Starting Woes

**wrinklearthur** · 28th May 2015, 07:59 AM

Back firing down hill can be a timing issue of the firing point, valve timing (unlikely) and/or the idle mixture being too lean.

Don't pull the distributor off to do the points as the timing should be already set, just clean the points and reset the points and spark plug gaps.

Then the timing could be tweaked if it's off after doing a check.
To do a quick check, align the timing marks to the desired advance for your petrol octane, with the key on, distributor cap off, slightly wiggle sideways the rotor button (don't twist it to do this) and that gentle movement should cause the points to make and break, you should hear the sparking / clicking as a result.

Those Solex carbies can have some fine rubbish build up in the bottom of the fuel galley's and in the seat of the idle mixture screw, there are a couple of brass plugs in the bottom of the carburetor that you can undo to let the petrol flush out most of the rubbish and for the blocked idle mixture, the mixture screw can be tightened in then returned to it's original setting (count the turns), this opens up the orifice and that loosened rubbish can also be flushed out by removing those brass plugs.

One thing to watch out for when the distributor cap is off, inside the distributor there is a flexible earthing wire that is between the moving plate and the inside body, make sure that wire (which looks like a fine braided wire) is in good condition.

You will be on your way in a few minutes.

**bee utey** · 28th May 2015, 08:13 AM

The most common cause of backfiring during deceleration is an exhaust leak somewhere in the exhaust letting air in and leaning out the unburnt fuel in the tailpipe.

**JDNSW** · 28th May 2015, 08:52 AM

Originally Posted by numpty

Thanks all for replies.

.......
The carby is the proper Solex and was rebuilt about 6 or 7 years ago and has not done many miles since. These carbys don't have a choke butterfly as such. I pull choke out for starting, but once running the choke needs to be returned as per my first post. ......
Cheers
Perry

You are aware that the "choke" actually has a halfway position, unless my memory is faulty. But this will be irrelevant to it starting, just may help after starting.

John

**numpty** · 29th May 2015, 06:42 AM

Ok. I cleaned and reset the points and checked the timing, which was way out. I think it must have been set at TDC instead of 10 deg BTDC. It certainly started and ran better after, although it has always run well.

Removed and cleaned the fuel bowl of years worth of detritus. It was then I noticed the correction jet in the carby was a little askew. It's threaded seat has almost broken away from it's position. I'm wondering whether to try glueing the threaded portion back in, or pulling apart and cleaning a spare carby I have and fitting that.

The carby came from an 80" 1600 and was rejetted to suit the 2 litre but the correction jet is sized 160 and should be 240 for the 2 litre according to my books. Maybe this has made a slight difference too.

More fun and games

**Pedro_The_Swift** · 29th May 2015, 06:55 AM

I think Leon is just trying to tell you something Perry---

can someone explain the choke thats not a choke please?

**B.S.F.** · 29th May 2015, 08:00 AM

Originally Posted by Pedro_The_Swift

I think Leon is just trying to tell you something Perry---

can someone explain the choke thats not a choke please?

From the Triumph Stag Site

Upon operation of the choke control, a lever on the side of the carburettor rotates a disc in the starter box. In the disc a set of holes of different diameters are drilled. When the disc is fully rotated, the largest hole is in communication with the starter circuit and provides the richest mixture.Fuel is drawn from the float-chambers via a vertical drilling adjacent to the central main fuel channels through the starter box and into the throttle body on the atmospheric side of the throttle plate. A cam, externally mounted on the choke lever, moves in conjunction with the starter disc, operating the throttle beyond the normal idle position to provide fast idle speed when the engine is cold.Progressively pushing in the choke rotates the disc and cam, bringing smaller holes in communication with the starting circuit thus weakening the mixture, while the cam allows the throttle linkage to return to the normal idling position.

**numpty** · 29th May 2015, 09:17 AM

Thanks BSF. I and I'm sure others are wiser now.

Originally Posted by Pedro_The_Swift

[FONT=Book Antiqua][COLOR=Gray][SIZE=4]I think Leon is just trying to tell you something Perry--- ;)

I know Pete, but as he's 4 years younger than me, he shouldn't be complaining so much. He should be all go for Glenreagh after this.

**roversmith** · 29th May 2015, 11:02 PM

Numpty, the one thing people always forget to check. Tappets, would also explain back fire.

Cheers Greg

**numpty** · 31st May 2015, 07:11 AM

Well.........I pulled down one of my other carbys and the one in the car and used the middle section of the spare with the base, accelerator pump and top of the original. Cleaned and checked all jets, cavities etc, reassembled and mounted it. It backfired a few times and then I reconnected the vacuum line

and it ran quite nicely.

I then removed the tappet covers and adjusted the tappets. Inlets were fine but exhaust were around 16 thou rather than 12. I know sometimes these are purposely opened up, but I took them back to 12 for now.

Took him for a run of about 25 k's on flat, uphill and down and runs like a charm with no backfiring on overrun anymore, which I'm quite chuffed with.

He's still sluggish on the starter though, so I'll be cleaning all of the contacts yet again.

Thanks to all who proffered help and advice. It was all taken onboard and acted upon as can be seen.

Perry

Oh and it idles on the choke now too.

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