Hey guys, I'm new to the HAMB & super glad I found it!! Its a wicked cool site!!! I had a question you veterans prob know the answer to. What years/makes did the GMC 8-71 blower come in? I can't afford a new one so I'm hoping to find an old one to rebuild. is this even worth dealing with? Any ***ist would be awesome!
Ebay is your friend, do a search for 8/71 or 871. I was just looking for 6/71 stuff and there is a lot of stuff out there. I just bought a 6V/71 (to go on my FE motor) which is the one you don't really want, but on my side of the pond we have to take what is available, and I like a challenge...
The 4 guys I have known in my area that have done this ended up with more money in the thing than if they would have saved up for a complete kit in the first place! This has also been discussed on the board a number of times with the same consensus a**** those that have done it.
If you buy one to rebuild, the important thing to remember it will need to be "street clearenced" on the rotors. Otherwise they are set for the diesel and will be to tight for a gas engine. Went through that once before. Good luck and good rodding!!!!!!
A 8-71 blower is a real pain to make a manifold for compared to a 6-71 that you can buy a manifold for. The draw backs of a 8-71 is the way the bolts "toenail" in an angle and the drive gears need to have machine work to give a register for the drive coupler, beside I think they are just ugly to look at. A 6-71 will be a better choice for all around ease of installation as there are parts made for it. The 6 will give you what you need for the majority of applications and save you money on a clearance for your use. Call me an I can hook you up with one with the proper clearances walk you through the installation. 316-393-1105 Gary Roushkolb Superchargers
You knida want to stay away from the V-series blowers 6V-71, 8V-71, etc, and stay with the inline models. Unless you have acces a machine shop to make all the parts for your blower, plus set the internal clearances for it your better off getting a kit, no matter what a blower setup isn't cheap no matter if you buy it or do it yourself.
Listen to Gary. He knows what he's talking about. He setup my 671 for me and has been great to work with. Stand up guy! I sprung for a new intake but got the snout and swing arm off of ebay. I whittled my own v-belt pulleys. Money can be saved if you are careful but blowers and the goodies to run them aren't cheap. They are addictive!!! I'd have a tough time giving mine up. For reference.
One thing that you may not be aware of....is that there is no such thing as a 8-71 blower from GMC, so far as I know. The 8-71 is strictly an aftermarket thing...made by using an aftermarket case, with either 8V-71 GMC rotors, or extended/pinned 6-71 rotors. GMC, as Gary was getting at, makes an 8V-71 (and 6V-71) which Morrisman showed....you can get an idea of the angled bolts. 6V-71s have occasionally been adapted, usually because they're cheap...but not particularly easy. I've never seen a 8V-71 adapted, but somebody probably has done it. There are also 8V-53 and 8-53 blowers, and you don't want those either. In the used diesel market, it's therefore pretty much the 6-71 (or 4-71) to look for; or you can try to find a used 8-71 auto blower for sale...more likely to find a complete 8-71 kit, though.
Well, buying a complete blower kit and getting it to the UK would be pushing the $5000 level, and would be very, very easy to do, apart from finding the cabbage to pay for it. Buying a ready built rod would be easier and cheaper than building one too, but I don't. I don't 'do' ready made and off-t******lf, if I can help it. I want the fun and challenge of sorting this myself, just like our hot rod brethren did 50+ years ago.
Thanks for the link, what you say makes sense, but I really like the idea of a challenge, and bolt on stuff just doesn't make it happen for me. I have the Offenhauser four barrel manifold and I'll probably build an adaptor plate to take the blower, then buy pulleys and stuff to drive it. The guy I bought the blower off, Nigel from UK Blowers, says it will be good enough as stock to make 3 or 4 psi without worrying about clearancing, though things will need doing with bearings and stuff. And obviously I'll need to sort a drive snout and things like that. Should be fun. I'm only after a little more 'go' and the appearance and sound of a blower. 'Toys for big boys' and all that stuff
I was refferring to the thread starter, I know you guys overseas have extra issues. For most guys over here, I say buy a kit. Myself, I am making a 4-53 work for a flatty
Thanx for the info & the link, lots of good info. It sounds like I just bust out the penny jar for a kit. The reason I was wanting the info is cuz of an article in DeLuxe mag. The guy had a 57' he called the axle twister. He said he bot the blower for his 409 off of "his friends old diesel truck". I'm thinking his pockets are deeper than mine. After hearing from all of you i can see where it would just be an *** whoopin to deal with.
Do you ever see any @ swap meets that are worth a ****? As far as my plan goes; a454 w/ a super stout bottom end to make some wicked power with some measure of drivability & reliability. I know, the best of both worlds right.
