• Hi Guest! Being a Paying Supporter is NOT a requirement to participate at BCF. However, subscribing will help ensure we can continue to serve the LBC community for years to come. If you enjoy BCF and find our forum a useful resource...Please consider supporting us by **Upgrading**
    (PS: Subscribers don't see this banner)
Tips
Tips

TR4/4A Stromberg CD175carb query

malbaby

Jedi Warrior
Country flag
Offline
Have early type CD175's with adjustable main jets at the bottom of the float bowls.
Currently using new needle/seats and new 100 main jets with new H2 needles, revs out well, but cannot get engine to nice low idle...OK at 1200rpm...running rich when at about 700rpm....cannot get any further mixture adjustment for nice low idle. Tried altering the fixed position of the needle a bit lower..no difference.
There are no apparent air leaks.... carbs are not flooding.
Should not be the needle size as all needles will have the same idle profile within 0.0001".
The only thing that I can think of is that the carb is over fuelling at idle. The float level has been set at what the manual says ie. 0.73" or 18.5mm.
Adjust float level so that the needle/seat closes earlier?
What is the correct main jet and metering needle size?
Comments appreciated...please do not suggest changing to SU's.
 

trrdster2000

Luke Skywalker
Country flag
Offline
Great carbs and have used them to replace SU's. The centering of the needle is very difficult and if it is hitting the sides of the jet, that could be a issue. The linkage on some have given me a fit. Every time you tighten up the little bolts the shaft moves slightly. Have you tried backing out the idle screw all the way on both. If it still idles up a leak of some sort is indicated.

Wish I was your way to help, getting ready for winter here.

Regards, Wayne
 

poolboy

Yoda
Country flag
Offline
The main jet should be 1/10 of an inch in diameter and perfectly round.
2H needles are .0980 at the base, then at 1/8th inch increments....0923,.0899,..0877,.0755
There's more, but those should be the measurements well within the range of idle speed.
 
OP
M

malbaby

Jedi Warrior
Country flag
Offline
Thanks guys.....idle screws, needle centering all OK.
Trying to ascertain whether altering float levels would have any effect at idle?
 

trrdster2000

Luke Skywalker
Country flag
Offline
All I have left is the centering of the butterfly, if it's out even a little, it will not close off. Just another thing we overlook when putting them back together, if we have never been caught and spent two days tiring to figure out a high idle. Been there done that.

Wayne
 

Merlin63Tr4

Jedi Trainee
Country flag
Offline
+1 on centering the butterflies, and also verify you have the butterfly chamfer oriented correctly....

M.
 
OP
M

malbaby

Jedi Warrior
Country flag
Offline
Thanks again.
I do not believe it is a butterfly issue as I can achieve a low idle, but over fuelling for undetermined reason.
 

titanic

Jedi Warrior
Country flag
Offline
If you have a TR4A with a PCV valve, they can cause a vac. leak and high idle speed. You might try plugging the hose from the manifold and see if there is a difference.
Berry
 
Similar threads
Thread starter Title Forum Replies Date
S TR6 Stromberg Bypass Valves - Question Triumph 11
T TR6 My '74 TR6 Zenith Stromberg Carbs Float Bowls Leaking Gas Triumph 11
T TR6 Carb Vacuum Port- TR6 Zenith-Stromberg Carbs Triumph 2
M General MG stromberg carb MG 5
Sarastro TR4/4A Stromberg linkage question Triumph 4
SherpaPilot TR6 Stromberg War, Finally Success Triumph 2
R TR2/3/3A Stromberg vs. SU carbs [discussion/advice] Triumph 17
D Stromberg Dash Pot Screws Jaguar 3
Merlin63Tr4 TR4/4A Cracked Zenith-Stromberg float assemblies Triumph 13
steveg Online SU and Stromberg needle database with comparison charting Austin Healey 2
R J-H Stromberg carb connections? Where do they go? Other British Cars 2
R GT6 Carb Floats for Stromberg 150 . Triumph 5
B Zenith Stromberg O ring question Other British Cars 8
K TR4/4A Stromberg..."coupler" that links vacuum outlet to diff vacuum line is N/A? Triumph 3
K TR4/4A Stromberg question. Triumph 13
SherpaPilot TR6 Stromberg CD 175 Carb Tuning Triumph 8
RickB MGB Stromberg on my 80 MGB - fast idle this morning MG 6
RickB MGB HS6 or HIF4 bolt right on in place of Stromberg? MG 6
Zimmycobra TR4/4A Zenith Stromberg questions Triumph 13
M TR4/4A Stromberg ? Triumph 4
L zenith-stromberg carbs Lotus 11
P TR6 Tr6 stromberg carb gas leak from starter valve bolt shaft Triumph 5
G Stromberg cd150 question Spridgets 1
TR6BobNF General Tech Midget Stromberg 150 Adjustment MG 8
Airfix Wedge TR8 Zenith Stromberg carbs slow deceleration Triumph 1
W Weber/stromberg air cleaners Jaguar 3
dklawson Early Stromberg Floats - 150CD Triumph 5
bighealeysource Stromberg carb help needed for TR buddy Triumph 8
W Zenith stromberg carbs Jaguar 3
J stromberg float source or x referance Triumph 2
L Stromberg 175 cd question Other British Cars 5
D TR6 76 TR6 Stromberg Air Valve Triumph 2
H Stromberg Carb Sync and adjust Triumph 6
T Stromberg Triumph 22
sundown 175cd stromberg carbs Triumph 4
JPSmit Stromberg Carb Question Triumph 15
R TR4/4A Tr4a, Stromberg float setting Triumph 6
regularman I found the fix for the stromberg on the 1500 Spridgets 6
A XKE Series II Stromberg Carb Upgrade Jaguar 4
C Stromberg carbs Triumph 8
R TR4/4A Tr4a, Stromberg rebuild Triumph 6
glemon Rebuilding stromberg Carbs Throttle Shaft Bushings Triumph 6
TR4 Stromberg Choke Issue Triumph 3
S Question on rebuilding Stromberg carb Triumph 24
R Zenith Stromberg CD 175 float replacements? Triumph 3
F Spitfire Spitfire 1500 - Stromberg CD 150 Question Triumph 9
R TR4/4A Tr4A , Stromberg carburetor Triumph 20
R Stromberg adjustment screw tight 175CD Triumph 10
T Gas leaks from the bottom of my Stromberg carbs. Triumph 7
T Triumph Stromberg carbs leaking from caps on botto Austin Healey 2

Similar threads

Top