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Re: Proper gas for 374 engine
#11
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55PackardGuy
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Quote:

don1260 wrote:
I found a list of pure gas (without enthanol). The highest octane rating was 93. I tried the tetraethyl before but it didn't seem to improve the performance.


Don,

You might want to shop a bit more for the "clear" gas. Around here, it's almost always sold (usually at Mobil stations) as "racing" gas and has an octane rating of at least 95--sometimes up to 100. This should solve any pinging problem. No toxic substances to add or extra hardware to hook up.

It's true that high octane gas will not really improve performance other than what it does to get rid of pre-ignition situations (and that WILL improve performance). It actually has fewer btu's of heat in it than lower octane gas, and, if you don't need the extra octane, it will lower your gas mileage. Buy if you are experiencing ping and spark knock, you'll lose even more mileage with lower octane fuels, because the engine isn't using the gasoline for power, just for "explosions" inside the cylinder (and the accompanying damage).

I bet if you look around for Mobil stations that carry "clear" high octane gas at the appropriate octane, your troubles will disappear. (Except for paying for the stuff--it's pricey.)

Posted on: 2011/2/23 0:09
Guy

[b]Not an Expert[/
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Re: Proper gas for 374 engine
#12
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patgreen
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94 when possible (readily available locally) 92 is all they frequently have in some rustic neighboring states and the car isn't overly happy with it.

Lead substitute per instructions.

ZDF or ZDP...whatever that stuff is in the oil.

Original engine, 73M miles, not quite as many smiles.....

Posted on: 2011/2/24 1:35
When two men ride the same horse, one has to be in the back...
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Re: Proper gas for 374 engine
#13
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Owen_Dyneto
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Simply adding tetraethyl lead (or other octane booster) will not in and of itself improve performance. But it increases octane rating so it may allow you to advance the ignition timing a bit before serious preignition occurs, and that generally will result in an improvement in performance.

But the other property of tetraethyl lead that may be more important to those who haven't rebuilt their engines with hardened exhaust valve seats is that it minimizes valve seat recession. So if you don't have hardened seats and drive aggressively, you might consider it (or other gasoline additives that make the same claim) for that reason alone.

Posted on: 2011/2/24 9:25
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Re: Proper gas for 374 engine
#14
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PackardV8
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Does a rebuilt engine with hardened valve seats necessarily assume that stainless steel valves were used also???

Posted on: 2011/2/24 10:33
VAPOR LOCK demystified: See paragraph SEVEN of PMCC documentaion as listed in post #11 of the following thread:f
http://packardinfo.com/xoops/html/mod ... ewtopic.php?topic_id=7245
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Re: Proper gas for 374 engine
#15
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Jack Vines
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1. You cannot buy real tetraethyl lead additive. In any form which would actually improve the knock rating of a tank of gasoline, it would be both illegal and extremely toxic to handle. The scammer who claims to sell it uses very misleading ads. Read his advertising and you will never find any facts as to percentage of lead or octane rating improvement. He carefully skirts the law and truth in advertising. Hemmings and the others who take money to allow him to steal from the old car hobby should be ashamed.

2. The octane boosters which are legal and sold in auto parts stores are marginally effective. They are better than nothing, but won't get us back to the days of 100-octane.

jack vines

Posted on: 2011/2/24 10:35
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Re: Proper gas for 374 engine
#16
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Owen_Dyneto
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Hi Jack: Thanks for the comments. It was my impression that what is illegal is selling or dispensing into an automobile gasoline containing TEL. But the sale of it per-se is not illegal - any registered chemist or chemical research company can buy it from laboratory chemical supply houses w/o permits.

But be that as it may, the material I buy states clearly on the label that it contains 14.8 grams of tetraethyl lead per quart. It also has a chart that shows the amount required per 20 gallons of 93 octane gasoline to raise the octane to various levels. Is this perhaps a different vendor than they one you were discussing? Some years back while still a working chemist I did analyze the product and did find (qualitatively) tetraethyl lead.

What you say about toxicity is true and not to be taken lightly.

Your certainly are a better source to answer PackardV8's question about whether hardened exhaust seats also automatically means stainless valves, but it seems to me that the answer must be no, it doesn't automatically mean that. Hardened seats with OEM Packard valves are not unheard of on rebuilt heads I've encountered. A hardened seat does not necessarily require a stainless valve - true?

Posted on: 2011/2/24 10:44
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Re: Proper gas for 374 engine
#17
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Jack Vines
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You have analyzed the product you purchased and I won't argue with that. The research chemist I consulted told me flatly tetraethyl lead was so toxic, it should never be handled by untrained personnel or without laboratory gloves and a respirator. He says even minute amounts are toxic. Read this for a real eye-opener TEL Toxcity

As to hardened seats requiring stainless valves, no more miles than our Packard V8s see, most anything will work. Exhaust valve recession is caused by long, high speed hard pulls where the heat build to extremely high levels. Ask yourself how often your Packard V8 pulls a trailer across the Grapevine.

As for me, I install hardened exhaust seats in everything I build, with or without stainless exhaust valves.

Jack Vines

Posted on: 2011/2/24 11:18
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Re: Proper gas for 374 engine
#18
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Randy Berger
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I have hardened valve seats in the 400. I do NOT have stainless steel valves. The seat, under prolonged hot driving, is what suffers damage. I don't flog my vehicles so I figure the car will outlast me.

Posted on: 2011/2/24 11:46
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Re: Proper gas for 374 engine
#19
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Owen_Dyneto
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Yes indeed, even at a dilution of 14.8 grams per quart, though toxicity concerns are somewhat diminished, GREAT CARE should be taken in handling. I don't recall just what the TEL content was of premium leaded in the days of old, something in the range of 2 grams per gallon comes to mind. TEL was reduced in stages, as I recall the final versions of regular leaded were in the range of 0.2 grams per gallon.

Think of all the gas pump jockeys of the day (and I was one)! Perhaps that explains some of my personality traits.

Posted on: 2011/2/24 11:47
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Re: Proper gas for 374 engine
#20
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Craig Hendrickson
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Jack Vines wrote: Quote:
Exhaust valve recession is caused by long, high speed hard pulls where the heat build to extremely high levels. Ask yourself how often your Packard V8 pulls a trailer across the Grapevine.


I pounded in the stock exhaust valve seats on my 55 Pat driving from Las Vegas to Reno (840 miles round trip) in August 1999, just keeping up with traffic. I had a set of 56 heads rebuilt with hardened exhaust seats and haven't had a problem since. Here's the valve recession chart I've posted before. The gray bar at about 19 lb/hp is my 55 Pat, so 85mph sustained (trip above) will definitely do it (click for larger view).

Resized Image

Craig

Posted on: 2011/2/24 12:35
Nuke them from orbit, it's the only way to be sure! Ellen Ripley "Aliens"
Time flies like an arrow. Frui
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