Replaced Hitachi with new Weber-Suggestions Needed

[650savag]

I was having some serious issues with my stock carb on my 78 620 so instead of trying to keep rebuilding it, I finally broke down and ordedred a new Weber 32/36 .  The problems that I was having with the stock carb were: 1.  Having to keep the choke (manual) almost completely closed after the engine warmed up in order for the engine to run half way decent. I had some typical leaks around the throttle shaft and other problems from a worn out carb.  2.  I was having some serious starting problems when the engine was warm and had sat for awhile. The last time that I drove it with the stock Hitachi carb on it, it would not start after it sat an hour or so.  It would cold start fine and I drove it about 2 miles to my son's house and helped him with a project for about an hour and when I got ready to leave, it would not crank (flooded, I think).  I left it and rode home with my wife and came back the next morning and it started right up.  I now have the new weber on it have the auto choke hooked up and got it adjusted.  I set the idle mixture screw to 2 rounds off bottom and the plugs are looking really nice.( light brown color). It starts up and runs really strong but I have noticed a slight stumble every time i give it gas. (Taking off and each time I let off the gas and shift (5 sp) and give it gas again, it hesitates (stumbles) just a bit.  Also, I still have to be careful when I try to re-start it when it's warm.  I have to crank it without using the throttle at all and let it idle a few seconds.  It acts like it still wants to flood when its warmed up.  I have another coil that I think I will try tomorrow and see if that helps.  I was wondering if anyone could offer some ideas about what is causing the two issues.  I can live with the little pause (stumble) if that is something that is typical with the weber but I would like to figure out why it's hard to start when the engine is warmed up and sits a few minutes. I haven't changed the timing (still stock timing). Any ideas or suggestions?

[MicroMachinery]

Never had a Weber that you didn't have to ease into the throttle to prevent it falling on it's face(stumble). That's why I opt to rebuild the Hitachi over using a Weber. Every time.

[650savag]

Thanks, Micrmachinery. I was afraid of that. Any ideas about the the hard starting issues with the warm engine? I can kill it and start it right back up, but let it sit for a few minutes and then you have to be careful to not flood it!

[Doctor510]

Make sure that the accelerator pump is working, if it is, use a larger idle jet size. 

[650savag]

Thanks, Doc! I will check and be sure the pump is working. I just assumed it was on a new carb. I pulled the distributor cap off to check the rotor and points but I think it may be electronic? I will try to put a pic on here. It is a stock 1978 620 Deluxe king cab. Do you know if this has single points, dual points or electronic?

 

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[620Turbo4X4]

That is electronic ignition. Igniter is located under glove box.

 

I had the exact same hard starting / flooding when hot issue with my '78. Mine was caused by the weber carb boiling over and dumping fuel into the intake. The intake and exhaust manifolds were bolted together rather than using coolant to heat intake. After about 5 minutes heat from exhaust would reach carb and cause fuel to boil. Never had this issue with hitachi. Take air cleaner off after driving listen for a boiling sound and see if you can see fuel dripping onto throttle plates after 5-10 minutes....

[650savag]

Thanks Turbo! I will check that out. My truck started doing that just recently and I was blaming the Hitachi carb for the problem because I was having other issues with it. The weber runs much stronger and now I have auto choke again but I'm still having the little bog and hard starting when warmed up. I'm beginning to think it's another issue altogether. I changed out the coil today and that didn't help. I manually checked the timing today by taking the distr cap off and rotating engine around to where the rotor was at the #1 position. The notch on The pulley was sitting a little past 20 degrees (probably like 22 or 23) btdc. I think I will buy a timing light and check it out.

E

[620Turbo4X4]

No problem. The way you described your hot start problem reminded me of my trucks past problems. Embarrassing when you come out of store and trucks flooded.....

 

The hesitation is problematic to the webers as said earlier. These are jetted as one size fits all, so on a 2.0l engine running close to sea level, you might be running borderline lean. (Mine with 140/140 main jetting was a tad) Just the smallest air leak can make things much worse. Before changing any jetting check for leaks with some flammable carb clean (some are non-flammable) or starting fluid sprayed around adapter (which are prone to leak right out of box) I like to use un-lit propane torch, but cooling fan can blow vapors away.

 

The hitachi I had got hot and boiled, but never did flood the engine to the point it wouldn't start. Perhaps your return line was/is plugged?

