There is 4 clyinders with less than 140 PSI which is what the Motors Manual says is correct for a 69 340. And yea the power brakes really suck advancing the timming past 10 degrees does increase vac to 16 inches. but with a 4 row classic ind. radiator with 15 psi cap and a jag fan clutch it does get hot on 90 degree days and yes I am running a correct fan shroud. was going back to direct drive fan but thought a good idea to check vac and do a comp test for anything that stood out.