Pinging doesn't sound like pinging . . . at all!

Damn you Arco! Hey did you know I worked at an Arco station for 3 years in highschool?
I'll swing by Monday and maybe if you can get me a good deal on the mallory we can make it work. As for the octane booster, I'm aware that it's anything but snake oil (even though I don't wanna rip on snake oil, never used it in an engine, maybe it works, who knows). I've come across about a lot of info in my forced induction research on octane boosters and their uses, very intersting.

 

LOL! ...87? the stock vehicle hand book for th 68-73 302 suggests a min of 92. i usually dial the motor in for 91 and run that, but you can get away with lower if you dial it in sometimes. then take into account that is averaged, so the chemist giving it a thumbs up as meeting the average min of 87 is getting the portion the batch maker pulled from, and a lower end refinery is more prone to sitting at the lower end. then if it isnt blended consistantly enough there could be some "spike points" in the 4 thousand pound batch that meet the requirement while the majority is lower. then it arrives at the station and who knows how well their storage tank is sealed. all that aside, if you prefer running 87 you may want to consider that for the new motor you are building but for now run 91

 

I thought octane rating should be picked on engine compression, as in higher compression engine should get higher octaine fuel. I think the motor in my beard trimmer has a higher compression than my stock 302 right now.

 

Think about the quench distance used in engines during those years, low compression and could still detonate.

 

this is interesting reading:
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Octane booster additives can give a substantial increase to the octane of pump fuel. A series of tests were run at San Diego State University where different “octane booster” additives were added to 92 octane Super Unleaded gasoline. The octane number of the fuel was measured on a supercharged CFR engine. The highest measured octane was 104.5 for Moroso 2 additive. They mixed 16 oz. of additive to 22 gallons of gasoline. This is a gain of 12.5 octane numbers. Other additives that were checked gave smaller, but still significant gains in octane. This, however, can be expensive. The Moroso 2 additive in the concentration tested, adds about $0.65 to the cost of each gallon of gasoline. Higher octane leaded “racing” gasolines with octane ratings of 107 or higher are also available in most areas, but these gasolines are also very expensive. Generally both the racing gasolines and the octane booster additives are too expensive to consider for the everyday street driven vehicle.​

 

The last time I tried octane boosters was in the mid 80's. With a 11.5 to 1 427. None of that crap worked then. What did work was mixing Avgas with leaded regular. Made the carbs leak like a sum-bitch though.

 

As for octane requirements in the late 60's to early 70's in the manuals, keep in mind that today's engines have the same comp ratios the engines then did. What works now will work on engine's made then. 87 is fine in a 9 to 1 motor today where the manuals then recommended 91 leaded regular.

 

Not true for all octane boosters. Many of the additives found in octane boosters are no longer approved for "on highway fuel use", and will not be found in pump gas.

 

I agree with everything else your saying but this i may be misunderstanding? lead acted as a detenation stabilizer and lubricant. unleaded fuels, especially the west coast "premium blend" junk would definately not make you able to run a lower octane without modding the motor in some way from stock without experiencing pre-detonation "pinging".
BTW, has anyone else caught the new comercials bragging about adding nitrogen to our oxygenated fuels for better burning? really nice of them to hook an air compressor to the feed line into their storage tank so they can charge us for more air bubbles passing through the pump vanes at the stations eh?

 

Back to dizzy,,, I would re-time, mark dist an engine so you can see if it turns. Some times the hold down wears an wont hold dist. tight. Also mark inner an outer dampner ring now, if it slips marks will not align. if timing slips an neither dist or dampner marks move, it's time to pull it out an see if gear pin broke or timing chain is on it's way out!

Before I would buy any new parts I would want to find out the problem so new parts are not damaged or you know for sure what you need. Good Luck

 

Yea, Kalifornia !!! The state that brought us MTBE !!!! The 87 we get here runs fine in 9 to 1 motors. But the nitrogen in Motiva's gasoline doesn't come from simply blowing air into the storage tank. It's a bit more complicated than that. And as they say, advertising works. Because of it, we're still able to buy Premium gasoline at the pump. Otherwise it would have gone the way of leaded gas. And the temperature difference of the fuel you buy makes more difference in the quantity you actually get than air bubbles. Fuel is sold at the rack (wher the truck loads it) by a set measure (the volume of the fuel @ 60*F) and sold at the pump at gross volume (whatever the volume is at the temperature it is when you pump it into your car) The fuel you dispense is rarely 60*F except in the dead of winter. When it falls below that point, is when the oil company looses money.