Lead additive

[cashtim]

The guy I brought the boat from told me I needed to add lead additive and than add the gas. Can somebody help me and tell me if I need to do that and tell me what kind of additive I need to get.Thanks

 

[bruceb58]

Re: Lead additive

What engine do you have and year?

Personally, I would just not use the additive and do a valve job at a later date if/when the valve seats wear out.

 

[roscoe]

Re: Lead additive

I don't know of any (non race) motor that would require a lead additive or octane boost solution.

 

[tashasdaddy]

Re: Lead additive

99% of all standard outboards, like 87 octane unleaded, and tcw 3 oil.

 

[ziggy]

Re: Lead additive

I don't know of any (non race) motor that would require a lead additive

i dunno, my 72 &75 L6 165hp mercruiser states right on the engine, use premium leaded fuel. also the 75 has a sticker that's almost gone right by the filler cap that says the same thing......unless

I would just not use the additive and do a valve job at a later date if/when the valve seats wear out.

cashtim, we need to know what year and engine ya got if ya want to know if it was designed for leaded fuel or not.......

yep, i do add lead additive. worthwhile or not. i dunno. but i have a stock engine and fig. if the mfg. wanted lead, and i have the option of additive. why not.....other than it may be a waste of $'s

 

[MikDee]

Re: Lead additive

i dunno, my 72 &75 L6 165hp mercruiser states right on the engine, use premium leaded fuel. also the 75 has a sticker that's almost gone right by the filler cap that says the same thing......unless

cashtim, we need to know what year and engine ya got if ya want to know if it was designed for leaded fuel or not.......

yep, i do add lead additive. worthwhile or not. i dunno. but i have a stock engine and fig. if the mfg. wanted lead, and i have the option of additive. why not.....other than it may be a waste of $'s

Wait, Hey Ziggy, Long ago, I bought a 74'- 18' Wellcraft Airslot with a 165hp Mercruiser (250cu in Chevy Nova engine). It was siezed when I got it, and to no avail I had to rebuild it, (see my signature) and nowhere did it say use premium unleaded? I can tell you by that low comression simple engine design, you don't have to use premium, or leaded, gas! 87, or 89 octane unleaded should work just fine! After I rebuilt mine, and put synthetic blend oil in it, it went like stink! at least 45mph, I was pulling 5,000 rpm with a 13X19" cupped prop, and never even knew about trimming up at WOT back then for more speed! I probably could have used a 13X21" prop, and hit 50, and that was a heavy boat.

 

[RubberFrog]

Re: Lead additive

Mik, older engines used lead as a lubricant for the exhaust valves. Premium leaded had more lead.

I've had lots of old cars and some of them I used lead and never had a valve problem. Others, I didn't use lead and just got the exhaust valves redone when they need it.

 

[MikDee]

Re: Lead additive

I understand, and I'm aware of what you're saying, but By 1971 all vehicles were made to run on unleaded 87 octane. That's when all the motors began to take a large compression drop, and were reconfigured to milder cams, by 1975 every car had a catalytic converter on it, for unleaded fuel only. This created a big drop in performance for quite a few yrs. Back around this time, Oldsmobile designed their engines with an exhaust valve rotator, to help prevent any issues with unleaded fuel, and the other car companies changed the metal compound in their exhaust valves to work better, & last longer, with unleaded fuel.

 

[ziggy]

Re: Lead additive

nowhere did it say use premium unleaded?

i think ya may have miss read......

use premium leaded fuel.

for my 72 L6. mercuiser service manual #1, tune up specs, fuel required. "93 Research Octane Minimum - Do NOT USE Lead-Free or No-Lead Fuels"

for my 75 L6. mercruiser service manual #2, tune up specs, fuel required. (note 4). note 4 states "Caution: Valve seat failure may occure from using lead-free gasolines.
Use any good grade automotive regular leaded or premium gasoline with a minimum average octane rating of 88* (93 research). In areas where leaded premium and non-leaded regular are the only gasolines available, leaded premium should be used during the initial break-in period. Non-leaded regular gasoline may be used after the initial break-in is completed, provided a minimum of one tankfull of leaded gasoline is used after each four tankfulls of non-leaded gasoline.

86 average actane (90 research) leaded gasoline (with 0.5-4.0 grams lead per gallon) may be used if the gasoline described abouve is not available, however, the ignition timing must be retarded 4* to prevent harmful detonation."

i do appear to be corrected about the use of regular fuel thuogh. but it seems to me that there may be ramifications if ya don't retard the timeing 4*............

the pic is of my 72 165 valve cover, i just went and looked, the 75 has the same sticker.

