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Folks, rebuilt 58 very stock, what type of gas? timing set 5 degree,
I do have 100 octane low lead at airport but expensive, should I mix this with 87 octane, this way I will have some lead in the gas, or does it really matter? this engine will never see over 4000 rpm, I am old fart that drives normal.
I thought there could be an issue with burning valves with 'no lead' gas, I thought these old engines needed lead for some reason. I heard the newer valves were hardened in the later model engines. but again, old fart with old stories in his head.
I've been running BP 87,89,93 octane, or is it 89,91,93 in my 65 327/300 for 20 years with no problems. Don't see a difference in any of the 3. I rebuilt my engine 20 years ago when I restored my 65.
Also run all 3 grades in my C6 LS2 with no problems.
The important thing is to drive them and not let them just sit in a garage.
I thought there could be an issue with burning valves with 'no lead' gas, I thought these old engines needed lead for some reason. I heard the newer valves were hardened in the later model engines. but again, old fart with old stories in his head.
It's really "valve seat recession", not burning, but it's a myth... only an issue on engines that run at high continuous load like medium duty trucks and trailer towing.
All '58 engines except the 290 HP FI version had an advertised CR of 9.5:1, and that was with the thin .018" steel shim gasket, but like most production engines it's probably lower due to higher than nominal deck height. Even if your engine was rebuilt "stock" it probably has a thick composition head gaskets, so the CR is probably in the mid eights.
87 PON should work fine. Let the tank get near empty, then add two or three gallons of 87. If it doesn't ping add two or three more when it gets near empty to verify. It if does detonate, run the test with 89.
I've been running BP 87,89,93 octane, or is it 89,91,93 in my 65 327/300 for 20 years with no problems. Don't see a difference in any of the 3. I rebuilt my engine 20 years ago when I restored my 65.
Also run all 3 grades in my C6 LS2 with no problems.
The important thing is to drive them and not let them just sit in a garage.
Your 327/300 was probably rebuilt with "low compression". That was common 20 years ago, but not really necessary and sacrificed output and fuel economy.
Modern Corvette base engines going back to the LS1 have a fuel recommendation that goes something like "premium recommended, but not required". That's because these engines have detonation sensors. and if detonation is detected the electronics retard timing temporarily or default to a less aggressive spark advance map.
You've got a Corvette man, buy decent gas. I would run at least 91 with that compression. There's not much you can do about the lead situation, all of the options are too much trouble or too expensive. As someone with 44 years of engine experience I'll say every thing with unleaded fuel should have hardened seats. Every head produced by either OEMs or the after market since 1973 has hardened seats. They don't do this because they have nothing better to do. Can you get by very possibly. I encluded pictures of an exhaust valve and seat from a head I just did a valve job on for a friend. This is what all exhaust valves look like running unleaded fuel today. This head does have hardened seats. You'll notice the pitting in both the valve and the seat. With plain unhardened seats it is only multiplied. As the valve operates it removes microscopic pieces of the valve seat. Sometimes it can be quite fast. You look at the pictures and you decide. I KNOW what I've learned from 44 years of engine work. Now I'll sit back and read all of the posts about they are not necessary and I don't know what I'm talking about.
You've got a Corvette man, buy decent gas. I would run at least 91 with that compression. There's not much you can do about the lead situation, all of the options are too much trouble or too expensive. As someone with 44 years of engine experience I'll say every time unleaded fuel should have hardened seats. Every head produced by either OEMs or the after market since 1973 has hardened seats. They don't do this because they have nothing better to do. Can you get by very possibly. I encluded pictures of an exhaust valve and seat from a head I just did a valve job on for a friend. This is what all exhaust valves look like running unleaded fuel today. This head does have hardened seats. You'll notice the pitting in both the valve and the seat. With plain unhardened seats it is only multiplied. As the valve operates it removes microscopic pieces of the valve seat. Sometimes it can be quite fast. You look at the pictures and you decide. I KNOW what I've learned from 44 years of engine work. Now I'll sit back and read all of the posts about they are not necessary and I don't know what I'm talking about.
