what type of gas

High ZINC oil for break in of FLAT TAPPET camshafts.

FSJunkie wrote: ...........10% ethanol fuel runs 3% leaner, which is significant. Some cars run too lean and need larger jets in the carburetor..........

I agree with this statement. I put a Carter YF on the 199 that was in The Rambler. It was a factory size jet. It was getting 18-20 MPG. I went up one size jet and my mpg jumped to 20-22. (That is the motor and transmission that is now in Rapid Delivery)

Having AMC Fun,
Ollie

Now that last statement is a fact! Modern gas will generally take more timing too, so set timing by the book to start with, then go out and find a hill to pull and bump it up until you get ping, then lower a bit. Might want to put a light on it to see where it is, record for future use. Setting it "by ear" like that on a cool day will likely require a slight adjustment on a hot day (more likely o get ping on a hot day), but it's the only way I know of to get the most timing on the gasoline you are running.

You need a "break-in additive" to break a new flat tappet cam in regardless of type of build -- stock to full race. After that regular "cheap" oil will be fine for stock valve springs as long as the oil has an API rating. Non-rated oils (some race oils) could be suspect, as they can be formulated however the company wants. Current oil is SN, but SF or more (F-N in the alphabet) is suitable. Actually, SD started in 1967 and would technically be fine for most of our cars. but the SAE only recommends SF or newer in all vehicles.

I got to have a discussion with an oil company engineer a few years ago regarding the removal of zinc. He stated that it was safe for all stock motors with the exception of some of the 1960s "hi-po" models. The general rule is anything with valve springs under around 300# of pressure open needs more high pressure lubricant than current oil standards have.  Crane sells a 330# spring for AMC six cylinders that should still be fine, but that's on the edge. So if you're building a race engine with a high lift/long duration cam and stiff springs you need to run an off-road racing oil or use an additive. I use the break-in additive to break a flat tappet motor in, then use it in the first oil change just to be safe, but none after that. There are other additives in modern oil that make if safer than older oil formulations. The engineer stated he'd not run older oil in anything. From the SAE specs page, SM oil was "Introduced in October 2010 for 2011 and older vehicles, designed to provide improved high temperature deposit protection for pistons, more stringent sludge control, and seal compatibility (than older spec oil)."

All the stuff about ethanol fuels is a joke, just like taking the lead out of gasoline ages ago. There is a little increase in wear with unleaded gas in an engine designed for leaded gas, but for 90% of engines it's very little. There is a noticeable increase on hard worked engines, such as heavy trucks (towing) and race engines. Even then it's in the 20-25% range -- for most it's 10% or less extra wear. So if you would rebuild a head at 100K miles, you do it at 90K or so instead. Even then valve seat inserts aren't really necessary -- the valves can generally be ground twice before the seats start to wear down into the head to the point inserts are required. Inserts are common enough now that they are relatively inexpensive to have installed, so you may as well if the engine is being rebuilt. Generally $15-25 a seat (if doing more than one), and you really only need to do the exhaust seats -- no extra wear on intake seats.

billd wrote: You have to be kidding me!? Factual? Ethanol sure does clean - if you ever worked as a tech when it first came out you'd know that. In fact most cleaners and gas line antifreeze contains alcohol. You can watch it work in a small tank with little water droplets in the bottom. It has an affinity for water and absorbs all it can, what it can't, is left - unless you add the gas line treatment to absorb the rest.  Where does it ever create manifold problems? This is crazy, more old myth and old wives' tails that fact - pure and simple. I have a degree in this sort of thing, training by SUN with a certificate on fuel systems and you believe the BS on the anti-ethanol sites and "my friend's brother in law had a cousin" instead of fact.  What a joke. Remind me to never let either of you touch any of my stuff.  People come here for facts, not BS like this. Of all the people who have run it in everything for decades, a couple of you come here not with real fact, but with stuff found on anti-ethanol sites. Not with real experiences, but with this sort of stuff.  When you study this in college and have over 40 years experience with ethanol in hundreds, not 3 or 4, but hundreds of cars, come back with FACT. For truth about ethanol fuels, go to ISU's site - the place where the computer and fax machine technology were invented, much space exploration technology came from, etc. They have dealt with the study of fuels for many years and they tell the good and the bad (fact is there's not as much bad as some would have you believe). You can believe fact, science and REAL EXPERIENCE, or stuff repeated over the years and like many things, keeps getting bigger and badder........... "Remind me to never let either of you two to touch my stuff".....likewise Billy Please stop on spreading your misinformation bill! Your perception of zinc in a flat tappet engine is completely wrong.. How many have you built? Are you 60 or 160 years old? I'm guessing 160, due to your VAST knowledge on everything you post on. SUN CERTIFICATE- lmao!!!!!

I have no dog in this fight.  I buy the cheapest gas that will work acceptably.  But I do note this post is going the same path as the synthetic oil one.