Weber 32/36 DGEV swap on L16

[Figbuck]

1973 620 with L16 ran OK for all these years with stock emissions and stock carb. I had two Hitachi carbs that I have rebuilt once each. Finally, I they are too much trouble to fool with anymore, the accelerator pumps need to be replaced... and I even have an unopened rebuild kit to do it.

 

I ordered a Weber 32/36 DEGV kit from California Datsun for $325 including shipping. Was delivered in 6 days. It was pretty straight forward to put the adapter plate on and hook up the throttle linkage. It was a little tedious to re bend the stock metal fuel line and re-connect the short section of fuel hose. Hooked up Vac Advance, connected the choke to 12v switched. plugged the evap return line to the fuel tank. 

 

It cranked a few times before it finally got fuel, then fired off in pops and starts. The third crank it ran as I blipped the throttle... I thought it was going to die becasue the throttle stop seemed way low. But it ran at like 500 rpm... and idled like a sewing machine cold. I was blown away. I bumped up the throttle stop to 900-1000 and realized the choke was working. I took it for a spin, runs great.

 

Adjusted the idle mixture, then the throttle stop back to 800. It started, ran and idled fine... running great on short 5 and 10 mile errands over three days. I just tried to start it and it cranks forever, but no fire. It was running great when I shut it off. 

 

I seems like it is not getting fuel. The choke plates are completely closed. I don't know how to open them... not going to force anything. tried to pour gas into over the choke plate on the primary a couple times... not firing. Seems amost electrical no spark, but all the distributor and pug wires are tight. Pulled #2 plug, no gas on it really. not fouled. 

 

I think it is not getting fuel. when I cycle the throttle, I don't hear fuel spray, don't real;y smell gas evaporating after pumping the throttle either. Cant' see into the throttle body. I loosened the choke ring and wiggled it and reseated it in the middle of it's adjustment range.  Seems like the choke plates are being held completely shut, no gap.

 

Why or how did the choke plates get stuck shut. Why doesn't the choke open the plates as it warms up or is cooled down and disconnected? 

 

 

[Figbuck]

Finally after wasting a bunch of time, the choke plates and their linkage were jammed shut. It's a brand new Carb, I didn't want to force anything. I loosened the adjustment screw for the choke shaft/step plate,  and loosened the choke ring so I could rotate it freely... the choke plates did not rotate on their shaft. WTF? 

 

it was so choked that even when I poured gas in it it didn't fire. I thought if it warmed up the choke would open?? I kept thinking it was electrical, sounded like loose coil/dist wire... no sparking.  Fuck, I knew it had to be something simple. But I wasn't understanding how or why this shit was stuck. It was running when it got shut off? Why can't I open the choke mechanism? This sucks. 

 

I suck my finger on the primary plate and pushed, thinking... this is out of frustration and so wrong... but pop, the linkage freed itself. It seemed like the choke plates were stuck in the throttle body and not the linkage binding. But I can not make them stick again!  Made sure all the throttle linkage was tight and put the choke in the middle of it's range. Saw gas spraying into the primary.

 

Fired it off first time. Idles great @ 850, crisp throttle response, great acceleration. Wow, happy guy finally after wasting a nice afternoon and blowing an appointment.

 

Now we will see what kind of gas milage we get...  

 

 

What should i do about the breather vent in the valve cover? Route it into the base of the carb with the plastic fitting fitting supplied? The stock air cleaner had the valve cover vent before the filter. This would be after the filter and directly into the carb. What needs to go on here?

[banzai510(hainz)]

Yes that what I did route it to the lower air cleaner with the L shaped tube

[Figbuck]

I have been driving the new carb for a couple weeks. I had to tweak the idle spring tension & idle speed screw a few times to get 850 or 900 rpm. It seems like I got the linkages working right. I set the Idle Speed Screw 1 1/2 turns in, making sure the linkage was completely closed. The Idle mixture screw got set a little less than two turns out. It was driving around fine. I re-set the choke, checked the Primary Idle screw so it was snug but not binding. I checked that the wire I used for the Choke is hot and switched by the ignition key.

 

I drove ten miles over streets, on and off the freeway, when all of a sudden it stalled at a stop light. Started again, but had to keep the throttle a little open to keep running. In a half mile, it started stalling as I gave it gas, like as the secondary opened up, it flooded or ran lean. It would only run badly on part throttle, wouldn't idle. wouldn't accelerate. Finally died and wouldn't start again. 

 

Dark, raining, no tools. Got towed home. I have gone through the carb set up procedure a dozen times. Checked gas flow and filter. Good battery that cranks like mad. Cleaned & gapped the plugs. The two outside plugs looked tan, the two inside were a little oiled, don't think it's flooding.

 

All 4 nuts securing the carb to the base plate were loose. I thought, perfect, that is what it is! It's like a vac leak, more throttle, more vacuum, more air leak. But no.

 

I stuck my old carbs in the Weber box took then to the storage building... Redline/Weber customer service hot line will talk to me, but not without telling them the production code number stamped on the box... 

 

It tries to fires for a few revs but won't run.  

