Stromberg carb tuning

[Philip Wardle]

Very brave. some of my mistakes are too embarassing to share

[Sheepdip]

As the two yearly "MoT" (TÜV) is coming up I thought I'd check my CO values. I have a recently calibrated Bosch exhaust gas analyser and, at the last TÜV it was a struggle to get down to around 4%. I've just measured in the left and right pipe and got 2.3% and 2.4%.

Then I recalled that a had a shedload of problems with the car dying on me a year or so back and, in the effort to hunt the cause I'd replaced plugs, leads, electronic ignition, float valves and probably a few other things which I've forgotten now. Seems to have had an effect!

In actual fact, in the course of chasing a fault I basically "lived Richardthestag's life" as it's more or less what he recommended in post 28 above!

Drew

Agree can be lots of things to look at, but timing spotr on and vacuum advance works (checked by sucking - have had this fail before!)

Unfortunately don't have access to CO analyser but as it flew thru MOT reluctant to make lots of changes at same time, i'll record currernt settings just in case then make changes as suggested in forum.

Ironic after hassle getting low enough couple years ago its now too low!

[jbuckl]

I once…in early days of stag ownership scrapped a whole rebuilt stag engine due to bead blasting & professional cleaning of the heads…. Which as it transpired looked clean but weren’t…

The block was also professionally cleaned too.

During the disassembly (2 hours) the heads landed about halfway down the lawn….. about 15 feet from the garage door. Distance isn’t important…. Message is! I’m not that strong !

Embarrassed… certainly …. Lessons learnt? Abso-flaming -lutely.

Bead blasting beware.
Trusting professional cleaning? Never again.

That was 30 years ago.
The cost of parts & services then was £1450. Literally had to start from scratch (geddit?)

[Sheepdip]

I once…in early days of stag ownership scrapped a whole rebuilt stag engine due to bead blasting & professional cleaning of the heads…. Which as it transpired looked clean but weren’t…

The block was also professionally cleaned too.

During the disassembly (2 hours) the heads landed about halfway down the lawn….. about 15 feet from the garage door. Distance isn’t important…. Message is! I’m not that strong !

Embarrassed… certainly …. Lessons learnt? Abso-flaming -lately.

Bead blasting beware.
Trusting professional cleaning? Never again.

That was 30 years ago.
The cost of parts & services then was £1450. Literally had to start from scratch (geddit?)

Feel for you but Interesting you say that, while these carbs were cleaned by me using paraffin I have a couple of webers which I bead blasted. Another forum suggested soda blasting as beads can get lodged inside.....I've also ultrasonic cleaned so will see what happens!

[Sheepdip]

Very brave. some of my mistakes are too embarassing to share

We've all done it

[Sheepdip]

Very brave. some of my mistakes are too embarassing to share

Perhaps we ought to have an anonymous thread on most embarassing mistakes we've made

[jbuckl]

Perhaps we ought to have an anonymous thread on most embarassing mistakes we've made

There May have been one?

It was just an off topic confession. Apologies. Might be helpful …. I would not even consider blasting cam covers without removing the flame trap now…. So many messed up cam bucket bores seen after that….. even recently on others engines. simply not worth any risk…. It’s just too big. I’ve blasted cam covers with the flame trap carefully ‘sealed off’…. It still finds its way in.

Took one nice Shropshire chap 2 rebuilds to rid his engine of blast media….recently….. all for pretty cam covers!!!

Nuff said…. Anyway Sheepdip,

Having read your carb woes, I can’t help thinking there is an unmetered air leak yet to be found. 0.5% c.o. Is pointing to that.

What is the H.C. Reading?

When a stag is running really lean, after a good run, the tailpipes will usually have a paler grey deposit.

Whilst exhaust popping is quite usual, it increases with lean running.

The throttle disc valve deletion also reduces exhaust popping too.

[Sheepdip]

Had a look at my carbs today and noted settings.

Neither needles had any marks so how do I know if correct? Both needles were 2.5 turns up from level with bridge.and at their max settings ie rich (wish I was!)

Both jets were 80thou down measured on outer edge.

No popettes in butterfly.

Fine idle adjuster 1 turn

temp compensators seemd ok, closed when cold and WD40 didn't flood thru.

Unscrewed and checked both chokes - presume the pics are ok? Only thing I found was one choke gasket had been crushed under the disc, don't think a problem as it did return to closed but removed gasket anyway.

Went with advice and:

1) Screwed fine mixture shut
2) Put gasket disc behind temp compensators so no longer having affect
3) Ran up to temp, 1 3/4 turns on needles seemed ok
4) checked carb balance at tickover and 1k RPM, ok.
5) Sprayed carb cleaner around joints, no affect.

Haven't tried it out yet but needle settings leaner. But non the wiser at moment.....

replaced rubber fuel lines couple weeks ago and took opportunity to replace overflows as well, probably originals

[trunt]

Whilst exhaust popping is quite usual….

Really? Have I been chasing my tail for 2 years??

[jbuckl]

Really? Have I been chasing my tail for 2 years??

Also a retarded spark will increase the exhaust popping too.

[trunt]

Also a retarded spark will increase the exhaust popping too.

Yup, just rechecked mine and took it up a couple of degrees to 16btdc, max advance at 4k is 38deg so all is in order there. I have a wide band so mixture is fine.. I’m assuming it may be due to the exhaust system, it came with the car and is a quality s/s system with the heat shields, but sounds pretty “open” Its not an issue really, but sometimes I feel I’m a bit old for all that!!

Terry

[jbuckl]

Really? Have I been chasing my tail for 2 years??

Also a retarded spark will increase the exhaust popping too.

[Sheepdip]

[QUOTE=richardthestag;n855210]


Did you replace the meter needles? B1AQ - number is found by pulling the needle out against it's spring and it is written around the shaft between the black washer and the body of the needle mount.

---------------------------------------------------------------------------------------------------

Checked but no markings at all on needle, looked at another old one and same - other than thety were supplied in teh kit I have no way of telling if correct?

[Sheepdip]

Just checked consumption over ESM trip and returned 28mpg (4spd auto)

[dasadrew]

Sorry lads - couldn't resist this one - I know at least rts will appreciate it!

SCAN-TOO 480.jpg