Alfa Romeo Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
151 Posts
Discussion Starter #1
My '74 GTV is a bit low on power. Engine compression is an even 150psi across all cylinders. Plugs look a bit rich. Idles fine though. What would be some of the typical reasons for low power during acceleration? Timing, injection pump? Not sure where to start.
 

·
Registered
Joined
·
52 Posts
I'd also adjust the fuel mixture. An overly rich mixture will affect power. When I first bought my car it was running very rich although the plugs didn't look too bad. It really came alive when I adjusted the injection system.
 

·
Registered
Joined
·
7,166 Posts
adjusted the injection system.
If it has Spica injection, that is not something you just get a screwdriver and start tinkering with.
 

·
Registered
Joined
·
7,166 Posts

·
Premium Member
Joined
·
5,474 Posts
SPICA pumps are NOT hard to tune - just different than carbs. The key is to use a very methodical approach to the tune up. The write ups by Roadtrip noted above are excellent and need to be studied carefully. There is also a document that was available from the Oregon chapter AROC that is an also an excellent step by step guide. Lately I have not been able to find it online and can't get my hands on my hard copy. If I find time this weekend I will find it and post.

I am at a point where I much prefer the logic (both figuratively and literally) of a SPICA system. Carbs seem to be much more of a black art because there are so many options available. Whereas there is not a lot can/should be fooling with. Once set up it is smooth and reliable and cool as heck!!
 

·
Registered
Joined
·
4,160 Posts
My '74 GTV is a bit low on power. Engine compression is an even 150psi across all cylinders. Plugs look a bit rich. Idles fine though. What would be some of the typical reasons for low power during acceleration? Timing, injection pump? Not sure where to start.
The first thing to do is a complete, start to finish, tune up. Start with new plugs then, as Pappajam suggests, make sure your points/dwell/timing are set, then move on to the fuel injection. As others have noted Spica injections aren't very hard to adjust. There are some good publications that will explain the process. Once you know what to do, it isn't very hard at all.

One thing that would really help in getting your mixture right is a Colortune. It's basically replacement spark plug with a clear top which allows you to see the combustion event. It's a good tool for setting idle mixutres with an injected motor. I got mine a number of years ago from the UK, but I'm sure they must be sold here in the States too.
 

·
Registered
Joined
·
77 Posts
Steve,

The distributor was pulled to properly set the gap and while the shop that did it is not a Alfa specialist, the owner is a pretty sharp guy. My suspicion was overly rich, especially looking at what's sitting on the new tail pipe, I just never got around to trying to diagnose. While the car was in my ownership I never tinkered with the SPICA, so a good tuneup would probably help.
 

·
Premium Member
Joined
·
21,373 Posts
When dealing with the dist, make sure the advance mechanism is free and working smoothly. It can freeze up over time from corrosion and old grease, etc. You can tell if it's working with the timing light; if the timing marks don't move as you open the throttle, you've got no advance. Failure to advance completely kills the power, though it will seem fine at idle.

Andrew
 

·
Registered
Joined
·
3,585 Posts
Giuliaguy, Is this a change in the way your cars operates, or has it always been this way? As others have noted start with a tune-up, Be systematic Points, condenser, cap, rotor, plugs, wires, they all need to be checked, set the ignition timng, does the advance work? Has the cam timing ever been checked? How about the valve clearence? Now to the SPICA, do you have a properly operating cold start solenoid? could it be mis-wired and always on? Is the themo-actuator appear to be working? or does the car have a Shankel Sure-Start? Could it be stuck on? Get all other variables set correctly before messing with the SPICA settings and check all the ancillinary SPICA functions before altering mixture and don't touch the linkage except as a last resort or to synch with a new thermo-actuator (if your isn't visably working) My $.02
 
1 - 12 of 12 Posts
Top