The Alfa Romeo GTV6 is not an ordinary car, and some of its mechanical components have a bit of an enigma surrounding them. One of these features is the mysterious markings on the crankshaft pulley used for ignition and valve timing. It is essential to have a perfect understanding of these marks, or you can get into trouble, so stick around.
While most cars use numbers or hashmark either on the crankshaft pulley or timing cover to verify engine timing, the Alfa GTV6 uses a confusing bunch of letters. On top of that, depending on if you have a US or Euro-spec car, only some of these letters coincide. So if you don't realize you are using a Euro-car repair manual or a North American manual, you can get screwed up. Fear not; we'll help decipher these letters like a pro.
Looking at the crank pulley on a North American GTV6, you will see R, F, P, and M etched into the crank pulley. This differs from Euro-spec cars that just have P, F, and M.
The letters correspond to the following Italian words:
- R - Ritardato or Retarded
- F - Fisso or Fixed
- P - Punto or Point/Dot
- M -Massimo or Maximum
Above the crank pulley, there will be a pointer on the front engine flange that you line up to these letters.
Early Alfa GTV6 Timing Mark
On a 1981 -mid-1983 North American GTV6, the marks correspond to:
- R- 5° +/- 1° ATDC (After Top Dead Center)
- F and P - TDC (Top Dead Center)
- M - 26-29° BTDC (Before Top Dead Center)
Base ignition timing at the 800 -1000 rpm idle with the distributor vacuum line connected should be at the R mark (or 5° +/- 1° ATDC). Note, with the vacuum hose disconnected, timing will advance to the P (TDC) mark.
Timing at 5,000 with the distributor vacuum line disconnected should be at the M mark ( 26-29° BTDC).
Late Alfa GTV6 Timing Marks
On some late-1983* and newer North American GTV6, the marks correspond to:
- P - TDC (Top Dead Center)
- F- 2° BTDC (Before Top Dead Center)
Cars from about late-83* and up use the Bosch EZ-L digital electronic ignition system where you just set initial advance. The distributor's internal centrifugal advance mechanism is eliminated and combined within the electronic control unit. In addition, a vacuum advance capsule boosts part-throttle performance and fuel economy during part throttle operation.
Initial ignition timing at the 950 +/- 50 rpm idle speed with vacuum hose disconnected is 2° BTDC.
European Alfa GTV6 Timing
- P - TDC (Top Dead Center)
- F- 7° - 10° BTDC (Before Top Dead Center)
- M - 28-31 ° BTDC (Before Top Dead Center)
The European GTV6 ignition system is similar to the early North American car's setup. Different initial timing, advance curve, and the elimination of vacuum retard are the main differences.
Base ignition timing at the 850 -1000 rpm idle with the distributor vacuum line disconnected should be at the F mark (or 7° - 10° BTDC).
Timing at 5,000 rpm with the distributor vacuum line disconnected should be at the M mark ( 28-31 ° BTDC).
Alfa GTV6 Top Dead Center Mark
P - TDC (Top Dead Center)
The P mark on the crank pulley corresponds to TDC on all GTV6 models.
Timing Mark Degreeing the GTV6 Crank Pulley
If you own an Alfa Romeo, you likely enjoy modifying and trying to improve its performance. If you are doing an engine mod, accurately knowing the crankshaft degrees during an event like ignition, valve opening/closing, etc., is vital. With the marks you have on the crank pulley, you can figure out the distance of each degree and mark them off. For example, on my North American 1982 GTV6, every degree is approximately .040" or 1.016mm apart.
I have a European distributor installed in my car and want to time my engine at 10° BTDC. I simply measured the distance between P and R (equals 5°) on my crank pulley and came up with approximately 5mm. So, I placed 2 marks 5mm apart BTDC, corresponding to 5° and 10°. Simple. You could do that all around the crank if you desire.
* Documentation shows 1983 50 State (California) emission compliant GTV6 models came with the late ignition systems.
a.jpg "81-83 Alfa GTV6 Timing Marks")
a.jpg "Alfa GTV6 Crank Markings")
