Weber 32/34 DFT Carb on 1981 Datsun 720 with a Z24

[620Bob]

I recently acquired an '81 Datsun 720 4WD that the previous owner had modified over the years.  The original truck had a Z22 engine and the owner put a California CARB approved Weber 32/34 DFT 9 carburetor to replace an aging Hitachi carb.  Then, a few years later, he swapped in a Z24 engine and moved the Weber over without modification.  Now I own the truck and I want it to all work well.  Does anyone know the jetting setup for the Weber 32/34 DFT when on the Z24?  I have removed and serviced the Weber, but the engine sometimes still hesitates at lower engine speeds when throttle is applied and I'd like to correct that.  The engine idles well and also runs well under throttle.

 

 

 

[Charlie69]

On a Z 24 I would not run less than a 32/36.  The 38 runs real strong on a fresh Z24.  32 34 is to small in my opinion.

 

Are you possitive your 81 has the Z24?  The Z24 was not available in 1981.

[ggzilla]

Tune that Weber! 32/36 is slightly smaller than the stock Z24 carburetor and is an excellent choice.

[datsunaholic]

A 32/34 DFT is a little small for a Z24.  It'll work, but you won't be racing it.

 

A 32/36 would be better, BUT it's not CARB approved and since you're in San Diego your only choices are the DFT or a stock Hitachi.

 

The hesitation is more likely the Weber's accelerator pump is either wearing out or undersized, but parts for a 32/34 aren't particularly easy to find.  You only need to change the main jets if it's running the wrong mixture, which really needs to be run on an analyzer to find out (or run a sensor to determine the mix). 

[620Bob]

Thank you all very much for your comments. I've known the previous owner of this '81 720 4WD for many years and the Z24 and the short-tail 5-speed came out of a low-mileage 1985 720 4WD vehicle I used to own.  The current performance of the Z24 in the 1981 with the Weber 32/34 DFT is about the same as the previous 1985 with the stock Hitachi.  What I'm trying to solve is the hesitation at low RPM with throttle change.  The Weber kit (K8649) was made for the Z22 and worked great on that engine.  I tried contacting Redline Weber directly and also through an authorized dealer, but they will only say that the DFT series is obsolete and they don't support it.  An Internet search found the California State CARB Executive Order approving the K8649 Weber DFT for use on the Z-series, and it includes a detailed summary of how to do the conversion and what emission equipment should be removed.  I've taken all of the vacuum hoses off of the Z24 and replaced them with new hoses that are grouped and connected as shown on Weber's instructions.  Now the truck runs 95% better and almost never hesitates.  I didn't find any leaking vacuum hoses, but there are fewer hoses now and I can comprehend the groupings.  Weber still makes the jets for the DFT, but you can't obtain any information about the part numbers by referring to the DFT.  I've ordered Braden's book on Weber Carburetors and it should arrive today in the mail.  The book was published in 1988, is rated 4.7 out of five stars, and it has an entire section on DFT applications.  Hopefully, I'll get some good information from the book.

 

[ggzilla]

Congrats!

 

It is often the little details, like cracked vacuum hoses.

Now the truck runs 95% better and almost never hesitates.

Too bad the carb books never explain about how to check old carbs. The 5% left might be a leaking idle pull off (common source of vacuum leak), a leaking air cleaner flap valve , a leaking distributor vacuum advance or one of the other vacuum devices .

[wayno]

I am curious, is the Weber 32/34 DFT 9A/11A nothing more than an emissions carb.

I ask because I have 2 of them and it appeared to me that they will bolt right onto a stock Datsun 320 E1 manifold, I thought they were really old Weber carbs from the 60s, but now I am wondering if they are just modern CA emissions carbs.

If they were old(60s carbs) then they would be period correct for the 320 although there is no way the stock air filter housing would fit on the carb adapter it has.

 

 

 

Edited July 29, 2019 by wayno

[Stoffregen Motorsports]

On 4/16/2014 at 7:54 AM, Charlie69 said:

On a Z 24 I would not run less than a 32/36.  The 38 runs real strong on a fresh Z24.  32 34 is to small in my opinion.

 

Are you possitive your 81 has the Z24?  The Z24 was not available in 1981.

Chevy sold millions of their V8s with single barrel carbs. I think this one will be fine.

[Stoffregen Motorsports]

We've had this discussion before. The "smog legal" Weber was very similar to ones found on Pintos, Fiats and other makes/models. There was even a Ford Motorcraft part number for a near identical carb, and they called it a "Holley Weber 5200".

 

You have obviously found out the hard way that there is little to no support for these smog legal carbs, but reading what you posted made me wonder if by searching for parts from a Fiat or Pinto, you may find that a lot of the parts (like jets) interchange.

 

28/32 ADF

34 DMSA

34 ADF

32/36 DFEV

 

These are just some of the names I found in a quick search for "Fiat Weber". Try one of these and see if any of the parts interchange. Maybe a call to Redline or Pierce would help clear this up.

[wayno]

I should have mentioned this was an old thread revival.

I have found gasket kits(rebuild?) for these carbs at Pierce Manifolds.

I guess mostly I was asking if these were period correct for the 320 truck, I got these carbs with a 1964 Datsun NL320 and this is why I thought they might be period correct, but now I understand they are 1980s??? carbs and not made back in the 60s.

[Stoffregen Motorsports]

I see that now.

 

No, these were not era correct to the 320. If they bolt to a stock manifold, I would still use one though. Good carbs.

[pishta]

This was a 76-83  Ford Fiesta California spec carbs and I think the CA spec was only leaner jetting. If you go to the CARB website and put in the EO number you'll find the Redline application and the jets and correctors they used to pass smog on this aftermarket carb on a Datsun or even a 74-82 Mazda B series/Courier truck. Basically they too a DFT9 or 11 and put 155/160 air correctors, 112/115 mains and 55/60 idle jets. My Mazda spec had the idle airs at 175/70 (misprint?) 1.5 inlet and 130 pump cam. I only had to change the primary side main and corrector and the primary idle jet from 47 to 55. This carb conversion was 1-10% less efficient MPG but 40-50% lower in HC and 20% lower in NOx. My jetting was the same for a 1.8 mazda to a 2.3 Ford. The main jets are also under DMTR model carbs.   https://arb.parts/Executive-Order/D-133-7.pdf