[DeTomaso] Valve seat fail and piston damage
Larry Stock
larrys at panteraparts.com
Wed Mar 27 11:34:16 EDT 2024
Mike,
The Cleveland heads used a local induction hardening process when new and did not require separate hardened valve seats for use with Leaded gasolines used at the time. With today's unleaded fuels, You can't rely on the induction hardening to be deep enough unless you are still using leaded race fuels, so any street engine I have offered had new valve seats installed in the Iron heads. The iron head seats don't typically fail since they fit tight and you don't have the expansion issues that you have with aluminum heads.
I summary, Iron heads didn't have separate hardened valve seats but they are certainly recommended for rebuilds of street use engines.
Larry
On 3/27/24, 12:50 AM, "DeTomaso on behalf of Mike Drew via DeTomaso" <detomaso-bounces at server.detomasolist.com <mailto:detomaso-bounces at server.detomasolist.com> on behalf of detomaso at server.detomasolist.com <mailto:detomaso at server.detomasolist.com>> wrote:
John,
I view the first question I have to ask is, why do your iron Ford heads have separate seats installed? Ford heads reportedly have a higher nickel content than those of other brands like GM and thus don’t need to have seats installed?
I have heard of this kind of failure before, which is much worse than the minimal seat erosion one might encounter with the stock seats.
Having said all that, I suffered a somewhat similar failure decades ago when my 302 swallowed an air cleaner stud. The top of the piston was dented much like yours and initially I hoped to just replace it. However the connecting rod was also slightly bent. So at a minimum I would expect to have to change out a rod.
I would also be very suspicious of the remaining seats.
I wish I had an engine builder recommendation but I can’t think of anybody near you….
Mike
Sent from my iPad
> On Mar 26, 2024, at 20:27, John McKee <johnmckee at cox.net <mailto:johnmckee at cox.net>> wrote:
>
> I need a recommendation for an engine builder/machine shop in Orange
> County, CA.
>
> Back story:
>
> After sitting for 10+ years I finally fired up my engine a few weeks
> ago. It sounded good for 10 minutes then I had a bad clatter in the
> valve train. At first it appeared to be a loose rocker but there was
> weird interaction with the valves of cylinder #4. I popped the head off
> and found that the exhaust seat had come loose! While dancing around
> the seat also made some deep marks on the piston head.
>
> My gut tells me the piston is trashed and needs to be replaced. I have
> a friend that says I should repair the head and go as is. I don't know
> if anybody on this forum has an opinion.... But, when is a "witness
> mark" a catastrophic failure in the waiting?
>
>
> I posted photos on the picture forum at this link.
>
> [1]https://pantera.infopop.cc/topic/valve-seat-failure-and-piston-damag <https://pantera.infopop.cc/topic/valve-seat-failure-and-piston-damag>
> e
>
>
>
> Thank you for your thoughts,
>
> John
>
> References
>
> 1. https://pantera.infopop.cc/topic/valve-seat-failure-and-piston-damage <https://pantera.infopop.cc/topic/valve-seat-failure-and-piston-damage>
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