I am in the process of reading a rather interesting book on motor petroleum, and it does make mention of a quite concerning increase in octane requirement with even small amounts of carbon build up. Once I have a bit of a re-read, I will remember what the figure was. Its is a book made after tetra-ethyl lead, but before MTBE was banned
Hi Tyler, I can give you my story on this, when I first bought my old Ford XC Falcon with the 302 V8, there was still good old Leaded Super available and the engine loved that stuff. Anyway after a few years they started phasing out Leaded Super and were replacing it with that LRP "Lead Replacement Petrol". Anyway after a while I noticed my engine started to make a metallic tapping type noise under hard revs. I didn't really quite know what this noise was I was thinking maybe something was a bit loose and rattling around the engine. Anyway I took my mate for a drive who was more into working on engines and race cars at the time and asked him what he thought this noise was. He said it sounds like the engine is pinging. I was like gees it never used to do that before. Then it clicked, it was the new damn LRP "Lead Replacement Petrol". It must have had a lower octane than the old Leaded Super where my engine never pinged at all. I never knew what the sound of pinging was when the car was always run on Leaded Super. Anyway there is my experience in finding out all about how good the old Leaded petrol was for those classic engines. I think back then Leaded Super had an octane rating of 97 or 98? That new LRP rubbish was like running water compared to good old Super!
Yes these days if you want to try and put a stop to your older engine from pinging your best bet is to try running it on Premium 98. In most cases it will stop the engine pinging because of the higher octane like the old Leaded Super used to be. I have ran some older 4 cylinder cars from the early 80's on premium 98 and it has stopped the pinging completely. If I run these engine's on anything lower than 98 they will ping. It's probably also from years of carbon build up in the chambers. Well I know running 98 has stopped the pinging on older engines and you don't have to mess around with rebuilding the distributor or adjusting the timing.
Then there's the other thing about how the older engines hard softer exhaust valve seats and this is where the old leaded petrol used to coat things and look after them. Some older cars had hardened valve seats and can be safely run on unleaded where others need some sort of additive added to the fuel to try and save the valve seats.
Cheers!
Zip a dee doo dah, zip a dee ay, another trash picked Victa, hip hip Hooray!
