CDaniel525

I have some troubles under hard braking with my engine almost stalling, so I wanted to try a vacuum can. Not even sure if thats going to cure it since I suspect it might be a bad seal in the booster, but figured a $50 vacuum can can't hurt. But then again, with the cam that I have, i guess its possible? However, I tried a few places to mount it but I can find anywhere that will work...
Just wondering where others have mounted them or if anyone has any ideas. The only palce I wanted to try was remove the washer fluid tank, and put it there, but there is no way possible without removing the master cyl and maybe even the booster... at that point, might as well get the new booster.
Any suggestions??
Thanks in advance!
Chris

Jason Staley

I purchase one from Summit (about the size of a large coffee can) and mounted it between the headlights to the front bumper support. You can't even see it .

chevymans 77

doesn't the 74 have the large canister under the front end?

vettfixr

A vacuum canister should have no effect on engine performance unless it's leaking. It sounds to me like your problem is more carb related than vacuum. When you brake hard the gas in the car tends to move forward. You might be experiencing a lean condition because of it. I don't know what carb you have but I would look there first for a cure. You may have a float level set too low.

cardo0

As cheymans pointed out the '74 has a large vac reservoir. It's that large round cross tube behind the head lights. U should see headlight actualtor vac hoses connected to it.

While trouble shooting vac leaks isn't hard to do the stalling problem under braking is carb/fuel related. Don't know the type or status of your carb but fuel sloshes in the bowls under hard braking and this is where i would look rather than eng vac.

Got a spare carb? Nice to have a toolbox carb just for troubleshooting. Brand new Holley spreadbore is $350 and a lot of $$$ for just a spare. But keep your eyes open for a good used carb - plenty of barely used carbs sold for half the cost of new. Just my 2 pennys here.
cardo0

CDaniel525

Thanks for the replies guys....
Dont think I mentioned this before, but I just wanted to run this canister for the vacuum brake booster. Not sure, but i guess the carb is slightly off, but I also have some brake problems? Pedal feels like it hits a flat spot and doesnt brake hard, unless i just hit the brakes hard immediately. The only thing I can think of is that im having the brake problems from lack of vacuum after the motor almost stalls due to the carb being tuned wrong?? Nopt sure if its worth mentioning, but my headlights also dont come up anymore, so not sure if thats an indicator of this problem??


Im going to install the canister since i have it anyway, but will look into tuning the carb better...I have a BG speed demon 750 (stock jets i think) on a zz4 with HOTCAM kit and single plane high rise intake... I figured with that cam and intake, there might be a lack of vacuum?
Im still wondering if I should have gotten a 650 for my setup?

Im going to try chevymans idea up under the front of the car.... didnt think of it first since id need to run a bunch of extra hose, but that can hurt, i would guess?

Sorry for the post being all over the place, but got quite a few, small issues with the car... realinzing its time to spend some time and money on her again!

68/70Vette

....and just keep in mind that GM sells electrically powered vacuum pumps. If you have an C3 that needs vacuum for your accessories and you have a big duration overlap cam, you may need to get an electical vacuum boost pump.

Also, I once had an experience with a manual transmission (brand new Richmond 5 speed) that got stuck in neutral and then the L88 clone engine died. This was on a two lane mountain road! With a loss of power brakes and power steering this was a big problem coming into a curve. Fortunately there was a little dirt road at the curve and I headed up that. Frightening. An electrically powered auxiliary vacuum pump would have been a really big help.