Su vs Weber vs Mikuni???

[skunk]

So i've been doing some searching but dont feel i've found all the info there is to find. And i dont feel i've had the three put up against one another.

I've saved up some money to get a set of dual side draft carbs for l20

just dont know if i want to go with 38mm SUs, weber dcoe 40mm or Dual Solex / Mikuni 40mm.

I feel like i should be 100% on the pros and cons of each of these set ups before i go spending this kind of money.

Any info some of you professionals out there are willing to share would be greatly appreciated

[ppeters914]

What are you putting 'em on, and what's your goal? I'm no pro, but see this routinely asked/discussed. For everyday driveability and best mpg, 38mm SU's. Webers and Solex/Mikuni will make more top end by sacrificing low-end, and take a lot more to dial in. FWIW, I'm sticking with SU's.

[skunk]

I just want some thing thats going to give me more go, i dont mind having to keep and eye on them and keeping them dialed in. and there going on a L20 (as i did say in first post) in a 620 not that that really matters

[benzo]

from what I have read and seen and experienced some. if you have a stock L20 I would just stick with a down draft or at the most go 38mm su's or dual mikuni 40's. Webers seem to be a bit of a pain to tune.

[Skib]

Im more partial to SUs.

 

there simple carbs and can deliver when it comes to more than stock motors.

[78kingcab]

too bad i just sold a set i had laying around to dat620guy for 75.00

[skunk]

so the one carb i feel like i know the least about (also the one that readdy for me to by like right now) is the dual 40mm mikuni set up. does any one have anything to say about them?

[zerow]

The dual 40mm Mikunis hog a lot of gas. And, like it has been mentioned, it depends on what your normal/typical driving style is going to be. Not a situation where you *might* go out for a race or two, or *might* be out to show a couple of Hondas what you've got under the hood. If you are a typical city driver, with occasional highway use, I would go with the SUs. They are what the Datsuns had for the first step in performance. If you don't care about gas mileage, then the Weber would be the next choice, and if its going to be raced, go for the dual 40mm Mikunis

[skunk]

:P well i drive like im racing to get every were i go.

[exit64]

Here's the problem. These carb set ups are all old and most of us are too cheap or broke to do it right. The best money I have spent on the Roadster every time is to switch over to a match box dizzy and get a set of Z therapy carbs. Those two thing pretty much solve drivability and reliability problems. Half the time people call me up to dial in their SU's and it usually a combination of worn out carbs and slop in the dizzy shaft to the point that the dwell is jumping all over the place. SU's are great for street use. Once they are set up correctly there is no reason to mess with them hardly ever. There is a great SU section in the wiki over on 311s.org. I use the micrometer method to get them set the first time and then tune from there. Spend the money for a set of rebuilt SU's from a known and reputable guru. These guys know what they are doing. They replace the throttle shafts and bushings that are the source of tunability issues. You have a vacume leak, you have a problem. If you go with Mikunis get a hold of Dan Garrison in Portland. He is the man. Once again, not cheap but how much is it worth to you to have it done right? I am saving my pennies right now so that I can afford to have the 44's gone through.

One last thing to think about. You can buy SU's on CL all day long for $100-150. There is a reason they are no longer on a car. Unless they are freshly rebuilt they are only worth the price of a core charge. You can see what that is on the Z therapy web site. These are just some of the conclusions that I have reached on my own through years of messing with Datsuns and roadsters in particular. Good luck and do a search on 311s.org as this subject has been beaten to death on that site.

[skunk]

:D thanks

[Nismopunch]

I also vote for SUs for street use! easy to tune, fairly inexepensive to have rebuilt. Ztherapy also has my vote as they are the SU GURUs imo..the rebuilds they put out are very high quality.

[Skib]

I also vote for SUs for street use! easy to tune, fairly inexepensive to have rebuilt. Ztherapy also has my vote as they are the SU GURUs imo..the rebuilds they put out are very high quality.

 

 

 

Ill chime in again since your mentioning Z Therapy (well with SUs how can you not lol)

 

 

Steve is a great guy and has helped me out alot (and still does) he knows just about all there is to know about SUs, Datsuns, and racing them. Between he and Pam they own 46 registered (not counting the multiple race cars or parts cars) Datsuns.

 

99% of the time your used SUs will never be 100% spot on no matter who tunes them, because the shaft for the butterfly's gets worn and is letting air leak in. ZTherapy carbs are a bit of coin (IMO) but if your plan is to run SUs then there definitely worth it. The quality of Steve's work is really bar none, and they look like they just came from the factory.

 

 

 

 

Triples have a RAD sound on a Zcar though :lol:

 

[ser240z]

Thought I'd chime is since I'm usually pretty quiet.

 

SU's are great. They really don't need much after they've been tuned, and if you overly concerned about MPG or out racing, even the beat up SU's run pretty well on a Datsun. I threw a beat up set on my Z and had them tuned by a pretty good guy, and they ran great while they were on. Bolt on and forget 'em.

 

I replaced the SU's with triple Solex's. Like Skib said, they soung great on a Z, and I always wanted triples. I've never taken it on a long trip, but I get like 8 MPG on the street and in LA traffic. They were rebuilt by Wolf Creek, who if anyone knows is really good with Mikuni/Solex, but they still have some issues. They are old carbs that are NLA, along with some parts. It is also common for the rear carb closest to the throttle linkage to develop some shaft play. This is common on Z's I would think it would be the same with duals.

 

My Roadster has Dual Mikuni's. I know for a fact that these were put on brand new, maybe on of the last pairs, and have less than 5k or so. They were also tuned by the same guy that tuned my triples, and I get around 30MPG on the way to Solvang. Street driving still sucks up gas, but tuned right, and they are reasonably efficient on the freeway. These also sound awesome!

 

Sorry I've never had any Weber's so I have nothing to share on them. But all of my cars are driven pretty hard, and have never been retuned. I'm sure they are a little off, but I've never had the need to mess with them once they were setup. Hope this helps some.

 

Scott

[Skib]

SU's are great. They really don't need much after they've been tuned, and if you overly concerned about MPG or out racing, even the beat up SU's run pretty well on a Datsun. I threw a beat up set on my Z and had them tuned by a pretty good guy, and they ran great while they were on. Bolt on and forget 'em.

 

 

ya a used set are still good as well, I had some old round tops on my L26 in the Z before the turbo swap and I kept em in tune from time to time but they kept up with that motor and it ran like a raped ape :lol:

[banzai510(hainz)]

SU that work are very good but that is getting harder and harder to find a good set then cost money to rebuild.

 

Try these and let us know if they work.

http://www.v-performance.com/products/air_fuel.html#mikuni_carbs

[hang_510]

so the one carb i feel like i know the least about (also the one that readdy for me to by like right now) is the dual 40mm mikuni set up. does any one have anything to say about them?

i have a set that i just went through, again, for the LZ22, so i cant say much, other than so far they seem no different than the webers, which i like :w00t:

 

i bought whatever i found first, at the better price. ;)

 

 

SU: call steve @ Z therapy :rofl:

:thumbup:

i sold the SU set i had as i was too old to learn something new. :fu:

 

 

from the link hainz provided "Unfortunately I wasn't able to get a dyno comparison between the Mukuni's and the ZS's. I can tell you I shaved 3 seconds off my lap times though. The throttle response is excellent."