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Classic Mustangs Tech Forum

Technical discussions specific to 1964-1967, 1968-1970, and 1971-1973 Classic Mustang. Discuss all tech related to in-line six cylinder and V8 powered Vintage Mustangs here.

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Unread 10-08-2012   #1 (permalink)
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Default Unleaded gas & valve seats

I'm wondering about this in my 289. The engine was replaced with a rebuilt one in 1981. Don't know if the valve seats were hardened. According to Wikipedia, lead phase-out began in 1973, and disappeared in 1996. I don't recall when I started running unleaded, since I don't remember when leaded was no longer available around here (TN). Wondering if anyone can shed any light here.

I'm getting ready to do a compression test, something I should have done before doing all the work I've done on the engine (I think I was in denial after looking at what a new set of Edelbrock heads cost...). It doesn't idle all that well, but runs fine at higher rpm. Don't remember the vacuum reading when I last checked, but think it was a little low. Because of a transmission leak, the car sat for several years w/o being driven, although I did run the engine occasionally.
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Unread 10-08-2012   #2 (permalink)
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There's lots of reasons why you can't get a good idle, worn distributor components and carburetor issues are the most common.

Does your timing light show a steady illumination on your crankshaft damper at idle? Does it advance smoothly with engine speed? If not then rebuild the distributor.

I rebuild carbs on my cars as often as every third oil change. It takes less than an hour with a 2 bbl carb and it makes the engine run so much better while using less gas.

Hardened valve seats require hardened valves as well. The old seats are machined out and new hardened steel one inserted into place. I'm currently having a set rebuilt for a 390, including hardened seats, new valves, springs and keepers and it's costing me $1400. Your 289 is made from a harder iron and this might not even be an issue for you.
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Unread 10-08-2012   #3 (permalink)
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From the EPA:
The Clean Air Act Amendments of 1990 mandate the elimination of lead from all U.S. motor fuel by January 1, 1996.


Unleaded gas came in the mid-70s and by 76-77 almost all new American cars were using it. My '77 BMW was one of the last new cars to NOT need unleaded and it used to p**s off people to see me filling up my new car with (cheaper) leaded when their new Chebby required unleaded ONLY. I think the '78 BMWs were the last leaded cars and '79s were catalyst cars with unleaded. By 1992 my records show I was sometimes buying leaded and sometimes unleaded depending upon where I was.

A 1981 rebuild may not have added hardened seats. People were still debating the end of the world that would surely come when leaded gas disappeared instead of adding the hardened seats that would solve the problem. Any Al head has always had hardened seats but cast iron Ford heads didn't have ANY seat inserts back then or even valve guides; they just had the valves working directly on the soft cast iron.

If you don't run the engine hard you can get by without hardened seats today but since its only about $100 to add them I do it automatically. The intakes don't really need it, only the hotter exhaust. I have a 1939 car that has to really work hard to keep up with modern traffic and I experienced valve seat recession on that head before I added hardened seats. It would not keep a valve adjustment for more than a few 100 miles; each valve was pounding a hole in the head and continually loosening the adjustment. The lead had acted as a cushion so the pounding didn't do as much damage. It was made much like a Ford; seats directly machined in the cast iron. Ironically when the car was new in 1939 it used the ORIGINAL unleaded fuel before leaded gas was common. In those days a short lifetime for the heads/car was what everyone expected since they didn't know about leaded gas.

Your idle problem may have nothing to do with valves. Do a leakdown test which will tell the condition of your valves.

Although you may well need new valves, there is nothing special about the valves used with hardened seats. The valves were always pretty hard to begin with. For my last 289 overhaul (Feb '12) the installed total cost for the 8 seats was $114, parts and labor. Looking at the bill they didn't replace any valves; just cleaned them up as part of a valve job (priced separately). That was apparently since they were fairly low mileage from an overhaul in 1980 ($342) when I did NOT add the seats or much of anything else . New valves from the same shop for the overhaul on another 289 in 2009 were $6/each.
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Unread 10-09-2012   #4 (permalink)
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I tried an experiment in the late '80s with two small blocks. One got hardened seats on the exhaust valves, and one did not get any special treatment other than a standard valve job. I put 40,000 miles on both motors, then removed the heads. The standard head showed some but very little recession, while the hardened seats were not worn; however, one of the seats had become loose and the head had to be scrapped. No real case was made for using the hardened seats from the experiment, but, as Ivy said, I always put them into any head I am having re-worked. With today's ethanol running a bit hotter, the unhardened seats are being challenged even moreso than in the '80s.
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Unread 10-09-2012   #5 (permalink)
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Quote:
Originally Posted by Yadkin View Post
There's lots of reasons why you can't get a good idle, worn distributor components and carburetor issues are the most common.

Does your timing light show a steady illumination on your crankshaft damper at idle? Does it advance smoothly with engine speed? If not then rebuild the distributor.

I rebuild carbs on my cars as often as every third oil change. It takes less than an hour with a 2 bbl carb and it makes the engine run so much better while using less gas...
I probably should have mentioned that the work I've done on the engine includes a new 4 barrel Holley, Edelbrock intake, MSD electronic ignition & coil, and headers. After I posted my original message I started wondering if the "new" engine may have been a short block. So I may still have the original heads, with 236K miles on them. In my defense that was 20 years ago. All I wrote in my maintenance log is "new engine." If it was a short block, even more reason that should have done the compression test first...

I'm pretty sure the timing light is steady, but will check to be sure. As I mentioned, the engine runs great when I advance it above idle. I've done all the standard checks for vacuum leaks that I know, and nothing obvious. I've adjusted the idle mixture screws on the carb, which helped some, even though the Holly instructions say not to mess with them. I don't really understand why they would say that.
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Unread 10-09-2012   #6 (permalink)
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Al,

Interesting experiment on the seat inserts. A seat coming loose is a possibility since most of them are simply pressed into a machined hole. Some are threaded, but the added-later variety are usually not. It has been a standard procedure for many years now and hopefully a shop would be better at it than they were in the 80s.

The data I have seen shows the increased temp from ethanol is fairly small and mostly at wide open throttle. But, WOT is when you have the most need for hardened seats anyway and any increased temp would not help the situation.
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Unread 10-09-2012   #7 (permalink)
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Quote:
Originally Posted by Charles Reeves View Post
I probably should have mentioned that the work I've done on the engine includes a new 4 barrel Holley, Edelbrock intake, MSD electronic ignition & coil, and headers. After I posted my original message I started wondering if the "new" engine may have been a short block. So I may still have the original heads, with 236K miles on them. In my defense that was 20 years ago. All I wrote in my maintenance log is "new engine." If it was a short block, even more reason that should have done the compression test first...

I'm pretty sure the timing light is steady, but will check to be sure. As I mentioned, the engine runs great when I advance it above idle. I've done all the standard checks for vacuum leaks that I know, and nothing obvious. I've adjusted the idle mixture screws on the carb, which helped some, even though the Holly instructions say not to mess with them. I don't really understand why they would say that.
Holley says not to mess with the idle mixture screws mainly because of of an EPA regulations snafu. That and lots of people don't understand what they do. Factory carbs of the late 70's and later had plastic caps installed to limit the adjustability. I've only worked on Autolite carbs, and for those while the engine is cold and not running you take the caps off, turn them in until they gently seat, then back out 1.5 turns. Then you start the car, tune the ignition, and when the engine is warm and idling at the specified rpm then you fine-tune the idle mixture screws. Turn one side in until it idles rough then back out 1/8 to 1/4, then do the other side, then re-adjust the idle speed, then repeat. This procedure will work with any carb although the initial setting may be different (if so the car will be hard to start.)

Lots of guys adjust the screws while the engine is at a higher rpm and that screws up the idle. At higher rpms the metering jets at the base of the float bowl take over and the idle mixture screws do very little is anything.
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No disagreement with anything you said except for the date.

Quote:
Originally Posted by Yadkin View Post
Factory carbs of the late 70's and later had plastic caps installed to limit the adjustability.
I think you meant to say 'late 60s'. Ford used them on my wife's new 302 in 1968. First time I had seen them.
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No disagreement with anything you said except for the date.

I think you meant to say 'late 60s'. Ford used them on my wife's new 302 in 1968. First time I had seen them.
No I meant to say early 70's, since that's the only new car that I worked on back then. Apparently I was wrong, and wrong. :hihi:
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Unread 10-18-2012   #10 (permalink)
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I was finally able to check the compression on my '66 289 (the tubing on my old tester and gotten so stiff I couldn't bend it enough to get it into some of the plug holes, so had to get a new one).

All were within spec (130-170), with all but two in the 140-150 range. The #4 was 170, which I thought a little strange, and one was 135. That is within 75% of the 170 reading, the criteria to judge by according to what I read.
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Unread 10-18-2012   #11 (permalink)
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Not every gasoline had lead additive, ever. Remember "Ethyl"gas, it was special.
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Unread 10-18-2012   #12 (permalink)
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25% variation between cylinders on a compression test is quite a lot. Most engine makers specify 10% and some as low as 5% difference between cylinders. That may say you have a slight problem caused by something. Without a leakdown test you won't know if it valves or rings.

Ethyl was the nickname for premium gas; nearly all 60s gas contained 'Ethyl' or lead, the more generic name. No gas had tetra ethyl lead (TEL or just plain 'lead') before the mid 20s when GM developed it. Not many had it until after WWII since it took time to overcome the 'problem' of it killing poeple. But the 'high-compression' Olds Rocket V8 of the 50s was one of the first to really need it. By the 50s nearly all US gas had TEL. Premium fuel became know as Ethyl since it used more TEL which was all sold by the Ethyl Corporation; a joint venture of GM and Standard Oil of NJ. To promote their product there were large ETHYL signs on the gas pumps to tout their wares. If unleaded was common back then there would have been no need to market a third, completely different fuel in the 70s - Unleaded.

I was an Army petroleum lab tech in the early 70s and we tested pump gas as part of our training. There were a very few unleaded fuels back then (1971) such as Unleaded Amoco which at that time used Diethyl Nickel to boost octane. In general, all gas had TEL which is why they were dyed red. Unleaded gasoline was nearly clear, i.e. white gas, since it had no TEL dye; i.e. Coleman fuel. TEL is deadly poisonous and the dye was required to warn users it was in there. GM killed several refinery workers in the 20s until they figured out how to make TEL in a safer manner. The premium fuels had so much of the stuff that the carbs would build up red junk inside from the dyes in the TEL mix.
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Unread 10-18-2012   #13 (permalink)
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Quote:
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Ethyl was the nickname for premium. Nearly all 60s gas had lead.

That is not an entirely correct statement. It had that name because of the lead, and it was also a premium additive to reduce knocking / pre-ignition, this was critical in warbirds and other aircraft. Why on earth would they call it Ethyl if it was not for the Tetraethyl lead...?

And a very large and popular gasoline/ oil company never did include Tetraethyl lead or sell ethyl. It was not in every gasoline sold.
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Unread 10-18-2012   #14 (permalink)
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Read the history of General Motors and Standard Oil of New Jersey, i.e. Exxon. They owned the Ethyl Corporation 50/50 until 1962. Every oil company who wanted to sell high octane fuel (all of them) had to buy the additive from the Ethyl Corp because it was a patented product.

It was only in 99.99% of all gasoline sold in the US for motor car use.
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Unread 10-18-2012   #15 (permalink)
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Amoco never used it. They chose to add octane in a different manner.
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