I hope that was a joke.

5" of vacuum isn't that much, especially with no engine load, and that electric pump isn't going to scale as RPM increases.

I'm dead serious when I say make sure and monitor that vacuum level during your first couple passes. If it loses vacuum at any time, you need to get out of it and ditch the pump.

From all of the stuff I've read, dead minimum vacuum you want is 10", and most regulators are pre-set to 15". Most pumps can pull up to 25-30" of vacuum and their volume scales with engine RPM since they're belt driven.

I'm just saying... be careful. I have nothing against doing things on the cheap, and this may work well for you. Just don't put yourself at risk if it doesn't keep vacuum on the crank case at max RPM.

x2 on what he said, I set mine to pull min of 12"

x 3

I had to buy the biggest star vac pump they make to accomodate a 632 bbc mine was set at 11. There is a big difference when your running at idle approx 1500-1900 rpm to when your on the top end of the track, wide open pulling 7500 to 8500 rpm.

And for the small cost of a check valve, I would certainly recommend it.

Don't get me wrong, In sincerely hope you have came up with an idea that is not only mechanically effective, but cost effective as well,

Good luck and keep us posted with your results.

It was no joke, I think everyone is losing sight of what we are doing with this and I do understand the positive crankcase situation. This engine, as many across the country does, ran fine with just a pan evac system. This pump moves way more volume than that ever would. it is only to remove moisture I don't think it will pull over 1 or 2 inches of vacuum on a pass.

Just to clarify something though. I have a mechanical pump on my car and we have one on the dragster that we have also. I posted this for the guys who always ask questions, which I have seen a hundred times, about how these work on an engine. I do appreciate the concern for our safety but we are not a bunch of newbs trying to do something with $12.00 dollars in our pocket.

AGAIN guys don't lose sight of what we are doing with this we are not trying to pull vacuum to make power. This car is tire limited with a 14-32 so we have to kill some bottom end as it is. I am not trying to be adversarial about this I just want everyone to understand that we do have a pretty good idea and knowledge about what we are doing, this was just for the guys who can't buy a Star or Moroso and would like some info.

Curtis

Keep in mind that a pan evac system is an open system. It's not being limited by the speed of that impeller within the electric pump.

The problem is that you never mentioned (unless I misread the post several times) that you also have a mechanical pump on the same motor. Nobody ever called you a newb or insinuated that you were poor.

Look at it from an outside perspective. If nobody knows you also have a mechanical pump, and you say this thing works, but because you know what you're doing it's not explained thoroughly in the post, someone who's wanting to do it on the cheap may want to try it (run on sentance, sorry).

Some young adult Johnny may try and put this on his big block street motor that has 14%+ leakdown when cold, push all the oil gaskets out at the top of the track, spray oil under the tires and wreck his car and hurt himself.

I'm glad it works for you. The hazards if it doesn't work for someone else also need to be pointed out so the end reader can determine if the reward is worth the risk.

You win.

I didn't know we were competing.

I think you have a good idea. At the price point, it's certainly worth exploring. It just has some risks that needed pointing out.

I see what WJ is trying to point out, in order for a vaccum pump to work properly the engine must be sealed up air tight. (With exception of the vaccum system plumbing)

When you do this, your vaccum pump must be up to the task of pulling more vaccum than the engine creates the oposite of (positive crankcase pressure). If that is not achieved, you will have problems with blown seals and pushed out gaskets.

IMO a pump that will only achieve 2" of vaccum will never do this.

I think he took his ball and went home.