Hardened Seats or NOT????

[Jim V.]

Seems there is a debate on popping for hardened exhaust seats when rebuilding old 461 cyclinder heads. I am in the process of noodling out a plan to rebuild an original '65 300hp motor. The "don't bother crowd" seem to feel that the risk of cracking the head (between the valve pockets) and the $200 or so for the machine work just aren't worth the time and money. I also understant that the whole rational was to enable the use of unleaded fuel which lacks some of the lubricating qualities of leaded. Any yep...the application is an around the block kinda deal, with some road trips sprinkled in to all those NCRS kinda drive aways....well maybe an occasional 5500rpm to bump up my heart rate occasionally.

Your thoughts, suggestions, rummors, anecdotal stories, recommendations are...greatly appreciated!

JimV

[Kevin M.]

Re: Hardened Seats or NOT????

Didn't do it on recomendations from Jerry Bramlett when he rebuilt my 67 327 300hp. Unless you going to race it or drive at high speeds for long amounts of time not needed if I remember right.

Kevin

[Mike M.]

Re: Hardened Seats or NOT????

doubt your driving style will need the case hardened seats. mike

[Duke W.]

Re: Hardened Seats or NOT????

461s are made from some of the toughest iron ever poured by Flint - higher nickel content than later alloys according to legend. Some sprint car engine builders preferred to start with 461s well into the seventies even after GM began offering specific "off-road" heads.

There are more reports of valve seats coming loose than integral seat recession. Just have a good valve job done - .060" exhaust seats and .040" on the inlet sides - and adjust the lifters properly. Grind the valves and seats both at 45 degrees then lap them in until the seat definition is good.

Pocket porting/port matching with a three angle valve job will really wake up a 300 HP engine. It will pull strong all the way to 5500+.

Way back in the seventies some GM published research showed that there was increased valve recession with unleaded fuels on engines that spent a lot of time at high speed/load, like medium duty truck engines. Thus the myth started, but the context was lost.

Duke

[Clem Z.]

if i remember correctly AMOCO gas was

lead free for years before the enviromental stuff started. my dad bought amoco "white" gas for his blowtorch when i was a kid and that was a few years ago.

[Verne Frantz]

Re: if i remember correctly AMOCO gas was

Clem,
I've been preaching that idea for years!!!!! Amoco "white gas" at a preimum octane level was available all through the high horsepower/hi compression years.
My view has always been that bad new travels fast, so if that gas "back then" was so bad, then "we" all would have heard about it and shunned it. Nope, nothing of the kind happened back then,. We all filled up, went to our local cruise spots and did our little dirty deeds on some back road. If unleaded gas was a problem back then, we "all" would have heard about it. Didn't happen!
I'm convinced that lead is not the only valve seat lubricator invented by man. Unleaded gas has additives to lubricate valve seats. The scare tactics one hears about today to force them into a machine shop for hardened valve seats are just a way to keep some peoples' economy moving. (in my humble opinion).

[Mark J.]

I probably don't want to know the answer, but...

...Are there any downsides to installing hardened seats? I've had this done to my last three midyears, mostly on the recommendation of the machine shop at the time.

MRJ

[Clem Z.]

verne i just noticed your field, microlithography

i did a little work in that field in my real job. did R&D on x-ray lithography machine for circle W many years ago.

[Wayne W.]

Re: verne i just noticed your field, microlithogra

I have a copy of the published study on this issue. It was done by university researchers with the funding by the EPA. It was 1974 just before the unleaded mandate. The results were two fold. First an engine had to be subject to continuous full throttle use for long peroids of time to show any appreciable recession. And two, No additives, except real lead, was usefull in preventing recession when it occurred. You literally had to put so much additive in the gas that it fouled the engine to make any difference in recession. So an automobile is not subject to this kind of operation as a rule and those additives at the part stores are useless.

[Duke W.]

Re: I probably don't want to know the answer, but.

The only downside is if the seats come loose, and there have been a few reported cases on the forum over that last few years.

IMO the overall risk favors a good valve job on the cast iron. Spend the dough you save on good connecting rods and head massaging.

Duke

[Duke W.]

A little TEL goes a long way because...

...the salutory effects of TEL start early and last a long time even if the TEL is removed later. On the other hand, it leads to increased plug fouling.

So, if you have any concern on a new engine, just dope the fuel with some LL avgas or leaded race gas for the first few tanks, and the benefits should last thousands of miles.

Duke

[Klaus Friedrich #33362]

Re: Hardened Seats or NOT????

Hi Jim,

I drove my 69 BB without hardened valve seats for 10 years now here in Germany.
Sometimes I drive it for hours on the highway with an average speed of 70 - 90 mph. We get only unleaded fuel here and the engine runs really fine on top octane fuel (98ROZ). No problems until now.

Klaus

[Verne Frantz]

Re: verne i just noticed your field, microlithogra

Clem,
X-ray was popular for awhile when there was a need for smaller critical dimensions and i-line resists hadn't been developed yet that could perform that well. It's cost-prohibitive though, as is e-beam direct write. I'm still muddling around with i-line and a new DUV tool (.5um and .25um respectively)
(sorry, no more shop talk)

[Mike B.]

Re: Hardened Seats or NOT????

My neighbor is a retired PhD metallurgist who was on the original catalytic converter development team back in the 1970s (a collaboration between Engelhard metals and Corning ceramics). I've spoken to him about the lead issue in the past and as I recall in the absence of lead, there are other byproduct chemical/physical process that occur to protect the valve train components. I'm sure he could supply the exact process but based on those discussions I never worried about lead again. Thus I concur with the majority positions presented above. Like Duke suggests, spend the money on something else that really will matter.

[Jack H.]

Yes, there WAS an alternative!

"I'm convinced that lead is not the only valve seat lubricator invented by man."

If you exercise your memory, you might recall Sinclair tried to differentiate their fuel from the competition with a radio/TV jingle...

"Sinclair puts the nickle in..."