L20b with dual weber now running...kind of

[KamakSun]

Hey all,

 

I now have the dual webers installed, linked and synched!

 

The car runs great at idle and revs smoothly at idle. When under load, all sorts of misfiring happens, especially under acceleration.

 

I have no idea where to start, a friend recommended checking the fuel pressure. Other sites say my jets may be to rich (running f8 60 idle jets). Other ratsun posts say it may be the dizzy (stock with the pertronix, let me know what I should be running and where to buy). Lastly the carbs may be junk. I did adjust the valves.

 

Sorry for the rambling. I'm just stuck and really want to hit the road in good shape.

 

Thank you!

 

KamakSun

[Draker]

Does it run at 2000 rpms steady? Or just under load?

 

Also, I'm sure there is a recommended jet setup for an l16 or l20. Would find that and reference it before assuming there are issues with other components.

[datzenmike]

Idle and hand revving isn't enough load. Accelerating in gear demands more gas. I would say it's too lean. How you would fix this on side drafts I have no idea.

 

 

See what jets others used on a 2 liter engine as a base starting point.

[racerx]

How does ur spark plugs look like

[banzai510(hainz)]

whats the timming at idle?

 

were these new or used carbs?  40 or 45 mm?

 

advance the timming to say 12-15 and try it then.

 

 

jets installed all the way and not dirty?

 

 

I seen where the accel pump diaphrame installed backwards on a Mikuni set once.  But hightly unlikely. You should hear gas squirting when not runnng. cycle the carb linkage

[scooter]

Idle jet may be a tad rich. What main jet, emulsion tube and air corrector are you using?

 

Stockish l20b? 40 or 45's or 48's?

 

Too rich will make it gurgle and fart and miss.. Too lean will sorta do that too.

 

How far out is your air mix screws? We also need to know the model number because dcoe 9's have a different thread pitch on the mixture screws than a 152

[scooter]

Heres a link for ya to help figure out some jetting.

Theres some very valuable hints in here.

 

http://www.classicrallyclub.com.au/docs/Tips_tuning_Weber_carburettors_DVAndrews.pdf

[KamakSun]

Hi all,

 

Sorry for the delay.

 

The misfiring happens only under load.

 

With regard to it running lean, I haven't changed the fuel pump so it may be providing just enough when sitting but not enough under load demands. In going to borrow the AutoZone fuel pressure tester.

 

The spark plugs are brand new and I only took her around the block a few times so reading them would be to premature.

 

I'm picking up a timing light tomorrow or Thursday. Ill set it at 14. The carbs are very old 45 dcoe but have been cleaned thoroughly and hopefully aren't too far gone.

 

Ill have to check my mains, but the idle jets are f8 60.

 

I hope I addressed everyone's posts. My next steps are going to be:

1 pray

2 check the timing

3 check the fuel pressure

4 inspect the carbs

5 resynch the carbs (sans the linkage)

6 reconnect the linkage

7 repeat step 1

8 test drive

 

 

Please let me know if I missed anything.

 

Thanks again,

 

KamakSun

[banzai510(hainz)]

Bullshit on the fuel pump. I run stock pump and they fine.   a stock pump squirts put alot of gas!!!!!!!!!!!!

 

If electric pump you better have about 3 pounds of pressure.

 

most carbs even jetting badly should work somewhat.

 

I seen  44mm Mikuni set bolted to a stock L16. it just ran better when it when faster

[KamakSun]

my concern is that the car sat for twenty five years and the diaphragm maybe worn. It is probably the original pump and like the rest of the car, it may need freshening. I do appreciate the input and every comment has me examining different systems a bit more in depth.

 

The fine folks at Weber do no want more than 3psi. Had there been a need to use a fuel pressure regulator?

[scooter]

If your using the stock pump you dont need a regulator

[banzai510(hainz)]

Im winging this hear but maybe the accel pump diapram dried out.

I had a good used pump under my seat them my pump went out and changed it on the side of the road and that one didn't work either. I assume once gas go to tit it dried and cracked. Im just guessing.

[Doctor510]

Weer DCOE carbs do not have an accelerator pump diaphragm, they have a brass barrel as the pump.

[scooter]

Still need to know main jet, emulsion tube and air corrector sizes, and venturi size.

[racerx]

Sat for 25 years? Same gas, i hope not.

[banzai510(hainz)]

weber no accel pump? I did not know that. Im smarter know

[Doctor510]

No diaphragm, it has an accelerator pump, just differnt than most