Small block combo suggestions
Ok, Ima gonna rant a bit, and this is not directed specifically at you,Jeff. This is for anybody that may be compromising a combo on a low-vacuum /perceived booster issue.
This is a pet peeve of mine. Low idle vacuum does not mean the brake booster will have issues. It really doesn't affect the booster to any great degree unless either the booster or the check-valve is faulty, or the vacuum is low clear up to the stall-speed.
Sure if your engine idles at sub 10 inches or so, the booster may not come on line the way you might expect, but almost the moment the vacuum goes up, the booster comes on line just like normal. It only needs maybe 12 inches to wake up.With a street type cam this vacuum level is usually achieved long before the stall speed. With an automatic and a TC,any TC,by the time the engine is reved up high enough to move the car, your booster will be all ready to go.The booster should store enough vacuum for a couple of stops at least.
And how often does your automatic car idle down low enough for this to be an issue. The check valve is supposed to lock the vacuum in there. If the booster is working right, once it is evacuated it should hold it's vacuum for a very long time, even if you shut the engine off. When you step on the brake you are actually letting atmospheric air into the booster, and out. Atmospheric air is doing all the work. Atmospheric air is moving into and out of the booster. The little control-valve in there is called an atmospheric valve.
I think there are only two times a low vacuum can be a problem; 1) when you first start it up with a normalized booster,and put it into gear in your garage and the brakes don't hold and you push the nose into the workbench;shame on you for not waiting 5 seconds for the booster to come on line, and 2) while sitting at a redlight with a leaky valve, and the car starts to creep forward. Ok simple solution; turn the idle speed down so it doesn't pull so hard, or put it in neutral.
But say you have a manual tranny. Same as above except rev it up a little before you back out of the garage. That's all there is to it. I've been driving like this for over 15 years. I don't even think about it any more. Look; to back a standard up,you almost always blip the throttle to get a little flywheel inertia going which you then use to get things moving. That lil blip wakes up the booster for me.Then once the car is moving,physics takes over which says a body in motion tends to remain in motion until a new stronger force acts on it.See I did too learn something in hi-school.By the time I am in first gear, again a lil throttle is applied and with that the vacuum rises above the booster threshold and all is good. I have had this same booster on several different combos , up to the 292/508/108 cam,and never have I noticed an issue. In fact, I have this dash-mounted timing control device that lets me crank in up to 7* advance, or dial out 8*, from the driver's seat. When I am moving real slow thru the parking lot, things get a lil jumpy under the hood with the 14* in the dizzy. By cranking the timing back the power pulses weaken and it suddenly gets a lot smoother, 'course the engine loses power, but hey it's a 360, it is fine with just 6* of advance. So with the power loss,the rpm is dropping and so is the vacuum. But you know what? I am riding the brake with one foot and maybe the clutch with the other. And the vacuum is way down deeeeeep in the basement, Yet the brakes are working just fine.
This booster came off a 73Dart 318, or maybe it was a 75, or maybe off the 77 Aspen slanty I striped out. In other words just a regular old A/F body booster.
So, Forget about brake booster issues, on engines with street type cams.
Now as to vacuum operated H-VAC controls I cannot say, except they make vacuum storage balls to help keep your ice cold air blowing to where you pointed it to.lol
Ok, here's the punch-line.
To limit an engines performance,just to ensure the booster is charged up the second you start 'er up, is IMO, um Gee, I can't even think what to compare it too. I tell you what, the go-to cam for a streeter is a 268 cam, pick any cam up to that 268,and the vacuum will be fine once you got the tune in her.Like I said I had no booster issues even with the 292/108/508. That would be an additional 14 degrees of cam, which is about 3 sizes.
Back to you Jeff; pick the cam for your application and operating requirements and don't give the booster any more thought.
To nm9, that was a best guess,based on the other numbers I randomly inserted and because the 232s have a machineable .050 q-pad, I didn't give it any more thought. The machinest can adjust the Q with the more than adequate pad.I estimated the factory heads to be machined down to 63cc, to go along with his statement of the pistons being down in the holes a lil bit. Since we know that they could well be .012 down, or more,I arbitrarily choose .003, which the math then spits out the 63 ish head ccs. Did I not say Pure Speculation?Lemme go check.
Nope I said;
Since the .039 FellPro is a tuff sob and it sets a nice tight squish on closed chamber heads, which yours kindof have to be to be down at around 63cc
And elsewhere;Keep it mind I made up all the number here for your perusal
