Tuning dual Webers, Looking for input in the PNW Options

[TC 914-8]

I just found out my wifes coworker, The Dr Vet's husband, has a 75 2.0 with a dual Weber downdraft conversion. I stopped by last weekend to take a look. it has some minor electrical issues which I should be able to sort out fairly quick with proper diagnostics. Horn, lights etc..
One of his main concerns is mis firing and sputtering during acceleration. It is a fairly clean set up bought from a guy in Bremerton back in 2000. I forgot his name but should be active on this site.
so under slight acceleration, reving the engine it sputters around 2500 RPM. with no gauges or tools I noticed the F/A screws on the driverside carb were out different ratios. I gave them a slight adjustment and it seemed to help. I figure we need a air flow meter to put over each venturi and dial in each barrel evenly. (IMG:style_emoticons/default/idea.gif)
Being a V-8 guy I would slap on a vaccume gauge and adj from there.... I did not see any vacume ports so its all new to me (IMG:style_emoticons/default/confused24.gif)
How do you boys dial these babys in?
I was also under the impression a stock FI cam is not really compatible running carbs... (IMG:style_emoticons/default/confused24.gif)
Shoot me some ideas , once I get him running, I will have a new teener buddy in the neighborhood to tool around with since you Teener Tuesday boys are afraid of coming accross on the ferry (IMG:style_emoticons/default/poke.gif)

[Ductech]

I would start with thinking about how long this car sat. 2000 was almost 12 years ago now. If it hasn't run regularly since then most likely the fuel system is full of debris and or bad gas. as the carbs can gum up with fuel varnish from sitting and not getting good fresh fuel now and again. ...

So start with cleaning the carbs if they have not been done recently, Maybe consider cleaning out the gas tank, Then reassemble and sync the carbs, If you have a liking for tuning get a lambda sensor preferably a wideband and setup the various adjustments that way. Also look into the chance of ignition miss-setup. Verify correct timing, check your points and the gap on them. I can't help with specs on the carbs or the ignition settings. Alas i have only worked on subaru powered teeners.

Good luck.
And if the owner isn't on here as a member get him to and get that vin in the system

[TC 914-8]

I would start with thinking about how long this car sat. 2000 was almost 12 years ago now. If it hasn't run regularly since then most likely the fuel system is full of debris and or bad gas. as the carbs can gum up with fuel varnish from sitting and not getting good fresh fuel now and again. ...

So start with cleaning the carbs if they have not been done recently, Maybe consider cleaning out the gas tank, Then reassemble and sync the carbs, If you have a liking for tuning get a lambda sensor preferably a wideband and setup the various adjustments that way. Also look into the chance of ignition miss-setup. Verify correct timing, check your points and the gap on them. I can't help with specs on the carbs or the ignition settings. Alas i have only worked on subaru powered teeners.

Good luck.
And if the owner isn't on here as a member get him to and get that vin in the system

The car has been running off and on since he bought it, he has maintained the car fairly well, except letting it sleep outside in the rain.

Good point on checking the points and timing. I'll start from scratch.
Syncing the carbs is what I was after, did it 35+years ago in high school, its all coming back to me now.

Thanks

[Ductech]

Some people used old sync gauges that would go over the throats of the carbs. I personally would look really hard for some vacuum ports on those bad boys and then use some sync sticks filled with mercury, or better yet a digital sync meter, like what you can get off the snap on truck. Both of the later would be better and more accurate than the old hand held sync meter. You want to be able to watch the sync and the relationship of how it changes as throttle is applied. sync sticks make this easier to see

[mrbubblehead]

i use a snail for synchronizing and an innovate air/fuel gauge for jetting. oh and tangerine racing throttle pulley system makes synchronizing the carbs a snap. sync em and forget em (IMG:style_emoticons/default/driving.gif)

[jaxdream]

Don't forget to adjust the valves before syncing and ignition checkout. Talk him into an electronic points replacement while your at it. Also check the advance mechanism in the distributor, make sure it advances and retards as it should. Good luck .....

