I have nothing but praise for Don Hampton, just recieved the 6-71 I ordered and he was always very helpful with any questions I had. He does come off a little rough at first, and has quite a mouth on him, but hey, the mans been doing it for 50 yrs I think he has it figured out. He even threw in carb studs and timing tape, I would recommend him to anyone.
Gary Roushkolb in Wichita. I've had him do all my blower rebuilding and he stands behind his work. He's a class act.
Why are the shaft seals necessary if sealed bearings are used? Will the internal pressure push grease out of the bearings (especially on the front side)? The oil holes could be tapped and plugged to prevent oil (front) or dust/water (rear) from getting past the bearings.
First off I don't come on here much and was a little ticked to see Rick's comments. In my article I say that I researched several articles on the net and took the best of them to put what I did together. Second, 18 lbs on a an SBC is NOTHING!!!!! I've run up to 25 lbs. Then there's some trouble!!! Third, the last blower I rebuilt with these techniques ran 4.95 in the 1/8 on a 355 in a 2100 lb car. Another I id has close to 15k miles on a street car. So, the "destructive advise" I'm accused of can be taken as a grain of salt from someone who is trying to make money off of what I tried to help DIY guys do themselves. About your CD. I have one. leaves a lot of questions. Sorry I offended you but if you just look at the bottom of the original post you'll see my half assed bibliography. Disclaimer : While I was researching how to rebuild a 6-71 I came across several articles on the net and in print. Each one lacked something that the others had. Not a one went into complete A to Z detail. Here I compiled what I felt was the best of all of them plus my own experiences to come up, with what I feel is, a pretty good guide to your rebuild. (Some pictures and text are not my own. I did not take pics of mine when I started, plus some of them are better than mine. As for the text cut and paste is easier than re typing.) sources: Street Supercharging by: Pat Ganahl several 60's through 80's Hot Rod, PHR and Drag mags www.project33.com
I'm rebuilding my first 6-71 and want to play with it on alcohol on my little fed small block. question is what should the clearance be. yes i bought ricks video, lots of books, but it must be a great secret or is there something i'm missing? or is there no difference? thanks for your time hotrod316
Unless you're having your rotors Teflon striped, clearances would be the same. Clearances are set to make the blower as efficient as possible at compressing air with minimal leakage around rotors and case, and rotors are timed to keep them from contacting under load. The blower doesn't know or care what fuel you're using.
You can "tighten" the clearances more with alcohol than gas because alcohol doesn't create heat like gas. Your blower WILL care if you run gas on a alcohol set up.
Thanks for all the info. I've got one I need to get back together Sent from my iPhone using Tapatalk 2
nice article. wizzards ware house sells the gear puller. a nice upgrade i performed on my intake was to convert it to a o-ring. this eliminates the costly paper gasket. i also torque my intake down then use a 3/4 inch thick plate with sand paper glued to the bottom i sand the intake surface flat. use dykem and pack the intake with rags first. you would be surprised how distorted the surface can be. even a few thousanths distortion is enough to cause rotor interferance. i always torque my manifold with a torque wrench. i go side to side and creep up slowly. it does make a differance to get the bolts all even. also before disassemble look at the rotors they form a v. i would stamp my case on top indicating the dirrection so in a thrash it would go back together the right way. you can put the rotors in wrong (side to side). if you would the v would be going the other way. ask me how i know. it will run but at higher rpms the engine will feel like it has a rev limiter on it. check this for yourself by putting your rotors side by side note the v shape. now pick up one rotor and place it on the other side of the rotor it was just on. the v has now changed direction. a shop rebuilt my blower and did just this. it took a while to figure it out.
Racer-x, That is some good info.I wouldn't have thought of that,and it would have taken forever to track that down. Thanks! Scott Posted using the Full Custom H.A.M.B. App!
