Vaccuum pumps...........

[IXLR8]

Well my dad and I just installed a vaccuum pump on my 85 blazer 3.4 and it really does make a difference. When idling if you pull the oil cap off you can hear a hiss from the pressure restoring back inside the motor, but if i rev the engine to around 2500rpm its hard to get the cap off. The engine seems to run smoother, there is a noticable amount of power increase.............it makes a cool liltle sound also. It was well worth what we spent and im gonna see if it helps gas mileage any.

[geoffinbc]

What was the reason for it?

[IXLR8]

it pulls pressure outta the crankcase sorta like a super pcv valve which makes the pistons run in a vaccuum and seals the rings better. http://www.gzmotorsports.com/customers-cars.html here check it out

[geoffinbc]

Cool.

Might be something to try one day.

Should try and steal one off a diesel pickup.

[IXLR8]

We made a vacuum pump out of the stock air pump that was on the 85 2.8.
We first removed the pulley and the plastic fan behind it. Next, we plugged off the intake hole behind the pulley. Then we removed the rear cover and drilled a hole on the back of the pump and threaded in a fitting.
We put the cover back on (Its a little tricky to get the vanes back in place and the back cover on.)
We then ran a hose up to the valve cover from the new fitting and ran another hose up to the air filter from the original outlet port.
We want to install a vacuum gauge and regulator to keep the vacuum around 15".(Recommended vacuum on the GZ motorsports site.)

[Doubt_Incarnate]

about how much is a replacment air pump you think? the smog pump from my crap truck is locked, sort of, and i was going to try the same thing. if i can find a cheap one i still want to try for it, but otherwise i guess i'll just make a dummy pulley to put where my a/c used to be.

[IXLR8]

Our original 85 air pump had a V-belt pulley and we had converted the 3.4 to a serpentine drive belt from an 89 S10 2.8. (We Bought all of the brackets and pulleys at the local junk yard for $50). We had originally tried to run the serpentine belt without the air pump, but we could not find a tensioner that would work right, so we decided to put the air pump back on. My Dad and I had both read about the vacuum pump and noticed that the vacuum pump casting looked EXACTLY like the old air pump. We went to another junk yard and got an air pump with the serpentine belt pulley and the bracket for $15.(We probably could have gotten it thrown in for the original $50...OH WELL!)
We checked several and got one that sounded the best and we oiled the bearings and vanes while we had it apart.

[Doubt_Incarnate]

im trying to get the one from my truck to spin again, it looks like the drum rusted up and the rust is preventing the it from spinning, you know how close the tollerances are. it says it flows somethng like 38 lbs/hr, maybe 33. i have the serpentine pulley for it. at least it wont need modified, it has an intake and discarge already. i think i can get one for $20 on ebay, like new, its even still shinny. just need to mount it up somehow, i'll have to find my old compressor that doesnt work with serpentine belts and get its brackets and such.

[IXLR8]

What year and model truck and what engine did it come off of?

[Doubt_Incarnate]

'89 f150, 5.0 efi. i can get a new-take-off from a 5.8 for $20 and some change on ebay.

its going on a 3.1 fwd motor.

[geoffinbc]

Try the late model electric A.I.R pumps. Then you dont have to mess with belts and brackets.

However you would have to figure out if you can tap it for vacuum.

[Doubt_Incarnate]

i need to take up space on the belt.