Jack

[nathansnathan]

Some people used old sync gauges that would go over the throats of the carbs. I personally would look really hard for some vacuum ports on those bad boys and then use some sync sticks filled with mercury, or better yet a digital sync meter, like what you can get off the snap on truck. Both of the later would be better and more accurate than the old hand held sync meter. You want to be able to watch the sync and the relationship of how it changes as throttle is applied. sync sticks make this easier to see

The digital syncrometer sounds awesome, but I can't find one anywhere. I see Digital Anemometers, not sure if that's the ticket though. I've always wanted this thing as I've got some European Dellorto drla 40's with the vacuum ports.
(IMG:http://www.914world.com/bbs2/uploads_offsite/www.carbtune.co.uk-11782-1323445257.1.jpg)
http://www.carbtune.com/

[914werke]

and there is the old standby...ditch the carbs & put the FI back on it.

[stownsen914]

Cars that haven't been run much can obviously develop issues, both carb and non-carb related. Syncing up the carbs is a good idea since it's pretty easy to do and can only help.

One thing that would be good to know is whether this problem occurred before, or is it brand new.

Rough running at certain RPM sounds like a classic carb circuit transition issue. At 2500 PRM it would probably be the transition from the idle circuit to the main circuit in your carbs. As you probably know, there should be a spring loaded idle circuit adjuster screw on the side of each carb barrel, and they work like a faucet. (To be clear, this is not the idle RPM adjuster that sets the butterfly position at idle, but the fuel adjustment. Also not the idle air adjustment.) Clockwise turning means less gas, counter-clockwise gives more gas. You can move them half a turn at a time (do the same adjustment for all four barrels), and see how it affects the rough running. You should see some difference in running within a couple turns one way or the other.

It's also pretty easy to clean jets, which can become clogged with debris or gummed up with old fuel residues. You can try that too.

Scott

[stownsen914]

Oops duplicate post

[messix]

Have I not taught you any thing?


Go give it an Italain tune up!

[J P Stein]

There are a number of things that could be causing these problems, snycing the carbs is just one of them. Keeping on this topic, synchronizing/tuning the carbs is fairly easy.....*when you know how*. It is not a poke & hope operation, but all in the methodology... but the mechanics of the carb linkage can make it near impossible to attain.
A Syncrometer (snail) is the choice of tools being inexpensive & fool proof.
It is best to take the car to some one that knows the "Webber dance" and pay close attention to how he does it. It has been my experience that internet tuning is a waste of time ....there are just too many variables. I know, I make it sound like some kinda black art.......well, it is.

[pt_700]

slightly ot but, i had an old mechanic friend once tune the side drafts on my '71 240z by ear with a plastic hose. damn if the old girl hadn't run better than ever...

black art indeed.

[TC 914-8]

Wow, thanks guys for all the input, I like the Carb-o-tune with 4 inputs I'll pass on the info to the owner see if he'll spring for one or a Snail.
He did ask me about putting the FI back in, at that point its getting a V-8. When I have time next week the first thing is taking it for Troy's Italian tune up!!!
I'll keep ya'll posted how things go, along with his new screen name when he joins the World. (IMG:style_emoticons/default/beerchug.gif)

[a914622]

Hey i have a snail syncer i could let you use to synce the carbs. I will be over in the east squim bay area deer hunting the 17th .

I would make sure the carbs are cleaned out if they are dirtty. But are you/him running a 009 dist? I rember i had a huge dead spot at 2400-2600 on my last 2.0 with 40's on it. Just a thought but i rigged a vacuum line back on a stock dist.


jcl

[mrbubblehead]

Just a thought but i rigged a vacuum line back on a stock dist.


jcl

(IMG:style_emoticons/default/agree.gif) same here. then i installed a SVDA distributor. now it pulls like a freight train.

[TC 914-8]

Hey i have a snail syncer i could let you use to synce the carbs. I will be over in the east squim bay area deer hunting the 17th .

I would make sure the carbs are cleaned out if they are dirtty. But are you/him running a 009 dist? I rember i had a huge dead spot at 2400-2600 on my last 2.0 with 40's on it. Just a thought but i rigged a vacuum line back on a stock dist.


jcl

Hey That would be great if you could bring the snail, I live in the diamond point area and the car is in Port Townsend.
Don't know where you will be hunting but east Sequim bay is very close.
PM me with your # and I'll give you a call to make arrangements.
Good call on the dist. I took a look at a glance and didn't see a vaccume line to it. I'll bone up on the dist and see what he has.