low octane damage to valve seats? - Team Camaro Tech
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post #1 of 18 (permalink) Old Apr 11th, 08, 06:55 PM Thread Starter
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low octane damage to valve seats?

I just spent some time going through the archives in an attempt to find a definitive answer to the question of using low octane fuel... but found mostly back and forth talk on the use of additives to the gasoline...a few mentions of low octane use, but not a lot.

With the price of the high octane gas, it's almost too much to bear watching the pump spinning faster than you can read.

So, the crux of the matter is...I didn't have the hardened seats put it in when I rebuilt the motor...and am worried about receding the valve seats with using lower octane fuel... which I tend to either use (sometimes), or will blend with the higher...keep in mind that our fuel prices are higher than even in the states. I'll bet that it's over $5 a gal, as it's $111.9L (almost a dollar and 12 cents) a litre here.

Bottom line...do I bite the bullet and go with the higher octane (really curtailing my driving), or can I sneak in the lower...and if I do will it cause damage to the unhardened seats in this engine? I probably travel 1000 to 1500 miles each season, but was hoping to extend my range a lot more this summer. That was until it hit the fan with the high prices.

I'll bet I'm not the only one out there going with the lower grades of fuel, eh?

capt
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post #2 of 18 (permalink) Old Apr 11th, 08, 07:10 PM
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Re: low octane damage to valve seats?

My understanding is it's the lack of led not the octane rating that you need hardened seats. It's also debatable as to there really being a problem in an engine that isn't going to see 100k plus miles in just a few years.

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post #3 of 18 (permalink) Old Apr 11th, 08, 07:14 PM
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Re: low octane damage to valve seats?

I do not know what heads you are running but most Pre 73 heads are thick casting with Hi-Nickel content. I have run Unleaded fuel in 68 Camel Hump and the BBC 781 Large oval ports for years with compressions around 10 to over a 11:1 and never have experienced valve seat problems with either the exhaust or intake.

Granted I can only refer to PSGR Car Automotive use. If you use the engine for Towing or Marine where it is under constant load I believe I would go the Valve Seat Insert route. However every now and then I do put a can of Bardal Upper Cylinder Top Lube in the tank.

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post #4 of 18 (permalink) Old Apr 11th, 08, 07:39 PM Thread Starter
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Re: low octane damage to valve seats?

Well you guys are making me feel better already. I cringe when I put the lower stuff in the tank.

And I have read as well, that it is the missing or lower lead content that the earlier motors fed on that actually causes any damage if any? But, I don't want to set off the "lead additive wars" that I found in the archives, where one side believes this and the other that.

I was hoping that someone on this site might have come across an in depth study or auto research paper that might have put this lower lead/octane use and the results.

Thanks for the input.

capt
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post #5 of 18 (permalink) Old Apr 11th, 08, 08:10 PM
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Re: low octane damage to valve seats?

Octane doesn't affect valve seat wear.
Detonation can affect lotsa thing wear.
As long as she don't ping, use the lowest octane that works.





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post #6 of 18 (permalink) Old Apr 11th, 08, 08:50 PM
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Re: low octane damage to valve seats?

What Jim said ^^^ The octane keeps the ping away. The lead softens the metal to metal contact of the valves. Two different things. Wouldnt worry about the lead unless you are driving alot.

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post #7 of 18 (permalink) Old Apr 11th, 08, 08:58 PM
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Re: low octane damage to valve seats?

Quote:
Originally Posted by 2x67rs/ss View Post
What Jim said ^^^ The octane keeps the ping away. The lead softens the metal to metal contact of the valves. Two different things. Wouldnt worry about the lead unless you are driving alot.
You mean lead additive? Definately no lead in our pump fuel. Also most all older model heads had the hard seats installed when the valve jobs were done the first time or at least your head person recommended it due to poor fuel. I believe the term was "satellite seats"? Also agree with Jim.

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post #8 of 18 (permalink) Old Apr 11th, 08, 09:33 PM
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Re: low octane damage to valve seats?

Yeah I think they took the lead out around 79 or 80. When I had the valve job done in 81 while doing the resto on the vert hardened seats were added. I think I still have a bottle of lead substitute in the garage some where.

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post #9 of 18 (permalink) Old Apr 11th, 08, 11:10 PM
 
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Re: low octane damage to valve seats?

Per Ron,

"However every now and then I do put a can of Bardal Upper Cylinder Top Lube in the tank."

Right Ron b/c I add a half a small bottle of good old MMO in BOTH my oil at change or so and at the same time into my gas tank at fill-up..

I figure it help's my valve seats just like it always did way back then.

pdq67

PS., imho MMO is a very GOOD top oil like it say's that it is so go from there as is Bardahl and if you can find it Wynn's..



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post #10 of 18 (permalink) Old Apr 12th, 08, 12:13 AM
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Re: low octane damage to valve seats?