 

[ziggy]

Re: Lead additive

I understand, and I'm aware of what you're saying, but By 1971 all vehicles were made to run on unleaded 87 octane. That's when all the motors began to take a large compression drop, and were reconfigured to milder cams, by 1975 every car had a catalytic converter on it, for unleaded fuel only. This created a big drop in performance for quite a few yrs. Back around this time, Oldsmobile designed their engines with an exhaust valve rotator, to help prevent any issues with unleaded fuel, and the other car companies changed the metal compound in their exhaust valves to work better, & last longer, with unleaded fuel.

that may all be true. but were talkin boats, not cars..........

cashtim, hope ya let us know what engine and year were discussing here. the whole conversation may be irrelevent to ya, depending on yer year......

 

[MikDee]

Re: Lead additive

I'm sorry, On my 74' Wellcraft with that same engine, and on my 70' Chevy Nova with that same engine I had no such label, or warning! Even in the Clymers manual I used for the rebuilding, there was no notation about that. So, I had no idea of what you were talking about. My next boat at that time was another 74'- 18' Wellcraft Airslot with a 188hp Mercruiser (or what was known as an "888" Mercruiser at the time) it was basically a 302 Ford V8 with a 2bbl carb. and it had no warning stickers like that either! Just to let you know my train of thought from my experience with these engines. Ziggy, don't get the idea, I'm just talking cars here, because I've had quite a bit of experience with cars, boats, and motorcycles over the years, I'm no rookie!

 

[Buttanic]

Re: Lead additive

Tetra-ethyl lead which is what was used is very poisonous. It can be absorbed through the skin and I highly dought any so called lead substitute contains any.
Here is a good article about the issue.

http://www.chevron.com/products/prodserv/fuels/bulletin/unld-gas/

 

[roscoe]

Re: Lead additive

It has been well documented over the years, that any engine that required leaded fuel, received enough of a lead lubricant coating during those first years of use, so that it is not needed now.

Whether it is true or not, ? But I have read that several times over the years.

 

[Boomyal]

Re: Lead additive

By 1975 automotive engines were being made with hardened exhaust valve seats to compensate for the lack of lead in the fuel. Marine engines, basic derivatives of automotive production engines lagged a year or two behind the changes in their automotive counterparts.

If your mid 70's boat engine says to use leaded fuel it is because they have cylinder heads without the hardened seats. It is not a matter of having run on leaded previously. There is no residual protection of the exhaust valve seats once leaded fuel was eliminated.

My 1976 Merc 888, 188 hp 302 Ford clearly states to use leaded fuel. That is because the lag time from auto factory manufacture til the marine manufacturer used that engine was probably two years.

Earlier engines would not have specified lead because it was the norm prior to 1975.

Now the question is, do you put enough hours on your motor to hurt the exhaust valves and seats without lead or it's substitute.

 

[ziggy]

Re: Lead additive

Now the question is, do you put enough hours on your motor to hurt the exhaust valves and seats without lead or it's substitute.

yep, thats the real question for sure. of corse, one question always brings up another. so how many hours would be enough hours to warrent the use of lead? i'm just gonna keep usein the additive. at least i can feel like i've tried to do the best for my engine that i can.....when it's time for a valve job i'll cure it with hard seats at that point.....

 

[Silvertip]

Re: Lead additive

Modern four stroke engines have hardened valve seats which tolerate unleaded fuel. Engines in the 70s and earlier did not have hardened seats nor did they require them since fuel was leaded. Many of those old engines are still in use today so there is indeed an issue with them. However, adding a lead additive is probably not as effective as one thinks and will not break the bank by using it, is a waste of money. Run it until the engine needs a valve job (if ever). If and when that time comes, install hardened valve seats and you will likely be dead before the engine dies.

 

[ziggy]

Re: Lead additive

However, adding a lead additive is probably not as effective as one thinks and will not break the bank by using it, is a waste of money. Run it until the engine needs a valve job (if ever). If and when that time comes, install hardened valve seats and you will likely be dead before the engine dies.

point taken........

 

[Buttanic]

Re: Lead additive

The problem with valve seat recession is that when it reaches a point that all the available valve clearence is taken up the valve no longer spends any time on the seat to transfer heat to the head and rapid erosion of the valve and seat takes place. It is best to periodically adjust the valves to maintain clearence. This applies to both hydrolic and mechnical lifters. It won't prevent the recession but it will prolong the time before a valve job is needed.

 

[Silvertip]

Re: Lead additive

Oldsmobile didn't invent valve rotators, they were used on Chevy stove bolt six cylinder truck engines back in the 50's.