Another carb question. weber 45s

[LOOGLE]

I know this has been covered in great detail but I'm starting to get confused with what applies to my scenario (And I'm a novice with carbs).

 

L20b with race cam and weber dcoe 45's. Was running okay but a little rich so I wanted to fine tune a little, specially with the incoming cold weather. 

 

I started to fine tune as per this video as it seemed to be a similar setup with an aggressive cam.

 https://www.youtube.com/watch?v=FoUOcPYqDmU&ab_channel=FastRust

 

1st- I set the idle speed higher @1100rpms. Was running about the same just not stumbling at idle as much. I drove it around and decided to go further into tuning.

 

2nd -  I decided to try my hand at balancing which is when I started having a problem. I started adjusting the balance screw and syncing via an air flow meter. They were synced pretty well but I started to notice a hesitation when I would goose the throttle. I tried to go back and thats when sh!t started to hit the fan.

 

3rd - I now have all the butterflies showing in the first hole of the progression ports. I set the Idle screw a 1/2 turn into the linkage. If it gets close to turning over the carbs pop and smoke. I stopped here as not to do any further damage. (I pulled the plugs and they were dark. OIi?)

 

Should I be going all the way to square one and do a baseline with idle mixture and air bleed screws? I thought I would have to go that far since it was running okay before. 

 

If it aint broke... I know. 

 

Any help is appreciated! 

 

[datzenmike]

That video sets the idle mix and balances all cylinders... but what about above idle? full throttle acceleration, part throttle and cruising speed? If the idle mix is set properly does that mean the mixture is correct all the way up?

[LOOGLE]

100% agree - It ran strong above 3k and a proper tune on dyno is in the future. I'm just trying to get it back to where it turns over. right now the carbs just burp and smoke then it cuts out. 

[banzai510(hainz)]

adjust the timing maybe that might get it going better

try 12-15deg BTDC

 

I dont know Webers.  I heard MIkunis were beter for the low end circuts

[LOOGLE]

Thanks for the hints. I think I need to back peddle a bit and see where I went wrong. I'm thinking I started to lose it when I started to adjust the balance and throttle hesitation started. Just not sure how to get back those settings. 

[LOOGLE]

After a little tinkering I think I'm onto something..

 

I had a hunch that maybe the carbs were clogged since it's running lean and backfiring out of the carbs. 

 

I turned on the ignition and have good pressure up to the carbs but when i blip the throttle there's only a little dribble down the plate. This is in idle, progression and acceleration. 

 

I think there should be more of a "jetting" rather than just a "dribble" correct? 

 

Ironically, I started having the starting problem when I filled the tank as I thought it wasn't starting because the tank was empty. Just happened to be the same time I started messing with the carb tuning. I'm thinking some sediment or rust made it's way up front? 

 

Can I clean the jets with compressed air and carb cleaner?  And if I get progress, remove the carbs for cleaning. 

[datzenmike]

Probably the diaphragm in the accelerator pump has worn out. The accelerator pump relieves the lean spot when the throttle is suddenly opened, usually resulting in a lean backfire.

[LOOGLE]

sorry, still learning. posted pic of the jet. need to inspect the pump! 

 

[LOOGLE]

Quote

Probably the diaphragm in the accelerator pump has worn out. The accelerator pump relieves the lean spot when the throttle is suddenly opened, usually resulting in a lean backfire.

 

Can you tell me which one the accelerator pump diaphragm is? I've looked at several pictures and assembly/cleaning/ reassembly/operation videos of Weber DCOE 45's and can not tell where or which one it is. 

 

 

http://  

 

 

Were you thinking they were 32/33 DGV Carbs? They are the only ones I can find an accelerator pump diaphragm for (See below). 

 

[datzenmike]

45s are well outside my wheel house. For all I know they may not even have accelerator pumps. All carburetors suffer from excessive lean on sudden opening of the throttle and usually some form of mechanical means is employed to fill this gap. Usually a pump.

[banzai510(hainz)]

when it come to sidedrafts I alway open the top to make sue the jets didnt back out,

 

the accel pump are on the bottom of the carbs on DCOE /PHH carbs

 

I would compared to the other if its really bad. Usually I can here the squirt of gas going in.

kinda DOUGHT THE ACCELL CIRCUT IS BAD

 

 

 

vid of the accell pump

https://240260280.com/Tech/Carbs/Weber/DCOE Theory Operation and Tuning.html

Edited October 11, 2023 by banzai510(hainz)

[Crashtd420]

55 minutes ago, LOOGLE said:

 

Can you tell me which one the accelerator pump diaphragm is? I've looked at several pictures and assembly/cleaning/ reassembly/operation videos of Weber DCOE 45's and can not tell where or which one it is. 

 

 

http://  

 

 

Were you thinking they were 32/33 DGV Carbs? They are the only ones I can find an accelerator pump diaphragm for (See below). 

 

On the dcoe I believe #60 is the pump....

#57 is the pump jet....

And in the bottom of the bowl is a return jet....

This returns some of the fuel back to the bowl.... sometimes it is recommended to install a zero jet there so nothing gets returned...

 

If you work the throttle blade you should see a good squirt of fuel... if not it could be clogged....

If I remember correctly I think there is an access hole for those....

Yup under the #59....

[LOOGLE]

Definitely think it's clogged somewhere. It's just a dribble when opening throttle. Have good fuel pressure all the way from the tank to the regulator. doubt the lines from the regulator to the carbs are clogged. Carb filters are clean. Accelerator jets and idle jets are clean. I do however see some sediment in the float basin and this did start happening when the tank ran close to empty for the first time. I'll be doing a thorough cleaning this afternoon hopefully. 