[Doctor510]

Thanks, Doc! I will check and be sure the pump is working. I just assumed it was on a new carb. I pulled the distributor cap off to check the rotor and points but I think it may be electronic? I will try to put a pic on here. It is a stock 1978 620 Deluxe king cab. Do you know if this has single points, dual points or electronic?

 

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Yup it's the electronic one.

[650savag]

Thanks, Turbo! Yes it can be a little embarrassing! Lol! It happened at Sonic last night. I thought is was not going to re-start and I would have to call wife to come get me. Thank goodness it finally started and ran rough a few seconds and then lined out. I will check the return line. Something has changed recently because it only started doing this about 2 weeks ago. I'm ordering a timing light on Amazon and should get it in 2 or 3 days (Amazon Prime). I'm going to check my timing with a light but it looks like it's set pretty high right now. 20 or 25 degrees! Can I just loosen that one bolt that goes through the slotted plate (it looks like a 10 mm hex with a Phillips in the middle) and then adjusts timing?

[Doctor510]

YUP, try 12* BTDC at idle to start.

[650savag]

Thanks,Doc. I ordered a timing light today and it should be here Friday. Is that one bolt the only one I need to loosen?

[Fat510]

It starts up and runs really strong but I have noticed a slight stumble every time i give it gas. (Taking off and each time I let off the gas and shift (5 sp) and give it gas again, it hesitates (stumbles) just a bit.  Also, I still have to be careful when I try to re-start it when it's warm.  I have to crank it without using the throttle at all and let it idle a few seconds.  It acts like it still wants to flood when its warmed up.  I have another coil that I think I will try tomorrow and see if that helps.  I was wondering if anyone could offer some ideas about what is causing the two issues.  I can live with the little pause (stumble) if that is something that is typical with the weber but I would like to figure out why it's hard to start when the engine is warmed up and sits a few minutes. I haven't changed the timing (still stock timing). Any ideas or suggestions?

 

This is normal Weber operation

 

Hard start up when the engine is hot is actually normal too

 

If it's rapidly losing and gaining power under acceleration, try replacing your cap and rotor

[TENDRIL]

 Something has changed recently because it only started doing this about 2 weeks ago

 

 

weather?

[Doctor510]

Thanks,Doc. I ordered a timing light today and it should be here Friday. Is that one bolt the only one I need to loosen?

There is one that hold the dist body to the plate, you may have to adjust the timing there if the larger one is not enough.

[650savag]

Thanks guys for all the suggestions..I did think that the warmer weather may be playing a role in all of this.  Has anyone ever tried using the phonolic spacer with the Weber carb?  One would have to use longer flat head bolts but that might help the issue of fuel getting too hot and boiling over.  Just a thought.  I noticed today when I forgot to hook up the wire for the choke that it didn't stumble as bad but that was probably because the fast idle was still on.  I'm going to check again for a vacuum leak.  The first time I installed the Weber, and started it up, I had a huge vacuum leak around the adapter plates.  It would not idle and was was running really rough and backfiring.  I sprayed some carb cleaner around the plates and realized I had a bad leak.  I took it all back off and used permatex on all the gaskets and tightened them down a little better and that seemed to solve the leak problem but I'm going to check good again tomorrow.  I will update tomorrow and if anyone else has an idea, please chime in!  Thanks again!  Is the bolt that holds the dizzy to the plate the one that is underneath on the oposite side of the adjustment screw?  I can feel the head of a bolt under there but didn't know if I needed to loosen that one or not to set my timing?

[620Turbo4X4]

Mine was the same way with the warmer weather making the flooding worse. I used a insulator from a pinto between carb and adapter (3/8" thick?) helped a little, but not enough during summer. The exhaust manifold heated intake they used on l20b is a lousy setup. I have the coolant heated intake now. Same carb, no flooding...

 

Permatex is not fuel resistant. You'll want to file the adapter surfaces flat and get it sealed up without any type of sealants. Be sure to use loc-tight on the fasteners. (Screw strength blue is fine) Wouldn't hurt to get some extr thick gasket material and make your own gaskets. Sounds like you still have some leaks with the mixture screw 2 turns out. Lean mixtures will cause high exhaust temps. which would contribute to the carb boiling over/flood.

 

Either distributer bolt will allow adjustment. The 10mm on top is easiest to get to...

[650savag]

Thanks for more good info, Turbo! I did lap both sides of the adapter plates and I used the blue loctite on all the bolts. I should have done more research and used a different gasket sealer. I have some thick gasket material and if I take the carb off again, I will make my own gaskets. Those gaskets that came with it looked pretty cheap to me. Like cardboard! Thanks again for your help. I know it's time you could be spending doing other things. I can live with the carb the way it is because my truck is not a daily driver since I retired, but I sure hope I make some improvement on the warm starting issue.

