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TR4/4A Wish I Could Give Up--My Carbs Still HS6 TR4A

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Charley-I think I have entered the Twilight Zone. My 1989 edition of Haynes SU manual lists the 284 spec HS6 carb with a QW needle, but that needle is in the.090" jet needle section. Another SU book-"SU Carb Tuning Tips&Techniques" list the 284 spec carb with QW needles and the jet spec.AUD9141-42, is for a .090" jet. I have always wondered why there was a different spec. for 1968 USA TR4As and why a HS6 carb would use a .090" jet&needle.
Anyway, I KVH's problem is solved by leveling the float chamber.
Berry
 
Berry,
actually I have yet to see a 284 carb. I have not been looking for them , but I have over the years looked for and purchased about 4 sets of 209 carbs. Actually one set was the body for a 209 with domes from H6 carbs ( you get some weird stuff off of eBay. All of the kits for the HS carbs I have seen included the .100 jet and I believe the TW Needle I switch that out for the SM needle which is richer than the recommended needles for the TR4A and is standard for the TR4, which the carbs are on.
So has anybody out there actually seen a 284 carb on a Tr4A?
Charley
 
Charley-If you google the QW needle profile, it is definitely for a .090" jet (first station is .089") and yet the VB catalog lists it as the needle for 65-67 TR4A. That has to be an error.
KVH-What needle are using? It should be TW or SM.
Berry
 
FWIW, the workshop manual supplement for emissions on Spit Mk 3 and TR4A shows both a .090" jet and a QW needle (and mentions the AUD 284 carbs). It also implies that they were fitted to cars sold here as 1968 models. Since TR4A production supposedly ended in July 67, that probably means there weren't very many produced to 1968 specs.

The Burlen site also mentions AUD 284 as being an "emissions" carb.

Makes sense to me that the smaller jet & needle would give more accurate metering. According to the above manual, the QW needle is also leaner.

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Randall-That is what I was thinking-that it was a quick&cheap band aid for the new emission laws. Ironically, the TR2 had H4 carbs with .090" jets.
Berry
 
I really do feel privileged to have a definitive resolution and some experience to relate:

Who was it here who said the problem with my carburetors is my distributor?

Well, I finally got the fuel level correct by going back to my original floats and put a fine fiber washer under the seat. I had to sand down the washers, as mine were too thick. But the fuel level seems correct in the jet. Finally.

However, I took the car for a spin and got the same skipping, hiccups and hesitation at take-off and hard acceleration. In other words, the problem looked resolved but not the symptom. I actually can still detect that the mixture is rich at the exhaust pipes.

But that was sort of the key. I recalled that prior to my engine rebuild, I always felt the mixture was rich, and yet the car ran great. Rich was a fact of life.

So, I pulled my Pertonix Flame Thrower Distributor and put my original British "points" distributor back in. Absolute perfection. It runs smooth and fast, and no missing or hiccups. I cannot begin to imagine how many tear downs of my carbs I've been through on this, back and forth with floats and jet needles, a pump pressure test, a new pump, and all other efforts. But, in the end, this all started with some debris that caused my bowls to overflow, leading me to see that the fuel was also too high and the car running poorly. Two unrelated issues.

The carbs were a technicality. The poor performance was a so-called new and improved distributor technology that simply failed for me, and I'll not consider anything like that again. The only "new and improved" on my TR4As from this point forward will be the spin on oil filter adapter. No fancy cam; no uprated valve lifters; no new funky head gasket, no alternator conversion (I realize some like it); nothing I don't need.

The problem with my carbs was my new distributor. Or, the problem with my carbs was a fix where no fixing was needed. Thank the Lord I can now head into the Presidential Debates with a clear mind.

Thanks for all the help guys.
 
KVH-Glad you found the solution to your problem, even if it wasn't where you expected to find it. Sometimes "New and improved" isn't.
Randall-According to Graham Robson's "Triumph TRs", the last TR4A rolled off the line on Aug. 2, 1967 and 12 USA 1968 (model year) cars were produced. Not much volume for the effort needed to comply with the new emission regs. No wonder the 284 spec. carbs are rarely seen.
Berry
 
Wow...quite an evolution! I have a friend who reminds me over and over, "it's always ignition". When I start to quibble, he just continues to repeat, "IT"S ALWAYS IGNITION!"

I have never used the Petronix, but I am starting to notice there are many more posts about problems with the Petronix than posts about problems with standard points.
 
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