|
12a, dual SU carbs
I've never seen these until now, they look pretty nice to me. I'm looking to buy a pair of these carbs, with intake manifold for my 12a. Previous owner pulled them off a streetport 12a he found in a junkyard. He says the size is 1.75'' each, which means nothing to me. What size in other carbs is it comparable to, dellorto 32 or 36??? How much do you think these are worth?
|
one pic of them mounted is here: http://www.hurleyrotary.com/images/1...Conversion.jpg
Once the forum stops being gay I'll try to post some better pics that I have on my comp. |
tuning dual carbs? you're brave :)
actually the triple carbs on the old 240Z were a bitch, but looked oh so cool :drool: |
Mmmm, tri-Webers...:drool:
One of the local AutoXers here in Skoon has a '69 240Z with the tri-webers. That car hauls ass. Very nice setup indeed. |
note sure what they are comparable to but they flow a lot of air ... you tune them by changing the tapered profile of the needles, I'm sure Hurley can hook you up with the correct bits
|
I have some good pics of these carbs, but the forum won't let me upload them now for some reason :(
|
SU's were used on British cars from the 1920's through the 1970's. They're actually very easy to tune, (I have a 1971 MG Midget) IF they are in good shape. What usually happens is that after many years of use, the throttle shaft wears out along with the bushings the shaft rides in, and air gets sucked in at the shaft. They can be easily repaired to as-new condition by an expert. Two carbs would cost about $300 to rebuild as-new. That would include EVERYTHING - throttle shafts, bushings, jets, needles, floats, etc. The best SU guy around is Joe Curto. He works out of New York, and does business by mail. You can find his ad in Hemmings, in the British cars section. My MG has a 1275cc engine, and uses 1.25" SU's. 1.75" seems a bit large for 12A. (1200cc)
|
SU's are great simple carbs. I'd say GO FOR IT.
I got a nice Grassroots Motorsports article on SU's I can scan and send to you if you buy them. Seeing that 1.00" is 25mm, 1.75" is 43.75mm. Seeing that most aftermarket carbs for 12a's are 44mm to 48mm, I'd say a 1.75" SU is a little small. If your motor is ported I'd reccomend 2.00" SU later, -bp- |
su carbs
i have a 73 triumph tr6 with 2 su carbs / they are 1.75s. the motor is 2500cc. i think two would work on a 12a.
they are very easy to rebuild and all parts are available. 1.75 is inches / there are 24.5 mm in one inch (i think). you do the math. the jet that the needle slides in will were out and make them run too rich. hope this is some help |
Yea.. these carbs are stupid simple to tune and rebuild.. I can rebuild these and Zenith-Strombergs (also used on a lot of 70's Brit iron) in my sleep. Nikki's aren't too complex, but SU's make one look like a 6000 piece jigsaw puzzle. And don't let anyone try to kid you and tell you horror stories about tuning them. Pick up a Uni-Syn (like $25 last time I checked), a Haynes manual for SU/Stromberg carbs and have at it. The problems people have are from those who have no clue how to tweak these carbs and just start screwing around with stuff. With constant depression carbs like these, going a size bigger than you need won't hurt like a normal 4-barrel, as the carb will only allow enough fuel out to satisfy the vacuum the engine is making. I'd say go with the 2" SU's as well, but you may have some trouble finding them. If I recall correctly, they were limited to Jags and the 6-cylinder big Healeys. Grab yer ankles if ya find a set.. :D
--Danny |
Originally posted by DriveFast7 Seeing that 1.00" is 25mm, 1.75" is 43.75mm. Seeing that most aftermarket carbs for 12a's are 44mm to 48mm, I'd say a 1.75" SU is a little small. If your motor is ported I'd reccomend 2.00" SU later, -bp- |
Also, what fuel pump & reg would you reccomend for running dual 1.75'' carbs. I have a stockport engine, with stock manifold, gutted cats, straight pipe to a 2.5'' straight thru stainless muffler. I will also be getting an RB header and presilencer to complete my exhaust setup soon.
|
pic1
Still won't let me upload anything :( I've got 6 good pics of them too... |
email me the pics and Ill host em... webmaster@frontfly.com
|
|
pic2
:( I got one up, still doesnt want me to upload though. |
Those are the nice ones. Some SU's had a sliding "plunger" like those do which varies airflow. The cool thing about the ones you have there is that at full throttle there is nothing blockling the airflow. Some of the other SU's used the typical butterfly setup. I'd love to get my hands on a set of those.
|
I think these might have that butterfly you're talking about. I have 5 more good pics of them, the forum just wont let me upload them :(
|
|
and if the pics dont show up for you, there are here:
http://coldy13.tripod.com/pic1.jpg http://coldy13.tripod.com/pic2.jpg http://coldy13.tripod.com/pic3.jpg http://coldy13.tripod.com/pic4.jpg http://coldy13.tripod.com/pic5.jpg http://coldy13.tripod.com/pic6.jpg |
Sorry for being a post-whore, but you have to copy and paste the url's, tripod is gay.
|
ALL SU's had the sliding needle setup with a butterfly after it.. these carbs are similar in design to motorcylce carbs, and they can require as much or more air than our engines do at full song. You don't see them choked for air do you? The pose very little threat in restriction of airflow... The only thing that varied with them was the float bowl setup, the needle and jet size, diameter of the intake and the bolt pattern on the back of the carb..