 

And of course thanks for the help!

 

Heres a motor shot for reference. 

 

http://

[banzai510(hainz)]

23 minutes ago, LOOGLE said:

tank ran close to empty for the first time. I'll be doing a thorough cleaning this afternoon hopefully. 

 

see if lots of sediment on the fuel filter

[Crashtd420]

I think the plug I circled has the pump jet in it... you could probably spray some carb cleaner down it....

Or remove and cycle the throttle a could times and see if you have anything flowing or if you have an obstruction somewhere else....

Careful if you remove the jet there is a tiny washer..... 

 

 

[datzenmike]

4 hours ago, LOOGLE said:

I do however see some sediment in the float basin and this did start happening when the tank ran close to empty for the first time.

 

 

Keeping sediment out of the carburetor float chamber is the job of an inline fuel filter.

[LOOGLE]

There was some a decent amount of sediment in the bottom of the fuel filter housing but I wouldn't think it was enough to reduce fuel pressure which was evident by a good reading on the fuel pressure regulator. Like datzenmike said " keeping sediment out of the carb is the job of the filter" .

 

Can anyone tell me if it's okay to use compressed air to clean carb passages and if so how much? 

 

 

[datzenmike]

Sediment in the float chamber won't affect fuel pressure any more than sediment in your toilet tank affects how fast it refills after a flush. The pressure only exists between the pump and the inlet needle valve on the carburetor.

 

I use a can of WD-40 to flush out the passages. I think they are just over 100PSI? The holes are so small very little volume is actually applied to move any obstruction.

 

One square inch is 25.4mm x 25.4mm or 645 sq mm. A 1mm (0.040") round orifice is actually 0.785 sq. mm. But 1 sq mm is good enough. Only 1/645th of 100PSI is air volume is actually getting through the hole. There may be 100PSI on one side but very little gets through. And then there are all the bends in any passage which adds resistance to flow.

[LOOGLE]

A little update: So "another carb question" has turned into "another distributor question". 

 

I tested everything: fuel, compression, timing, etc.  and gave up and took it to my local classic car guy. He's saying 90% positive it's the distributor. Cracked rotor and burnt points. 

 

This is an old Mallory distributor and a cap and rotor seem impossible to find. So the question arises - Replace distributor but with what kind? 

 

Again L20b w/ ka24 pistons, isky comp cam etc.. Ignition: Msd 6al , MSD blaster 2 coil 

 

I know datzenmike speaks highly of the 200sx matchbox but would this be compatible with the current msd ignition system (I'd rather not rewire the entire ignition just yet)? 

 

Also weber dcoe carbs so no vacuum advance.

 

As always, I'm super appreciative of all the help thus far. You guys make owning one of these much less overwhelming. I can't even begin to wrap my head around how some people here became so knowledgeable.       

[datzenmike]

I assume the Mallory doesn't have vacuum advance and is a points distributor? Didn't someone test them and they performed worse than the stock one?

 

Well pointless to put an EI distributor in if you already have an MSG. That's like hiring a lawyer to tell your lawyer what to do. A headlight switch connected to another headlight switch. Just get a simple points distributor. 

 

Myself, I think MSG is over priced over hyped and average. Sell it and get a matchbox.

[banzai510(hainz)]

1 hour ago, LOOGLE said:

burnt points. 

Replace points. If points burn up the wrong coil set up is in there. arching out is too much current.

But soemone told me with MSD they make the points a low voltage trigger so they dont wear. So Im no help dont know.

 

photos of set up

Edited October 19, 2023 by banzai510(hainz)

[fiveoneO]

I've used the MSD box to replace a bad matchbox on a electronic distributor before. It did make a more powerful spark at the plugs, but I didn't feel any performance gain. 

[LOOGLE]

Keep running into a wall here. 

 

I know ripping out the MSD and going matchbox pertronix, HEI, etc.. is the way to go AND in time I'll be doing that BUT for now I'm just trying to find a points distributor with no vacuum advance - I have weber dcoe's without a vacuum line. Some MG people have successfully tapped into manifold for vacuum line but there are mixed reviews on whether that works or not. 

 

MSD/Mallory doesnt make a distributor for an L20 whether they're garbage or I want to pay half a g or not. 

[banzai510(hainz)]

I think you making this harder than it is

I wouldnt worry hooking up the vaccum line. just advanced the dist to above 12 to 14 and see how it  runs.  Dual carbs  have LOW vacuum as mine was one using one port and it pulsates  on one cyl so I never got that how it worked.

 

My yellow car had no ports at all and open vacumm line with 44mmMikinus

 

key for you does the MSD work?

 

you pull the cent coil wire and place near ground do you get spark? if yes I would think its working.

 

Motor timed?

 

Jets didnt back out of the carb?  my 510 would do this the jet block would back out higher rpm seem like it run out of gas, Idle was fine.But this is MIkunis I dont know DCOE carbs

 

if you still have points point gap ok? also if a old dist. make sure the point bushing is not worn out where you have side play in the dist shaft where if loose makes the points open up anyway cause its loose.

 

 

this mechanic show you the cracked rotor?I like to see it. I havent changed a rotor in 15years!!!!!!!!

Edited October 20, 2023 by banzai510(hainz)

[LOOGLE]

and another stupid question... 

 

after looking through this thread could I run a matchbox (with msd's ) without hooking up the vacuum advance for now until I can tap into the manifold?  Would have the same sh!tty idle, mpg, etc. until mechanical takes over @ around 3k