My Dino has developed an issue over the course of my 2,500 mile journey to Maranello and back. When I accelerate, it coughs and splutters below 3,000 rpm, then clears its throat usually by about 4,000, and accelerates cleanly thereafter, though occasionally a slight misfire continues up the rev range. It also does a lot of popping and banging on the overrun. Prior to the trip, it had new plugs, leads, coils and Dinoplex and was running fine. Any thoughts?
Sounds like a blocked idle jet or two, the main jets kick in at around that rev range and if you accelerate hard then the accelerator pump jets are masking the problem. Popping and banging on the over run is a sign of lean condition. (exhaust or through the carbs?) Could be plugs but you say it clears above 4K Tony
Real misfire is most of the time ignition related and a surging loss of power carburettor related. With what kind of coil has the original one been replaced? Is it still the original AEC103 dinoplex? Still running on points? Sent from my SM-A320FL using FerrariChat.com mobile app
Yes, that's why we concentrated on the ignition system (this condition had surfaced before) and all seemed to be OK. New "dinoplex" is the current Superformance offering, described as "Direct replacement for Original AEC 103A system". Still using points and I have tried it on both coils - electronic / points. Makes very little difference (other than loss of rev counter!).
I have of necessity been running on different fuels. Mostly 98 in France and 100 in Italy, and one tankful of 95. No noticeable difference.
I’d also bet on a blocked idle jet. In any case, easy to check and clear out. Also having the right coil when you go directly from coil to points bypassing the CD box makes a huge difference. I use a Pertronix 40511 (3 ohms) for both the CD coil and the emergency coil as per recommendation of Fred Winterburn. https://www.summitracing.com/parts/pnx-40511
Along with checking the idle jets to see if they have any obstruction, I would check it with a coil such as the Pertronix 40511. It doesn’t require a ballast running directly to the points. Fred Winterburn was very specific about the spec when he recommended this to me. This would give you some evidence if it’s the Dinoplex giving an issue. I would also check all the ignition leads and put dielectric grease on the contacts going into the coil, distrutor cap and plug connections. I would also remove the plugs to see if they’re clean or fouling. I run the NGK BPR7EIX Iridium plugs. I like the way they run. Never fouled. Checking the points would be next on my list. I’m not a mechanic but this has helped me in the past. I bet your problem is small and can be cured by simple problem solving.
I’ve been dealing with similar issues recently. With the help of people here I’ve been eliminating things. New plugs and wires Cleaned idle jets....no apparent blockage Performed compression testing.....very consistent numbers Sprayed a load of carb cleaner down the barrels.....it loved that ! I’m convinced mine just needs the carbs adjusted. It only has issues below 4,000 and may be better now after cleaning the idle jets. I’ve only run it in the garage since. Working on getting my mechanic to adjust the carbs soon. Good luck on the journey......
If you have access to a distributor testmachine i would just test your distributor. In that case you'll know for sure whether the points/advance etc. etc. are functioning properly. If the problem occurs both with the 'dinoplex' as well as with the normal points setup than it's quite possible you have a problem with the points setup. The points setup with the Superformance replacement dinoplex is also a bit more sensitive to how the distributor is set up than with the original dinoplex ignition. The superformance replacement dinoplex ignition is a transistor ignition compared to the original dinoplex ignition which is a capacitive discharge ignition. The transistor ignition relies on correct dwell setting of the points where this is not an important factor with the capacitive discharge ignition. This means that in the real world you can only set up these dual points distributors correctly if you have a distributor testmachine. It's indeed also a good idea to check if your idle jets are not blocked.
I would highly recommend the Winterburn CD ignition with the Pertronix 40511 coil for a points system. I also replaced my emergency coil with the same as it functions w/o a ballast and is the correct 3 OHMS. I sourced the correct male/female plastic connections for a true replace and plug in. If you go with the Winterburn, I’d be more than happy to send you a set of connectors and which wire goes where. Super simple to set up and is a true replacement for the Dinoplex. I’m not a mechanic or electrician. If I can do it, you can do it! Fred Winterburn posts here and is a huge help when it comes to the original points system and will dispel a lot of myths. His father, Lloyd Winterburn was a pioneer in CD ignition https://www.linkedin.com/pulse/unsung-motor-industry-hero-fl-winterburn-his-capacitor-nicholas-gomez Freeman
Thanks, Freeman. Having just replaced virtually the entire ignition system, I am loth to resort to further replacements, as it really should work OK (it did before it went in for service a couple of months back!). I am coming around to the view that maybe it is not the ignition system that is the culprit and that we need to look at the carburettors. I have booked my car in for some attention when I get back to the UK the day after tomorrow, and we'll take it from there.
Freeman, I just purchased a’74 246 GTS and am experiencing the same misfire issue. Based upon the comments here I contacted Fred Winterburn and have purchased one of his units. I’ve also ordered the Petronix coil. Fred mentioned that the Ferrari wires aren’t color coded the same as his are. If you’ve already gone through the process any pointers would be appreciated including what wire and male female connectors you recommend. Best, Mark
John, I understand. BTW, Fred sells the Winterburn CDI for around $400 and the coils are $30 each. He hand makes each one. More of a hobby to support the enthusiast than a business. Good luck! Freeman
Mark, Of course. PM me with your contact details. Adrian created a wiring diagram for me to convert the Winterburn colors to the Dino wire colors. It was Adrian that originally pointed me in the direction of Winterburn some years ago (Thank you Adrian!). Maybe he would be kind enough to post it and the variations through the model years and country specs. I think there are a variations of the loom for different years and country specs. As an example, my car 03932 is an Italian spec. Shawn and Francis have the car directly before and after mine and are US spec and French spec! So much for production efficiency! If you can, take some photos of the loom and connectors connecting your CD ignition system. Between Adrian and Fred, you’ll get pointed in the right direction. Freeman
This ight be worth checking if it applies. A friend had misfires at certain rpm/speeds in a Trans Am (‘76?). . It was due to a partially broken wire beneath the points mounting base plate, which would break connection when timing advance actuated by pulling the base plate in the direction of the actuator. This plate movement caused the opening and closing of the fault resulting in the misfire. His however, ran well at lower speeds and broke up when it called for an advance of timing. I ran the symptoms by a mechanic friend over the phone. He came by and removed the cap,and base plate and showed us the broken wire.
normally a leaking exhaust gasket at the manifolds will cause this or a vac leak on the induction side but that tends to show up on idle tick over. Don't think its ignition related as you said it clears above 4K, the modern points for these cars are rubbish and the heel tends to wear rapidly so after a long run to Italy the points may have altered slightly. You need to check carbs and timing together. Tony
Tony, I noticed that my PCV valve flapper and cage are missing, but the two small hoses from the valve to the intake manifold are still in place. What symptoms would this missing flapper cause ? Thanks Skipp
