unleaded fuel in older engines?

[seafever]

I have a 1974 mercruiser powered by a Ford 302 v-8. I suspect, (and the manual says) unleaded fuel will burn the valves.
It has 351W heads how do I tell the difference between old valves and newer unleaded types? If I run less than 50 hours per year I am thinking the old valves might last longer than I will??
I recall an additive for using unleaded fuel in older engines but cant seem to find any these days.
Anyone still using that stuff?
Thanks

 

[Bondo]

Re: unleaded fuel in older engines?

I have a 1974 mercruiser powered by a Ford 302 v-8. I suspect, (and the manual says) unleaded fuel will burn the valves.
It has 351W heads how do I tell the difference between old valves and newer unleaded types? If I run less than 50 hours per year I am thinking the old valves might last longer than I will??
I recall an additive for using unleaded fuel in older engines but cant seem to find any these days.
Anyone still using that stuff?
Thanks

Ayuh,.... It's really a Non-issue at 50, or even a few hundred hours per season,...

 

[ziggy]

Re: unleaded fuel in older engines?

i'm inclined to think bondo may be onto the facts.
however, this is one case where i don't follow.
my old 165 L6 says on the valve cover it wants premium leaded fuel. just like yours does apparently. so i give it premium + lead substitute.
i get my lead substitute from orileys, which is my local auto parts store. they have gunk brand lead substitute.
what i do may be wasted funds. but it makes me feel better to do as i do.

 

[Walt T]

Re: unleaded fuel in older engines?

Whatever floats your boat. Try running midgrade gas if it doesnt ping, it's fine. As for the valves, Ditto Bondo.

 

[ken51k]

Re: unleaded fuel in older engines?

The issue with non leaded fuel in an older engine is the valve seats. When they came out with no lead gas they started using a harder
valve seat in the heads. You can use a lead substitute (bought at any auto store) or just run it like that. Worst thing that will happen
is the valve seats will start to go and you'll have to do a valve job. That could take quite awhile to happen too. I would just have fun and not worry about it.

 

[HT32BSX115]

Re: unleaded fuel in older engines?

The issue with non leaded fuel in an older engine is the valve seats. When they came out with no lead gas they started using a harder
valve seat in the heads. You can use a lead substitute (bought at any auto store) or just run it like that. Worst thing that will happen
is the valve seats will start to go and you'll have to do a valve job. That could take quite awhile to happen too. I would just have fun and not worry about it.

Yeah. It's an "Old Wives" tale.....

Otherwise all the propane (and natural gas) powered vehicles would be having problems I suppose and I know people who used propane in the 70's before unleaded fuel became popular................... My last boat (a 1966 Mercruiser L6) ran 39 years on unleaded fuel and never had the head off.....

Lead was in gasoline to increase Octane and knock reduction. If the engine doesn't detonate on regular unleaded, it'll run until it wears out.

The engine will wear out before the valve seats do.

If it doesn't ping on "Regular" or Midgrade, just use it.

 

[Walt T]

Re: unleaded fuel in older engines?

But.... but... Premium gas gives more horsepower and better fuel economy and makes my pants fit looser, my bald spot grow smaller, women flock to my front door, they flock for the 100 dollar bills I put out but they flock none the less

 

[ziggy]

Re: unleaded fuel in older engines?

But.... but... Premium gas gives more horsepower and better fuel economy and makes my pants fit looser, my bald spot grow smaller, women flock to my front door, they flock for the 100 dollar bills I put out but they flock none the less

wow, i've never had that happen before. but if that's what works for you, go for it man... .
i generally thought that it was more the anti detonation properties that seemed like a good idea. specially in my 38 year old, non rebuilt (best i know), likely carboned up engine, w/uneven compression that's barely above spec. anything i can do to maybe help make it last one more year ya know..

fwiw. the 'new' regular fuel around here is now always enriched (or maybe enhanced facepalm is the word they use on the pump, if they make note of that fact at all) w/ 10% corn fuel. the higher octane unleaded fuel is 15% ethanol. i don't wanna use corn fuel at all in my '75 engine. that, i'm pretty sure it wasn't made to run very well on. so i'll stick with my premium, for now. reason i say it that way, is i've read in the news that within the year premium may start to become scarce. if that happens, then i don't know what i'm gonna do for my old engine...

 

[HT32BSX115]

Re: unleaded fuel in older engines?

fwiw. the 'new' regular fuel around here is now always enriched (or maybe enhanced facepalm is the word they use on the pump, if they make note of that fact at all) w/ 10% corn fuel. the higher octane unleaded fuel is 15% ethanol. i don't wanna use corn fuel at all in my '75 engine. that, i'm pretty sure it wasn't made to run very well on. so i'll stick with my premium, for now. reason i say it that way, is i've read in the news that within the year premium may start to become scarce. if that happens, then i don't know what i'm gonna do for my old engine...

Yeah. NE first had E-15 in 2012.
First Retailer in Nebraska to Offer E15 | RFA: Renewable Fuels Association

I would stay away from that stuff. ESPECIALLY in a marine engine! NO marine manufacturer will warrant a new engine if they discover the owner using it!

If you want non ethanol gas, go to Ethanol-free gas stations in the U.S. and Canada But to be sure, you'll still have to test it.
Ethanol Fuel Testing | Ethanol in Gas

 

[Walt T]

Re: unleaded fuel in older engines?

Just be glad ya'll don't have to keep bottles of 104 in your boat because you stupidly built a bad boy motor that doesn't like pump gas too much. Heck maybe be even stupider and make a head change to bring compression up to 10.74:1. While boating around local lakes isn't a problem Lake Powell could be. Might have to have a fuel barge helicoptered in to my campsite. Hey that might be kinda cool actually.