Get comfortable, because there'll be plenty.....and rightfully so
I won't comment any more. You may or may not have noticed but I've got pretty thick skin and after 42 years in different types of machine shops you really need it. I'll let the pictures speak for themselves as they are 100% unaltered fact. You have your truths and I have mine!
I have a '65 327/300 in my '65. I use premium 100% gas (no ethanol). For the last 20 years I have also added a product called MAXLEAD 2000, which had been sold by Jack Podell at Carlisle (I am running out of what I bought from him). He no longer sells it...comes from a company called Kemco. From what I read, this can only be sold from inventory, not manufactured. It is now sold by another supplier under a different name, same stuff....go to www.octanesupreme.com. Lots of research out there indicating the "additives" sold at places like Walmart do little to nothing for you and can even be counterproductive. It may be unnecessary of course, so use your own discretion, but I have had no trouble whatsoever in 20 years of use/ownership. I will have to decide about continued use as well. Oh....I also don't drive my car hard.
Mike I may come across as a know it all. That is certainly not my intention. I'm only presenting the facts. Not "I've read where you don't need hardened seats or the Internet says it's a myth". These pictures are just normal unleaded fuel valves. You car or truck looks just like that even with hardened seats. Mine too. The whole reason for the seats is to prevent the erosion. You would look at the pics and say mine don't look like that they wouldn't seal up . But they do. I took these pics just Saturday because this pops up quite often. All I would ask is all of the nay sayers how many valve jobs have you done? Not seen or read about. And I would love to see an automotive person come on and say I do valve jobs on non hardened seats and I guarantee them. This probably comes across the wrong way and is not my intention. You can look at the pics and make up your own mind. I haven't done engine work as a profession for many years I only do a few jobs for friends. But I came into it in the spring of 74 as the unleaded fuel thing was unfolding. Remember the adapters to put leaded fuel in the unleaded restrictiors. And lastly would someone enlighten me as to why EVERY single head produced since then has hardened seats, not most EVERY. They don't do this because they read about a myth on the Internet. No back to our regularly scheduled bashing!
You don't need to add any additives. Now, I would like to run some VP racing fuel. I might try it when I am running low and go to my friend's speed shop. He sells it.
This topic is like religion here for some reason.
You will find people 100% sure with only anecdotal proof.
People will ignore evidence presented.
My advise: Do your own research (other then here).
Talk to some machine shops (consider they may have a bias too).
Make a decision you can live with.
Living in California sucks because all of the other crap added to our fuel. Eventually, you have to add fuel stabilizer if it sits for a long period of time otherwise you have to rebuild the carburetor. Adding Stabil is a good thing if you do not plan on driving often.
In my case, I usually can take a drive about once every two weeks based on the weather. That helps keep the lines fresh and clean.
Valve seat recession is not related to pinging.
Pinging is caused by use of fuel with inadequate octane for a engine's CR.
Valve seat recession is caused by inadequate lubrication of the valve/seat.
Lead raises the fuel octane AND provides lubrication to the valve seats.
Valve seat recession is not related to pinging.
Pinging is caused by use of fuel with inadequate octane for a engine's CR.
Valve seat recession is caused by inadequate lubrication of the valve/seat.
Lead raises the fuel octane AND provides lubrication to the valve seats.
I guess my point is what does the OP think he is having an issue with the current gas he is running? I know my son's 292 required running lead with the old valves. We took the head to a machine shop for some work and new valve seats were done.
Lead raises the fuel octane AND provides lubrication to the valve seats.
I may be wrong but how does gas lube the valve seat when it’s closed and when it’s open the gas is on fire? So at what point does gas reach the valve seats?
01-23-2018, 07:28 AM
type of gas in my 58
