engine If the needle varies more than 4 degrees the distributor may be worn out Note Some older Dwell Meters use an 8 cylinder gauge If so correct measurement is 25 degrees plus or minus one degree If reading is more than 52 degrees the
12. hen the point set is replaced with an aftermarket electronic ignition kit lenition Coil Connections for Opels with point set ignitions www opelclub com 6 2006 Weber 32 36 DGEV Carburetor Installation The Weber 32 36 DGEV carburetor is the most popular carburetor operated on the Opel 1 9 liter engine Unlike most Solex 32DIDTA carburetors the Weber offers a steady idle speed reliable performance and generally better fuel economy Proper operation of the Weber 32 36 carburetor depends on correct installation and correct tuning Air Filter Option 2 1 2 tall Weber air filter kit Most Weber carb installations also use the Weber air filter kit The other option is using the Opel GT original air filter cap with an adaptor that mounts to the top of the Weber To clear the underside of the GT hood it may be necessary to trim the lower edge of the cap about 1 2 Other alternatives include the K amp N brand air filter kit and the newer Weber air induction cap which works with the original GT round air filter cannister Weber 32 36 DGEV Carb Electric choke version shown Weber Aftermarket Air Filter Original Opel GT Air Filter Cap Electric Chokes are the best upgrade but Water chokes can also be used te Note Water chokes work best in relatively cold weather below 45F te t o e Current Weber versions are series 33B inscribed on the lower edge te i Electric Chok
13. hen the choke is closed is about 1700 RPM Water Choke The hoses attach to 2 T fittings coming from the heater hoses Electric Chokes Wire to the 2 fuse same switched circuit as the radio on the Opel GT fuse box Avoiding Vapor Lock This is a particular problem with all Opel s in Summer time Route fuel hose away from all hot engine surfaces Only install fuel filters after the fuel pump near the carburetor staying clear of the thermostat housing Installing a clear plastic fuel filter near the carb will let you see when fuel is vaporizing Carrying and using starter spray is a quick fix A Carburetor heat shield also helps Weber Fuel Inlet Fitting Newer Weber carbs have a reversible 14mm brass fuel inlet fitting so you can relocate the fuel hose away from the engine Fuel Regulator A good prevention move is installing a fuel pressure regulator on the hose leading to the carb set at 3 5psi Some new mechanical fuel pumps and some aftermarket electric fuel pumps can develop excessive pressure which can flood some Webers Additional Information Weber technical guides discuss operational circuit function and provide float adjustment specifications Weber carburetors are also highly tunable If you upgrade cams exhaust ignition the Weber is easily tuned for more performance by changing the main fuel and idle fuel jets Replacement parts are also readily available www opelclub com 6 2006 Too far in Opel 1 9 Vacuum
14. ines are assembled in the 4 TDC position but not rotated to 1 TDC position before installing distributor This is because of mistakes in the service manuals and confusion caused because the crank pulley groove and crank keyway amp flywheel ball pin align at 6 12 o clock when the engine is at both 1 and 4 TDC Crank turns twice to every camshaft rotation Sometimes uninformed mechanics install distributors 180 degrees off Therefore the only mark location that really counts is the camshaft dowel pin www opelclub com 6 2006 Opel Distributor Installation amp Adjustment Once the engine timing marks are confirmed to be properly aligned then the distributor rotor should be located where it is pointing at the mark on its housing for the firing position for the 1 cylinder gt If the distributor is misaligned so ee cen on ree nied much that the rotor points to a firing distributor clamp to adjust or p ee position for another cylinder or so remove distributor 4 dry with that the vacuum canister is turned a No sealer close to the engine then the distributor should be removed which requires removing the mechanical fuel pump first then reinstalled correctly with its thin gasket also set in place To install the Opel 1 9 distributor so that the rotor lines up with the 1 TDC mark you need to reach a pE into the distributor mounting area IR Nagi Align gear cog with a
15. long flat blade screwdriver keyway to to rotate the oil pump gear cog toa pst SIS IDULOE position approximately 15 to 20 degrees clockwise of the 1TDC mark or to the position the dist shaft requires Removing an Opel distributor requires Distributor eee T P In most cases this is a position that would be about 4 30 on a 12 hour clock mecnanical tue must sude n first Always inte pear coe when looking straight from the fender When you set the distributor in place reinstall with the for distributor the rotor will move counter clockwise that 15 to 20 degrees because of action required fuel pump to fully seat of the angled drive gear teeth on the distributor shaft After installing the dis l 8 8 8 spacer gasket in mounthole tributor correctly then apply sealer to pump spacer and re install fuel pump Opel 1 9 Distributor Notes 1968 1969 type Features separate vacuum canisters for ignition advance and retard which sit on engine side of housing Also has unique round hole condenser and a unique 1968 69 only distributor cap has indentation on lower inside ring of cap I F e 1968 1969 hoo 1968 1969 1970 1972 type Features combined vacuum canister for both advance and retard functions evans Retard Has a round hole in casing for condenser wire Breaker plates amp vacuum canister are Vacuum Vacuum non interchangeable with 1973 74 type condensers and housings 1973 1974 type Appears identical
