120/140/165 inline's. When to use lead substitute?

[Fordiesel69]

1974' 120HP 4cyl, and 1977' 165HP 6cyl

Do either of these engines need lead substitute? If so, what happens if you don't.

 

[mkast]

Re: 120/140/165 inline's. When to use lead substitute?

what happens if you don't.

Nothing, by 1974, hardened valve seats were installed in the heads.

 

[Fordiesel69]

Re: 120/140/165 inline's. When to use lead substitute?

Nothing, by 1974, hardened valve seats were installed in the heads.

What year did they go to hardened?

 

[HT32BSX115]

Re: 120/140/165 inline's. When to use lead substitute?

1974' 120HP 4cyl, and 1977' 165HP 6cyl

Do either of these engines need lead substitute? If so, what happens if you don't.

No.

Nothing. My previous boat (1966 Mercruiser 150) ran for 39 years and got unleaded fuel when it became availble until I sold it in 2005. It NEVER had the head off. Don't waste your money on fuel additive snake oils......

 

[Bondo]

Re: 120/140/165 inline's. When to use lead substitute?

Originally Posted by mkast
Nothing, by 1974, hardened valve seats were installed in the heads.

What year did they go to hardened?

Ayuh,... If Rick had put, say 500 hrs. a year on his for 39 years,...

The valves mighta receded into the head a few thousandths...

 

[mkast]

Re: 120/140/165 inline's. When to use lead substitute?

What year did they go to hardened?

What engine?

 

[Fordiesel69]

Re: 120/140/165 inline's. When to use lead substitute?

Ummmm, 120/140/165 inlines.....

The statement of "by 1974, hardened valve seats were installed" indicates that I am safe with my two model years I indicated. Which year did merc officially use hardened seat.

 

[mkast]

Re: 120/140/165 inline's. When to use lead substitute?

Which year did merc officially use hardened seat.

Mercruiser didn't, GM did.

 

[HT32BSX115]

Re: 120/140/165 inline's. When to use lead substitute?

Ayuh,... If Rick had put, say 500 hrs. a year on his for 39 years,...

The valves mighta receded into the head a few thousandths...

Yeah......In about 1980, the hour meter broke and Dad didn't replace it. I think the engine had about 1800hrs on it then. He didn't put 500 hours a year on the boat but I'll bet he put 50 on it!!

My guess is that whether you have hardened seat or not, you're going to wear the engine out before you have valve problems during normal use.

One must remember, pretty much ALL the snake oil claims are made by the people trying to get you to buy the stuff. They're not always going to tell you the truth.....and once in a while, they get caught!!