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Triumph TR6 - HI-LO RPM

Hello All,
Fired up the beast and it started off pretty good but after an hour she would not idle right...went back and forth from 500 to 1300 all by herself..like it was breathing !. I adjusted my bypass valves from 4 turns to 8 turns ( from fully clockwise ) and that cleared that problem a little bit. If I give it a quick rev she drops way down to 500 and below and almost stalls then picks back up...Once I'm driving it's pretty good at high speed in all gears.
Vac at 15 to 16 and steady..I've got my timing at about 6 ATC ( I tried 4,8 and 12 with no luck )and the carbs are roughly balanced but it's tricky when something is out of whack.
Any one else run into this ??
Thanks
Charlie
Charlie Ballard

Charlie

Check RickOs post on the 74 carb diffs. Remember when I was playing with that valve under the carbon canister? Did pretty much the same.

I think your valve and canister may be causing greaf? Seals go and cannister will plug up.

Bill
Bill Brayford

Hi Bill,
I overhauled and cleaned the filter in the canister and replaced the charcoal. I also made sure the valve is working, I can also hear it click a couple of seconds after the car is shut off.
Charlie
Charlie Ballard

Charlie--Couple of things to consider:

1. Do you really mean 6 degrees ATDC? If so, that's way too retarded. On my 72, I'm at 10 degrees BTDC (dynamic strobe at idle) and it runs great, no idle problem.

2. If your carbs are the late style with the fuel bowl vent valve, you should check/adjust the vent valve operation. On my rear carb, it was shut in all throttle positions and that was causing problems similar to yours. Basically, the fuel bowl was being pressurized resulting in a near constant flooding condition. If interested, I can e-mail a PDF of the adjustment procedure.

3. Where are your needles at (full rich?).

Rick O.

Rick Orthen

Hi Rick,
I just got back in from working on the car. Yes I meant BTDC ( that is above the timing line which is TDC correct ? ) I have it bumped it up to about 10 also and it improved..I was using a strobe. As you were typing your thought waves must have travelled to me !! haha
I checked the float valves and they open and close properly, I also tested them when the carbs were apart and they allow or stop air as required.
My biggest improvement however was the bypass valves, I turned them fully clockwise one at a time and they both sped up the idle. I now have them both set at 5 turns from fully clockwise and the HI-LO idle problem has gone.The car now idles about 790 on my digital test meter and seems good..if the rain stops I'll take it for a run...I'd like to see that adjustment procedure if you don't mind..I'll e-mail you.
Thanks for the help guys
Charlie
Charlie Ballard

UPDATE
Tried going for a drive but it bogs,misses under load But I think I'm on the right track as the idle still holds steady..after lunch I'll try again !
Charlie
Charlie Ballard

Good Charlie. Yes, the TDC line should move away from you (when standing on the dizzy side of the car) when advancing. I have my by-pass valves blanked off with a solid gasket, but it sounds like yours are functioning properly.

If you are still having stumbling, perhaps:

1. Needles are too lean.
2. Electrical side of things needs attention. I had stumbling problems that were cured by a new dizzy cap. Check for tracks on the inside of yours.

Rick O.
Rick Orthen

When looking at the crank pulley (while standing on the drivers side) and you see the timing line on the pulley. All the marks above that line (towards the pass side) is considered BTDC and below that line
(towards the floor) is ATDC..correct ?
Just making sure..
Charlie
Charlie Ballard

I think you have it backwards and it hard to explain this without confustion. To advance, you want the graduations that are to the LEFT (looking from the crank side of the pulley, not the radiator side) of the long (TDC) mark to move backwards under the pointer affixed to the timing cover. The marks on the LEFT side run up to 24 degrees or so; the marks on the right only go to 10 or so. 10 BTDC occurs when the 10 degree graduation is under the pointer with the TDC mark on the RIGHT side of the pointer.

Does that make it any clearer?

Rick O.
Rick Orthen

I think we are saying the same thing Rick
I have lined up the pointer with the 10 from the 4 to 16 (not the 4 to 24) markings.. that is BTDC ?
If you have the Haynes book look at page 89, they show a sketch from the front view with BTDC being on the passenger side of the crank pulley
I checked my cap,wires etc (all new last year) and all are good.
It starts easy and idles pretty good but still "misses" when pulling away..I pulled my plug wires one at a time and can tell when each one is disc. and put back. I also richened the mixture by one turn It seems ok at speed through the gears and accelerating at speed. I removed the bypass valves and taped the holes with no difference.
Now I know why these carbs are called Constant Depression.
Charlie
Charlie Ballard

Charlie - Have you checked the diaphragms for holes? Also, try squirting WD-40 or carb cleaner on the shaft spindle seals - if the idle drops down you have worn spindles or a bad seal that's leaking air.

Brent
Brent B

Hi Brent,
Yes I did check the diaphragms and they and the seals were replaced last year but I'll still try the spray trick
thx
Charlie
Charlie Ballard

Air leak, yep, yep. Air leak. It's nothing but a vacuum leak. It's a classic case of vacuum leak.

You got a vacuum gauge? Idle vacuum should be around 16 hg or slightly higher.

Try that.

Jim
Jim Deatsch

Hey Charlie

Just thought of one thing could the gas be old? I use sta-bil and it prevents the stuff oranging up but it runs lousy till I put in new.

Just a thought. May save a lot of messing with.
Bill
Bill Brayford

Jim,Bill,
I added stabilzer to the tank when I parked it..I'll add some fresh gas soon to try it. My vacuum is steady @ 17
Charlie
Charlie Ballard

Charlie--Your "constant depression" remark is priceless.

Something nobody has mentioned yet: are you positive the carb-to-manifold spacer and sandwiching gaskets are oriented with the vent slot uncovered? I think that vent is just for bypass valve operation, so it shouldn't matter in your situation.

What about that vac takeoff on the bottom of the rear carb? In use or plugged?

Keep on it!

Rick O.
Rick Orthen

Now that's interesting. I'd have bet anything we were looking at a vacuum leak.

Jeesh, I wish MY vacuum was steady at 17hg like the Goose's.

J
Jim Deatsch

This thread was discussed between 21/04/2004 and 22/04/2004

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