Sometimes. The problem is that it can be fairly difficult to THOROUGHLY check one without dis***embling it; you can check C & CC clearances & so on, but it's hard to fully inspect the case for damage. Another thing to consider is that ***uming the clearances need some work, one method is to swap drive gears (one or both); it's easiest to have a pile of them sitting around, and to further complicate things there are more than one type. Pretty easy for a professional builder to do, not so much for a regular person. On the other hand, I know of a couple of people who have bought diesel blowers and lucked out. Another thing to think about is to find a truck or bus shop that works on Detroit Diesels, or a fleet shop. They often have blowers sitting around, used & new, and I even know of one guy who bought 3-4 GM-rebuilt blowers, still in the boxes, for $50 each...the fleet was trading in the last few trucks with Detroits & switching to ***mins power for everything...had to get rid of the parts inventory somehow. I've been told that it isn't too expensive to just buy a rebuilt diesel 6-71 from a shop, just a few hundred...I've never looked to verify that. You still have to convert it for automotive use, and it's not just a question of machining off the case lip. As I pointed out in the other thread, if you get a core that will need to be completely rebuilt and converted, and you can't do the work yourself, or want a pro's experience...it makes no sense to pay much for a core, because you can buy a completely reworked unit for only a little more than the cost of having all the work done to your unit. I don't want to discourage anyone from doing it on their own...and for our overseas members, that may be the only option. However, I've known a LOT of guys who bought a used diesel blower for $300-$700, and then found out that they would have to spend a ton of money, just to end up with a reworked, unpolished unit, that cost more than a polished/new case blower from a shop...then they have still to buy ALL the rest of the gear. And, no one ever considers the cost of things like carburetors, linkage, fuel lines... There are a lot of used diesel blower doorstops sitting in garages, and there's a reason why. Faster, as a final note, I would recommend the book Street Supercharging by Pat Ganahl; it's not perfect but very good, and it will give you a good idea as to what to look for in a used blower; might save you a lot of grief & money in the long run, for $20 investment. This CAN be done; it takes patience, bargain finding skills, and willingness to work on details.
The best old blower story I know of is a pal of mine that was in the Marines. He got stationed out in the desert in Cali to keep up a couple trucks on the range. He found an old Grader I think that had been blown to bits but the blower was still tucked away in good shape. He had nothing but time on his hands so Uncle Sam donated a 6-71 to the cause!
Least they could do...probably maintained pretty well, too. Nice, dry air. BTW, I did find some pics & info on those PENCO blowers (basically a re-cased 4-53 like we were talking about a couple of weeks back...) I don't think it will help you much, (& it's all SBC kit pics anyway, not so much help for a flatty) but when I get it scanned I'll send it in a PM. Took a while to scrounge it up, my stuff is a bit disorganized.
Ok ....I also have a 8V-71 blower that I will be running on my 390 FE engine. When I got the blower (paid $25.00 for it) I did my research and know that it needs clearanced for street (gasoline) use. A local shop (Supercharging Systems Inc or SSI) told me about $600 for the work on the blower....not including the drive unit...Now there is a guy on ebay that sells these "conversion kits" and he says thats all you need to convert these blowers to gasoline use...any truth to this?? I emailed the guy a while back and he ***ured me that thats all I need....I never bought the kit cuz I wasn't convinced...I will look and see if he has any of these kits on ebay and post a link so you can see what I'm talkin about....I am leaning toward what SSI told me...they have a hell of a good rep with superchargers ....
here is the link to the guy on ebay I was refering to.... http://cgi.ebay.com/ebaymotors/8v71...yZ107070QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
That's the guy that Flamedabone got his blower from. He can't say enough good things about Dean Blowers.
I worked with this stuff for 30+ years on the GM Diesels. But never on hot rods. This guy on ebay is selling seals and bearings. Basically what you need to freshen up a blower. These things are really simple, GM designed these in like 1929 and basically unchanged except for minor improvemets til the 90's. If you buy a GM diesel service manual, or can find a scan online of the blower section, from the 40's, 50's or 60's. they go into great detail on the rebuilding of them. Later books aren't worth ****, later books are for parts changers. Anyways, the rotors are clearanced and timed by adjusting the two gears, which are bevel gears. You adjust them by shimming the back side. This changes the clearance by changing the relationship of the two gears. If you get a blower kit from GM, seals, bearings, gaskets, it also has shims. You also need to get pressurized oil to each end case and a drain line from each end, too. Unless you get end plates that allow a sump, I've seen these. but I would want oil to circulate to help cool the bearings and gears. These things run at 2 x's engine speed on the GM's. the 71's would run @ 2200 rpm so the blower is going 4400, for a million miles! The 53's can run 2800, so the blowers are going 5600. We used to play around with these things, If you got one on a workbench, and spin the input shaft with a big electric drill, the air flow will lift the blower off the bench and float it. takes two guys to do this Frank
Personally I know nothing about this company....so it's not just some guy selling ya line of bs to get your money?
I just bought a rebuild kit from Dean 6-71 blowers off E-GAY and it seems like good stuff. Now that I have the part # I will just order the stuff from my local bearing supplier next time. I thought the $65 was well worth it for the kit.
Looks like I'll be ordering the kit to do it myself and save ooohhhh about $500 in doin so.....next to find a rear bearing cover and then on to the drive unit....
Not on one converted for gas. The rear bearings are often sealed but sometimes a zerk is used. The front case is sealed and gear lube is used.
