• The Roadster Factory Recovery Fund - Friends, as you may have heard, The Roadster Factory, a respected British Car Parts business in PA, suffered a total loss in a fire on Christmas Day. Read about it, discuss or ask questions >> HERE. The Triumph Register of America is sponsoring a fund raiser to help TRF get back on their feet. If you can help, vist >> their GoFundMe page.
  • Hey there Guest!
    If you enjoy BCF and find our forum a useful resource, if you appreciate not having ads pop up all over the place and you want to ensure we can stay online - Please consider supporting with an "optional" low-cost annual subscription.
    **Upgrade Now**
    (PS: Subscribers don't see this UGLY banner)
Tips
Tips

Colortune for HD8 Carbs?

wangdango

Jedi Hopeful
Country flag
Offline
I would like to buy a Colortune to help tune my carbs, I see there is several sizes available, what size works with a HD8 Su? Is the purchase worth it?
Thanks
Ed
 

BJ8Healeys

Jedi Warrior
Country flag
Offline
I would like to buy a Colortune to help tune my carbs, I see there is several sizes available, what size works with a HD8 Su? Is the purchase worth it?
Thanks
Ed

My only complaint about the Colortune is that it seems tremendously expensive for a small handful of plastic parts. I bought my kit back in the '80s when the price was more reasonable. I like it. It works well. I didn't know they came in different sizes. I no longer have the box it came in, so I can't check that for any part number or size.
 

Keoke

Great Pumpkin
Country flag
Offline
Colortune to help tune my HD8 Su carbs?

Is the purchase price worth it?----------> IMOP NO!

There are other SU carb tuning kits that do an excellent job.
 
Country flag
Offline
I think they are terrific! But the best results are when you have two to compare the flame colors simultaneously. The are very reasonable on Ebay. The sizes are for the different type plugs. Motorcycles use a smaller plug. I believe it is the 14mm you need.
 

Patrick67BJ8

Obi Wan
Silver
Country flag
Offline
Colortune to help tune my HD8 Su carbs?

Is the purchase price worth it?----------> IMOP NO!

There are other SU carb tuning kits that do an excellent job.
What other kits are you referring to?
 

EV2239

Jedi Warrior
Offline
If you synchronise the butterflies properly, make sure the float height is correct and set you jets (on HD8s) down 0.075" down from the jet bridge, the carbs will be as near perfect as you get.

do bear in mind that if you're still on original needles, the car may be weak and a rolling road is the safest bet. Otherwise, search for an SU needle chart and go for 10% richer through the range. It's what modern fuel needs.
 

RAC68

Darth Vader
Offline
Hi All,

I have acquired 2 Colortune units over the years in response to the idea that it would be better to use one on each HD8 to reveal the best adjustment results. Sadly, I have never been successful adjusting my carburetors with a Colortune, either one at a time or both together. In specific, I have not been able to see the color difference and would appreciate knowing what others are seeing. Also, I have even tried using the Colortune at night with minimal ambient lighting and still find no success in determining color changes when adjusting the carbs. I would like to use these units but have not.

I do think wonder how available Rolling Road facilities are in the UK as I have not seen much of their presence in the US. I can see that adjusting a number of settings could be more effective when made in such a dynamic facility. However, the cost could be prohibitive.

Ray(64BJ8P1)
 

Keoke

Great Pumpkin
Country flag
Offline
What other kits are you referring to?

The Standard SU balance Kit is one that works well.

However,The following by EV2239 is excellent:

"If you synchronize the butterflies properly, make sure the float height is correct and set you jets (on HD8s) down 0.075" down from the jet bridge, the carbs will be as near perfect as you get."

OH! Fore I forget:
A set of Grosse jets replacing standard type needles will help a lot here too.
 

Bob_Spidell

Yoda
Gold
Country flag
Offline
I've had/used 2 Colortunes for many years. On my BJ8, I put them on #2 and #5 cylinders. For years, I couldn't get any color on #2; come to find out that cylinder was all but dead with only about 60PSI compression. After an overhaul, I could get the coveted 'bunsen blue' on #2 and #5. I used 2 as well on our BN2, and was able to get blue on 2 cyls after an overhaul--didn't test before as we started a resto almost as soon as we got the car--and that engine has 160-170PSI compression on all 4.

