I have a 1955 Cadillac Motor with a 4-71 supercharger. This is my first supercharger. I was wondering how to check and fill the oil on the snout,the front and rear bearings. How often and what type of oil to use. Thank you
post a picture of the other side of the front of the blower, and the back of the blower. Usually they have sealed bearings at the back, so no maintenance is required back there. Front there may be a sight glass or a plug, but we can't see it because of the angle of your photo. generally the plan is to keep it filled with 90 wt gear oil, to the level of the sight glass. The sight glass is usually about 1/3 of the way up the front cover.
about once a year you also want to pull the carbs and take a look at the rotors to make sure they are not scuffing each other, the housing or the endplates , gaskets are cheap and available , you do not need the screen type ones those are for heavy equipment to keep sticks and rocks out if a air cleaner gets knocked off as there is nothing to protect them otherwise .
or in my case, gloves.... , lost a set of the brown cotton gloves on a 8v92 that didn't have a shutter housing on it when I was working on it , just set them down I realized it and thump away they got sucked away and went into the airbox , lucky my fingers were not near the hole as it will take them off like a food processor , after that all our Jimmys got screens . ( the gloves were mashed up and some of it went thru the cylinder ports and was blowing out the pipes in burning pieces , had to tear the top end down and in a Cabover thats a PITA ... I was lucky they didn't stick to the rotor as it would have fractured it or the bearing supports when it came on the return side
Or the rag in you pocket if you have the cover off and someone sticks the rack open. Actually some racers used to believe that a screen under the carb would help with atomization. Maybe some still do because you can still buy performance carb gaskets with the screen in them.
always carried a piece of plywood and a co2 fire extingusher with me after my first runaway experience .. its amazing how well and fast a warm one will run on dirty oil ... as for the screens the ones we used had a 1/4-3/8 " mesh so no real advantage will be found , the ones that use the fine screen door mesh , it might be plausible ..
heard that many times at the ship yard I worked at when they swung stuff out to the drydock in the slip . and heard many a plunk splash too afterwords ( one was a $125,000 bronze tug propellor) , Murphy and his family worked overtime there ..
you want to poke the pressure relief valve after every run, check your belts for slop, they will stretch when replacing belts try to get them in consecutive numbers or as close as possible and from the same run.
Yep no use in shutting the fuel off they will run on anything that burns and suck if from anyplace they can. And the scream just freakin deafening .
According to Gene Mooneyham, run 90wt gear oil in the front gear case on a street blower. Should be filled to the middle bolt on the triangle plate. Rear bearings are sealed, no lube in there. My screen has 3/16 mesh. Keeps the larger rocks out. If you ever have the blower apart, have the rotors Tefloned. It's good protection from scoring when the helical gears wear.
There are 3 brass bolts. One on the snout, rear bearing end plate and front bearing end plate and no sight glass.
The Blower Shop sells a pressure relief valve and sight glass combination. Others would sell similar units.
I didn't put any of that stuff in the old GMC cover I put on my BDS blower, when I put it in the Chevy II. I have to pull a bolt to check the level, and the pressure has to find it's own way out. We'll see how long it lasts. 4500 miles so far.
Another horror story, I was running a blown 392 on Nitro at Rodd NAS in Corpus Christi and the chute didn't open so I coasted through the shut down area and threw up a cloud of pea gravel and a few went through the Hilborns into the blower. It split the end cases and gouged out grooves in the case as well as shearing the drive pins on the rotors. About the only parts that were salvageable were the injector pump and rear cover. I always ran the screen from then on.
Unless you are taking it apart don't relieve the pressure (via pressure relief) The positative pressure keeps the lip seal engaged. Also if it's a NHRA style racer no screen if anything else run the screen...
I have put thousands and thousands miles on my 471 I occasionally check the fluid level in the front cover. I've had to replace the Idler bearings a few times but never a problem with the blower itself. Ive had the same 2" gilmer belt on it forever but i do carry a spare. I will likely take it back up to Dyers one of these winters to have it gone through, as its been about 10 years since it was built.
Squirrel thats because the OEm usage really does not develop any pressure in the housing as its used as a scavange pump and the unit is equal or undersize of the motor size , in automotive use when used for Boost you should use some sort of relief in case a seal in the case ruptures as it will blow the gearbox seals out the nose or blow the cover gasket out and they ussually fail on the underside .
The BDS cover that I ran for over 100k miles has a pressure relief valve and sight glass. The valve is a push button, sealed by an O ring. I think it is designed to let air in, and not let it out. every time I'd push it, some pressure would come out. It's not a vent.
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