HELP!!! Best fuel additive

[Simon 1867]

Ever since i changed my 83 1200ST nova form Lead to Unleaded petrol I have had a fuel issue where it ticks over fine but as soon as you drive and accelerate through the gears it starts to struggle, eventally cutting out and stalling. Whats the best fuel additive I can use, im currently filling the car up with Super unleaded as the Octane level is 99 which I thought would be closer to lead petrol being 100.
how offen should I use the additive and best place to buy it.

Thanks in advance

[Jon_nova1]

has it been converted?

[Royston]

4 star petrol was 96 octane, 5 star petrol, (you and I are a little young........)was 100 octane

I run my sport and SR on super unleaded, the SR has a later head.

Back in the day to "convert" them Vauxhall retarded the ignition 2-3 degrees for the drop to std unleaded 95 octane.

The original heads had steel inserts in then, but we don't know if they are hard enough for unleaded fuel, chances are as long as you don't cane it to death it should run fine and last a long time, I have never had any issues with valve seat regression.

I have never used any additives......... but there are some good ones out there

I think you may have an issue elsewhere....

This may be of interest, from the Rover SD1 forum
http://www.roversd1club.net/forum/topic.asp?TOPIC_ID=9660

[Jon_nova1]

My friend ran an unconverted engine on unleaded, it ran for around 9 months then flames came out of the carb and it ran like a pile of crap lol

[Iain]

My mums mk1 Fiesta seems quite happy on unleaded and something like half a bottle of Redex in every tank, having ran on leaded for most of its life.

[Simon 1867]

no heads not been coverted. I think unleaded is the way forward as aposed to super unleaded.

[mowgli]

right. the 12st was designed to run on unleaded... if you are unsure, look at the engine code on the block. if it has a big asterisk (see below). simply retard the timing till it runs right. it sound more like the advance retard diaphragm has failed. pull the vac pipe off at the carb end with the engine running & suck on it. if the engine note changes, then it is ok, but if it doesn't, your diaphragm is shot. it was very common back in the day
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[Simon 1867]

right. the 12st was designed to run on unleaded... if you are unsure, look at the engine code on the block. if it has a big asterisk (see below). simply retard the timing till it runs right. it sound more like the advance retard diaphragm has failed. pull the vac pipe off at the carb end with the engine running & suck on it. if the engine note changes, then it is ok, but if it doesn't, your diaphragm is shot. it was very common back in the day
*


Thankyou... Only problem i see is engine code isnt as visiable as it used to be, worn away abit now...will try that when i get in form work.

[Jon_nova1]

the engine code is on the front left where the cylinder head meets the block, theres like a little ledge, im pretty sure thats where it is, give it a clean and it will be visible, especially with all the crap stuck in the engraved in the code