16. or housing where condenser is mounted to assure good ground Vacuum Retard Distributors are known to wear on the internal central brass bushing over time which causes only used with eae f l E Fuel mechan the main shaft to wobble excessively and wear out ignition point rubbing surface quickly yp 1975 type Replacement of ignition points with electronic ignition systems will prolong failure but the solution is to replace worn out distributors with rebuilt models www opelclub com 6 2006 Opel CIH Ignition Point Dwell Adjustment Opel owners know that the Opel distributor can eat ignition points quickly This is because the high RPM s of a 4 cylinder Opel engine combined with improper maintenance wears the internal distributor bushings within about 70 000 miles and the center distributor shaft wobbles on the rubbing block of the point set One symptom of worn out points is idle speed drops Higher voltage caused by failing ignition coils and circuit resistance wires to that coil also results in premature pitting on contact surfaces of point sets Procedure Opel GT Ignition Point Set Point Set G0 BS PKG ACES PLISICoO BY Tw iS Tle js 1c A SCREWORIVER Hold down screw Top of shaft lobe Inspecting Contact Surfaces 1 Unscrew the hold down screw remove clip to condenser and remove point set from distributor 2 Inspect the contact surfaces to check
17. points are not open enough Stop engine and re adjust the point set gap a bit more open If the readout is below 48 degrees that means the points are too far open Stop engine and readjust point gap a bit more closed Repeat above procedure until dwell readout is steady and within the proper measurement range Ignition Coil Notes The wire to the tachometer connects to the coil s negative terminal If the tach gauge needle jumps a lot this wire connector is loose Original style ignition coils have 1 5 ohms resistance measures 2 3 amps at the positive terminal with engine running and 13 5 to 14 5 volts alternator output A non original resistance type coil used when the clear resistance wire is replaced measures 3 ohms Tach Dwell Meter Correct Reading SE Degrees 2 Meter Wire J Connects to Negative Terminal on Ignition Coil Ground Wire connects To Center Connector Negative terminal on Top of Distributor Cap To Condensor on Distributor Positive terminal Switched Power from The fusebox via clear resistance wire and The starter solenoid bypass circuit Note The Clear coated resistance wire limits current to the ignition coil This helps to prevent pitting on contact surface of ignition points This clear resistance wire should be replaced with a 1 8 ohm after market ballast resistor if the points are pitting quickly or w
18. sages Reinstall the Idle Jet amp _ rl fully screw in the Idle Mixture Screw lightly bottoming 5 ie k Ai out the screw and back it off 2 full 360 degree turns piur 14mm Fuel a Inlet fitting reversible Che kda Hose Port for on newer Vacuum Advance models Linkage Adaptor Bracket amp Ball Stud Nut Passenger Side Linkage 4 Next check the adjustment and full operation of Driver s Side Linkave inicasetoward 4c Throttle the carburetor acceleration linkage Drawings are Not to Scale Carburetor Grommet at Gl 4a Check the 3 gas pedal to firewall mounting y firewall gt amp screws are tight 4d Adjust oe t tt i _ 4b Ensure the ball and socket fittings on the link Throttle age are cleaned and lubricated check for missing Control Rod hege pp Rene spring clip retainers j b 4c Clean Spring 4c Check that the two throttle grommets on the i and lube rod 4b Spring firewall are present clean and greased p s pa gt a p clip attaches 4d Adjust Throttle Control Rod so that carburetor Automatic g 4a grommet i rod end to linkage is fully opened when the gas pedal is floored Transmission Ga in the firewall 3 Fac a NOTE If equipped with an automatic transmission ee ee Pedal Pn the also adjust the Kickdown detent cable See Opel SCIEWS fender b if equipped Attaches to Carburetor factory service manual for instr
19. to 1970 1972 type distributor but uses a square hole in casing for condenser wire A round hole type condenser will fit in this distributor but breaker plates and vacuum canister are not interchangeable with 1970 72 housings This model can be modified with experience and skill to full mechanical advance using parts from Bosch VW A009 distributor 1975 type Originally installed only on factory fuel injected 1975 Opels Features internal P o o o mechanical advance retard only vacuum port and unique ignition points set to 016 gap T p Sometimes installed on Opels modified with dual side draft carburetors which do not have Z l ported vacuum fittings for the vacuum advance or vehicles with high lift camshafts producing irregular vacuum No performance gain if you use it on a stock engine i Round or uae Doe 1970 72 and ALL Distributor Models require maintenance Place drops of oil onto the felt Need to look here 4 to verify ed a in the center of the top of main shaft to help keep mechanical advance adequately which type lubricated Lubricate the points rubbing block and cam lobes with ignition lube Retard Advance There are slight variations in advance profiles between various distributor models see number on housing to verify applications Also periodically disassemble clean amp lubricate surfaces between the internal breaker plates and on the main distributor shaft lobes ALWAYS clean distribut
20. uctions Weber Carb Lean Idle Adjustment Method at home idle Speed Adjustment Screw Run the engine until it is warmed up and the choke is fully opened and disengaged Rotate the Idle Speed screw counter clockwise until tachometer reads about 600 700 rpm s as low as it can idle with the engine still running Next rotate the Idle Mixture crew 3b also known as the fuel mixture adjustment screw clockwise until the engine runs rough Next turn the Idle Mixture screw counter clockwise 1 2 to 3 4 of a full turn so that O j Aja k a Idle Mixture Screw 3b the engine again runs smoother Next increase the idle speed by rotating the Idle a Pr At T dta Speed Adjustment Screw Speed screw clockwise Most Opels Factory idle speed setting is 850RPM but most wie owners adjust their idle between 1000 1100 RPM cin E smc Note Too High of an idle speed will engage the distributors mechanical advance i gt View is from the windshield affecting ignition timing area where carb linkage is Note Above procedure is for home Exact Fuel Mixture adjustment is performed at a shop Additional Weber Carb Notes Setting Choke The choke is adjusted by loosening the three screws on its ring then rotating the choke clockwise for less choke and counter clockwise for more choke Note The Fast Idle Speed screw is located behind the choke itself and can be adjusted to increase or decrease the fast idle rpm A good fast idle speed w
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