You should be able to get a yellow flame if the cylinder is running very rich; I think as you lean the color may change from yellow to invisible without passing through blue if the cylinder is weak, or maybe other anomalies can cause it.
 
Country flag
Offline
Ray, I'm not sure why you are having trouble unless you are using the crappy mirrors supplied. If you look directly down the "plug" you get a very clear picture of what is going on.
I have a lot of other tuning devices including the tube float device. On a BJ8 you must remove the front air filter. A real pain.
The Gunison fuel analyzer sits in the box (new) because it is too complicated. There is an inexpensive set of wires that fits into the top of the dash pots that works fairly well.
 

BJ8Healeys

Jedi Warrior
Country flag
Offline
Ray, I'm not sure why you are having trouble unless you are using the crappy mirrors supplied. If you look directly down the "plug" you get a very clear picture of what is going on.
I have a lot of other tuning devices including the tube float device. On a BJ8 you must remove the front air filter. A real pain.
The Gunison fuel analyzer sits in the box (new) because it is too complicated. There is an inexpensive set of wires that fits into the top of the dash pots that works fairly well.

The mirrors are pretty crappy, being just chromed plastic. Mine finally broke off, so I get a better view straight down the tube. The SU tuning kit wires that fit into the dash pot tubes indicate whether the air flow is balanced (equal) through both front and rear carbs, but they don't indicate proper mixture which is what the Colortune does. You're supposed to turn the mixture screw for the carb until you get a rich (yellow) flame, then back it off gradually until you get the Bunsen blue color. You have to be able to judge the difference between Bunsen blue (perfect mixture) and whitish blue (lean). If you get it right, you'll have a gray deposit in the tail pipes and gray or light tan on the plugs. Too rich, and the deposit will be black. If you have trouble getting the blue, the Gunson instructions that come with the kit give you some reasons why that might happen.
 

John Turney

Yoda
Silver
Country flag
Online
I don't use the tubes. I just look at the (clear) plugs. The pair I have work fine. The difference between yellow and blue is about a quarter turn on the mixture adjustment on my HD8s.
 

dougie

Luke Skywalker
Country flag
Offline
Hi All,

I have acquired 2 Colortune units over the years in response to the idea that it would be better to use one on each HD8 to reveal the best adjustment results. Sadly, I have never been successful adjusting my carburetors with a Colortune, either one at a time or both together. In specific, I have not been able to see the color difference and would appreciate knowing what others are seeing. Also, I have even tried using the Colortune at night with minimal ambient lighting and still find no success in determining color changes when adjusting the carbs. I would like to use these units but have not.

I do think wonder how available Rolling Road facilities are in the UK as I have not seen much of their presence in the US. I can see that adjusting a number of settings could be more effective when made in such a dynamic facility. However, the cost could be prohibitive.

Ray(64BJ8P1)

Rolling Roads or "Dynos" are widely used out here in the Wild West. There's about half a dozen right here in Portland, OR. I test my '57 vintage racer before every season. I used a new shop this year, Portland Speed Industries, $175.00 for about an hour and a half for baseline settings. Well worth the money, I was way lean which both spark plugs and exhaust residue didn't indicate after a track day at PIR.

Portland Speed Industries Dyno.jpg


https://www.tunedbypsi.com/services.php?Dyno-Info-3
 

Hangtown Healey

Jedi Hopeful
Country flag
Offline
They used to work pretty well for me in the days of non unleaded fuel. Not so good anymore. I need to go much richer than bunsen blue.
 

Hangtown Healey

Jedi Hopeful
Country flag
Offline
They used to work pretty well for me in the days of non ethanol fuel. Not so good anymore. I need to go much richer than bunsen blue.
 

