Anyone ever seen this done? I have 3 1-3/4 SU Carbs sitting around, with linkage. I know where there are another 2 setups cheap. I've always thought they would make a cool looking alternative multi-carb setup. Got to wondering about making my own sheet metal intake for a bunch of them (6 or 8) atop a roots blower. Are they typically easy to setup to work with forced induction, or would it be crazy to try?
SU Carbs are a "constant vacuum" design. That means they can work really well on blown engines. Somewhere I have a pic of a Roots blown Ferrari with SU's on it. ( how is that for a unusual combination of parts...) I'll see if I can find it, so I can scan and post it.
AWESOME! That's what I was hoping. I read somewhere that the Predator CV carb that was used on all the cheezy 80's blown "fairground machines" was basically a giant boxy SU. Looks like I'd just need to weld SU flanges to hardware store pipe elbows then! The fuel line alone on this thing is gonna be a work of art, not to mention a bunch of those cool bell tops and little velocity stacks off to the side. This will probably end up atop a 379 or 391 cube Poly 318. Next question...Anyone know anywhere I can get a 6-71 Flange to weld to Weiand's single plane single 4 bbl Poly 318 intake?
the only experience I have with SU carbs is from the volvo long ago...they fed 109 cubic inches with two of them, so with a blower feeding say 300 cubes you'd want 8 or so carbs. Quite the exotic plumbing setup when you're done with it.
SU's were made in different bore sizes. They were used on anything from small 4 cyls to the larger Jags, etc... I also read its best not to use too much carb on a blown engine. Edit. To be totally honest, I'm not a fan of SU's at all. But I wouldnt mind using them on a blown engine. Because they would work well, and there probably wouldn't be a problem synchonising them...
I imported this from Australia to use on my '66 Dart Wagon, then sold it to make room for her '55 Buick before I got to install it. It uses the same SU's off of the Jags, which are everywhere here in Pick-N-Pull My Volvo had smaller SU's, IIRC. I replaced 'em with DCOE's!
well...you could turn the blower 90 degrees and drive it off the front of the engine. draw from one side and spit out the other via an aftercooler...or you could just give the carbs to me so i can bolt them to my mg...(i have some 40 dcom you can have...)
180 Degrees. Wasn't planning installing a blower sideways. Even if it IS on a Mopar. And if I did the whole crank mount thing where would my radiator go? and talk about linkage nightmares with a Potvin setup on a full bodied car...Blower's going through a hole in the hood. Gonna hunt for a stock diesel 6-71 case on a government liquidator type site. I can rebuild the thing and grind the tabs off of it myself in the living room when the rainy season hits. Can't be too hard to swap plates and change gaskets, and I sure don't need to cough up $2,000 for basic machine work and show polishing. One of the guys I know in Santa Rosa has been building roots blown cars for years. I'll just have him double-check my handiwork. Dude, these are MY carbs. MINE! Go **** your own ****py foreign cars. You walked right past the XJ-6 and the Datsun Z at one of those Woodland yards yesterday. D'oh!
I like the 90 degree idea. Have it mounted vertically in front of the engine, "top" of the blower forward, "bottom" of the blower to the rear, driven with a right angle gearbox off the crank, two short tubes to the intake manifold, and the carbs stacked up in front of the blower. Now that you mention it....
AHHHHHHHHH That's what he meant. Only seen that done on motorcycles. Side to side might work the best as it leaves more room for carbs and plumbing, but then I have to deal with the water pump and getting an electric fan in there. Also, Seems like linkage or cable routing would still be a nightmare in a full bodied car.
Quick Google Bentley search to see how they did it shows one clearly mounted like a Potvin setup in front of the grille shell, with SU's off the p***enger side. That's cool!
Hampton and Dyers I know for sure still sell a weld on 6-71 adapter for intakes. The last time I talked to Bill Dyer he quoted me $300 for one but, if you acess to a mill making one shouldn't be that bad. just remember to fly cut the intake after you weld it just incase it warps at all. Dyers does not have it listed on their site but, I know they have them. Built a manifold for my buddies 409 the same way.
SU carbs are very easy to set up. They will idle perfectly and run somewhat acceptably on almost anything because they work on a constant vacuum principle. The difficulty is getting them to work well throughout the rev range. This is done by choosing the correct needle from the hundreds of needle profiles available. There is a way of doing this and it's spelled out clearly in "How to Build & Powertune SU Carburettors" by Des Hammill (one of the Speedpro Series books). There's also a very neat computer programme available. PM me with your email address and I'll send you the programme. I could also photocopy and send the relevant chapter from the book if you need it. If you have access to a lathe you can start with a "blank" needle and profile your own for an exact match. With regard to which carb to use, the nicest, most reliable and easiest to set up and work on are the last one - the HIF series (Integral Float chamber). They came in 44mm and 38mm throat size. I looks like you have the 1 3/4" HS6. They're good too. I don't think you would need more than the 3. Two of them work fine on a 4.2 litre Jag engine. You might just need richer (i.e. thinner) needles. If you do want to put eight of the ******s on there then I would suggest using HIF series carbs as they are much more compact without the separate float chamber. I would start with the leanest needles avaialbe and actually use them as a blank to turn up a custom profile (much cheaper than buying a range of needles non a cut and try basis - the needles are £10 each now. Times 8 = £80 and then times whatever number of sets you use on a trial and error basis. Ouch!!). Over here is the UK the HIF38 and HIF44 was fitted to a huge range of vehicles - from 998cc Mini engines to 5600cc Jag V12s - I'd be happy to help put together a set of eight for you. I pay around £15 for a decent SU. Finally, the source for all spares, linkages, tech advice and even brand new SUs is Burlens - go to http://www.burlen.co.uk/
you are such a goober. if you want a standard lay down style mounting (the drive of the blower mounts straight to the crankshaft) look at the MG K3 Magnette, "Blower" Bentleys. If you want one w/a 90 degree vertical drive look up ERA's (Romulus, Remus, and Hanuman). You can also try Austin 7 Ulsters. The britsh were infamous for supercharging everything. And if you need any help i have a **** load of various articles and pics of this stuff, remember i do own an mg... you know I will have to go check out the jag, i thought it was an EFI car.
[/QUOTE] Dude, these are MY carbs. MINE! Go **** your own ****py foreign cars. You walked right past the XJ-6 and the Datsun Z at one of those Woodland yards yesterday. D'oh! [/QUOTE] also, the z car will have mikuni's...not SU's
I just received my first 6x2 tops for strombergs or ford 94s for the 6-71 blower from the foundary last friday. They are surfaced drilled and tapped with CNC.. They are nice.. They are ready for sale also Aaron 805 368 3876
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