• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Stromberg mixture how-to, once again.

Share this page

T

Tinster

Guest
Guest
Offline
I have my Stromberg carbs back on and balanced at a nice 900 rpm each.
I have adjustable air valve needles and adjustment hex tool.
I can smell my car is running very rich.

I have read Buckeye Carb III, over and over and cannot grasp how to get the carb mixture correct and the balance correct.

All advice appreciated.

thanks
 
I hope the PM solves the problem but I was looking forward to read the approach. Maybe when you get it sorted you can go over the steps you took to resolve the apparent rich condition.
 
If the carbs were set properly and the car was running well last year, hold off on adjusting the carbs. They don't just go out of tune. Take the car for a long drive and check the plugs for richness.

The smell of richness could be the chokes hanging up or another easy fix.
 
Doug- I took both carbs completely apart to clean them after sitting for 5 months. I cleaned the mixture needles of glaze build-up. Also, I installed the newer version needle valves. My plugs are deep, sooty black. My tail pipes deep sooty black also. Also some small backfires thru the exhaust make me think the mixture is rich.
 
Float height set? The Allen wrench should be turned counter-clockwise to lean the mix, but in small increments. If the thing doesn't lean out somewhat after half a turn, methinks something else is outta whack.

The RPM should increase as you go leaner, too, so you'll need to adjust idle screws to compensate.
 
DrEntropy said:
Float height set? The Allen wrench should be turned counter-clockwise to lean the mix, but in small increments. If the thing doesn't lean out somewhat after half a turn, methinks something else is outta whack.

The RPM should increase as you go leaner, too, so you'll need to adjust idle screws to compensate.
Click to expand...

Thanks Doc, yes I re-set the floats.

I am doing the lean/rich backwards, it seems. I have been turning clockwise to lean.

Thanks andd Wayne is going to help me over the phone later today. Billows of smoke out the back when I turned the needle 1/2 turn clockwise. Engine roared and then died.

Thanks for the help.

dale
 
Another thing to be aware of is the "star" retainer can be loose, resulting in the adjuster rising rather than the needle lowering as you try adjusting. A good thing is to push down on the Allen tool after each 1/8-turn... this WILL stall it if you do it when running. You might consider a ColourTune if ya don't have one. Not cheap, but work quite well for the task.
 
DrEntropy said:
Another thing to be aware of is the "star" retainer can be loose, resulting in the adjuster rising rather than the needle lowering as you try adjusting. A good thing is to push down on the Allen tool after each 1/8-turn... this WILL stall it if you do it when running. You might consider a ColourTune if ya don't have one. Not cheap, but work quite well for the task.
Click to expand...

+1 on the ColourTune Dale - provides immediate feedback and an easy to use guide.
 
BLARGH!!!

The front carb choke cable broke off from the knob end today.
Gotta order a new one.

Had the engine running for over half an hour today. Used starter fluid since one choke broken.

VERY fast idle of 1800 on a warm engine. Idle screws not touching anything, up in the air. Eight counter-clockwise
turns with the hex tool brought the rpms down to 1400 but
still backfires thru the exhaust manifold. Plugs black.

Suggestions?

thanks,

dale
 
Well, first you're going to have to fix the damage caused by turning the adjustment too far. The entire range is only about 2 turns.

Then the usual things, like are the diaphragms in good shape (hint: you may need to stretch them in your fingers to see any holes); do the pistons move smoothly and easily (except for the damper action). Are they properly assembled?

Do you have a leaking float valve, or fuel pressure too high?

If you have an emissions canister connected, perhaps it is full of fuel.

Are the float bowl vents open to the atmosphere? Later carbs (sorry, don't recall offhand what Amos is wearing) use an alternate route through the carbon canister at idle, if that is blocked off it could upset mixture badly.

Hmm, that fast idle sounds suspicious too. Are you sure both chokes are fully released? Some ZS carbs don't even have a return spring on the choke lever, so if the cable breaks the choke may stay on.
 
If the idle screws aren't touching anything could it be the linkage is adjusted wrong?
 
