Octane and Lead
 

Truck came with original owners manual and it claims the 360 in it wants 94 octane to keep it happy. Did a search on the forum and found that since the combustion ratio is so low on these that 94 isn't necessary. Now being the tight wad that I am, everything I drive has always been fed low grade which is 85 around here. What are you guys using and is lead additive needed or is the valve train able to handle decaf.

Wow, I didn't know 85 octane was used north of Mexico! There's something wrong if your low c/r FE won't run on 87. It will run much better if you add compression, but that costs ...
Eric

Everything I own has to drink plain 87.



John :-X06

with my mods i still run mid grade
stock motor run the 87

Thanks for the reply's...I'm going with 87 and may even try a partial tank of 85 and see if she protests.

How about the valve seats, are they on the soft side wanting some lube provided by a lead additive or are they hard enough to go without?

In time you'll will start getting some popping back in the carb and the front will take a nose dive when to are trying to pass or going up a hill. This the valves seats being burned away. 1972 was when ford started installing harden seats with the D2TE-AA if I remember correct. So yes you should be running the additive to CYA. If you do any hauling or towing is when it's really hard on the motors w/o hard seats. Cost between $600-$800 to have your heads done just depending where you live. Or like a lot of guys do hunt a pair down in the junk yards... Hot weather you may have to run 87+ or set your timing down a few degree's to run the lower octane juice. I run every other tank of 91 when the price drops below $4 bucks a gal. .. Back in the day these polled on new cheap stuff regular was 94octane @ like 28 cents a gal in Los Angele..
orich

Thanks Orich...So I'm guessing a leak down test might be the best way to determine if there is any valve seat damage with out pulling the heads? Doesn't have any popping coming out of the carb and power is good...I'm just curious what stage of the possible damage I might be at from PO's.

Here our regular is 85 and the mid grade 87 has alcohol in it. My old 390 hated that alcohol crap and wouldn't idle for sour beans when I tried to run it. That was a low compression 1970 car engine and I put 40,000 miles on it after I got it with no noticeable valve seat issues. And the engine was tired when I got it.
I heard once when lead was being phased out that there was enough residual lead on the seats for maybe 25,000 miles of easy normal driving.
The 1972 360/390 heads might be hard, D2s should be, but I had a late production 72 with a 300 six and those weren't. I was rebuilding the engine and questioned my cylinder head guy multiple times about my concern if it was hard seats. He said don't worry about it. 9,000 miles later my ported head was trash, some seats pounded out 300 thousandths, not even reparable as the fattest seats available were .250