Okay, we have a GMC 100 with the 228 straight 6 in it (I'm lookin to build a 261 Chebby for a car eventually too) so I was thinking about carbs for this kind of setup with 3 ports for 6 cylinders. Would it be completely loopy to put 3 SU's on there? I was thinking of getting some with throttle bores roughly the same size as the ports at the intake flange (like H4's maybe)? I have thought about the Carter YH's (Corvette) and everyone I have asked tells me the rear one won't clear the firewall in anything I want to put them in (without surgurey and I don't want to do that there). So I expect the Zenith and Stromberg side drafts would have the same problem. The SU's I have seen are all mounted on somewhat of an angle (and I see different angle floats listed for them). So I might be able to angle the carbs away from interference. I could use Mikunis or Keihin (sp) but in my mind's eye the SU's look better in that picture. I figure it's harder to overcarb an engine with a Constant Depression type carb too. I have no problem with fabbing my own intake for these (which is good cause I'm sure I'll have to). I am asking this here because there seem to be several (former, closet, whatever) sporty car types here, but the kind that did their own work that probably have the practical experience with these that I lack. No rush as this is likely a (next) fall project at the soonest. It's just been buggin' me.
in relation to your questions: SU's will work, especailly w the same size bores as the ports. I have some pics of one built somewhere on one of the computers we have. YH's will clear the truck firewall won't it??? fab it - or buy it. I know of a guy who has a Nicson side-draft manifold w Zeniths for sale. PM me if you want the details - he ain't a computer person.
SU's work on almost anything - choose the right size and you can usually get a good idle with the needle it came with. I run SU's on the Citroen 2CV engine in my trike - tested the concept by just bolting on an ancient SU off a Morris Minor onto a standard 2CV manifold using an adaptor made from a scrap bit of exhaust bend. Straight away it worked better than the standard Solex - idled better, pulled harder, better mileage (a great feature of the SU) and was just a nicer drive. The SU of choice has to be an HIF - 3 HIF44 carbs should be ideal for your application. I have a book called something like "Tuning the SU for Power" and this gives a routine for selecting (or making) a suitable needle. There are several websites dedicated to tuning SU's and there are also some needle selection programmes. http://www.triumphclub.co.nz/su_carbs.html Burlens are STILL making them new - a friend bought 3 last week for £100 each. However, the HIF's wear very well and a £15 rebuild kit will sort out most. You just want to avoid any with buggered screws and other signs of poor maintainence. You will probably find them on either Minis, Jags or Range Rovers out there. Good luck with it.
You mean like this ? This is an old rod built down here that has SU's on a 216 Chev - a real cool old car.
Simon Sez, yeah, pretty much. I was thinking of shorter tubes from the carb to the head (planning on Nicon or Fenton iron, Manifolds? Headers? whatever you call them) for as much clearance as I can get (and probably a heat shield too). Do you know any specifics to that setup, like size SU's what rod and jet? I appreciate the help so far, thanks.
Triple SU,s were / still are common on the hot Holden 6 cylinders in Australia. 6 cylinder Triumphs and MGB had them too. What about the early Datsun 240Z ?
I have been trying to find more info on the 240 setup. I figured that would have a fair amount of info, but I have not had alot of luck finding much on those. I have found a few things that cover a dual SU looking setup (I think they were the off brand though) and lots of stuff on both side draft and downdraft Webbers. But a tripple SU setup (especially with linkage) I haven't found except in the post abbove. Thanks 34 GAZ.
I was more thinking it might be a good way to get carb sizes and setup info for a comparable size engine.
That's an excellent point. I would like to find 3 of the same regardless. Thank you, again. Does anyone have any opinion on the compensator spring type VS the fixed type (I am reading that the newer ones have a bi-metal thermal compensating spring in them) in an aplication with a hood? I expect it would be les prone to malfunction in an open setup (less likely to have a problem with heat soak).
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