New fuel/old engines

[patterdale]

My lovely wife just bought me a 1970 bronco after informing me that she really wanted me to rebuild the 76 we had before but didn't tell me till years after the sale. (The engine went bad) This new one is sweet as all get out. 13980 some odd original miles. Virtually all original minus the hub caps and some sort of damage to the right front fender. Interior looks like it just came out if the showroom. Anyway to the question. Since the engine is stock original should I be using a lead substitute in the fuel?

 

[ol gray mare]

I'd say yes. My 70 ran 175K on the original engine and still didn't use oil. I ran leaded fuel where I could find it in the 80s, but after leaded fuel was no longer available, it didn't take long to take a couple of valves out. The other option is to put hardened seats in.

 

[lonesouth]

i'll vote for hardened seats...

 

[thunderbolt]

x3 on the hardened exhaust seats

 

[rekoj71]

I had to clean up my heads twice at about 4000 miles each time before the third time replacing the head with a newer one with hardened seats (takes me awhile to learn sometimes). I'd go with new seats as the additive will get annoying if you drive it much.

 

[lonesouth]

As an aside, it may be cheaper to get some basic aftermarket heads than to have the valves/seats done.

 

[00gyrhed]

Some of you are going to disagree but my experience is just run it. I have had a lot of high mile experience and this valve recession is not near the problem some people make it out to be. The major cause of this recession and how this all got started was the use of rotators that rotated the valve every time it stroked to keep it clean. I have been told that an engine that started life on leaded fuel will last longer on unleaeded that one that started life on unleaded. This is due to lead being attached to the seat at the microscopic level.

I ran an old solid lifter 55 chevrolet I-6 over 120K miles on unleaded fuel. Figured I would just run the old engine until it died. When it finally did it was due to a bad bearing and not valve seat recession. It had right at 200K miles on it total and the last 120K were exclusively unleaded fuel with no additives.

I ran a 73 jeep I-6 for 79K miles on unleaded and never used any additives. This engine had at least 90K miles on the broken odometer before I bought it in 1985 so I have no idea how much unleaded was used prior to that point. I replced the underpowered 232 CI engine with a chevy 350 because the engine was under powered. I pulled it apart to look at the heads and there was no significant recession.

I am not saying that the cast iron seats do not receed, but I am saying from my experience that recessionion isn't worth the cost and trouble of the additives, and really isn't something you need to loose a lot of sleep over. Do what I am doing on my 71. Just run it, and start looking arround and saving up for when you need a valve job. Start looking for some more heads or just wait util it needs work. You may find that you don't drive it enough to ever have a problem.

By all means if you are taking the top end off the engine for some other reason you might get hardened seats put in, but to just tear it down and do it, no I wouodn't recommend that.

 

[lonesouth]

x2 00, if it ain't broke don't fix it. Got all caught up in a solution to a problem that may not exist.

 

[DirtDonk]

I didn't mind using the lead substitute at each filling. I can't say it would not have lasted just as long without it, but it was worth the peace of mind using it.
Of course, that was after I found the brand that came in a handy dispenser bottle and was good for like 100 tankfulls or something ridiculous like that. As opposed to the "buy a bottle for every fill-up" types. What a pain those are.
Either way, i wasn't manic about it, since I didn't use it on every tank and didn't lose any sleep over it. But I used it as often as I could.
If you do a lot of freeway, or higher rpm driving, I'd say use it as cheap insurance.

Paul

 

[67Stallion]

Adding lead here, no big deal, cheap insurance, as dirtdonk did, i forget a tank here and there, but it dont go far on a tank, so back at the pump soon enough!

 

[Ratch]

My lovely wife just bought me a 1970 bronco after informing me that she really wanted me to rebuild the 76 we had before but didn't tell me till years after the sale. (The engine went bad) This new one is sweet as all get out. 13980 some odd original miles. Virtually all original minus the hub caps and some sort of damage to the right front fender. Interior looks like it just came out if the showroom. Anyway to the question. Since the engine is stock original should I be using a lead substitute in the fuel?

5.0 fuel injected, problem solved. .
Not that I would encourage such behavior. :-X

 

[patterdale]

Thanks for all the valuable info guys/gals. Valve recession was the death of my 76's engine and the reason for selling it. DOH!. Someone had killed the original engine and put heads with the old seats in. I did a lot of highway/high rpm driving with it and the guy that got it said the seats were basically gone when he tore the engine down. I have a similar problem as I have antique tractors as well but they don't run high enough rpms to bang anything apart. The one has been running unleaded since 1980 and is still fine.

 

[br0nc0xrapt0r]

I love baby seals and polar bears! put hardened seals in! this was the death of my 74's motor, well that and I was 16.

 

[broncnaz]

I'd run it as is. Especailly if its not a daily driver every once in awhile add some lead substitute. Maybe every other tank or so. non leaded fuel will not kill the whole engine Sooner or later the valves may start to leak but at that point you can either replace the heads with something better or just rebuild what you have.

 

[Pedestrian]

Not sure how much the additive costs, but I would just put that money aside every time I filled the tank. eventually you will need to rebuild/ replace the motor and You can raid the additive stash fund to do so.