timing of a leaded head running on unleaded

timing of a leaded head running on unleaded - with aditive

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RS - 17 Apr 2006 18:56 GMT

timing of a leaded head running on unleaded - with aditive, on a 1981 998cc,

i (will) set the timing at 8 degrees as per haynes manual - but do i have to
advance or retard at all if running unleaded with additive on a leaded head?

thanks

Ryan

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Taffy - 17 Apr 2006 19:55 GMT

Well if you get pinking problems you should retard it slightly I think.
As
it happens a few years ago my sister was running an 87' Mayfair and
using
Car Plan Additive and it ran fine with no adjustment, where as her
daughter
(my niece) was running an 85' Mayfair and that started pinking under
load,
so I just took it to a local mobile tuner and he sorted it out for a
tenner
and it ran like a watch afterwards.

Taffy

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miniman - 17 Apr 2006 22:32 GMT

> timing of a leaded head running on unleaded - with aditive, on a 1981 998cc,
>
[quoted text clipped - 5 lines]
>
> Ryan

Hi Ryan

It should be fine if the additive has octane booster.

best method is to drive up steep hill in third at full throttle and
listen for pinking,

If it pinks then retard the timing a little, (turn the dizzy anti
clockwise ever so slightly)

repeat untill it doesn't pink!

Garages tend to set engines up to the factory settings that sometimes
aren't quite right if you have modified the engine slightly or live at
odd altitudes or temperatures!

Miniman

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Fitzy - 18 Apr 2006 09:36 GMT

>> timing of a leaded head running on unleaded - with aditive, on a 1981
>> 998cc,
[quoted text clipped - 24 lines]
>
> Miniman

Hi,
I agree with Taff and Miniman,
Just drive the car, put it under load, if it pinks, then jump out , retard
the ignition slightly,(turn dizzy anti-clockwise) and repeat the test,
its got to be one of the quickest DIY fixes ever,

Note;
timing lights and settings noted in books are redundant
when doing this adjustment,

Fitzy

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Martin - 18 Apr 2006 16:26 GMT

I had a similar problem, pinking like mad on 97 RON unleaded, worse on 95
RON both this additive plus Octane boost, It would net even start properly,
Now running at about 15Deg BTDC @ 1500rpm with vacuum advance off

1986 998cc Mayfair std

>>> timing of a leaded head running on unleaded - with aditive, on a 1981
>>> 998cc,
[quoted text clipped - 36 lines]
>
> Fitzy

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Jim - 18 Apr 2006 18:41 GMT

>>> timing of a leaded head running on unleaded - with aditive, on a 1981
>>> 998cc,
[quoted text clipped - 35 lines]
>
> Fitzy

But once you do get it right, it may be an idea to get a strobe on there
anyway to find out what the timing is for future reference.
Most additives claim that the timing needs no adjustment, but they tend
to get that wrong.

HTH
Jim

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