 

It fires for the first few revolutions, like it's wants to start... it's trying to start. But it just cranks and cranks, like the distributer wire is disconnected. Come back after a while and the same thing, it kinda wants to fire, but then just spins...

 

I've been through the basic carb set-up procedure a dozen times. Idle speed screw, Idle mixture screw, choke spring tension and fast idle screw.

 

Any ideas? 

 

 

[wayno]

I had an engine way back act like that, it seemed to want to start but it would not, turned out the distributor timing got screwed up somehow.

I also had one that when I went around corners the engine flooded out, that one turned out to be a bad needle/seat.

[Stoffregen Motorsports]

Will it start if you lean into the throttle? Or floor the throttle?

 

It is not uncommon to have to lean into the throttle while starting an older carbureted vehicle. Bad running though? Does it pop out of the carb or out of the exhaust?

[datzenmike]

Is the choke on? Did it reset for a cold start???

 

If yes hold it open and try starting. May take a while to clear out.

If no pump gas several times to force a rich condition and try again, should fire up.

 

 

 

[Figbuck]

42 minutes ago, datzenmike said:

Is the choke on? Did it reset for a cold start???

 

If yes hold it open and try starting. May take a while to clear out.

If no pump gas several times to force a rich condition and try again, should fire up.

 

 

 

 

 

3 hours ago, Stoffregen Motorsports said:

Will it start if you lean into the throttle? Or floor the throttle?

 

It is not uncommon to have to lean into the throttle while starting an older carbureted vehicle. Bad running though? Does it pop out of the carb or out of the exhaust?

 

No. I did try to hold the throttle wide open and start it as if it was flooded. I though the same thing Mike suggested. No dice.

 

Now that I got it running and tuned; Turn ignition key to power choke. Pump gas once to set choke linkage. Turn starter, engine starts and idles about 1100, 1200 rpm. Wait a bit then tap the throttle and the choke resets. Runs pretty good cold it think. Idles at 850 900 once it warms up.  Accelerates great! Makes good power through out the rev range. I'm going to have to resist the urge to wind it out all the time! hahaha

 

 

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21 hours ago, wayno said:

I had an engine way back act like that, it seemed to want to start but it would not, turned out the distributor timing got screwed up somehow.

I also had one that when I went around corners the engine flooded out, that one turned out to be a bad needle/seat.

   

Or in my case maybe wiring to the dist short or open. No It was running, I looked everything over and ruled ignition out. I fooled with this for three days. When I got frustrated, I quit and did something else. I knew I was going to figure this out and it would some stupid simple... I'm going to fell like an idiot.

 

But, you called it too Wayne! One of the problems was crap in the Idle Mixture screw. Pulled it to inspect, re-seated it them back it out 2 turns... started running badly... but it started and ran.

 

 

 

In the end my girlfriend who used to run the office for a Jaguar shop said, Oh that's a Vacuum leak! With no hesitation.

 

So I tried to think back to installing the new carb a couple weeks ago. The installation guide said to use thread lock on intake manifold threads. I remember thinking does that mean, apply thread lock to the nuts holding the carb body too? Nah... really? I thought no. I cranked the fuck outta those little nuts I thought. I didn't want to strip the intake manifold, and could see cracking the base to the carb!  It did occur to me a few times to check that they were still torqued down. Somehow I never did that, chasing other things that might cause the symptom.

 

Shit. When she said Vac Leak, the first thing I did was see if the studs were tight. Studs were thread locked, but all 4 nuts were a turn, or turn and a half loose. Fixed that and fired right off. Set Idle Speed, Idle Mixture, Fast Idle and the Choke Spring.  Starts, runs, idles.

 

Now the problem I'm having is as i hooked breather vent back up... it is totally fucking with the choke operation and carb in general . 

 

I saw a YouTube video of a guy who put a webber on a Mazda truck... he had what I assumed is a canister mounted on the firewall in between the valve cover and the air cleaner. I don't think I have ever seen this set-up on a Datsun... anybody run a breather filter?  

 

 

[wayno]

I don't believe I mentioned anything other than timing and a bad needle/seat.

This issue you had is a common one, that carb needs to seal to that intake manifold tight without any vacuum leaks, they run like crap if they run at all when the carb is loose.

 

[Stoffregen Motorsports]

17 hours ago, Figbuck said:

 

I saw a YouTube video of a guy who put a webber on a Mazda truck... he had what I assumed is a canister mounted on the firewall in between the valve cover and the air cleaner. I don't think I have ever seen this set-up on a Datsun... anybody run a breather filter?  

 

 

Could be an oil air separator. Engines will puke oil out of the valve cover occasionally and sometimes that gets sucked into the intake. An oil air separator will catch the oil. They usually have a drain or a removable lid or lower section. I've used them before, both store bought and hand fabricated.

[bilzbobaggins]

Im using red loctite on my weber these days.  I would tighten the shit outta it with the lesser colors and end up with a leak after a few hundo miles.  

[Stoffregen Motorsports]

Use red loctite where the studs go into the adapter and the manifold too, otherwise when yo loosen the nut, you'll likely loosen the stud.