Rotor DAC2745 vs. JLM9624
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Senior Member
Joined: Mar 2010
Posts: 256
Likes: 77
From: Hodonin, Czech Republic
Rotor DAC2745 vs. JLM9624
My long long way to the happy idling 
After changing and refubrishing V12 engine I got refubrished distributor from one company in UK. All right, I can start. YES works. But idling is bad, it seems, that some cylinder(s) are not working.
So : new pump. new fuel presssure regulators, cleanup injectors, new injectors, new sparks, new ignition cables, new coil, new amplifier, new AAV, cleanup and setting overrun valves, all new vac lines, test and stop air leaking. A lot of money and result was the same as in the begining. RPM from 400 to 800, intake manifold pressure from 5 to 11. The last idea was the refubrished distributor. After openning I take off rotor. And start search new one. BUT my rotor (I have 12 teeth circle and Hall sensor (Lucas), had opposite end with MAGNET. And was for other version of ignition (with 12 small coils on PCB). It was DAC2745.
I bought new WITHOUT magnet - JLM9624. I put together distributor, start engine and voila - stable 750 RPM, intake manifold pressure stable 11. No bad idling. On the fuel rail stands the coin now. Not long, but stands.
Resume: BAD rotor fitted by profesionals. When the magnetic end was moving above Hall magnet (which make signal for ampilifier, coil and spark), sometimes cancel Hall process of creation of signal. And some cylinders were without spark. When RPM was high, it was not so critical, because magnet was moving above Hall sensor fast and could not cancel making signal for amplifier.
Uf. One advantage. I have all critical parts new or checked. And good feeling of finding a bug.
After changing and refubrishing V12 engine I got refubrished distributor from one company in UK. All right, I can start. YES works. But idling is bad, it seems, that some cylinder(s) are not working.
So : new pump. new fuel presssure regulators, cleanup injectors, new injectors, new sparks, new ignition cables, new coil, new amplifier, new AAV, cleanup and setting overrun valves, all new vac lines, test and stop air leaking. A lot of money and result was the same as in the begining. RPM from 400 to 800, intake manifold pressure from 5 to 11. The last idea was the refubrished distributor. After openning I take off rotor. And start search new one. BUT my rotor (I have 12 teeth circle and Hall sensor (Lucas), had opposite end with MAGNET. And was for other version of ignition (with 12 small coils on PCB). It was DAC2745.
I bought new WITHOUT magnet - JLM9624. I put together distributor, start engine and voila - stable 750 RPM, intake manifold pressure stable 11. No bad idling. On the fuel rail stands the coin now. Not long, but stands.
Resume: BAD rotor fitted by profesionals. When the magnetic end was moving above Hall magnet (which make signal for ampilifier, coil and spark), sometimes cancel Hall process of creation of signal. And some cylinders were without spark. When RPM was high, it was not so critical, because magnet was moving above Hall sensor fast and could not cancel making signal for amplifier.
Uf. One advantage. I have all critical parts new or checked. And good feeling of finding a bug.
Joined: Feb 2010
Posts: 28,785
Likes: 11,265
From: Adelaide Stralia
Well done.
Doug is correct, that magnet rotor is for the PreHE EFI engines.
Sadly, the "experts" do lack old style info at times, and the 'looks like am Duck, quacks like a Duck, must be a Duck" mentality creeps in.
Good for another 20+ years now.
Doug is correct, that magnet rotor is for the PreHE EFI engines.
Sadly, the "experts" do lack old style info at times, and the 'looks like am Duck, quacks like a Duck, must be a Duck" mentality creeps in.
Good for another 20+ years now.