[650savag]

Just an update.  I checked the return fuel line today and it is open all the way to the tank so I should be getting circulation.  I have a regulator and have my fuel line pressure set to 3 pounds.  I cranked it up and let it warm up and checked for leaks around the base..There was a very slight leak so I shut it down and snugged up the 4 13mm nuts.  When I started it back up, I couldn't detect any leaks at all.  I checked the mixture screw and it was set to 3 turns out instead of 2 so I backed it off to 2 turns and it ran worse and still had the little bog.  So my timing light should be in tomorrow and I will check that.  Also, I let it warm up good and killed it and let it set for about 5 minutes and listened for fuel boiling and watched for fuel dripping down on the throttle plates.  I did not see any sign of fuel boiling over in the carb.  I will set my mixture screw back to where it runs the best and I may just have to live with the slight stumble and the hard starting when warm.  I still like the weber much better than the worn out Hitachi.

[bilzbobaggins]

Wouldn't hurt to try set timing by ear. I just played with the dizzy and carb till I got the best smooth low idle. You could do this today to see if you can get it running better and if successful, check to see where its at tomorrow with your new light. I set mine by ear and have no problems with weber. Idles right at 700 rpms. It is a L16 though with the separate manifolds. Does get hotter than piss down here but I have not had any vapor lock or general hard start problems. No hesitation what so ever on throttle. Just an idea for the day.

 

Good luck.

 

Jeff

[650savag]

Thanks Jeff. I think I will probably wait until tomorrow to tinker with it again. It's already hot here and thunderstorms just to our east! I drove it over to my sons about an hour ago and it seems to be doing some better since I snugged up the carb. It cranked right up after it say about 10 minutes. Do you know what your timing is set on? I don't have any experience in adjusting timing by ear or with a light either so I need to be careful with what I loosen and move. Just from looking at the little notch in the pulley it looks like it's past 20 degrees so I guess you call that advanced. I don't see any paint on the notch but I don't know if it shows with a light or not?

[Stoffregen Motorsports]

Never had a Weber that you didn't have to ease into the throttle to prevent it falling on it's face(stumble). That's why I opt to rebuild the Hitachi over using a Weber. Every time.

Tuning. That's all that needs.

 

The only time I've ever had a prolem with a DGV was when I had one on my first rock crawler. It flooded over.

 

I love the tunability of the DGV. And modifications are endless with a DGV too. Custom auxilliary venturis, remove seconday choke plate and shaft, larger needle and seat, shave the  power valve...lots of things you can do to them.

[Doctor510]

You are on the right track.  Put some yellow or white paint on the TDC notch on the pulley (it's the big one) and adjust accordingly.  For the air/fuel mixture, while the motor is idling, turn the AF screw IN until the motor starts to stumble, then screw it OUT until the motor starts to stumble, the screw it IN until the idle is smooth.  Re-adjust the idle speed to 800-900 RPM.  Don't believe the book, it's a good place to start and besides, I never met a Datsun that could read.

[620Turbo4X4]

Wouldn't hurt to put a dab of paint on the timing notch. Makes it a whole lot easier to see with timing light

 

When you do/did the visual check be sure your turning the crankshaft clockwise. There could easily be 10 deg. of slop in the gears/ drive spindle. If you had notch on top and turned backwards to the 20 mark your seeing the timing AND the slack in drive spindle. Best to just wait for your timing light to arrive.

 

Still sounds like theirs a vac leak somewhere. Every stock l20b that I've put a weber on ran best at 1-1/4 - 1-1/2 turns out on mixture screw, at 3 turns your adding quite a bit of additional fuel at idle, and beyond the normal adjustment range of 3/4 - 2 turns out

[650savag]

Thanks guys! I will put a spot of paint on the pulley notch before I try to adjust the timing. The way I checked it manually was I took the cap off and bumped it around with the starter untill the rotor contact got close to the #1 position (I had marked it before removing the cap). Then I turned it by hand untill the rotor contact was dead on the #1 position. When I looked at the pulley, the notch was past the 20 degree mark on the plate. Probably like 5 degrees past. I figured there was some slack to deal with but i still think it !might be advanced too much. Would you call that advanced ? Would it still run OK there? What would cause it to move because no one has ever worked on the truck that I know of and it has 116,000 actual miles on it.