Patrick67BJ8

Obi Wan
Silver
Country flag
Offline
If you synchronise the butterflies properly, make sure the float height is correct and set you jets (on HD8s) down 0.075" down from the jet bridge, the carbs will be as near perfect as you get.

do bear in mind that if you're still on original needles, the car may be weak and a rolling road is the safest bet. Otherwise, search for an SU needle chart and go for 10% richer through the range. It's what modern fuel needs.
What tool is available to measure the 0.075".
thanks
 

steveg

Yoda
Gold
Country flag
Offline
If you synchronise the butterflies properly, make sure the float height is correct and set you jets (on HD8s) down 0.075" down from the jet bridge, the carbs will be as near perfect as you get.

do bear in mind that if you're still on original needles, the car may be weak and a rolling road is the safest bet. Otherwise, search for an SU needle chart and go for 10% richer through the range. It's what modern fuel needs.

What jet would you recommend to be 10% richer. Have heard that number before but without a jet suggestion.

Correction: What needle...? Sr moment
 
Last edited:
Similar threads
Thread starter Title Forum Replies Date
B TR6 Gunson Colortune Triumph 4
C Gunson colortune Austin Healey 9
R Colortune test plugs Triumph 3
M Colortune question Triumph 12
tahoe healey Gunson colortune follow-up Austin Healey 17
tahoe healey Gunson Colortune Austin Healey 14
tahoe healey Gunson Colortune Restoration & Tools 7
M Proper use of the Gunson Colortune Triumph 41
M colortune plug. Triumph 2
Gundy Colortune cleaning fluid Restoration & Tools 2
livinginthepast Colortune: Your opinions... Spridgets 8
CraigLandrum Colortune vs Old School carb mixture adjustment Triumph 17
healeyboz gunsons colortune Spridgets 14
B Colortune?? Spridgets 20
R ColorTune and Exhaust Gas Analyzer MG 6
A ColorTune MG 2
A ColorTune MG 3
RSMTR8 Wedge TR8 Colortune Triumph 8
J Colortune usefulness? Triumph 10
Rob_T Colortune? Restoration & Tools 6
jsneddon Interesting Carb Tuning with Colortune article Triumph 6
R Colortune MG 4
Moose33 Gunson's Colortune - Anyone used 'em? MG 4
C Colortune carb tuning Austin Healey 2
J Rough Idle-Colortune-weak spark? MG 9
Bret Gastester & Colortune revisited – A status report Restoration & Tools 1
Bret Tree Huggers Vs. LBC Lovers. [was: Gastester/Colortune] Restoration & Tools 37
Bret Gastester vs. Colortune debate MG 0
Bret Gastester vs. Colortune the debate. Restoration & Tools 23
M New Member with an HD8 Carb Question Austin Healey 1
Zitch For Sale HD8 carbs and 2" intake Austin Healey Classifieds 9
G HD8 Carb Leak Austin Healey 7
G HD8 Carb Banjo Bolts Austin Healey 2
G HD8 Idle Adjust Screw Austin Healey 10
BoyRacer Wanted Orphan HD8 carburetor for parts Austin Healey Classifieds 6
O HD8 carb on Healey 3000 Austin Healey 62
Patrick67BJ8 HD8 Carb Repair Austin Healey 15
ArchieMcAllister Wanted Rebuildable set of HD8's Austin Healey Classifieds 4
AUSMHLY HD8 drop test time in seconds Austin Healey 3
AUSMHLY HD8 Carburetor rebuild help Austin Healey 46
AUSMHLY HD8 damper with Brass or plastic cap? Austin Healey 8
J Wanted HD8 SU carb set Austin Healey Classifieds 6
B mysterious leaking of SU HD8 Jaguar 9
J HD8 carbs, what is minimum fuel rate to keep bowls full, car is dying. Austin Healey 18
vette Adjusting HD8 Carbs Austin Healey 21
D S.U. HD8 Carburetor Drawing Austin Healey 6
S Float valves for HD8 - Grose Type Austin Healey 20
steveg HD8 high idle aggravation Austin Healey 11
AUSMHLY HD8 pin & spring assembly Austin Healey 6
Jeepster HD8 carb float bowls Austin Healey 7

Similar threads

Top