Weber velocity stack length

Full Throttle Al · #1 (**permalink**) 08-07-2011, 07:20 PM

As I recall, more than 20 degrees, I think in the 26 degree range. I'm sure you've done this but any chance fuel pressure is higher than the suggested 2-3PSI for Webers or that the floats are set too high? High pressure fuel pump?

Full Throttle Al · #2 (**permalink**) 08-07-2011, 07:24 PM

Full throttle would be too much in this car, motor dyno'd with 629HP in 1967 with a single 560cfm Holley, more now. I have it rev limited at 6500 and the throttle limited to 3/4 throw to prevent sudden death, to the engine, car or occupants!

Car just won Best of Show at the Tulsa Shelby Meet in June, an unexpected honor. I hadn't even cleaned it up from 2 days on the track.

lemans24 · #3 (**permalink**) 08-07-2011, 08:05 PM

Jim Inglese says 38 degrees full advance on the timing. If you have a digital MSD, you might need a separate battery to power certain types of timing lights that will give a unstable reading.(per MSD Tech support)

Eljaro · #4 (**permalink**) 08-08-2011, 04:50 AM

Quote:

Originally Posted by Full Throttle Al

As I recall, more than 20 degrees, I think in the 26 degree range. I'm sure you've done this but any chance fuel pressure is higher than the suggested 2-3PSI for Webers or that the floats are set too high? High pressure fuel pump?

I suspect the timing here has something to do with the excessive heat and maybe also with my engine running rich no matter what. If I go down with the idle jets the engine starts spitting, but the A/F gauge keeps saying rich.
I am at 20º advance at idle now, max is 38º. Will try to go up with the initial advance, as I suspected you are over that figure.
I will turn the distributor for more advance and watch at the same time the A/F ratio gauge to see if something changes. Maybe there is something interesting there.
Initial advance with the Holley was factory set at 12º and the engine was always dieseling and getting rather hot. I never got to change the advance when I had the Holleys, but I am sure the cure for the dieseling would have been more initial advance.
Maybe these aluminum engines with these roller camshaft just need lots of advance to run well.
I will also check the maximum advance over 38º, fitting a stethoscope to the heads and drive to hear at which max advance the engine starts pinging.

Will try it out this week.
In the meanwhile the wider scoop is ordered and so I will get the clearance issue done with.