Thread: Unleaded Additives Series 2A 2.6 Litre

I read some years ago that you need to be careful switching between different types of lead replacement additive. Different substances are used in different brands and there is the possibility of corrosion within the engine because of the interaction between different formulations.
Can't remember where I read it but it was a UK magazine that carried out some trials.

Here is some 'fuel' info from the Federation of British Vehicle Clubs, obviously some of the additives listed may not be available here.

Fuel Information


Colin

The main thing that causes the exhaust valves to burn out is when the small ports that come off the copper tube that runs from the front to the back of the motor & feeds water to cool the valve seats block up.

Where is this copper tube ? didn't see it when i had the head off

Originally Posted by gromit

I read some years ago that you need to be careful switching between different types of lead replacement additive. Different substances are used in different brands and there is the possibility of corrosion within the engine because of the interaction between different formulations.
Can't remember where I read it but it was a UK magazine that carried out some trials.

Here is some 'fuel' info from the Federation of British Vehicle Clubs, obviously some of the additives listed may not be available here.

Fuel Information


Colin

Hi Colin,
we have had plenty of time between additives as we have burnt nearly 5000L of fuel Having dual tanks makes it easy too. None of the additives really made much difference performance wise except the penrite one. Seemed a bit more lively and smoother at idle.

Lots of people in UK now are running their older engines on this stuff now:
Aspen Fuel :: Home

The ethanol that is added to all UK petrol is causing havoc with vehicles that are left unused for a while. Rotting pipes, tanks, etc etc.

My father (he's 80 years old) recently changed to it in his chainsaws as he couldn't start them. Problem solved. They now start first time, every time.

When we are back in Perth soon i will do a "dry" compression test. I fully expect all cylinders to be even at 150psi as they were when we left Sydney.

Will report back soon.

Nobby

Originally Posted by Nobby07836

Hi Colin,
we have had plenty of time between additives as we have burnt nearly 5000L of fuel Having dual tanks makes it easy too. None of the additives really made much difference performance wise except the penrite one. Seemed a bit more lively and smoother at idle.

Lots of people in UK now are running their older engines on this stuff now:
Aspen Fuel :: Home

The ethanol that is added to all UK petrol is causing havoc with vehicles that are left unused for a while. Rotting pipes, tanks, etc etc.

My father (he's 80 years old) recently changed to it in his chainsaws as he couldn't start them. Problem solved. They now start first time, every time.

When we are back in Perth soon i will do a "dry" compression test. I fully expect all cylinders to be even at 150psi as they were when we left Sydney.

Will report back soon.

Nobby

Nobby,
Most additives I've seen are meant to stop valve seat recession and not aimed at improving performance.

Ethanol here also causes problems, I found something on a Goverment website a while ago that suggested you shouldn't use ethanol blends in small engines and fire fighting equipment. The ethanol absorbs water then separates out at the bottom of the tank (where the fuel pickup is).

Problem is that some States have legislated that a set percentage of fuel sales must be ethanol. Biofuels legislation - NSW Resources and Energy

Colin

Originally Posted by Nobby07836

Where is this copper tube ? didn't see it when i had the head off

You won't - remember the exhaust valves are in the block. It runs the length of the block inside the water jacket, inserted from the front, and helps distribute the coolant in the block. I have an idea you need to have the water pump off to see the plate bolted to the front of the block that holds it.

Few people seem to know it even exists or what it is for.

John

That explains it. As i pressed the 'post' button i thought i might have asked a stupid question
I expect our cooling system is quite clean as the previous owner had almost certainly used WA water and very little coolant additive. We found the evidence when i replaced the valves a while ago. We had to get the small coolant holes in the head welded and re-drilled to stop them leaking by the edge of the head gasket. That kind of corrosion has probably kept the tubes free flowing

I'm planning to strip the motor soon anyway so everything will be checked and new shells etc etc.

The next part of our trip will be shipping the car to Singapore and overland back to UK so i dont want to be stuck in some remote place with a silly problem that could be easily sorted in decent workshop facilities beforehand.

R

just so I don’t ruin my rebuilt 2.6l 6-pot by doing something stupid, is it correct that your understanding is that the 2.6l engines already had hardened values and therefore don’t need lead additives?

more context in case it’s relevant: 1981 Series III 109 2.6l 6-cylinder ex-military.

thank you very much!!!!

Originally Posted by JDNSW

The 2.6 engine has hardened steel exhaust valve seats, and as such does not require lead in fuel to lubricate the valve seats.

It is also low compression (7:1), and hence can run on any petrol sold today in Australia.

So the answer is, no additives are required.

For completeness, the four cylinder engine has the exhaust valves seated in the cast iron of the head. This means that the engine is possibly susceptible to valve seat recession without lead or a substitute in the fuel, although experience shows that this is not a problem unless the engine is used with sustained high speed and power operation. And even then, regular tappet checks will show if it is happening, and steel inserts can be added to the head when it is overhauled.

The 7:1 four will be happy on any fuel sold here today, but the 8:1 may prefer 95, and if the compression has been raised above that expect to need 95 or higher.

John