--Danny |
Really? I saw a couple taken apart. Didn't know that. Good info. Its not like they are restrictive anyways.
|
I had 2 SUs on my 59 Sprite and they worked like a charm. Easy to tune and reliable.
That direct sidedraft hookup looks really good. B |
su carbs are good for a stock car, but for hi performance they suck!!!!! i had them on my 64 vovo!!!!! 1/" 3/4
and on my dads 59 austin healy bugeye, 1" the webers are much better! |
Originally posted by 680RWHP12A su carbs are good for a stock car, but for hi performance they suck!!!!! i had them on my 64 vovo!!!!! 1/" 3/4 and on my dads 59 austin healy bugeye, 1" the webers are much better! |
SU's are also good for turbocharging
Elford Turbo RX7's came with SU's as did several other turbocharged cars in the UK |
Originally posted by White84SE Umm.. no.. SUs are good for hi-performance cars. The race car we sponsor runs SUs.. he could run Webers, but doesn't want the headaches associated with one, not to mention the fact it'd bump him up into a class where he wouldn't be competitive.. Webers may be better for ultimate topend power, but are much more difficult to tune for a street driven car. if you are in a class restricted from running webers then su's will work ok(grab the big ones off the early e-type jag) put some thin oil in the dashpots , grose needle valve and thats all you can do! no venturies, fuel jets , air jets, just a dashpot with a slide! some common su to weber conversions mini cooper 2 su's to a single weber early volvo's 2 su's to single or dual weber setup trimph tr3, tr4, tr7, spitfire all have su carbs weber conversions for all models (avail. single or dual weber converions) all austin healy's came with su's but have weber conversions! there are many more but the point is to upgrade your carb, not downgrade!!!!webers are superior hi performance carbs in every aspect!! but su carbs will work, just not as good! |
*says the guy who sells Weber carbs*
:p: |
Originally posted by SilverRocket *says the guy who sells Weber carbs* :p: |
Ok ok... it's just hard not to observe a certain incentive on your part to say stuff like that!
|
LMAO I've seen quite a few British cars come through that have Weber cars replacing the factory carbs, and ya know what? I've yet to see a Weber setup that is anywhere near as livable in every day driving when compared to a SU or Stromberg setup. As I said, topend power, yes, the Weber will usually win, mainly because of the fact it's bores are larger and can flow more air. And as far as not replacing fuel jets, what the hell are you talking about? Obviously you didn't know that you can buy different needles for them, which is what changes the jet size. The Grose valve you refer to has nothing to do with all out power, as it's is simply a way to ensure the valve into the flowbowl will not stick open. Most of the guys who race these cars run NO fluid in the dashpot, and the dashpot is PART of the slide. Please, if you're going to argue about something, get a clue...
--Danny |
Re: su carbs
Originally posted by masterrigger i have a 73 triumph tr6 with 2 su carbs / they are 1.75s. the motor is 2500cc. i think two would work on a 12a. they are very easy to rebuild and all parts are available. 1.75 is inches / there are 24.5 mm in one inch (i think). you do the math. the jet that the needle slides in will were out and make them run too rich. hope this is some help 1 inch = 25.4mm 1.75" = 44.45mm |
How many CFM's are these carbs? Anyone know.
|
Originally posted by White84SE LMAO I've seen quite a few British cars come through that have Weber cars replacing the factory carbs, and ya know what? I've yet to see a Weber setup that is anywhere near as livable in every day driving when compared to a SU or Stromberg setup. As I said, topend power, yes, the Weber will usually win, mainly because of the fact it's bores are larger and can flow more air. And as far as not replacing fuel jets, what the hell are you talking about? Obviously you didn't know that you can buy different needles for them, which is what changes the jet size. The Grose valve you refer to has nothing to do with all out power, as it's is simply a way to ensure the valve into the flowbowl will not stick open. Most of the guys who race these cars run NO fluid in the dashpot, and the dashpot is PART of the slide. Please, if you're going to argue about something, get a clue... --Danny shit boy you got OWNED! |
sorry im a little rusty on my knowledge on SU carbs from the 50's ,and 60's that are not my specialty!! he busted me, i will admit it!!!but, you bring your mazda with SU carbs, and i will bring my mazda with a weber, and we will see wich one makes more power, im very confident the winner eill be a weber! ANYDAY!
p/s anytime i ever changed the needle you spoke of the car ran like shit!(must have done something wrong)and when my oil leaked out of the dashpot(it was bad) the car ran like shit also! |
Well, when I eventually get these onto my car, I'll let you guys know how they perform. I doubt it will be much better than stock until I get a RB header and presilencer on there, but these carbs were at the right price, and I couldn't pass them up.
|
Originally posted by coldy13 It's TWO 1.75'' carbs :) -bp- |
Thanks, I get that now. I wasn't sure on how webers were rated, if a 48mm was 2x48mm, or 48mm total. But I knew these were 44.5mm each. They will defiantly flow enough for a stock port.
|
Do they come with a manifold? How is the OMP plumbed in?
Dan |
i used to have twin strombergs sucking through a t4 turbo. It was a crude little set up but it worked a treat. I have some pics of it somewhere.
|
| All times are GMT -5. The time now is 07:20 PM. |
© 2024 MH Sub I, LLC dba Internet Brands