Don't laugh, but my truck is older than I am and I don't recall when unleaded fuel was introduced.

I have a 75 F250 w/ a390. Would it have hardened valve seats and be ready to run unleaded without a problem?

When I am towing or hauling a load, should I be using a lead additive?

Thanks!

 

Sorry for bouncing off your post, but my truck is almost older than me just like you. If an engine need leaded fuel, what will happen if you run unleaded fuel in the engine? This is my question. Thanks.

 

It probably doesn't have hardened seats. The only way this would have happened is if someone went through the heads and put them in.

Lead additive isn't the real thing, and imo doesn't do anything to help. Not unless it has TEL(Tetra Ethyl Lead, or something like that) in it, which is the real thing.

Without the lead, the seats will recess and eventually you'll have exhaust gases escaping into the valve covers through the broken seat, it will run like crap, and is generally not a good thing. How long does this take to happen? Not sure. But it will happen eventually.

John

 

The pressure won't go into the valve cover area. The cylinder will just loose pressure before it is supposed to. This pressure will still go through the exhaust port.

 

75F250 could you write down the head ID numbers and post them here. I guess that some of the fe heads had hardened seats . they are supposed to be the ..DT2E-AA heads It was said here that not all of them have the hardened seats ..maybe you have them maybe you dont ..Below the fuel gauge does it say unleaded fuel only? A nother way that may send you in the right direction is to look at the filler hole for your gas tank . Usually if the hole is big (big enough that a diesel nossle will fit in) it is supposed to run on leaded fuel. This is not always true as my old '78 bronco had this large hole in the filler but it HAD the hardened seats . Another way to tell is did your truck originally have a Cat converter on it. I really doubt it did due to the fact its a F250 . so again post those head numbers and check the fuel gauhe for evedence of leaded or unleaded , and check the fuel filler !
Hope this helps
Jon

 

chas1234,

I'll check what you suggested. I don't re-call if it has the unleaded fuel only notice or not, but the gas filler necks are about the same size as every other unleaded set-up. I don't think they are big enough for a diesel, but I'll double check. Is it related that the gas filler neck will not let me pump fuel at at high rate? The thing spits fuel back out and even just pools around the opening and runs down the side of the truck unless I position the gas filler just right and pump slowly....

 

My buddies 73 I borrowed was the same way. It became quite rediculous. I think it has to do with the different pump nozzle designs. I dunno.

 

sounds like you have a plugged vent or the filler hose is callapsed ..try posting that probem in the 73-79 truck forum and also try the Fuel injection and carboration frum they should be able to help you . Again it the hole will fit a diesel nossle in it then it may be for leaded . Around this time the country started changing over from leaded to unleaded in which case if it had a cat on it the lead in the gasoiline would plug up the cat(s)..check it out ..I know there are some "non lead" type additves out there and they seem to work ok but it may be more worth while to get your seats changed , by the way post your head numbers !
Ps my '78 F100 used to do it talk about a pain ..there was a few gas stations I wouldnt got to because it took forever to fill it

 

Rat,

Thought I heard someone mentioning backflow into the crankcase/valvecover area from a badly recessed valve. But thinkin a bit more about it, sounds a little far fetched unless there was some severe guide damage, which would be causing other problems.

 

75F250Colorado,

Chances are very good that you have hardened exhuast seats. If for some reason you don't have D2TE-AA heads then you do not have hardened exhuast seats. The D2's were the only ones that got them. Before thos heads were introduced leaded fuel was very abundant. So, most heads produced before that time had no hardened seats.




Scotty

 

I thought that the big push to unleaded fuel as standard for new vehicles was in '75, but correct me if I'm wrong.

When I bought my '68 from its original owner in a small Texas town back in '96, there was still a nearby station with leaded fuel where he filled it up for me before I picked it up. Even though I thought that retailers couldn't sell it anymore.

 

Leaded fuel is acctually still available at a few stations. Most don't carry it becuase there is no call for it. But, i remeber in the early to mid 80's My Dad removed the thing in the gas door opening so he could use leaded fuel, cuase it was cheaper. The car was a '79 Thunderbird. I thought that was the coolest car ever. Well it was pretty sweet in 1979. My Brother and I wrecked it when we were in High school. And to this Day my Mom won't let him drive one of her cars. Of course he is an Attorney now so he has nicer Cars, but i still don't think she would let him. Anyway hope this helps.


Scotty

 

No, it ain't, and No, he didn't. Leaded fuel for automobiles dissappeared in the mid eightys. If the EPA thought there was someone out there selling leaded, they would be all over them like stink on s---. Tetraethyl lead is nasty, toxic stuff. We are better off without it. Most of the 'lead additives' folks buy are really made of phosphorous and zinc. Leaded fuel is currently only available as racing gas and avaiation fuel, and those will be unleaded someday in the not to distant future. Have hardened seats put under your exhausts and don't worry about it. DF

 

Look DF you are intitled to your opinion. But, I know for damn fact that my dad did do that to the gas filler. Don't even start your crap about you know freaking everything. I get so sick of you always trying to prove people wrong, and tell them what they saw and know happened. So until you learn to respect other peoples words EDITED FOR PROFANITY


I do realize you have some good insight into things, but at the same time don't even start with what I know my Dad did and didn't do. I know cuase i used to put reagular fuel in that car when i was younger. Also, if the EPA was worried about people burnig leaded fuel wouldn't htye make lead additive illegal??


I f I were the first person you told what happened or didn't then I wouldn't be writing this. I know cuase I have read it, so that is why I Write this now.


Edited for more profanity


Scotty

 

The use of the old leaded type of gasoline on the roads in the U.S. has been banned for a while. This old type of leaded gasoline is still available for off road use and racing. Lots of developing countries still widely use it and have very little going on in the way of getting rid of it.

The lead additive sold separately today is a different formula than the original type we used to get in our gasoline at the pump. It doesn't just create a cushion for the valves and seats, it also raises the octane level. It is safer or the EPA would have regulations against it being used on the road.

If a truck is used for pulling and hauling quite a lot then the wear on the valve seats increases. If a truck is used for light duty or just daily driving then it will experience less wear on the valve seats. All of the non hardened valve seat engines will experience valve seat wear. The type of use and mileage will play major roles as to when the wear becomes a problem. All of this is with the use of unleaded fuel and no lead additives.

I have the D2TE-AA heads on my 428 and have had no problems, so I go along with them having hardened seats. These heads had stainless valves installed also. I don't think they were needed really, but I did it anyway. Overkill on my part, but I wasn't aware of the things that are known today about unleaded gasoline and the effects it has on valves and seats. It is a constant learning process to keep an older vehicle on the road and it will never end.