I ran across this blower a little while ago and it was one of those "now or never" kind of deals. I know just enough to be dangerous so I bought it. Can someone tell me what I have. I don't even know how to tell if it's a 671 or 871. Any help would be greatly appreciated.
GMC 671, not positive but it may be what is called a "big bore" case. Edit Squirrel will know whether this is true. Still has the hanger flanges on it, don't see them with them too much any more, usually removed to mount on automotive intakes. The "remanufactured" stenciled on it more than likely meens it came from a diesel rebuilder, but also (possibly) meens it has not been converted for gasoline use yet.
you kind of have to mill off the flange when you convert it to gasoline, and also change the cover plate...so yeah, it looks like it's a rebuilt unit ready to go on a diesel.. It needs work to make it into a gas engine blower.
Can't quite tell but those two lines in between the ribs on one side are not familiar. Lots of info here: https://www.google.com/search?q=gmc...QIHY5tB1sQ_AUoAnoECAwQAg#imgrc=G8wZPXn-IbBbvM:
$450. I figured for that price it wouldn't hurt too bad if it was useless and if I could use it then I'd be getting a good deal.
I don't profess to know a lot however a previous Google search established that there are two different 6-71 blower sizes commonly used, case depth measured at inlet:- Large diameter with 1/2" case thickness (11% more volume); and Small diameter with 3/4" case thickness. If you measure the distance from the rotor to the top of the blower case, 3/4" is a large bore case and if it's 7/8" it's a small bore case. Here's a old HAMB thread, apparently the recesses on either end of your case seem to be present on small bore cases and filled on large bore cases; also the square cross supports appear to be on small bore cases with the round cross supports on large bore cases. I still kick myself for selling a 6-71 years ago with manifold etc etc Large bore Small bore
So you have to mill the flanges off and change the cover plate and maybe add some teflon seals to the rotors. Is there anything else that needs to be done in order to run this on gas and on the street. I do know that you have to have a low compression motor and a blower intake manifold plus a carb plate on top. I see these blowers up for sale every once in awhile but don't know enough about them to buy one.
That is indeed a Diesel blower. Need quite a bit of work to convert to gas but doable. Google will be your friend here.. also other threads from HAMB.. https://www.jalopyjournal.com/forum...wer-info-converting-to-automotive-use.529337/ https://www.onallcylinders.com/2013...tuning-and-upgrading-for-maximum-performance/ The Flanges was used to "hang" the blower on the side of the engine. Most machine those off but have a seen a couple that was left on. The blower will need to be reclearanced for gas use also new rear plate and sealed rear bearings The rotors wll need to be Pinned for the higher revolutions it will be spinning. Deans Blower service has a complete "HOW TO" CD and all parts to do the job. Also you DO NOT need to put Teflon on those rotors, For a driver car it is not needed. But for a drag car running more than 10lbs of boost it is recommended.
Contact Gale Plummer of " Blown Plum Crazy" in Portland Oregon. 503-292-5516 that's the last number I have for him... I think he may have a web site under the same name... he's the best around this area...and good to work with.....really knows his stuff ... there's alot of sites that tell you how to test and set up a used blower..... Sent from my QTASUN1 using The H.A.M.B. mobile app
No teflon, unless your doing top fuel or ProMod. They will wear out on a street driven car. Pick up a cool rear bearing cover like this...https://www.diamondp.com/Supercharger_Bearing_Plates_s/147.htm There is a retired drag racer of 40+ yrs that sets these up for gas located in Wichita KS. He did mine, new bearings, phased rotors, clearanced ends for 200 and change. His name is Gary. https://www.jalopyjournal.com/forum/members/garyr.20071/
$200 and change to convert it for gas/street use. That’s a good price. You would still be into the blower for a respectable amount for a useable street blower. I saw that in the classifieds and thought long and hard about reliving my blower days... wait a minute, that didn’t come out right, or sound right, or something... I’ll shut up now... Just do it. r Sent from my iPhone using H.A.M.B.
Manual milling 101... we've all been there, and it works. Sent from my SM-G900P using The H.A.M.B. mobile app
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