is a 671 blower too big for on a flathead?? i know this is a vague question but just wondering what anyone may have done thanks zach
I think it looks wrong and most likely is to much blower unless it's a seriously built motor.... I think the 4-71 looks better on the Flatheads and most likely is a better size for the motor...
I'm planning on using a 6-53. It's a better all around match for the motor. The blower itself is the same length as the 6-71, but it's not as wide. Also the flow is better matched for all but a full race flathead, in my opinion. Joe Abbin of Roadrunner Engineering has a really good book called 'Blown Flathead'. It's all about setting up blowers on flatheads, and they back up their info with dyno tests.
there is a bloke in NY area who runs a blue 32 tudor with a 6/71 on it, there has been a few photos of it on here. but I personally like this, but then I'm biased, I reckon 4/71's just fit better, the 6/71's near look too big for the motor.
What kind of intakes does everybody run to adapt to a flatty? I would love to build mine up with a 471
My intake and 4-71 blower came from Roadrunners in N.M which someone already mentioned.Ive put about 3000 trouble free miles this year.
Heres that 6-71 32 Tudor that Flatoz was talkin about. Yes they can and do work however at low rpm they normally impede airlflow b/c of their sizing.The ci of a flathead isnt really well matched to a 6-71. Visually IMHO they look so-so depending on your viewpoint and they do help to "fill" the engine bay nicely. But then again im biased like Flatoz haha... Rat
The 6-71 was designed to feed a six cyliinder engine with 71 cubic inches each, for a total of 426 cubic inches. A 4-71 would be a closer match at (4x71=302) 302 cubic inches. A blower too large will convert some wasted energy to heat. You see large blowers on top fuel engines because the vaporizing fuel has a cooling effect. Gasoline doesn't work like that.
What really matters is boost - you can overdrive a smaller blower or underdrive a larger blower & end up with the same boost. So either a 4-71 or a 6-71 will work fine - you'll end up playing with your drive to get what you need/want in the boost department. FWIW, I think the 4-71 looks better on a flatty though - 6-71 looks too big & cartoonish - unless, of course, you're racing!
how much boost are guys safely running on flatties? aside from the pc of bar stock to the the center main, what else is available?
The guy in NZ that makes the blower intakes and also twin plug heads is Haydn Mitchell. Beuatiful piece of work and he is also starting to manufacture quick change rear ends. I have a early seventies US HOT ROD annual that has a strory on Cotton Werksmann building a 6-71 blown flathead with 6 or 8 97's on top. It looked *****in.
under driving a 6 71 isnt the greatest idea because they are very innefiecent at low rpm. 6-7 lbs boost with stock heads on high octane fuel is lots. If you use a high compression head (any finned head) than you may have problems with detonation. MSD makes a ignition for blown engines that help you put more pulley on and control spark/advance. This helps eliminate detonation when using more pulley and higher compression. The msd unit is based on the MSD 6 series box. do a google search on msd 6btm to read all about it. the older castings on the 4-71 6-71 are fairly rough and wont polish well. Also, these old blowers will generally have up to a million miles on them before you get them. Most were built for city buses and semi trucks. Another reason to just buy new. The new blowers offered now are a much nicer casting. A new weind 142 is about 1700 US and nicely suited to a flathead. Thats what guys like Joe Abbin are selling for flatheads. Nice package. moe
Here's the unit Joe Abbin sells on a 268 cuin Merc. Pulley's sized for about 6# max. Pulley's available for up to around 12# I think. Don't know if the 3 mains could handle 12# for very many miles or high revs.
Beefy main caps and girdles. http://www.wilcap.com/webdoc6.htm http://www.baronracingequipment.com/productsBaronMainBearingCapsandSupports.htm There are others.
I have the little brother 3-71 that I am trying to decide whether to build up for my flatty or just buy the full unit from road runner engineering. Can't seem to find where to buy the manifold or drive pulleys etc for the flatty. Any ideas would sure be helpfull. Thanks, Fourdy
Tell me more please this looks unreal.... I am wanting to biuld a top fuel type flat motor and put it in my coupe for the Nostalgia Drags
I've done quite a bit of work on blower motors and you'll find that on a flatty up to about 260 inches, even a 3-71 is fine. I'd run a 4-71 if I was trying to run some heavier boost on a bigger cube motor. Keep in mind, that every belt driven blower takes horsepower to run, so having the right sized blower for your engine also means that you'll be getting the best possible gain - for what you're giving up. I'll be doing the fabrication on both 3-71 and 4-71 setups this winter -- with both v-belts and 2" 1/2 pitch belts. Obviously having a bunch of v-belts looks more like a 50's rod, but a modern cog belt is a much better solution. With v-belts, you want to segregate the ones that drive the blower from the ones that drive the water pumps (especially if you're running the old style bronze bushings) -- as the belt tension you need to keep the v-belts belts from slipping on rapid throttle opening will wear out the old style flathead water pumps in a hurry. Also - you might consider having the blower case "trimmed" which makes it look better on a traditional flathead (where the manifold is so narrow). Enough of my babble -- will post some pictures in a few months (once we get our drive setups and CNC work done). Happy Thanksgiving!
If you have the time/ability to do the machine work, it isn't all that tough to setup the drive. A 3-71 is a really good sized blower for smaller non-race flatheads (remember the one thar Barney Navarro pioneered with 4 Stromber 48's!). You can probably purchase a manfold from Joe Abbin or Barney Navarro -- you'll have to handle the blower drive (though there are plenty of guys that can make you one). You might also consider adapting a SBC small harmonic ballancer to fit the flatty - then bolting the blower puller to it. If it was me, I'd run a 2" gilmer belt -- with a single v-belt pulley to drive the water pumps and fan (if you can get all that to fit!). One of the problems is having enough room to fit all fo this in a stock engine compartment. For a more compact solution, it may be far easier to spend the cash and buy Joe Abbin's "ready to rock" setup -- everybody I know loves the setup and he prices it more than fair. Best of luck . . .
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