How Hard Can a SP-11 Suck?

[syrupkid]

I have aquired a SP-11 that was laying around at my dads shop (he owns a Westfalia Surge dealership) and even he doesnt know how much vaccum it can pull without running it too hot and siezing it up. So i was wondering if any of you traders out there run SP-11's and how much vaccum you pull with them. Thanks.

[lpakiz]

Syrupkid,
I have an SP-11 I ran with a 3 HP Tecumseh motor. It easily made 20 HG and usually 22, sometimes 23 HG. A dealer rep (for CDL) told me to throw away the regulator, which I did.
The trick to not overheating (I think) is not how high of a vacuum you pull, but rather the RPM you run it at. With the gas engine, I could reduce RPMs to get the most vacuum without flunking the spit-sizzle test. This was done on only 200 taps and I kept a close watch on leaks. Good Luck!!

[tuckermtn]

I have had the same performance out of two of my sp-11's- 20 to 22 inches of Hg

[syrupkid]

You say slow it down... about how fast does your pump actually spin?

[tuckermtn]

stock they are supposed to turn between 440 to 470 rpm.

[MASSEY JACK]

I would caution you about slowing it down. They are splash lubricated and if it goes too slow it will not throw enough oil up on the cylinder walls to lube the piston rings. I had one gum up with fine metal particles off the rings and cylinder walls because I slowed it down figuring it would last longer. My SP22 was running around 200 rpm's. I was lucky that mine cleaned up OK and still pulls vac. I run 20 to 22 inches and have seen 24.

Massey Jack

[lpakiz]

Massey Jack,
THANKS for the tip about running TOO slow. Makes perfect sense.

[mapleack]

I agree with not slowing it down. Let it run at the rpm it was designed for, buy a vacuum regulator for 30 bucks to set the vac level at 22". This intentional leak will also allow cool air in near the pump to help keep it cool.