Page 2 of 2
Re: How much vacuum do you need?
Posted: Tue Jul 07, 2020 7:26 am
by ozbilt
Reason why I questioned why is because the can was only on a/c equiped cars. The can only held enough to work the a/c controls if needed without interfering with the booster.
Reality is, you don't need it.
Re: How much vacuum do you need?
Posted: Tue Jul 07, 2020 7:13 pm
by Shaunp
mungus wrote:Thanks Shaun. If needed I'll compare them. As I don't have factory AC, originality isn't a big issue. New aftermarket brake vacuum cans are pretty cheap, half the price of a little OEM AC can. All the aftermarket cans look the same, as far as I can see the only difference is whether or not it comes with a cam makers sticker on it. (doubles the price).
Just checking the US concourse site, the 67-70 OEM AC vacuum cans, mounted on their side on the RHS inner fender, look odd anyway and I trust the brake canister fittings and non return valve more than the AC cans one.
Some of the OEM AC cans I've seen do make me laugh a bit though. They remind me of a big tin of peaches, but with a non return valve plonked on top...
Early 67 cars have different can, which is quite nice, and a non return valve goes in the hose.
Re: How much vacuum do you need?
Posted: Tue Jul 07, 2020 8:10 pm
by mungus
"Early 67 cars have different can, which is quite nice, and a non return valve goes in the hose."
Like this? I saw them over on the concourse site. Apparently they started life as Thunderbird AC vac cans, plenty available stateside. Yes I agree, they look way better (and bigger) than the little "can of peaches" late 67'-70' AC can. I reckon at a glance, a generic brake vac can, turned on its side almost looks similar enough that in an AC car, painted satin black, few would notice. And if a 67', it would look tops. But I'm thinking that for a 68' maybe its still better hidden under the fender. (shorter hoses etc). Anyway we'll see when the time comes. Thanks though, a good suggestion.
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Re: How much vacuum do you need?
Posted: Thu Dec 24, 2020 7:31 am
by mungus
Update:
So after 9.5 months away I was finally allowed to go home for a few weeks. Finished the engine test stand and ran the motor. Went well. Started easy, no leaks, good oil pressure etc. Anyway the lowest steady warm idle I got was around 840 RPM. At that I was getting 9-10" of vacuum. At 1,000 RPM it was around 11". 1,500 RPM gets 16" and so on. So we will see how the brake booster goes with that and if necessary I'll fit a can.
So that's what you get vacuum wise, on a bored 390 with an XR280HR roller cam, 730 Holley 4150, headers, Pertronix 3 etc.
Away again now. Hopefully back home in late Jan for a few days. At this rate I'll never get her finished!
Re: How much vacuum do you need?
Posted: Thu Dec 24, 2020 8:10 am
by Dwayne
mungus wrote:
So after 9.5 months away I was finally allowed to go home for a few weeks.
Sounds like my brother, he's still stuck on a rig off the coast of Guyana working 12hr days, 7day weeks for many months straight, plus 2wks hotel quarantine at either end. Think he's only been home for 2mths this year.