Dual Carb Installation, Success - She Screams Options

[jmill]

Did you turn the throttle stops on both carbs equally so you have a high idle? When warm back them down.

[Mblizzard]

Set the idle screws on both the the 1/2 turn after making contact on both carbs. The engine starts out with a high 1100 RPM then drops to a very low 600 RPM after a minute or so even if nothin is touched on the carbs. To me this drop seems to be a fuel limitation. But I can't seem to find what causes the limit as it seems to disappear for the same minute interval when the engine is shut of and restarted.

I guess I will just have to take everything back out and recheck.

[ldsgeek]

Try disconnecting the linkage from the carbs and setting the carbs up individually, using a vacuum gauge set to verify that each barrel is matched to the others. Once that is done then reconnect the linkage and adjust only that to get back to sync. Keep in mind that any adjustment to the linkage must be done with the engine at full temp as the dimensions will change as it warms up.

[rhodyguy]

mike, you didn't get back to me. does the idle fall off when you match the air flow @ idle when the linkage is disconnected? if it's stable at an acceptable rpm with the linkage off you found the problem. after telling me about the facet pump/am reg, don't freakout til you get the new pump. on the bottom of the fuel inlets there is a large closing nut. there may or may not be a mesh screen contained above them. part #3 in the exploded parts diagram, p.50 of the cb book. see if there's crap in there. you thought the idle jets might have picked up some debris. did closing the idle air mixture screws, one at a time pausing to see what happens, have any effect on the idle? sneezy/snappy out the carbs or a faint grumble/back fire out the exhaust? it's a shame your new carbs are giving you fits right out of the box. this should not be the case. give me another call when the car is shut off. i couldn't make out what you were saying half of the time.

edit: from the cb trouble shooting guide pages 34 ,35, 36. "Cylinder is not responding to mixture screw adjustment (actual term would be Idle Air Mixture Needle Screw), follow procedures: 3, 4, 5, 6, 14, 16 & 17. buy this book if you don't have one.

k

[Mblizzard]

Kevin sorry I did not get back to you I was kind of miffed. But I never could get the thing to ever run well or respond to the mixture screw adjustment.

Pulled everything off and I am going through it again checking everything. It coughed and spit and never got better. Verified fuel pressure and lack of vacuum leaks. I closed off the mixture screws completely with no change and even backed one completely out and noted no change.

I will start over and give it one more shot.

How would one use a vacuum gauge to check each barrel. I verified with the flow meter that they were close.

[ThePaintedMan]

Kevin sorry I did not get back to you I was kind of miffed. But I never could get the thing to ever run well or respond to the mixture screw adjustment.

Pulled everything off and I am going through it again checking everything. It coughed and spit and never got better. Verified fuel pressure and lack of vacuum leaks. I closed off the mixture screws completely with no change and even backed one completely out and noted no change.

I will start over and give it one more shot.

How would one use a vacuum gauge to check each barrel. I verified with the flow meter that they were close.

So none of the mixture screws are working? I'd go with Kevin on this one, that it could be pump related. Webers are very dependent on correct fuel pressure (no more than 3.5 PSI, but preferably as close to 3-3.5 PSI as possible). Facets are all over the place and even if they provide sufficient pressure, may not provide adequate volume.

Can you tell if it's running super rich, or on the verge of flooding? If it's one carb that is giving you most of the issues, it could be an improperly set float. Also, the later Webers came pre-drilled with "enrichment circuits" on the top and outer edge of the carb. These are underneath the little two-screw flat cover and consist of two valves which are held down by springs. The valves can be opened with the correct linkage (sold separately) to allow additional fuel into the throttle bodies when the car is idling at initial startup, till it is warm. Sometimes the springs that hold them closed car rust/break and allow the valves to get stuck open, which essentially floods the throttle bodies with fuel. But I would imagine this would only happen on one carb or another, not both at once.

[Mblizzard]

True with the faucet pump. But I have a reasonable accurate pressure regulator on the pump that is adjustable in 1/2 lb intervals. So as part of checking the fuel pressure I ran the car on every pressure setting and got the same results on every setting. Even given the potential inaccuracies of the regulator, at some point along the line the pressure should have been what was needed and if the problem was strictly pressure related then it would would not have occurred at every pressure setting.

Seeing as the carbs are brand new I don't think there is much of a chance for rust.

It seemed that it has to be running rich if the complete closing of the mixture screw would not change the idle. I am betting on float problems.

[DBCooper]

mike, i prefer the bar on the front. space is tight enough as it is. with it on the rear, dealing the drop link adjs, and access to the throttle stop screws you be working a little blind and all bent over leaning. imho. plus you'll be making the throttle cable working distance that much longer. did a cable holder come with the package? personally i'd go with the cbtall intakes, not the shortys. if you don't have the cb weber book GET ONE! save yourself a bunch of bs and do the pre-install proceedure. it's clearly written to the point even a caveman can do it. buy the synco tool as well you're going to need one. did you purchase 40s or 44s? while you have them in hand confirm the current jetting. idle, and the components in the main stack. again, easier now than later. be methodical in your approach and don't get frustrated. double check your valve adj NOW! before you fire it up. if the old carb is still on confirm your timing too. not later when your chasing your tail dialing them in. good luck...enjoy the ride.

k

Good advcie. The book is at CB HERE ( a big thirteen bucks). The best portable synchronizer (my opinion) is actually a Twinmax, for motorcycles, but at half the price the most usable common Weber/Dellorto tool is the "snail" type, HERE (only forty five bucks). Those may not seem like "only" prices, but they reduce grief enough that they're worth it.

