vac advance or not for FE Cobra

Luke427 · #1 (**permalink**) 07-03-2016, 04:39 PM

I've never worked on FEs before my current 427 but from 4 to 12 cylinders even race engines I've always found vaccum to be an advantage.

Some says there's no difference between vaccum and not, particularly on track cars. I challenge this especially on powerful engines - when driver maintains engine mid-range during a curve before the throttle gets hit WOT for the straight. The well timed ignition system - so vaccumed in our case will have more linear response ensuring a progressive power curve thus better times

Once we tested same track same driver with and without vaccum.
Driver thought his times were better without, it was actually the opposite.
No vaccum compensated advance will increase the feeling of kick in the bottom thus make the driver believe it's more powerful. Don't be fooled

Luke427 · #2 (**permalink**) 07-03-2016, 04:43 PM

Btw i'm replacing the current pertronix with a stock recurved Ford distri with vaccum. Will share results if anything tangible can be measured...

lippy · #3 (**permalink**) 07-04-2016, 07:51 AM

I use an MSD programmable 6530 with a MAP sensor to give me the adjustability of a vacuum advance and even more flexibility. I like vacuum. Better light load response and fuel mileage plus a cooler engine.

Grubby · #4 (**permalink**) 07-05-2016, 06:31 PM

Lippy,

Was the MSD unit easy to program? For a street driven Cobra, does it offer any additional flexibility over a distributor with vac advance?

Can you give us an idea of how much advance you are adding using the MAP sensor?

It sounds like a pretty good product, but I have no experience with anything like it.

John

lovehamr · #5 (**permalink**) 07-07-2016, 11:37 AM

Quote:

Originally Posted by lippy

I use an MSD programmable 6530 with a MAP sensor to give me the adjustability of a vacuum advance and even more flexibility. I like vacuum. Better light load response and fuel mileage plus a cooler engine.

Same thing I did on my last Cobra. Locked the dist @ 35 degrees which is where it made the most power on the dyno, then used the MSD box to retard when necessary. Had it mounted right under the passenger side dash with the serial port facing down for easy access.