TRExp

TR6 Tech Forum

Plug reading

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

bikeboy Avatar
bikeboy Silver Member Ian F
Lara, Victoria, Australia   AUS
I've just discovered the rear 3 plugs seem to be running a bit rich? Number 6 is on the left in the pic. I have twin webers fitted, and I'm thinking the rear one is either dirty, or needs tweaking? Would a quick-fix be to run some carb cleaner through the fuel, or is a more mechanical approach be called for?

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

Attachments:
plugs.JPG    29.7 KB
plugs.JPG

F1000RACER Avatar
F1000RACER Platinum Member Gary H
Alpine, CA, USA   USA
With Webers I would say most likely a jetting issue. I'd be curious to compare the jets from the both carbs. Also check the float level on the rear carb.

GH

tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
Have you reversed the plugs in the bores, 1 to 6 etc, to check that they get the same black deposit, and exclude a plug problem?
Unlikely - but worth excluding.

Carb cleaer also unlikely to cure, but cheap. AS Gary says, almost certauinly the carb needs adjusting.
John

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
bikeboy Avatar
bikeboy Silver Member Ian F
Lara, Victoria, Australia   AUS
Thanks guys. I only suggested carb cleaner because this seems to have been a gradually worsening condition? It was running OK when I got it a year ago. Anyone got a source for weber jet kits?

cheers
ian

poolboy Avatar
poolboy Ken D
Sandy Hook, MS, USA   USA
If these are the DG downdraft carbs,try the tuning first....although anything is possible, having different size jets in an otherwise matched pair is a stretch.
http://www.justbrits.com/Articles/TuneWeber.html
But if you need parts:
http://www.carburetion.com/diags/3236DGVDiaginfo.asp

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1540095 by bikeboy I've just discovered the rear 3 plugs seem to be running a bit rich? Number 6 is on the left in the pic. I have twin webers fitted, and I'm thinking the rear one is either dirty, or needs tweaking? Would a quick-fix be to run some carb cleaner through the fuel, or is a more mechanical approach be called for?

Ian:

This is more food for thought than anything, as it does appear that your rear carb needs some adjusting.

You didn't mention what year your car is. In the US at least, there were two different heat ranges recommended for the TR6. Champion N9Y and N12Y, the latter being much hotter.

You are running NGK BP6, which is a match to the colder heat range. I would ask if that is the recommended heat range for your TR6? It might be you would benefit from running BP5s, which would run hotter and be more aggressive at self cleaning.

I want to caution you that I think this is unlikely to be your problem, as there is such a profound difference between the front and rear carbs. So put this last on your list of things to check, and cross it off completely if the recommended plug for your engine in the colder N9Y/BP6.

BTW, your front three plugs really seem to be running in the sweet spot. Get the back three plugs looking good, and you are likely to pick up a couple ponies in addition to avoiding the fouling issue.

When you check the jetting, be sure you check the emulsion tubes. On the Webers, it is not just the jets that change the mixture, but the emulsion tubes are important as well. I suggest you get a book, like the Haynes series, on tuning Webers. I got the Haynes on Zenith carbs (well worn, as it is out of print), and it was the best $10 I ever spent.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

bikeboy Avatar
bikeboy Silver Member Ian F
Lara, Victoria, Australia   AUS
Thanks Vance, good info. I've got a '72. I'll see if I can grab a manual. I've got some good links from Ken as well, so a bit of reading to catch up on.
cheers
ian

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions




Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club

Sign in to ask questions, share photos, and access all website features

Your Cars

1979 Triumph Spitfire 1500

Text Size

Larger Smaller
Reset Save

Sponsor Links