Dale, way too much adjustment with little results. Just as info, when you cleaned the bowls and adjusted the floats, did you take the needle and seats out and spray some carb cleaner on them. You might be looking at a stuck open seat. Sorry about the choke cable, painful.

Wayne
 
Dale and all, Since we have not gotten above freezing for a couple of days, I grabbed and old carb and tried to duplicate the problem Dale created with turning the adjuster too far. What happened was after about four turns anticlockwise he disengaged the adjustment screw inside the jet. The only thing holding the needle in the piston was the set screw, making it a floating needle. What needs to be done now is a bit of a pain, you should pull the top off the crab with four screws, keeping the orientation of the top in mind to make sure it goes back on the same way. Pull the spring and piston out and turn the piston upside down, watch out for oil and there should be a washer fall out also. Take your adjuster tool or a long 1/8 Allen wrench, push the needle base inward, holding the piston by hand, (no need to use the slotted part, and crank the adjuster clockwise until it stops. This should draw the needle up into the piston about a 1/8 inch. Now go anticlockwise for 2 turns and this should give you a level base of the needle with the bottom of the piston, if not turn either way until you achieve this. You are now at neutral in your adjustment. Put is all back together, keeping in mind you may have to tighten the top screws a little at the time to keep the piston free, painful at best. Don't forget the little tab in the hole on the diaphragm.
You can now start the car for adjustment. There are 2 turns in either direction, any more and will have to start all over again.

Dale, if you put in the new grose jets, they have a grease coating and should be cleaned before installing with carb cleaner.

Let me know how it goes, you are not on the phone so I bet you gave up when the cable broke and headed out to sea. Hope you are having luck.

These instructions are not a bad way to start any adjustment on the carbs as you will always know you are starting in the middle.

Wayne
 
You know me well, Wayne. The broken choke cables make things difficult.
I thought I unwound the needle out of the seat but no use messing with it until the choke cables arrive.

Yupper, I was 20 miles or so out to sea when you called. LOL
A fantastic day fishing Tuesday in my friend's boat on the south side
of the island. We were trying a new (to us) trolling technique.
High speed trolling at 20 to 23 mph. In 3-4 chop, 23" foot
sportfisherman. Every bone in my body aches. Ramon hired a local
young captain (Johnny) to pilot Ramon's boat.

We caught a boatload of 3 to 4 foot 'Cudas we threw back and one very nice
Wahoo of about #25 to 30#. He's in the freezer. We also saw 2 humpback whales.
One came withing 50 feet of our boat. We saw a few schools of dolphin (mammal)
and headed in the opposite direction. A great day on the water. But 4:00 AM until
11:00 PM is a long day for a 62 year old geezer with severe COPD !!

I'll give you a hollar!


wahoo3-1.jpg
 
Another dummy question:


There is a small hole near the bottom of the air valve. Inside is a tiny screw (I think). Does this come into play at all?

Randall- yes, I went thru your check list when I cleaned the carbs. The engine was running pretty well except it was very rich and I would get small backfires into the exhaust manifold.
front 3 plugs were toasty brown, rear carb-plugs were very sooty black.

thanks,

d
 
Dale, great day on the high seas, what time is supper???

The tiny screw is of no concern at this time, I really can't picture it right now, will have a look later.

Talk to you later.


Wayne
 
It is a retainer screw, Wayne.

If there was some way I could get you some of that Wahoo,
it would melt in your mouth. One of the best tasting fish
in the ocean. Meat pure white and flaky. Yummy.

d
 
OOOOH, you are a tease, next you will be telling me about your 80 degree weather!!!!

Wayne
 
Did as instructed with air valves (one had no washer inside.
Cranked until stop and then 2 turns counterclocks. Installed,
sprayed carb throat with choke cleaner, car started instantly
and zoomed up to 2700 RPM where it held nicely for 10 minutes
or so, backfiring like a war zone. Leaned out 1/4 turn- no
lowering of RPM.

Guess I'll check the throttle linkage.

I hate carbs!

d
 
Back
Top