Marvel Mystery Oil (MMO)is sold at Wal Mart, and they are everywhere.
i think it's like $2.50 for a bottle that you can add to your gas every couple thousand miles or so.
i don't know if it will do anything to help the valve seats- which i wouldn't worry about, anyways, unless the motor is in a dump truck- but it does a good job of keeping the fuel system clean.

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post #11 of 18 (permalink) Old Apr 12th, 08, 09:46 AM
 
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Re: low octane damage to valve seats?

We can buy Kemco 130 Lead Supreme that has real tetra-ethyl lead in it.

It can increase octane by whole numbers, not just by points. Like from 92.0 to 96.0, not 92.0 to 92.6!

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post #12 of 18 (permalink) Old Apr 12th, 08, 11:13 AM
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Re: low octane damage to valve seats?

just filled up my F-350 at a $145.00 for 3-4 days of driving that really S--KS So spending the extra coin on my car is a treat.
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post #13 of 18 (permalink) Old Apr 12th, 08, 01:39 PM Thread Starter
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Re: low octane damage to valve seats?

After reading the comments/suggestions, it looks like I have two options to the priceless liquid going into the Cam: 1. Keep the drives to shorter ones. 2. add a lead additive.

I'd always thought that the lead would give the engine a layer that would help in the transfer of heat, thus prolonging the valve seats. But after doing a bit of looking on the net, came across an interesting article on the use of lead free gas and its application which goes beyond the heat transfer theory.

Of all places to find it? On a British car club site- "lead free gas red river triumph club" which is out of Dallas. Take a peek that what they have to say about lead free gas and motor damage...like I said it makes for an interesting read, eh?

And Kirk...I gotta admire your courage to fill her up...I just put in $40 or so at a time, and that hurts!


Thanks again for your opinions/info, guys.

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post #14 of 18 (permalink) Old Apr 12th, 08, 03:04 PM
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Re: low octane damage to valve seats?

I have done quite a bit of work on unleaded, low octane, valve rescintion issues as not only am I not only invloved in SB chevy but english vintage which ran British unleaded pool fuel around 65 yo 75 octane

The octane if correct for the engine will not cause valve rescession issues unless the engine is being loaded and used above the orginal design of the engine
Even then burnt valves will appear as an issue before rescission.

If u need to drop the ocatane rasting of as fuel use A1 Jet fuel..this is not Common Kero, it is a highly refined faction of kero with lubricants and anti bactrial agents agged
Kero will wash bores and unless the engine is working hard cause gunning
A 15% A1 Jet and 91 will give a octane of about 73

This old issue of lead/octane/valves has been around for a long time...
In WW2 during the Italian campaine, the troops where using the jeeps..these ran on unleaded low ocatane, but troops being troops decided to try the Flighter plane high octane leaded fuels...and yes the jeeps with a little timing adjustment went like bat out of hell...for a couple weeks and died. They killed enough jeeps to cause a taxtical logistal problem..because of head /valve problems.
The fighter plans used the lead to artifially increase octane rating so they could run the super chargers and higher compressions when a poilt needed the exra power when he got in the poo.

Very basically historically lead was not introduced till after the war as an octane booster.
It was then found that valve ression was reduced because of the buffering nature as a side benfit...and more so on high performace engines.
The companies that made the lead aditives where making a lot of money, a whole industry devaloped around the lead.
Then the greenies poked their heads in a few decades later, which threatened the existance of the lead companies...so a heap of political lobbing back and forth, mis information and propagana was put out for aonther couple decades...in the mean time the lead companies still made a lot of money..till the greenies won the day
At this time engine technology had made the old high performance engine something that rolled off the production line as the norm.
Yes without hardened seats did have more ression, but before this became a real issue in the engine things other things like worn rings, bores, valve guides, clutch plates needed attention anyway...so it was a non issue unless one had a track race car
Also before the lead was removed at the pump 99% of engine manufacturers and rebuilders had gone to hardened seats year before hand anyway.


Today the old misinformation and proganda still exists, and is still strong enough as a common Joe public belief for many companies to be able to produce make money and sell their lead altenative, octane booster, valve lube wonder products.

The background of my studies and engine tials is based on my intial belief some yrs back that our old low compression un hardened seats etc do not run as well as they did when they came out of the factory.. My orginal 'trade' was an industrial chemist.
It also involved post discussions with car owners and competitors of the Peking to Paris vintage car race... Which is an interesting story in is self.
I took 3 approahes to the subject...
1/Actual historical information of fuels, their compossion and engines
2/Adapting modern non leaded fuels to vintage engines
3/Adapting (redesigning) vintage engines to modern non leaded fuels ..cam desigin, compressions, chamber design etc
The latter is work inprogess with a engine ready to drop into one of my vintages
The intention is not to 'soop up' the engines, just to get them to run as well as they orginally did.

My Spelling is not incorrect...it is creative

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post #15 of 18 (permalink) Old Apr 13th, 08, 08:01 AM Thread Starter
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Re: low octane damage to valve seats?

Thanks for the historical/informative background to this lead free issue. No more cringing at the pumps.

capt
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