A few years ago I had the DCOE Webber carburetors on my Giulia Sprint GT re-jetted because the mixture was too lean at low revs (2000 – 3000) and the car was running very poorly in this range.
The new jets greatly improved things but the tuner warned me that the car was now running too rich at high revs.
I recently took the head off to put in a new gasket and it took me a fair while to clean the carbon deposits from the ports. I decided to take the car back to see if a compromise could be found that would make the mixture a bit leaner at high revs.
After looking at the car on his dyno the tuner decided that this was not possible and that there was something fundamentally wrong with the car. He suggested that the cams might not match the block or that there are too many mufflers (i.e. 1 in the middle and 2 at the rear).
I know a fair bit about the history of this car and I’m pretty sure the block is original. The number on the cams is: 10 502 032 000 1, perhaps someone on this forum knows if they are the original specification? Ditto for the mufflers?
Up until now I have tended to view this problem as a design limitation of the car which I can live with. I rarely rev the engine over 4000 rpm possibly because if feels a bit rough beyond this point and doesn’t seem to produce any additional power (the tuner says the power actually drops away). I’m also not sure how much of the carbon in the ports was produced by the larger jets.
If however something can be done to fix it I would be very pleased.
Any suggestions would be welcome.
The new jets greatly improved things but the tuner warned me that the car was now running too rich at high revs.
I recently took the head off to put in a new gasket and it took me a fair while to clean the carbon deposits from the ports. I decided to take the car back to see if a compromise could be found that would make the mixture a bit leaner at high revs.
After looking at the car on his dyno the tuner decided that this was not possible and that there was something fundamentally wrong with the car. He suggested that the cams might not match the block or that there are too many mufflers (i.e. 1 in the middle and 2 at the rear).
I know a fair bit about the history of this car and I’m pretty sure the block is original. The number on the cams is: 10 502 032 000 1, perhaps someone on this forum knows if they are the original specification? Ditto for the mufflers?
Up until now I have tended to view this problem as a design limitation of the car which I can live with. I rarely rev the engine over 4000 rpm possibly because if feels a bit rough beyond this point and doesn’t seem to produce any additional power (the tuner says the power actually drops away). I’m also not sure how much of the carbon in the ports was produced by the larger jets.
If however something can be done to fix it I would be very pleased.
Any suggestions would be welcome.