Street Rat

I have a lack of good vacuum sources on my intake manifold. I was wondering about using an electric vacuum pump. Are they noisy? Pros and cons please.

Street Rat

mikem350

My sb 350 has a Victor Jr intake with NO vacuum ports! This is from the PO and I am thinking of going RPM Air Gap if it fits under hood. Search the archives there is some info about adding them buy drilling and tapping ports. If you are talking about pumps there is info about hydroboost ones, maybe electric too.

gerry72

I used to. They are noisy and vibrate quite a bit even with isolators. Unless you are driven to use one due to very low vacuum conditions, seek another solution. The upside is they develop vacuum well beyond what you're likely to see from engine vacuum so the power booster is always going to provide maximum assist.

dugsgms74

Cant see the point what with the price of viagra being so low nowadays. Sorry, couldnt resist.

7T1vette

Unless your engine is a 'full-race' build with a very radical cam, it should produce over 10"Hg (stock engines produce around 20"Hg); and that's enough to operate all vacuum operated components in a C3.

You likely have vacuum leak issues that you will still have if you install another vacuum pump. Remove and plug all vacuum lines on the intake manifold except for the distributor advance can (remove and plug off the power brake hose, too). Then check your [baseline] vacuum level at idle. If it is lower than 10"Hg, you have some problems or a very wild cam. My bet is that you will have over 12"Hg and that you just need to find and fix the vacuum leaks in your systems.

Street Rat

My engine isn't installed yet. It should have plenty of vacuum as it has quite a docile cam in it. I only have the 3/8 port on the back of my Holley 650 DP for vacuum accessories . I built a vacuum (tree) that provides a port for everything but I don't know if it will be enough vacuum for everything. I don't want to pull the intake off my assembled engine to drill some extra ports. But that may be what I end up doing or the vacuum pump.

Street Rat

I don't know where you are getting your Viagra but mine is high dollar.

tshort

I've run a vacuum pump (very radical solid cam with no vacuum) for about 5 years. As mentioned, they put out a lot of vacuum and keep brakes solid. I've converted everything except for the brakes over to electric and when the funds are available I will end up with hydraboost and finally get rid of the vacuum pump. They are noisy which is my number 1 complaint. But it works well. I put mine behind the driver side gills. Plenty of room and plenty of air flow to keep cool. I have it powered on off of a relay.

Rebelrob

I have 3 manifold vac ports and 1 ported on my Holley Vac Secondary Carb.
Then I have 1 vac port off of the Air Gap intake. You could tap/drill more ports if needed.
Check your carb out and see if you have any additional. I have a dedicated vac line for the booster and PCV. Although I have been told that my booster is bad, as it does not seem to hold vaccum.

7T1vette

If you still have your emissions equipment on the car (including the vapor recovery cansiter), you will need 3 vacuum connections as a minimum.

1) a large fitting at the base of the carb which should connect with the power brake booster (if you have one; if not, you can use this for ALL manifold vacuum lines). If you have power brakes, you do NOT want to connect any other vacuum lines to this connection. The power brake vacuum line should be all by itself.

2) a fitting that is 'manifold' vacuum which should connect with the vacuum reservoir tank as the supply source. All other manifold vacuum lines can then connect to the tank outlet. It is best to have a line filter and a one-way check valve in this main feed line; the check valve would then maintain max vacuum in the reservoir tank, even when under acceleration.

3) a fitting that is 'timed/ported' vacuum for connecting emissions-related equipment and the actuator valve on the vapor recovery canister.

All carbs should have at least those 3 fittings on them. Otherwise, you would not be able to connect all equipment to the carb.

If your carb does not have a manifold vacuum source fitting, you must then find a point on the intake manifold where you can connect a vacuum source fitting to send to the vacuum reservoir tank. Most manifolds have a pipe plug in them for this purpose. If there is none, you would need to drill and tap for a fitting...somewhere behind the carb would be best.

hugie82

I have a booster assist vac pump on my 2003 SS Silverado. It kicks on when I'm trailering with very little noise. I would think any GM vehicle with the LQ9 engine would have this pump if you want to search salvage yards.

mikem350

With a mild cam there is no way you should even consider adding a pump! I have exactly same problem...see my answer in #3 response

13BoostedGS

Excellent write up! What gauge and amperage add a fuse did you use?