for Lamborghini Enthusiasts

Vintage List Email Archive Search - Message Detail

Previous  Next





[VintageLambo] Re: My Jarama quit running, any ideas?


Body of Message

This will be a short test. Get a tee handle thin wall plug tool from Sears. Remove and mark all plugs. If they are ALL dark, almost black, you generally have a spark problem, if some are dark, it may be related to carb float levels. Attach a new RN7YC or equiv plug to the wire on the drivers front ignition wire. Set the plug on the cam cover so the base is grounded. Insure the fuel is connected to the rails, and have someone turn over the car while you watch the new plug. It should be a BLUE spark, if not, you will have to mark and remove the distributor to check the point gap at .35-.40mm for all FOUR points. Do the same test for the pass side bank. If one is blue, and one is not, it could be a bad coil, points(2), condenser, or ballast resistor. Test each with a voltmeter working from the ballast (12V one side 9V other), to the coil + to the coil - (pulses while engine is turned over). Key off, Set meter to ohms, remove cap and rotor, using a mirror, gear-bump around so that two set of points are open. Now black meter lead to the dist housing, and red lead to a condenser, it shouldcharge quickly for a second the slow down it"s charge. Verify other condenser, after bumping other set of points open. Find NON-internally-ballasted coils from Napa or something and try it with the new coil. Spark at the plug should be BLUE, not gold or yellow.Leave the plugs OUT. Attach a batt charger on low, remove the wire from each ballast resistor (either wire). Block the throttles all the way open. Remove the air cleaners. Turn on the key, listen for the fuel pump wobble or tick. If you have a new style pump it may hum. The sound should be rapid for 20-45 seconds as the carb bowls fill. Then the sound should taper down as they become full, and no more fuel is required. If the Jarama has a return line (I think not in 1971), the sound will remain the same as fuel is going back to the tank via the return line. DO NOT remove anything from any carb yet. Using the mirror, look into the carb throats for fuel running down the intake, or fuel running out the top of the carb vent. Turn over the engine and check for fuel sloshing out the plug holes, if so, get it all out before putting the plugs in. Reattach the ballast wires. Smell the plug holes using a 12" x 1/2" heater hose. You will be able to smell a fuel smell, it should not be overwhelming. If two adjacent cylinders smell a lot this is an indication of fuel entering the cylinders. Shut off the key. Replace the ballast wires. If any carbs are out of float adjustment have a competent mechanic set them between 8.5 to 15mm for the 20/21 carbs, and 9.5-18mm for the 22/23. Since your car was running for quite awhile, we can rule out cam timing/chain problems. But, being that it was recently rebuilt, I would check the intake nuts being tight (use a 13mm 1/4 drive universal socket from Snap-On), and also once the engine starts, insure that you have exhaust gasses coming out of both pipes without restriction. Remove and block off the vacuum line from the left front of the intake to the brake booster canister. The car will not have power brakes now so be careful. Check the line for brake fluid, there should be NONE. if there is any brake fluid in the vacuum line, don"t reconnect it as the brake fluid will wash the cylinders down, and your new engine will fail very soon (I know). Check that you have to add brake fluid often, if so, rebuild or replace brake boosters. Summary: Likely coil, ballast, or condenser failure on temp rise. Points getting too small gap to charge coil adequately. Blocked exhaust due to excess unburnt fuel in system (should be black smoke). Massive and increasing vacuum leaks from intake or brake booster. Plugs will tell the story, should be dark tan to light brown depending on mixture. Write off list if you want more detailed instructions (mirror "@"<


Previous  Next


Information provided by members of the Vintage Lamborghini Group

Maintenance Techniques included in these pages should be attempted by a suitable qualified person only.

No Liability is accepted for errors or omissions!

Last modified: 12th January 2020