People I will tell my story how it started, in February 2011, I replaced a lot to my car 1. camshaft seals 2. valve cover gaskets 3. tuning fork 4. replace belts 5. compression measured (okay) 6. cilinderlek test carried out (okay) 7. carb adjustment 8. ignition adjustment 9. valves had been checked (okay) 10. 8x new spark plugs bosch platinum car would run fine. 8 Mar 2011 / when I got the following problems; 1. high speeds (from 4500/5000 and higher) content and stuttering 2. during normal driving (constant speed urban road) pop / thud from the exhaust. Back to the garage and was established the following; 1. 1x weak coil replaced coil with 2 new ones 2. 2x spark plug extenders worn out so i bought a complete new wire set but the extenders are backordered and are now still NOT on). 3. ignition points replaced 4. 2x condensators were replaced in the ignition (I have 2) 5. I believe ignition timing set at 42 degrees or 43 degrees instead of 39 degrees (because it would run better) the car would run perfectly; I go get it yesterday and yes he was perfect, came back nicely in the high rpm range without problems. But three hours after having driven a setback again today; 1.When stop (idle) the car would turn off 2. during normal driving (constant speed urban road) pop / thud from the exhaust 3. stuttering and content acceleration from standstill to 2000/2500 rpm, above rpms are a great. You understand that ... I'm tired, I can go back to the garage to return April 11 to investigate what is going on .... pfffffffff Any ideas?? Thanks for the help!
Hi Micha, The joys of points ignition! I too had my fair share of this and could be many things but in the long run will be something simple, the chore is finding it. Are your plugs correct? is there dampness in the ht leads at the plugs? (this causes havoc) Have you replaced the ht leads? (old ones go soft with heat) Are your condensors ok? (try changing them) Have you got the correct ballast resistors? (make sure your coils support them) Is your dwell set correct? Is your distributor pins clean? Have you changed to a new rotor arm? (expensive marreli replacement but made a difference) Im only suggesting these because I had many problems with mine and almost changed everything which made a massive difference. Next year I plan to (carefully put all my origional ignition stuff into a box) and go electronic ignition from superformance
Did the 77 GTB's come with Thermo Valves?Your symptoms sound like what happened to me,I was Cleaning the engine when i must have knocked off one of the Connections to the Thermo Valve.Started the car ran to it's usual 2500 rpm,when the Engine got to Runnunig Temp the RPM's went to 4000,I shut it off. Looking around I found i had knocked off one Connector,Restarted the car it went to Idle at 1000 Rpm had no more problems.Again I Don't Know If the 77's have this valve,i don't have a shop manual on that year.
Just a few random thoughts on this -- Did you check the distributor caps and rotors? If your caps and rotors are old, they can develope cracks, which can cause problems as the car heats up. Even a very slight hairline crack can cause ignition problems. Did you change the rotor, but not the cap? If so, they may not be compatible. Check the fit and make sure the clearance is proper. Check the rotor. Some of the "new" rotors out there are made very poorly. They can be loose on the shaft. Also, the blade on the rotor can shift around and give intermittent contact/spark. I've had this problem with my old Jaguar XKE. The after-market rotors suck, to put it mildly. I had to go with OEM rotors to fix ignition problem. I finally gave up and installed a Pertronix in the old Lucas distributor which fixed the problem permanently. Check the rod in the top of the cap that makes contact between the cap and rotor for the coil lead. If it is worn, or if you changed rotors to a non-OEM rotor, you may not be making good contact. It is also possible that it is not sitting right or is just worn and needs to be replaced. Did you do anything with the carbs? If you adjusted them, cleaned them, changed the jets, or anything else, you could have created a problem. Check to make sure you don't have a stuck float on one of them. Just be really careful when you take the filter housing off that you don't drop one of those little grommets that sit under the filter housing down into a carb. That will ruin your day really fast. So, let us know what you find as you go forward with this. Old rule of thumb when troubleshooting old cars like this -- if the car was running fine BEFORE you did something, and a new problem arose AFTER, don't assume it is something new. Go back to what you just did and most likely, you'll find the problem in what you just did.
Guys, Thnx for your help. Now Saturday the car is going back to the garage and i will give him this information. I will keep you informed what the problem could be. Greetings Micha
Micha, My GT4 had 1 set of points where the little contact came loose in the moving arm.It was like a rev limiter it would pop and backfire at about 5500 rpm and not rev past that.I replaced both sets of points and still wasn't quite right.Then an ex racedriver and 308 owner told me he could never get plugs to work correctly after they had fouled no matter how he cleaned them.I put in new plugs and instant success.I now run Pertronix and Iridium plugs and its a different car altogether. Ken
Guys, The problem is in the carbs. They will have to be revised. I will do this in the winter. Thanks for your input! Greetings Micha
What COLOR is the wire on the point sets? White, or, Black? Are/were they delivered in a sealed bag, or, a sealed package/on a cardboard card which SAID in BOLD lettering: Marelli? If Black wires, sold in a heat sealed bag.... this is the problem.... new ones MIGHT last 2-300 miles???? {PS-once unleaded fuel has fouled a plkug, it will NEVER fire properly again...ever...lab proven...see SAE article on web somewherer, interesting reading, its from a tech brief as part of a fuel additive for the CARB in a patent app!} That is what I am seeing...and hearing from other practitioners of the trade... FWIW....black leads are made in.... China....
