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Out of Gas
#21
(05-18-2019, 08:03 AM)OMS Wrote:
(05-15-2019, 04:50 PM)goodnigh Wrote:
(05-15-2019, 11:45 AM)c9zx Wrote: I would not use 100% 100 octane Low Lead. Low lead is mis-leading, it still has much more lead than our old leaded fuel contained. I think it will prematurely lead foul the plugs. Also, it is way more octane than you need. Avgas is rated by the MON (Motor Octane Number) method. Our old (circa 1970) gasoline was rated by the RON (Research Octane Number) method. In most cases the RON number will be 8-10 numbers higher than the MON number. So, Avgas 100LL has a RON number of about 110. The current method for rating octane in the U.S. is RON+MON/2, also referred to as "anti-knock index" (AKI). So, using the AKI method 100 LL avgas is about 105 octane. Using Avgas blended with pump premium, at a reasonable ratio, would likely be fine.
You may remember Sunoco 260 Super Premium from the old days. The RON number was used at that time and was 102. Using the AKI method it was 97-98 octane. I don't know the specifics of your engine, compression and cam specs, but I suspect pump 93 AKI should work without detonation unless you have too much advance, the curve is too fast, the rear gear starts with a 2, or the Dynamic Compression is higher than I would guess.
I've never built an OC 4V headed 351C so I can speak to how much advance it may want. The CC 4V headed 351Cs I've built wanted 36 degrees total as verified on the Dyno. Initial timing varies a bit with cam specs however, a reasonable street cam usually likes 16 degrees.
Let us know how you decide to go. It may help others later on. Chuck

Can only get 91 octane E10 here, car runs pretty good now although having never driven
a Mustang I have nothing to compare it to.  My mechanic worked on these back in the day
and stated this engine is cherry.  We believe this is closed chamber having D0AE block markings.
Will try and get a reading of the VIN on the block which may tell me something.  Also has some
kind of cam.  Measured valve lift at 0.58 although a forum member said that is hard to do after
the engine is assembled.  Have a recording of the engine and was told it does not sound like that
radical a cam.  Also, purchased (stole) this never fired rebuilt long block from Don of OMS, 'nuff said.

mike

Yes it is CC heads, should be a bit over 10 : 1  cam is not that radical ... stick with the 14 degrees , you daily driver it .
Did you install the 350 trac lock I sent you ????  OR are those 275's still out back whistling 
That gear swap will be the biggest change you will feel but your rear tires will not like you , the guy at the tire store will rofl
My mechanic tells me I don't need the 350 and I may not need my mechanic.  It was installed
but they forgot the juice so it made some noise.  Took it out and still sits in my trunk.
But, it will be installed within the month...promise.  Now that makes the cheese binding.
Good job Don!  Has to go in now, I'm a Buckeye.  Who wants a 275 anyway?  Probably scrap it.

mike
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#22
It is a small world. I'm originally from New Richmond, Ohio. It is a small town about 20 miles up river from Cincinnati. Tell your mechanic owning a car of this vintage has nothing to do with need, it is about desire. You will love the 3.50:1 gear. Chuck
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