Whats the real deal about running a GMC 6-71? I came across a manifold for a small block for next to nothing and low and behold my father in law has a GMC 6-71 tucked under a pile of vintage Hemi parts, I know, I've tried. Anyways do you really have to rebuild them or just run them? Not really looking to run abunch of boost, but a blower w/ 4-2's... any info or links would be great!
There is a guy on Egay who rebuilds and clearances GMC blowers for gasoline engine use. Just type in blower rebuild and his listing should come up. I am certain there are others but Google kept taking me to egay and his listing.
I ran mine at stock clearances for years with no problems whatsoever. But,,,,"they" say you shouldn't,,,but who are "they" anyway?
Not so much the clearances as the bearings that keep you from running it on a V8. Clearances can be adjusted with shims. And to me the term "converting for gas use" is sort of misleading. You're not really converting it to handle a different fuel, but a higher RPM - hence the upgraded bearings.
Kevin may be right about the bearings. Although we ran the old type bearings without any problem we did have to have constant oil pressure running to the bearings which is no problem either. You just have to run lines to them. But you will also have to have drain backs from the blower to the engine to return the oil to the engine. Many people use pre-lubed bearings (no oil needed), but the gears up front will have to have oil pressure anda rteurn to the engine to keep thears lubed and cool.
I have a 471 GMC blower that I have been running for five years on a slant six. The only modifications that were made was the snout on the front to run a belt, sealed bearings on the back, and the ones in the front have a cover that is sealed and I use 90-120 weight gear lube in them.
any of you have to mill the case top and bottom? as for the gear oil...any leakage into the blower? I figure it would be easy to oil the rear bearings right off the motor block but the front? also, who has the hot v groove belt set up?
Cut through all the BS and static and call Don Hampton at Hampton Blowers. He's nice, informative and doesn't feed you any BS. His number is 562-803-9484. -Bigchief.
I ran a 6/71 on my last rod which covered 25000 miles with no problems.I rebuilt ,strengthened and clearanced the blower myself.I have done a few now and its no big deal.I got most of the info from an old magazine article ,if you let me have an email address I will try to send you a copy. My son is running a small Wade blower on his 4 pot powered rod, this was also ment for a diesel engine, he has covered over 10000 miles in the last year with no trouble.
I'm running a single v-belt on mine and got it from Big Al's Toybox in Conn. His pulleys are designed to stack and run as many as you want.
there are lots of experts out there when you start talking blowers. You can listen to the experts or you can bolt that sucker on and run it. I have been playing with junkyard gmc blowers for 30 years.the only millwork I do is milling off the flange on the base.simple bridgeport operation,and its nothing really precise.I have run a stock 6-71 on my hot rod (street) for about 25 years.I am currently running a 4-71 that was a freebie, manifold,pulleys,and blower,cost me nada,zip,zero. I deal with deans blowers on e-gay,he's a good source for bearings and parts. Its not rocket science,enjoy.
what 671 said is right. Rick Dean of ebay is a good guy too. Is it straight off the diesel engine? You may have to flip the rotors in the case so they are rotating the correct direction. The diesels drove them from the rear. The lip you have to cut off the bottom was from where it hung on the side of the diesel. It could be done easily at home with a grinder and some skill. Nothing has to be done to the top. the hot v groove set up is not readily available and will probably have to be custom made unless you can find one. They ran gilmer belts in the 50's and 60's. Don Hampton about cussed me out when I asked him to set me up a v belt drive. He said he'd do it but it would cost me. He also said the v belts slipped and were a pain in the ass since belts were defferent lengths. I think he was trying to make gobs of boost on race engines rather than a street engine. REJ says he runs his with V's no probs. I think the V's do look the best. I ended up with a 2" gilmer type belt since my car is 60's style anyway. I also spent 1.5 years on the phone with Don Hampton trying to get my 471 rebuilt. I sent him a 471 my buddy gave me that was straight off a diesel. He was cool the whole time, he just was very busy building race blowers and didn't want to stop and build my piss ant blower. I called him every other month or so and he'd say he'd get to it after race season or something else. Then he got slowed down when he got inducted into the Hall of Fame and was gone for a couple weeks! Like that is excuse - ha ha just kidding. He got it done and it is very nice. The hardest thing to come by is a cheap drive snout. You need to keep a close eye on ebay for snouts after you figure out how long a snout you need. The snout will bolt on the stock front cover, you need a coupler to go with your snout that has splines. The couple bolts to the blower rotor gear. Basically to convert a blower from diesel to street use they: 1. cut the lip off the bottom of the case. 2. change the rear bearings to sealed ones - these are available off ebay for like 20 bucks 3. Flip the rotors in the case so the rotor drive gears are on the front 4. Set the clearances on the rotors and case - then tripple pin the rotor drive gear to the rotor -this keeps the clearances between the rotors and case if there is a back fire. Basically the rotor drive gears can't spin on the rotor shaft once this is done. 5. Replace the bearings and seals on the front of the rotors where the will seal off the front bearing oil bath - keep your gear lube out of the blower. 6. Pin the bearing plates to the case once the tolerances are set You can get all sorts of aftermaket front and rear covers that replace the stock GMC pieces to dress up your blower and provide better bearing support. The pictures are of the ends of a 471 and there are two pictures of a 671 straight off a diesel with the diesel drive still on it. the shiny one is the 471 Hampton did for me.