if anyone goes the o-ring route there are a few things to know. go to a hydraulics store for the o-ring material. i buy it in 12 foot lengths. i put in in the groove and grazy glue the ends together. over time you will save a lot of cash. i think the gaskets sell for 25-35 dollars and rarely can be re used. ask the person at the counter how wide and how deep to make the groove its critical. if its too deep or too wide there will be insufficient crush on the gasket. too little and the blower won't sit on the manifold. i think i set my groove around .134 and the rubber was around .125 if i remember right. but its around that. all you need is a mill and the right width cutter. buy a few extra and go slow. on another subject how many times have you heard someone say look at that guys pullies he's not running any boost. or he's making big boost with those pullies. its flat out b.s. the only way to know the boost is with a boost gauge. a small port head or small valve head will have a higher pressure than my big valve large port hemi. yet not flow as much volume of air. a modern case with the small pie opening in the bottom rear as compared to the stock equal size exhaust port will support the rotors better reducing flex making a more efficient air pump. throw in a set of rotors with more helix and you now have a very modern efficient blower. a blower that can run at a slower speed using up less hp to drive it and run cooler. now take it a step further. the main case is the same between a 6 and a 8 only the front gear housing is different. change the front housing and rotors and you now have a 8-71. even more air if driven the same speed. its only one inch bigger. due to the heat generated by boost a methanol injector can do wonders. also a boost retard ignition can pull timing out as boost goes up. these two things add up to big power while keeping the engine very happy. too much heat can knock the tops right off the piston or close plug gap. if you don't have a a/f gauge get one. between the boost and a/f gauges you will be able to see what is going on under boost conditions. allowing you to tune the engine with pulley changes or fuel changes staying away from detonation. if you don't know what is going on inside how can you make a educated tuning decision. just because you saw someone else run a certain pulley combo does not mean it will work in your engine. its all about the volume of air going into the engine. this determines rich or lean conditions. don't fall prey into the car show guys mentality of just looking at pulley sizes. its only a small part of the over all picture.
old school in a tight fitting rotor combo there is the chance of a hydraulic failure. if all the fuel is coming from above the blower. look at all the old pics of blower explosions back in the day. the explosions went away the day port nozzles were invented. fuel takes up space and will tighten a blower. too much volume in too little of a space can get exiting real quick. there is a delicate balance that needs to be maintained. i would go with a good case good rotors good machining and no flex with more clearance any day. any fuel injected below the blower will also benefit the engine by not being pre heated. i would consult a reputable blower manufacturer for proper clearance. i have had great service and product from littlefield blowers.
Parker Hanifin manual on O-rings: smooth flat bottom,groove wider than O-ring, tapered zero to 5 deg. sides like a valley. O-ring needs room to expand, don't radius bottom,don't work. Typical .015" crush ei: .125" O-ring .010' deep groove. ask the person at the counter how wide and how deep to make the groove its critical. if its too deep or too wide there will be insufficient crush on the gasket. too little and the blower won't sit on the manifold. i think i set my groove around .134 and the rubber was around .125 if i remember right. but its around that. all you need is a mill and the right width cutter. buy a few extra and go slow. on another subject. Ago
I also bought the Dean blower CD and would have to say that it was of very little help. It tells you about how to put a blower together but does not give you any numbers that you need for clearance. I felt like I totally wasted my money.
I'm building a 4-71 for my roadster. I also bought the CD but so far have found the original Detroit Diesel maintenance manual and this thread we are reading to be the most help. Although there was some helpful info in the CD. The two pages from the Detroit manual I have attached here give the most info on how to shim the gears to get the proper clearance at the rotors. Of course, the numbers in the chart are for a diesel installation so I temper that with what is in this thread. When you see that a .003" shim will move the rotor .001" it doesn't look like it will take too many shims but when I tore down my blower it had .065" shims behind the upper gear. So I don't quite know what to expect when I go back together
Here is a link to a series of articles on a 6-71 rebuild that talks about the proper clearances for a gas blower. This link may be posted earlier in this thread but it is worth looking at. http://www.project33.com/article.cfm?ID=9
Instead of shims it is recomended for gas conversions to machine the gears for proper engagement because the shims can fret and come out and then your rotors collide. ago
Yes, I've read that and may end up doing it that way. I'm kind of feeling my way through this project a little at a time.
Thanks everyone for posting on here,I have all the parts for my 6-71 just have to polish the case. Then I will be assembling Posted using the Full Custom H.A.M.B. App!
what drive lenght for a 350 chevy with weiend blower manifold? I have a 6 inch fuel pump drive extension
One of the best threads I have read in a long time, excellent info on the 6-71 blower. Could anyone direct me to a part by part breakdown diagram of the 6-71, an exploded view would be great, thanks
Took my blower apart yesterday, and ordered parts. Thanks for posting this thread, it makes it all look as easy as it really is.
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