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Upgrade Carby Thread

CLASSIC symptoms of a major vacuum leak ~ look at the joint between the carby body and the lower piece that contains the butterfly ~ that's the common culprit .

If it were a bad/wrong jet , it'd lean out and stall when you cupped the inlet , not idle .

I managed top chop the tip off my right thumb to-day , hard to typ , pi$$ or do anything else with this BIG silly looking bandage on my thumb ~ Dr. says ' look at the bright side ~ since there's no tip , NO STITCHES :D '

Ow .
 
Nate, sorry to hear about your accident!

However, you should try to be more like me. My thumb is always protected because 99% of the time it's stuck somewhere that it can't get hurt:eek:!

Now the "ring" finger on my right hand is a different story. I still don't have any feeling in it from the first knuckle to the tip thanks to foolishly trying to get a brush-hog on a tractor back in May.

Heel up my friend, so we can see a "thumbs up" soon!
 
YEOOOOWWWWW!!! Sorry to hear that...makes my thumb hurt just thinking about it!

I'll stay on the track of the notorious vacuum leak then!

Thanks and Get Well Soon!
Bob
 
I'll Be Fine

I just cannot ride my Moto (I won't go 'round the block sans leather gloves) nor work on machinery :mad:

I allready have scars like road maps on my hands and several funky looking knuckles (note to self : REMOVE HANDS before setting engine down !) so this is just one more " character " point...

You don't know how much having opposing thumbs means until you loose the use of one... :rolleyes:

I had a '68 Malibu DeLuxe once , it had a 230 CID 6 Banger and a Rottenchester series BC carby that used to like to loosen the two large screws that held the bottom , cast iron part to the pot - metal bowl part and have just this sort of idle problem , it'd just stop idling , then I'd gorilla grip the screws tight and they'd be O.K.. for 9 or 10 thousand miles again...

I suppose I coulda use red Loctite but then I'da never been able to take it apart again...

If this new carby is rebuilt , take the bottom part off and look closely at the gasket , it might be ripped or the wrong one .
 
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Yessiree, thumbs are pretty darned important for doing much of anything with your hands!

Just because I can't find the leak doesn't mean it ain't there. One thing I am (besides inexperienced with carbs) is persistent, and I'll get it eventually.

Thanks!
Bob
 
Try This :

Bottom out the idle _speed_ screw (on the throttle stop arm) so the engine runs to fast then get some ether (starting fluid) or other stuff in a Foo-Foo can but NOT carby cleaner nor WD40 , insert the snorkel and begin spraying here & there in small bursts .

Don't forget to check the three intake manifold to cylinder head port joints (they'll be the unrusted ports) as these can develop vacum leaks too .

Keep us posted .
 
Starting fluid

Nate, I read about using starting fluid on another one of your posts and tried that already but couldn't find any leaks. I'll try speeding the engine up a little and see if that works. Stuff in a Foo Foo can??...is there a product made just for this, or are you talking about hair spray, cheeze whiz, or what? How about some Everclear in a squirt gun?

We'll see what tomorrow brings. Thanks!

Bob
 
Stuff In Foo-Foo Cans

It doesn't matter too much what you use as long as you avoid carby cleaner and WD-40 ,

Aerosol contact cleaner , brake cleaner or Ether (starting fluid) all work well , I have used old Windex trigger sprayers filled with water .

Or , an unlit propane plumber's torch but that's *very* flammable so be careful ! .

Was it idling O.K. with the old carby ? .
 
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Yes Nate, it idled fine with the old carb.

Unexpected change in plans for the weekend though, so it won't happen tomorrow. Have to chase down an important part for my other project.

Bob
 
O.K. , I was Just Checking

As one never knows....

If you hold the throttle , how slowly can you have the engine run before it dies ? .
 
Hey Dave

I am trying to look at your carby upgrade pic but they sure load slowly (I'm on dailup) and it doesn't appear to have the ' slideshow ' feature .

Maybe I'll take a look next week if this doesn't work , I want to look at the old green / white brand " F ' too .
 
Idle speed

Nate, sorry for taking so long to get back. Had to take off for the weekend...priorities.

Anyway, it will idle down nice and smoothly to 500 rpm or so by choking off the air. Without doing that, it runs rough but I have to turn the idle speed screw up to where it would probably run several hundred rpm faster if it were smooth. It will run roughly pretty slowly, guessing maybe 300 or so before it dies.

Bob
 
So Then

Using the snorkel should make it fairly easy to find the vacuum leak .

I was looking at ?Dave's? pictures and re-reading where he cautions not to draw the flanges to-gether by the nuts else it'll leak .

I have heated & bent some snorkels 45° ~ 90° to facilitate spraying into a close area ......
 
Flange nuts

Yes, Dave has some excellent advice. Before I put mine together I trimmed a hair off the shank of the bolts where it goes through the adapter so it fit together nice and flat. I didn't touch the adapter itself.

Just have to stay on it! I'll find it eventually.

Thanks for the support,
Bob
 
Update on vacuum leak

Yesterday I removed the carburetor, removed the adapter, rechecked my assembly, and put it back on. Afterwards, I did find a very slight leak in the throttle shaft, but everything else still acts the same, and still no response from the mixture screw. Is this leak enough to mess up the idle this bad (need some experience here)? It just barely raises the rpm and smoothness when I spray directly at it. I still can't find any leaks anywhere else, even at slightly higher rpms.

Also, I removed the idle jets. They are easy to get to from both sides...everything seemed clean and clear. Primary is a 50, secondary is a 55. Air bleed sizes are 180 primary and 165 secondary. I haven't had anything apart to see what main jets are in it, but from what I've read these air bleeders are for calibration only and not to be messed with.

Sorry if I'm being a pain here...just trying to learn about this thing.:confused:

Maybe time to call Tom and see what he says????????

Adios,
Bob
 
Bob ;

A little bit of throttle shaft looseness shouldn't make it die , forget about that .

Yes , maybe it is time to call Tom and see what he says , maybe you'll have to drain it well , triple bag it and ship it back so he can fiddle with it .
 
Hi Bob,

Sorry to hear you're having to struggle. Was wondering if you put on the little fuel pressure regulator to drop your pressure down to 3.5 psi. Langdon mentions it and it can be found at Autozone or Advanced /Discount auto for about $25.00. You don't really need a pressure gauge as mine is dead-on when set at 3.5. I've put on 3 of the Weber carbs, bolted them on, hooked up the linkage and electric choke, cranked the engine, backed the idle down a tad and made about a 1/8 correction to the idle mixture screw. Instant starts, smooth idle and no hesitation during acceleration and best of all no Rochester sucking air and bleeding gas all over my engine.

Reread Tom's instruction sheet for installation and tuning.....if you call him I wouldn't mention that you've been inside the carb...the jetting is correct from him......he'll send you out an exchange. If you're absolutely sure you don't have a vac leak, you've followed his instructions to the letter, and you've dropped the fuel pressure to 3.5 psi, I'd give him a call.

Dave
 
H/W idle problem

EUREKA! I've found it!

Called Tom Langdon this morning...he has been gone for a while. Anyway, he told me to take the idle jet out of the primary side, close off the mixture screw and blow some air through there and the secondary side too.

Must have been a speck of something in there somewhere!

Idles great now!
Bob
 
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