Ive had two blowers gave to me and I have been toying with this also, More for looks than anything What are you doing to the lower end I'm running a rebuilt 350 with stock guts. What cam should I use? if I underdrive it and not race it can I get by with a cast crank? I know they say to run a steel crank. like I said this will be more for looks than anything.
Here is mine on the mock up motor. I DEFINATELY recommend Rick Dean. He is a retired racer/builder who lives for nothing but making and talking about blowers. Great guy. He can rebuild yours for well under 600 bills. Rick Dean 360 451 2119 -Abone.
Squirrel? and a couple of HAMBers had some recent good comments on a post regarding street driven blowers.
RE: Fowler Engines - Columbus Ohio If you're looking for a professional shop to rebuild any blower, and you're in the midwest area, then think about Fowler Engines in Columbus Ohio. These guys REALLY know their blower stuff -- and rebuild everything from 4-71s to the top-end blown alcohol stuff for the Pros. They have a "blower room" and have a dedicated guy who does nothing but build blowers, injectors, etc.. If you want to have a OEM one polished - no problem. Need to build a drive setup and insure that everything works for your chassis combo - they'll figure it out. Fowler does all my engine machine work - and they do really excellent work. (Blown 392 with special heads, custom blower drive and pulleys, etc). The build damn near everything --> from tractor pull diesels, flatheads, blown alcohol motors for funny cars, etc.. Give Jeff Fowler a call or checkout his WEB site - you won't be dissappointed in their work and knowledge: Fowler Engines Inc. 3021 Switzer Avenue Columbus, Ohio 43219 Phone: [614] 258-2924 http://www.fowlerengines.com
I got my 4-71 from the same dude on Ebay for a killer price. All works well and no probs on the Flathead. The only issue I have is I think that the front cover is slightly warped and lets a little gear lube drip out under pressure, even though it has a pressure relief valve. No biggie, just something I have to get my lazy ass around to re doing thats all. Its not rocket science and anyone can tear it down and scope out its inner workings. Rat
Lets talk about how to pull the rotor gears off the rotors. That seems to be the trickiest thing about these suckers. The need to come off at the same time because of the way they mesh. I have seen special pullers.
I use two "steering wheel" pullers when I have to pull them. Pull one a little and when it binds, get on the other one untill it binds. I just keep swapping back and forth untill they come off. The only time you need to do this is when swapping rotation or replacing seals or bearings. One other thing, they are making a new seal for these blowers that I got from a diesel shop, and they seem to be way better than the old ones. I was using a little oil out of the front case when I first got it on the road. Ran it that way for about a year and replaced the seals with the new type and have not lost a drop since then. They are a pain in the ass to get on, but they are worth it in my opinion. The old seals were like a grease seal in a wheel bearing, the new ones are made out of a silicon based material and are very soft.
now thar is some good information! can you tell us your experience with the amount of boost you have run and what compression motors you have put what boost on???? also - who has run the lower pulley on a balancer without adding the additional key way?
My blower setup is on a slant six. I am using the pulley that the power steering was on, and it is bolted to the balancer. I'm using two tensioners that I built. I am using a v-belt on mine, single. I have put 15 lbs on mine, lifted the head and retorqued it. My motor is 8:1 compression, stock engine with 96,000 on it when I put the blower on. No internal modifications at all. Homemade intake, headers and a 600 Holley carb.
Here's some mock up pics of my v-belt drive. If you have a lathe it's no big deal to make the pulleys. Funny. Making the drive setup didn't scare me but actually building the blower myself does. I'm going to send mine off to Rick Dean beginning of next year.
nice work - it will be ready to dust Flamedabone RIGHT!! Looks like a little under drive -what is your intent?
The goal is to have her running the blower this spring. I've got one year to get Flamedabone. Once he gets his blower motor built I won't stand a chance. I am a bit tired of just seeing his taillights on the track. Yep, it's underdriven. She's primarily street driven so I really don't want to get to radical but it sure is tempting. With the old hemi (read expensive parts) and no o-rings in the heads I'm going to keep the pressure down to around 5 to 6 pounds. Should get me pretty deep into the 12's if I can hook it up.
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