Hello, I recently acquired this GM 6-71 Blower with a Dyers Kit. As I have no experience with superchargers apart from a few hours of reading and studying; the gears seem to be backwards? by someone who has maybe rebuilt this. If I were to place the snout that comes with the kit it would place the Dyers upside down - Typically the pulley is always on the right side. And since the snout can only attach to the three bolt I assume that the gears need switched from left to right. Am I crazy or is this thing backwards? If it is indeed backwards, is this going to take any special tools or considerations as I don't want to damage anything. Any ideas? NMKII IMG_8358 by NMKII posted Jan 14, 2016 at 4:41 PM Image2 by NMKII posted Jan 14, 2016 at 4:41 PM Image1 by NMKII posted Jan 14, 2016 at 4:41 PM
Yes, it is indeed set up backwards to a normal automotive application. The gears have been switched. The only reason I can think of as to why, would be a Marine Reverse Rotation Engine. I am not even sure if they do this with Blowers though, a reversed crank hooked up to this blower would turn the blower the correct way. I hope this makes sense what I am trying to say.
I believe what you have purchased is a blower right off a diesel that has never been converted for automotive use, along with a Dyers drive kit. I see it still has the tabs on the side of the case also. What does the rear bearing plate look like, is it an aftermarket?
Could be, I purchased everything together. The kit and also this blower. Here is the back of the 671. As I have no experience with these, is it smarter to take this along to a specialist and ask for a conversion?
After looking at all the Pics, this is what you have. 1933Willys has it right. Taking it to an experienced builder would be the thing to do now for the conversion. Good luck with your project!
Thank you gentlemen for all the help, I will do this. Truly a day of drinking coffee, staring at gears and scratching my head and it looking back at me and nothing happening. God bless the forum.
You might want to ask Jim Forbes (Squirrel on here). I think he might guide you through it. While I understand that no one wants to screw up their pieces, how will you ever learn anything by having someone else do it?
Don't run or I should say you cant run it like that on a standard rotation motor. The rotors would try to "inhale" the air out of the motor and pump it out through the carbs or injectors. You would be running a 6-71 Sucker. Yes must be switched around.
I don't recall the exact thread title, but last year (IIRC) here, there was a thread that showed (a lot of) the OEM repair manual text and photos on rebuild procedures. Pretty neat read even if you choose to farm out the work. Looked for it, couldn't find it, but did find this thread. http://www.jalopyjournal.com/forum/threads/tech-week-6-71-blower-rebuild.367403/
When a GM blower is converted for hot rod use the case /rotors are reversed. Hot rodders have always worked things out for themselves Lots of info if you search, here is a start http://www.project33.com/category.cfm?Category=Engine
Like they said, the blower hasn't been converted yet. You can't just change the gears without also setting the clearances, the backs of the gears get machined to get the "timing" just right. The drive pulley has to go on the other side...
You give Gary Roushkolb in Witchita, KS a call and he will get you fixed up with any parts you need or will do the diesel to gas conversion. Really nice guy to deal with. He just did a 6-71 for me and it looks great.
Dyers Blowers can probably convert it for you. Bill and Gary are great people to deal with. Gary Dyer has been building blowers for 40 years.
Get ahold of this guy, he's alittle closer to you,,, in Norway http://www.jalopyjournal.com/forum/members/fenderless.13448/ ,,Have fun Tim Jones
agreed, there is a ton of info here on how to rebuild/refresh/ convert, whatever you want to call it, tackle that bad boy yourself!
I rebuilt many of the 71 series blowers when I was in the Navy. To remove the gears you need a special set of gear pullers that removes both gears at the same time. You will also need a way to lubricate the gears and return the oil back to the oil pan. Most of the aftermarket kits either have sealed bearings or end plates drilled for oiling. It isn't rocket science buy it must be done correctly, clearance between the rotors and end plates and between the rotors and case is critical.
[QUOTE="aaggie, post: 11342686, member: 98315" You will also need a way to lubricate the gears and return the oil back to the oil pan. [/QUOTE] Really? since when? 25 years of running a blower and NEVER had to do that
Really? since when? 25 years of running a blower and NEVER had to do that[/QUOTE] Ain't done that, either.
Rotors must be converted. Need to remove quide pins. Then You tight bearing blocks and move slowly as long as backlash is good. fixed end small, moving end bigger. If too much backlash, You grind core. If too small, You lathe rotors or another rotor. when all are just in their right places tigjht bearing blocks and drill quide pin holes and use oversize pins Easy job. takes only one long day, if not need to make too much machinery jobs. Aulis
So Gimpy and Dre you are telling me that for 25 years you have been running a blower with no lubrication to the rotor drive gears? Read my post, I said you will need a way to lubricate. Some setups use a drain and fill plug so in that case no oil return to the pan is necessary, they also use a sealed bearing so no lube is required. In those setups you have to periodically drain and refill the end cases. The better conversions will either have a sight glass similar to a Holley carb float bowl installed or a plug you can unscrew to check the oil level. One of the easiest ways to lube the blower on SBCs was to remove the plug from the front oil gallery above the timing cover and run a line up to the blower. Drill and tap the side of the end plate and run the return line to a fitting on the timing cover.
I have seen backyard builds that use the original end plates and and bearings, using a plate at the rear, and a drive cover at the front to make two reservoirs for oil (one with a tube connecting both ends). I have seen sealed bearings in the rear, and original style bearings in the front, with oil in the front, for the bearings and gears. Lastly, I have seen sealed bearings at both ends, and oil in the front, just for the gears. Vents, sightglasses, plugs, you name it. In my entire lifetime, I have yet to see in-person a GMC whatever-71 series blower, converted to run on a gasoline (or alcohol, etc.) that has an oil feed/return from the engine. Not one, ever, never. Not saying that it is not, or was not done. Sure, it might be easy, but if it were common, I might have seen it, oh say, maybe, ever. I have been on about 1/4 of the dragstrips in the US, and on a few dry lakes. I have lived and worked in 5-states.
X4 !!! Converting the 71 series are not that Difficult , There was a book in mid 80s showed step by step ,
In your post "Lubricate the gears and return the oil back to the oil pan" I felt it was un-nessasary for me to describe the way mine and most blowers are set up to run sealed bearings and having some oil in the front cover.
looking at the pics i think i can see green paint on the blower housing in spots.that is the same shade of green that gmc used to paint them on they're diesels.you can't just switch the gears and go.i would send it to a blower shop and have it done right.i had one done a couple of years ago at deans671 blowers in i think it was in washington state for about $350 .hope this helps
Get the book "Street supercharging" tells you everything you need to know including step by step with pictures.
GM diesels are built that turn either way. The blowers are easily reversible. On my 4-71 I pulled the end plates with the rotors still in the front plate and put the plates in the other ends. Done! Sealed bearings in the back and oil in the front reservoir.
I have received the 671 conversion kit and instructional DVD from Dean Blower on eBay. I will give it a go this week. http://www.ebay.com/itm/8v71-Blower...sel-/370823672012?vxp=mtr&hash=item5656d030cc
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