OK. Not to be mean, and not slamming the eBay guy, but there is more involved in that $600 quote from SSI than the few parts he shows....which is, as Frank noted, basically a rebuild kit, with an additional top screened gasket. For example.... Normally on a customer rebuild, a blower shop will: clean it up; gl***-bead the case, & remove minor scratches; machine out the top & bottom case ribs; machine off the flange lip on the side (not on a Vee-series blower, true); set all the clearances, by swapping gears or shimming*; double or triple-pin the rotors on the shafts; install new seals, bearings, oil plugs, and gaskets**; install oversized dowel pins***; and either machine the front & rear plates# or give you new front & rear plates##. Some may include other services as well. ### *: Setting the rotor & case clearances is known as "timing" the blower. Frank mentioned shimming, which is how diesel guys do it. Some auto blower guys do too, but many prefer to swap gears or use other methods as the shims tend to get chewed up under rough use. This was why I made the comment earlier about having a pile of gears to choose from; you can slightly change clearances by using one or both different gears, and machining the backs of the gears. For street use, it's debatable whether the shims would be a problem, but a lot of blower guys avoid them anyway. In addition, there are cast iron gears and steel gears, and the steel gears come in 30 deg. helix (STRONGLY preferred) and 45 deg. Many blower shops will ONLY use the steel 30 deg. gears. You also have to set end clearances, which may involve machining the rotors or rotor shafts. **: Blower shops use different bearings than GM did, as the back bearings are sloppy, & the fronts aren't heavy enough. They also use neoprene seals, as the GM seals tend to come apart under auto use. You would want to check with the eBay guy to see what he includes. ***: Once all the clearances are set, a blower shop will re-dowel the endplates with larger pins, to permanently lock the clearances, and to allow the blower to be dis***embled without having to go though timing it all over again (tedious with a capital T ). Not strictly necessary, but nice; also, the original GM dowels have been known to move around. When this happens, if the rotors hit each other or the case, you have a problem. #: Stock plates are reinforced with a steel support ring around each bearing boss...a fair amount of machine work. ##: New aftermarket plates are reinforced around the bosses, have slightly different oil provisions, and are stronger generally...also, better looking. ###: Some blower shops hard-anodize the rotors and case to toughen the surfaces, and to slightly tighten up clearances. "Is all this **** really necessary?" I suppose that depends. If a person primarily wants a blower for looks, and doesn't plan to use it for much, if any, performance, you can get away without doing a lot of the machine work. Setting the clearances is not really an optional thing, but some of the other items may be. And I haven't even discussed blower snouts & drives... Beyond this, guys, I don't have a lot else to say. I have to admit that I am slightly prejudiced; it seems completely illogical to me to run a blower, with all the work, cost, weight, h***le, visibility issues, and so on, without getting a hell of a lot of performance in return. Beyond this, I'm habitually inclined to flog my vehicles mercilessly. So to me, if I was doing this, I'd want to make certain that the blower was not going to be the weak link. Would a stock GMC, with the bare minimum of work necessary, work all right? Probably for a while, in certain situations. Can a regular guy do everything necessary to get the equivalent of that $600 (which incidentally sounds pretty damned cheap...compared to other quotes I've heard)? Yeah, but if he has to pay for a lot of machine work, it may be close to that $600 by the time he's done.
the $600 quote I got was for them to put new bearings and seals, retime the blower, clearance the blower by 20 thousanths, install new dowel pins, something about teflon leading edge and make a rear cover....they told me they would have to see what I had before they could get into the snout and drive ***embly.....
I LOOOOOOVE my blower guy. He is a one man band who is a retired race blower guy and all he does now is builds blowers and talk to people about blowers. He is a HUGE wherehouse of knowledge and a hell of a nice guy. He does all teh stuff Homespun was talking about, at about the best price you are gonna find. The best part..He says it will be done this day and cost X ammount and it is, and does. I sent him a check and less than 2 weeks later, a 6-71 built to my specs was sitting at my door. He also walked me through the drive set up (which is funky for a Pontiac.) Rick Dean 360 451 2119. He is in Washington state, but I think it only cost 30 bucks to ship mine all the way to S. Carolina. By the way, I have almost a year of daily driving and a 3K round trip to the HAMB drags on this one with out so much as a hiccup. -Abone.
And thats a nice looking blower and drive there, Abone. Thanks for the detailed info, Homespun91. I think since guys been doing these blowers since the 50's for performance gas use, all the stuff you mention must be from the evolution of trying to make them bulletproof. I'm thinking the normal 71 air box pressure was 6 to 7 psi at full speed. and nothing but a breeze at idle. Which really has nothing to do with anything. Except that the pressures that street engines run are well within that. I did have a 6V-92 which had a turbo before the blower, and that thing would get up to 30 psi, but the engine didn't live real long. One more Question, GM used a spring loaded coupling on the drive gear to absorb pulses and not rattle the lobes, and also a torsion bar quill drive shaft from the timing gear train to the blower coupling, again to smooth out the drive, do these converted drives have the same or similar setup? Thanks, Frank
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