Hardened valve seats. What year????

-
604

604

Well-Known Member
Joined
Jul 7, 2011
Messages
1,128
Reaction score
28
Location
Brooksville, KY
Any one happen to know what year Mopar small blocks started having hardened valve seats? I thought I had it written down some were but can not seem to find it. I was thinking it was 72 or 73. Thanks!
 
Anybody know how they did it? They weren't inserts. They must have been heat treated them after the heads were cast. Mike
 
heads cast in 73 is what I would say from what I have seen...though they were only flame hardened.

I believe the everything after 73 even through the magnum series as well was flame hardened.
 
I've seen the arguement both for and against. This 331 Hemi truck engine I have came with hardened exhaust seat inserts from the factory in 1956, so there must be something to it. All of the Hemi truck and marine applications came with them. There's a school of thought that unless you pull heavy loads for long periods, such as a truck, you do not need the hardened seats. I have seen people not run them and never have a problem. On the flip side, I have seen people run them and have valve seat recession anyway. Just food for thought.
 
66fs said:
yes, to both above. Induction hardened, actually.
Click to expand...

yep.lol I always mix them up.
back when they did used to flame harden cranks, like some 413/426 engines, but the induction hardening was used on heads and was more consistent & faster than the trial flame hardening they experimented with.
 
Thanks to all for the input! I thought it was 73, but was doubting my self.
 
I saw this before, but it only talks about the v6 having hardened seats in '72.
 

Attachments

  • 72_Valiant_Duster_14.jpg
    120.8 KB · Views: 519
I have a set of '71 318 heads I just took off tonight that have just fine unhardened seats, makes you wonder how long they would have gone had I just left them on, 40 years so far.
 
Yep,
I wonder the same thing. I took apart a 1971 318, and a 1973 318 this weakened my self. And the valves looked WAY better on the 71. Looked like new. And that engine had not been apart since 1971. The 73's valves looked a little sunken in, and the seats had allot more were. But I have no idea what the history of that engine is though. Could tell the heads had already been worked over at least once though. Had a few guides replaced.
 
res1vw21 said:
I have a set of '71 318 heads I just took off tonight that have just fine unhardened seats, makes you wonder how long they would have gone had I just left them on, 40 years so far.
Click to expand...

I've torn down a ton of engines without hardened seats and in good shap as well. That's why I posted what I did. Trucks have always been an application perfect for hardened seats because they pull heavy loads for long periods of time and that equates to really high exhaust temps. Hot rods are generally vehicles that are more powerful than the norm, but lighter than the norm. I'm not arguing against hardened seats, I think they are a good idea. I do think though that it becomes a toss up, especially with high powered light cars where the engine doesn't have to work too hard to get the job done.
 
You must log in or register to reply here.
-

Back
Top