I'm trying to figure out if I'm missing something in my timing.
I have a 1974 318 .030 over with Kieth Black kb167 pistons that are .005 down in each bore, Cam is a Comp XE268H setting straight up, heads are stock 360 milled to 64CC with a stock gasket Summits calculator shows about 9.58:1 compression. My cranking compression is 145 to 150 on all cylinders and I'm losing from 3 and 5 psi all past the rings on a 100 psi leak down across the cylinders. I just installed a new Quick Fuel 600 CFM carb on the Edelbrock 2176 performer intake which is working real nice right out of the box. The dizzy is a billet with with 20 degree mechanical advance (no vacuum advance)

The only thing that bothers me is with the timing set at 16 BTDC it starts nice and idles ok but I'm only getting 15 inches of vacuum at 950 rpm's when it gets to about 1100 rpm's it's up to 17+ inches. WOT from idle has a slight stumble, if I move the timing to 24 degrees BTDC at 950 to get 17 inches at idle but that seems like to much timing. I haven't tried any WOT at that setting due to the 20+ mechanical advance.

What would moving the cam a couple of degrees do for the vacuum.

Thanks

If you don't have vacuum advance, why do you care what the vacuum is?

I'm not sure how wild that cam is but I'd want it to idle lower. If bumping the initial gives more vacuum then it wants that much initial. I'd use the "vacuum gauge method" which is the initial that gives you max vacuum while lowering the idle speed back to the lowest it will function at then back off the timing till it loses 1" of vacuum & that's the initial it wants in drive with Ebrake on if auto or in neutral if a stick. right now I'd WOT nail it with 24 initial & see how that affects the bog. You can shorten the slots & since bumping the initial is giving you more vacuum you will have to shorten them anyhow once you get the initial finalized. Yes advancing the cam will give you more low end torque & is done first before the ignition timing. I'd take another compression test after you advance it & go with the setting that gives you the highest compression reading. After changing the cam timing you will need to readjust the dist timing. I'd set the initial then the slots to 35 (with vac adv capped) then springs then plug in/adj the vac adv. It definitely needs/wants more than 16 initial

That's a moderately big cam for a 318 and vacuum is lower than OE as a result. Sounds about right to me. Timing at around 16-17 sounds about right also. Power brakes (if applicable) should work fine. If it runs well be happy! It would be worth checking total mechanical advance. Total advance at higher RPM should generally be 34-36 for a wedge with vacuum disconnected. Make sure adjusting the initial doesn't give excessive mechanical advance. Adjust the distributor slots as needed.

I have a mild "about like a 340" cam in my 318 and run about 15--17 intitial, 20 or so in the dist, for 35--37 total less vacuum. Vacuum advance adds another dab.