.

[ThePaintedMan]

Seeing as the carbs are brand new I don't think there is much of a chance for rust.

It seemed that it has to be running rich if the complete closing of the mixture screw would not change the idle. I am betting on float problems.

Sorry, I guess I missed that part, or I forgot, lol. A few folks on here have described getting new carbs and the float settings being way off. This is likely do the bowls being empty during transit and the floats banging up and down, throwing the factory specs off.

Obviously rust isn't an issue, but while you have the carbs apart, might check the enrichment circuits on the sides to ensure that they are closed/seated fully.

[jmill]

(IMG:style_emoticons/default/agree.gif)

I always check the float level out of the box. They are rarely set the same or correctly. Low idle with no carb pops when you close off the mixture screw sounds rich. Float could be high and over flowing out of the mains. It's pretty easy to check at idle. Just look down the carb throat and see fuel dripping out the aux vent. You'll also see it hit the top off the butterfly. If it's real bad you'll see it with the pump running and the engine off.

BTW IMHO 1/2 turn isn't enough. Set it a couple of turns.

Clicky pumps suck. Get the CB rotary with an internal regulator. You'll never look back.

[jmill]

On a side note. I had a real steep driveway when I lived in CA. Carb tuning on a sloped driveway doesn't work well. Especially when your float level is set a bit high. I ended up setting mine a bit lower than spec to avoid flooding issues. Tune it on a fairly level surface.

[Mblizzard]

So I checked the float on one of the carbs. I guess 17 instead of 10 may make a difference. That would explain a lot if that turns out to be the problem. Hope to check the other one and install tonight.

[rhodyguy]

hope i wasn't part of the "miffed". floats off...sucks. right out of the box (IMG:style_emoticons/default/WTF.gif) (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif). pull one plug and look at it or swipe a finger in the exhaust pipe and see if your finger comes out black/sooty. i would be amazed if all 4 idle jets were fouled. procedure #4 in the trouble shooting guide is spot on re "excessive fuel spilling thru the main fuel ports caused by an improperly set float level or clogged or jammed fuel inlet valve"..."fuel spillage during engine operation can be checked by placing a mirror over the carburetor throat and checking the upper surface of the butterflies for drops of fuel"..."excessive fuel pressure (over 5 #), impurities, improper float settings and worn fuel inlet valves can all lead to fuel spillage that will make your engine run rough". (IMG:style_emoticons/default/dry.gif) the trouble shooting guide is super simple to use. dif solutions, check them off one at a time starting from the lowest to the highest #.

and, unlike vac leaks and idle with djet (high idle), it's the inverse with carbs and ljet. the idle will be low. weak vac signal.
k

[Mblizzard]

Kevin you were not part of it! Your advice was the key to me taking everything back down. At the end I noted too much fuel in the carbs like you stated. You mentioned this during our call so you helped me get to where I needed to be.

I think the float level being so far out accounted for the car running well for a bit after starting. The bowl must have been reaching the right level during the time the car was off and then as the bowl filled too much it started running worse and overriding the idle mixture screw adjustment.

I hope to reset the other one and get it back together tonight. I will keep you posted.

My rotary fuel pump should be here this week.

[rhodyguy]

party on garth. (IMG:style_emoticons/default/wink.gif) (IMG:style_emoticons/default/smile.gif)

[ThePaintedMan]

I think the float level being so far out accounted for the car running well for a bit after starting. The bowl must have been reaching the right level during the time the car was off and then as the bowl filled too much it started running worse and overriding the idle mixture screw adjustment.

Yup, that's why I thought it was floats. Especially since you mentioned it would go away and then return if you let the car sit. The lack of response upon adjustment on the mixture screw, but the fact the car still ran is an indicator IMHO that the carbs are actually flooding, not that the jets themselves are plugged.

Kevin is the man though - he taught me all of this stuff.

You'll get it figured out, don't get frustrated. Will check back in tonight to see how things go.

[rhodyguy]

the carbs found a way to relieve the fuel pressure. they don't care where the fuel exits. on another note, for a REAL old skool non permanent mold sand casting process webers are pretty sophisticated. lots of cores to create the passageways. if the cleanup room process is shoddy residual core sand will be left behind and it's a nightmare right from the get go.

[Mblizzard]

I have read a number of the post on this forum where the same advice is given several times. Just wanted to let you guys know that I listened and my Weber tech book is on the way and the right fuel pump was ordered.

I hope to install the cross bar in the trash at some point but the options for replacement are a little costly at this point. But it is on the list. Hopefully tonight will go better.

As a side note, I rechecked all of the throttle body operations and the one with a closer set float was binding a bit.

[Mblizzard]

John Kevin I am happy to a large degree of success. (IMG:style_emoticons/default/evilgrin.gif) The carbs seem to work now. No flooding out and I was able to set the mixture screws and they all changed and worked. All sides barnacled out at a nice 950 idle. My wife even commented on how quite and smooth the idle was!

Of course the next task is trying to install the bar and sync the carbs. Somehow at 530 this morning I installed a throttle lever tat won't work with the bar! I am really hating that bar. So I will have to switch that and then hopefully it will work.

Thanks for all of the support. I owe you guys a beer or 20 (IMG:style_emoticons/default/beer3.gif)

[jmill]

So I checked the float on one of the carbs. I guess 17 instead of 10 may make a difference. That would explain a lot if that turns out to be the problem. Hope to check the other one and install tonight.

17 means the float was set low not high. It should have had lean pops. Strange it ran rich. Glad it all worked out for you.