• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

Ever heard of this happening???

Share this page

LastDeadLast

LastDeadLast

Jedi Knight
Country flag
Offline
OK, so yesterday was a beautiful day here in NC and I've been able to take my TR to work most every day. It's been a week without anything breaking, which is nearly a record (two weeks is the record).

Anyway, so I'm at this traffic light that happens to be a two-lane right-hand turn onto a three lane road. The way the road is marked when my two lanes turn onto the three lane road, of which I'm in the near lane, we merge into the two far lanes... If that makes sense. Well when we start rolling the lady next to me decides that she wants my lane and really doesn't want to wait for me to get out of the way. I'm still in first gear so I nail the throttle to keep from getting hit. I wind up to about 5000rpm in 1st and drop it into second a little hard, but not hard enough to bark the tires. At that moment I feel something not right with the engine power. I give it gas and sure enough it's missing badly.

I limp it home but can't really find anything wrong except that the first two spark plugs are black as night. Since I've got triple carbs, I think "hey it's the first carb killing the motor", so I take the carb apart. I really don't find anything wrong with it, but I verify the float adjustment and spray everything down with carb cleaner, reassemble and replace the two bad plugs. I take it for a test drive, every thing's fine.

Confused? Yes! Any opinions about what happened?
 
I dunno, I took the bowl off before I took the entire carb off the manifold and sprayed the valve pretty good and made sure it wasn't stuck. It still missed when I took for a test run. I then decided to take it all apart. Can those things get stuck open and "look" functional? I must admit, I've never broken one of those ZS carbs apart before, I really don't know that much about them. I found out all my info from web articles.
 
Is it possible you got some dirt in the carb and cleaning it fixed the problem? How does your fuel filter look?
 
Hey - The carbs are really pretty simple once you take them apart a time or two...:smile:
Sounds like some crud in the front (rich) carb needle valve which kept it from shutting when it should have. Had the same thing happen to me after going to 3 carbs. Still happened with Grose jets, but I was able to pick the crud out with tweezers and fix them. All well now - I highly recommend the Grose jets (Moss).
 
Hey Shannon,
The same exact thing happens to me and it is a true enigma. My 3 carbs are as perfect as ZS carbs can be. (Rebuilt all three, twice!, because of this) I have a nice box of totally fouled sparkplugs that I keep as evidence. I have tried lengthening the fuel line to the first carb hoping to maybe modify the flow. The first carb is leaned as far as it can go and still be compatible with the triple setup. Maybe we should approach Richard Good on this phenomenon. I am at a loss. It often seems to happen after a really aggressive acceleration from a slow run. Meaning, dogging the s**t out of it. But keeping the whole run at an aggressive pace doesn't seem to bother. You would think I was running triple Webers the way it acts.

Bill
 
Bill,

Hmmm... Yep same here. I've got the same box of fouled spark plugs as you do...all on #1 and #2 cylinders. I was thinking today as I was bolting on the carb for the fourth time in two days if the fuel split has something to do with all this, I have Richards fuel line kit. I'm wondering if I should get a fuel distribution block such as this:
https://store.summitracing.com/default.as...mp;autoview=sku

What do you think?
 
I dunno, my setup is a little unique already in that the front carb has the fuel intake pipe entering the rear of the carb body and the 2nd and 3rd carbs both have their fuel enter the front of the carb body. This causes the 1st and 2nd carbs to have fuel intakes literally facing each other. This resulted in making the front carb fuel line (1/4" rubber fuel line) longer than Richard intended and equalength to the second line. And, the whole apparatus hangs down a bit lower beneath the carbs than I would like, and a bit too close to my headers (maybe 4"). Soooo, I'm thinking that my front and middle carbs are both getting the same pressure of juice, maybe yes, maybe no. I have always felt the the fuel lines should ride atop the carbs in this setup, maybe the distribution block would allow this to happen with some nice Earl's plumbing. Check with Richard (I am so tied up with hurricane issues down here).
Do know that I am tired of the front 1/3 of my engine fouling out all the time. Maybe God never intended for Triumphs to have three carbs. You think?

An aside, most of the members of the British Motoring Club of New Orleans have lost their cars to Katrina, or so rumor has it. Some still under 8 feet of water. Not good.


Bill
 
I am following this thread with interest. I do not have the triple carb setup, but it is on my wish list. I would also suspect the fuel line length. I checked out my old E-Type workshop manual and noticed that the Jag triple carb setup used a setup where fuel was delivered via a single line, fed from fuel pump to a point in the vicinity of the middle carb, with near equal distance to the front and back carbs, and not three individual lines. FWIW
I also read somewhere that Grose jets had a tendency to stick open at high rpms, but I can't find the reference.
 
Another thought: if the float bowl is not properly vented the vapor pressure that builds up will act to force fuel through the jet as if there had been an increase in the fuel level, which would mimic a stuck float or needle valve.
 
Hello Shannon,

were the plugs wet or dry (sooty)? I must admit this sounds strange especially as other also experience it.

I personally don't think that fuel line length or distribution will affect the running as long as the bore is large enough, which I would assume to be in the 1\4" or so, which is OK.

Alec
 
The distribution idea is an interesting line of investigation that could reveal satisfactory results.

I had to change the needles on my triple carb set up. Since I live at high altitude, the stock B1AF needles were way to rich even when fully lean. With Joe Curto's help I am now using B1CE needles. These are set nearly fully rich but the result was dramatic and fantastic. /ubbthreads/images/graemlins/driving.gif

I am still using the mechanical fuel pump but also wonder if using an electronic pump and doing away with any RPM related fuel pressure changes might have an effect as well as the ditribution ideas.

Now I'm contemplating some changes. Thanks guys.

/ubbthreads/images/graemlins/cheers.gif
 
Back
Top