Is there anything to be giained by going from the standard roundtop SU's to a set of Weber DGV's?

Nope, not really. The intake and S.U's were designed for a straight in flow of fuel.

Look at the picture above and follow where the fuel and air will flow. You'll see that is hits the bottom of the manifold, swirls around then makes it's way thru the intake and into the engine. Not nearly as efficiant as SU's.

Don't get me wrong, Weber DGV's are awesome, but not as good as a set of clean, tuned SU's on an L-series motor.

This is of coarse, Just my own opinion, others may vary.

Dave

My advice--keep the SU carbs, or better yet, get a rebuilt pair from Z Therapy. That's what I'm going to do this time around. I ran the Webers DGVs for several years after my SU carbs gave up the ghost. That was a mistake. In my opinion, the SU carbs gave better power and were actually easier to tune.

wow one would think since these carbs are sold as an upgrade by MSA for $1K they would provide atleast a slight power gain.

http://www.thezstore.com/page/TZS/PROD/PFFC02/11-3005

If you want a power upgrade, I'll sell you my complete set of Triple Weber 40DCOE's with Cannon intake and linkage. They just need to be blown out, cleaned and rebuilt.

You can have them for $700. If you know a Weber tech or expert, to rebuild and tune them for you, You can't go wrong. But with any used piece of equipment, it will need fine tuning and patience. but the pay-off is worth it.

DCOE's, like SU's, are sidedraft carbs. That's what the L-series motors like.

Dave

They aren't THIS clean anymore but easily cleanable. Will need 1 or 2 new K&N filters. I say $700 cause I'm a fare man, you will need to buy a few parts and the money you save here, will be spent elsewhere.

DGV's and 4 barrel setups are best used by people who don't understand SU's and won't take the time to learn.

If you want to learn about SU's, just get the video from www.ztherapy.com. I think it is $20, and then you can get better performance than you would through the downdraft carbs and you can spend the rest of the money you saved on more go fast stuff for the car.

I have a set of tripple 40s as well-great for the cool factor, but for smooth running performance and virtually no maintenance, a set of SUs from Z Therapt simply can't be beat. One of the magazines did a side by side and found that Webers aided performance by lightening the car(the weight came out of your wallet!), but that SUs delivered slightly better performance at a lower price...

Will

DGV's and 4 barrel setups are best used by people who don't understand SU's and won't take the time to learn.

If you want to learn about SU's, just get the video from www.ztherapy.com. I think it is $20, and then you can get better performance than you would through the downdraft carbs and you can spend the rest of the money you saved on more go fast stuff for the car.

I agree Mort:beer:

LOGAN

Skinner Union got it right with the side draught....oooopppps side draft carburettors. Easily tunable, reliable and simple. If you are looking to enhance HP a set of good triple side drafts is the way to go. I will not suggest one over the other but I will tell you that Datsuns tend to perform better with 44MM and larger.

"DGV's and 4 barrel setups are best used by people who don't understand SU's and won't take the time to learn."

Wow, I understand this is a pro-SU site but this is bit of an exaggeration. I spent a LOT of time and money trying to diagnose my SU's before switching to a 4-barrel carb. I got the video, rebuilt them but in the end I was looking at just ordering a new set. I went with the 4-barrel for an electric choke and a brand new carb that was easier to tune and cheaper.

My z runs great , thank you very much.

Edited February 12, 201114 yr by 73_240z

"DGV's and 4 barrel setups are best used by people who don't understand SU's and won't take the time to learn."

Wow, I understand this is a pro-SU site but this is bit of an exaggeration. I spent a LOT of time and money trying to diagnose my SU's before switching to a 4-barrel carb. I got the video, rebuilt them but in the end I was looking at just ordering a new set. I went with the 4-barrel for an electric choke and a brand new carb that was easier to tune and cheaper.

My z runs great , thank you very much.

I ran with SU's for a few years and a few things come to mind: the mid range torque and the sound of those carbs.

I don't know how hard it is to tune DGV's but with a mechanical secondary on each carb, I'd like to hear them at WOT!

And yes, the Holley gets whipped again

What's new?

Edited February 12, 201114 yr by ozconnection

I had a pair of DGVs on a 260 and they were great for highway cruising and with a 5-speed you could probably squeeze out a few more mpg. You could tell when the extra barrels kicked in but it wasn't some kind of neck snapping experience. I am not a Weber tuner and I get the impression the DGVs were not a performance carb as much as they were a passenger car carb.

I would say if there's anything to be gained it's in highway mileage when the DGVs are paired with a 5-speed.