I am putting an Edelbrock package in my 78 with a 350 that will include aluminum heads,  new intake and cam etc.  One of the mechanics asked me about the vacuum with these upgrades.  I have read quite a few post about these sort of upgrades and do not remember seeing any comments about needing to make special modifications for vacuum.
Should I expect any vacuum problems?  He seemed concerned that I might lose vacuum needed to run the brakes and headlights.
Thanks for any help.
 

That's going to depend on the amount of duration, and overlap, the cam has. If you put in a cam with a lot of duration, like anything over 240-260deg, vacuum is gonna suffer a little. If you go wild, and go 280-300deg., vacuum is gonna be non-existent.
The longer the intake valve is open(duration) during the intake stroke of the piston, the less vacuum the engine is capable of making.
You may need to get an extra vacuum reservoir, to have enough to run all of the vac. stuff on a Shark car, but it all depends on the cam.
There are also vacuum pumps that can be installed, if needed.

Thanks for the info.
I'm new at this so if you don't mind which measurement do you use to judge by the duration at .006 or .05
Here are the numbers for the cam

Duration at 0.006" Lift:	Intake: 278°	Exhaust: 288°
Duration at 0.050" Lift:	Intake: 204°	Exhaust: 214°
Lift at Cam:	Intake: 0.280"	Exhaust: 0.295"
Lift at Valve:	Intake: 0.420"	Exhaust: 0.442"
Timing at 0.050" lift:	Open	Close
Intake:	5° ATDC	29° ABDC
Exhaust:	44° BBDC	10° BTDC
Centerlines:	Lobe Separation - 112°	Intake Centerline - 107°

If I look a the duration at .006 I will probably be in trouble.
Appreciate your thoughts.
Thank you

Most duration numbers are taken/advertised @ .050", so you should be otay. It will have a little "lope" to it, but not enough to drastically effect vacuum. The cam doesn't really have a lot of life(comparatively speaking), so it can use the extra little boost from the extended duration. Looks like a pretty good choice. I'd recommend at least a 9.0:1 compression ratio, to really make the cam useful. So, depending on the chamber volume of the heads, the gasket thickness, and the pistons you're starting with(stock/original?), it might work out pretty close to that.

I'm going with the Edelbrock E-Tec heads (vortec) with 64 cc runners - supposed to produce 9.5:1 plus using fel-pro gaskets and matching intake, so expecting to pep up the L48 a bit.
Also adding a new distributor, carb and MSD ignition, and roller rockers.
Thanks for the  info.  This forum has helped me big time.  I just hope I can learn enough someday to help someone else.
Thank you

Ever think of converting lights from vacuum to electric?

If you have that link I'd like to read that article.
Sounds interesting.
Thanks