Ignition Timing

[Polly-Red7]

Hi,
After quite a lay up I'm preparing Polly for this year's MOT. One or two problems sorted with the odd drama including about 3 litres of water in the petrol tank!

All of this is hopefully behind me, however, I have a problem misfire/exhaust popping under normal acceleration. It's fine when stood both on idle and revving the engine, but on the road I'm still to get out of second gear! I've gone through all the basics, points,plugs, dizzy etc etc but the only thing I can see out of the ordinary is the ignition timing which using my strobe is showing 12' BTDC not the 10 as per the manual, should I alter this as a matter of course or do you think it's retarded for unleaded?
Thanks in advance,
Chris

[Hasbeen]

That sounds a bit like fuel starvation to me.

Could you still have water in your carbs, or have water in an in line fuel filter?

Have you cleaned out the fuel pump, & are you sure you are getting adequate fuel supply?

Hasbeen

[FI Spyder]

No. 12 degrees BTDC is 2 degrees advanced not retarded from 10 degrees BTDC. Advancing timing usually results in pinging (pinking is UK speak) under load (usually at lower RPM). Exhaust popping is usually unburned hydrocarbons being burnt in the exhaust (running rich, sooted spark plugs). Unburned hydro carbons in exhaust could be failure of ignition in cylinder because of weak or failed spark.

Three litres of water in gas tank is a lot of water for condensation, I would suspect failed seal on gas cap and blocked holes to let water drain from inlet hole. Locking gas caps are said to allow water egress as they sit horizontally and not vertically like on most cars. No personal experience on that but seems plausible.


- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[Hasbeen]

Be careful where you buy your fuel, & it is best not to buy fuel, while a tanker is filling the stations tanks.

A mate of mine got a heap of water from a country service station a while back. Within 15 kilometers he was losing most of his power, & found his inline filter full of water. There was a lot in his tank, which he had drained just a few weeks before.

My local service station advised me to come back later when I went to fill the S2000 Honda recently. They had a tanker filling the 98 octane tank, & they reckoned it took about an hour for the dirt stirred up to settle.

Nice of them to warn me I thought.

Hasbeen

[Workshop Help]

You have a defective ignition cable(s). Please direct your attention to my article in The Workshop Manual on 'Spark Plug Wires'. Remember, just because an ignition cable is new doesn't mean it's good.

Mildred Hargis

[Polly-Red7]

Thanks for the swift replies, I'm certainly learning stuff! Would never in a million years have thought 12 degrees was advanced of 10. I've put one filter near the tank, looks ok at the moment. Pretty sure all the water is out as far as I can. Siphoned off from the tank last week. Carbs, floats pump etc all stripped and cleaned several times. If anything I was worried about flooding the cards because when I do take the pot off there is fuel still in the chamber?

Re fuel cap assembly, I think it has been fitted incorrectly in the past. Tried on two occasions to strip it down and no matter how much pulling and tugging I can't get it off

Will have a look at the timing in the morning, again many thanks,
Chris

[Workshop Help]

Please inspect and report on the condition of the spark plugs as noted above. A photo of them would be a big help.

Do you have an Ohm Meter to test the spark plug wires?
How old is the condensor?
Is the point gap set correctly and the wire connections tight?

Mildred Hargis

[saabfast]

When you 'went through' the dizzy did you replace the cap (and other internal components)? I have had misfire problems when there was invisible tracking (at least I could not see it). Changing the cap cured the problem. This could give one plug not sparking properly giving the misfire and unburnt fuel in the exhaust.

Alan
Saab 9000 Stg 1 (now passed to son for his family car)
Saab 9000 2.3 FPT Auto (now gone that others might live)
Saab 9000 2.3 LPT Auto (sold on, wish I had it back)
Saab 9-5 2.3 Vector Auto Estate
'81 TR7 DHC

[Polly-Red7]

Will try and post pictures of plugs later. Had a simular misfire etc last year. Everything bar the dizzy cap was replaced at that time and I've probably only covered about 1000 miles since. The problem cleared that time, so I'm presuming the components are still good. Reset the points as a matter of course as well as cleaning/setting the plugs. I do have oil fouling on cylinders 2 and 4.

[saabfast]

I would still suggest changing the cap as a quick and easy way to eliminate that. If 2 and 4 were not firing they would be wet. If it is oil have you tried a compression test?

Alan
Saab 9000 Stg 1 (now passed to son for his family car)
Saab 9000 2.3 FPT Auto (now gone that others might live)
Saab 9000 2.3 LPT Auto (sold on, wish I had it back)
Saab 9-5 2.3 Vector Auto Estate
'81 TR7 DHC

[Polly-Red7]

Will order a cap, will be annoyed if it's just that lol! Haven't do a compression test yet, on my list of things to do!

[76tr7rules]

Have you had a chance to look at the spark plugs and see if they are burning rich. Also is it possible you just have a vacuum leak? Ive had a few cars that popped under acceleration and it turned out to be a good vacuum leak.

On a related note, do Zeniths have an accelerator pump like regular carburetors?

[FI Spyder]

Constant velocity carbs (like Zeniths) don't need an accelerator pump like static (regular) carbs.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT