gas additives

B

bsky59

Junior Member
should i be adding a lead additive to my gas for my 59 352 engine? i am using
enzyme additive to counter the effects of the methnol. i allways fill up with
premium fuel
 
Pull the heads over the winter and have hardened exhaust seats installed. You can then run 87 or 89 octane and skip the additive. Rebuilding the carb with a current kit may help with the ethanol in the gas. Other members here may be able to speak more to the ethanol resistant materials found in currently sold carb kits.
 
Do you put a lot of miles on the engine. If you are only running around 2,000 miles or less a year, you should be okay without the lead additive and hardened seats.
 
I have been using stainless steel valves in my overhauled Y blocks on the enlarged factory material, no hard seats. No problems yet. I adjust the valves every year or two. If the exhausts start to tighten up, that will tell me the seats are sinking.
 
i dont know of anyone around here who put in hard seats.if your only putting on a few thousand miles a year forget it.
 
I used to run a machine shop and in the late 70's started installing hard seats in many of the pre-unleaded engines. At that time these were daily drivers, so they got some miles on them. Most of the original soft exhaust seats were pretty well recessed by the time they had 75000 miles on them. Part of the reason the seats went away was that because the lead, which is a lubricant, was now gone. The valve stems wore out and the guides got sloppy, this hammered the seats all the more.

Do you know the history behind your 352, after 55 years it's likely to have had valve work at one time in it's life, possibly it has later heads that have factory flame hardened seats on it now. If it runs good now and you only drive a few thousand miles a year, leave it alone. I read about people getting excited about the ethanol in the fuel. I have never had a problem, but I don't let the stuff sit in the fuel tank for long. Either run it, drain it or use lots of fuel stabilizer, but if it sits for long periods of time it will ruin rubber fuel lines, carb gaskets, power valves and make an unbelievable gummy mess in the fuel tank as well as disolving the fuel sender float!
 
My tuneup man is suggesting that 4 oz of Marvel Mystery Oil per ten gal of unleaded fuel, will eliminate/minimize most of the problems caused by the ethanol blended fuels.
I also use "Stable" fuel additive in the fuel I use in engines that don't get run on a regular basis..
 
" i allways fill up with
premium fuel"

BSKY,
Unless your engine has a pretty high compression ratio (i.e. 10 to 1 or more) you are wasting your money buying high-test gas. Go to the lowest octane that allows you to drive without "spark knock". I think you will find your car actually starts better with the lower octane gas and you may actually get a bit better gas mileage.
 
Last edited:
sidevalve8ba said:
" i allways fill up with
premium fuel"

BSKY,
Unless your engine has a pretty high compression ration (i.e. 10 to 1 or more) you are wasting your money buying high-test gas. Go to the lowest octane that allows you to drive without "spark knock". I think you will find your car actually starts better with the lower octane gas and you may actually get a bit better gas mileage.
Click to expand...


I agree that regular grade fuel is probably better for staring, especially when the engine is cold.

Premium fuel is actually less volatile than regular fuel, and burns slower. That's how it helps prevent spark knock. Waste of money, unless you really need it.

Sal
 
sidevalve8ba said:
" i allways fill up with
premium fuel"

BSKY,
Unless your engine has a pretty high compression ration (i.e. 10 to 1 or more) you are wasting your money buying high-test gas. Go to the lowest octane that allows you to drive without "spark knock". I think you will find your car actually starts better with the lower octane gas and you may actually get a bit better gas mileage.
Click to expand...

If you're not checking your fuel for the percentage of ethanol within it, you should. I get to check the ethanol content no less than once per week simply due to customers providing their own fuel for dyno testing. Aged blended gasoline gets even worse as I've come across up to 30% ethanol and that's simply a result of the ethanol falling out of suspension in the underground storage tanks at the service stations. Generally the premium fuel is at 5% ethanol versus 10% in the 87 & 89 grades. For that reason alone, premium fuel is what I recommend for any car running a carburetor.
 
Lots of different schools of thought on this subject. I read once when lead was first fisappearing that there would be enough residual lead on the seats for quite a while. I have ran some old, non hardend seat, engines a lot of miles but also once I rebuilt the 300-6 in my 72 pickup and specifically asked the guy doing my head if the seats were hard. He said don't worry about it. I should have. It was a head I had 15 hours of porting into and within 10,000 miles the seats were so pounded out that the head was ruined. The thickest replacements were .250 and it would have needed at least .350. In conclusion, I think if you have head work done, it's prudent to have hard seats installed.
 
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