Hi All This comes up from time to time. I can tell you that I was an Olds dealer tech at the time and vividly remember the factory rep coming around and telling us that they were worried about getting the 73's out of warranty before they needed valve work. Remember in those days warranty was 12 months or 12K miles whichever came first. I took him at his word and have always added lead substitute to anything built before 75. that's was when the cats were installed and non leaded gas was mandated so hardened valve seats were necessary. John Kelsey Dayton Ohio TOA#009
--- [EMAIL PROTECTED] wrote: From: "Infinite Space Systems, Inc." <[EMAIL PROTECTED]> To: <[email protected]> Subject: Re: Hardened Valve Seats; WAS: needs 73 98 455 engine specs... Date: Wed, 30 Aug 2006 11:54:46 -0700 Steve, GM *****did not***** install actual separate hardened ring valve seats in their engines until sometime in the very late '70s or early '80s. Fred would know when the separate hardened valve seat was added. Starting in '75, GM *****flame***** hardened the cast iron valve seat in engine heads. That did help, but it is nothing like an actual separate hard steel alloy valve seat. How do I know? First, starting in 1973, our machine shop at the speed shop started to get a half-a-dozen heads per week from '71 and '72 engines with as little as 10K miles with burnt valves from owners who made the unwise decision to run unleaded gasoline. My '76 Chevy Impala 350 burned 4 intake valves, even with the flame hardened cast iron valve seats. That's because GM had yet to switch over to stainless steel valves for the intakes. GM was still using alloy steel. The exhaust valves were stainless steel for '76. To survive unleaded gasoline, one *****must***** have separate alloy steel hardened valve seats installed in the heads and stainless steel intake and exhaust valves. Your '71-'72 455 has alloy steel intake valves, stainless steel exhaust valves, and ordinary cast iron valve seats in the heads just like all 425/455 production from 1965 to 1975, at the earliest. Milton Schick 1964 442 Cutlass [EMAIL PROTECTED] ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[email protected]> Sent: Wednesday, August 30, 2006 8:26 AM Subject: Hardened Valve Seats; WAS: needs 73 98 455 engine specs... > Hi All, > > I thought hardened valve seat came into production Olds in '71 or '72. I > am basing this assumption on (as you pointed out) the owners manual says > unleaded gas is approved. I have not addedt lead substitute to this car, > but will start to do so if hardened valve seaats are not installed. > > Can others confirm this? (No offense, John!) > > Steve K. > > > [EMAIL PROTECTED] wrote on 08/30/2006 01:17:40 AM: > >> >> Hi >> I have a 73 toronado and was a dealership tech back then. I don't >> have hard numbers at my fingertips, this was the intro year for EGR, >> but I can tell you that power is down a good bit. The 73 also did >> not have hardened valve seats.... John Kelsey > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.405 / Virus Database: 268.11.7/433 - Release Date: 8/30/2006 > > _____________________________________________________________ Netscape. Just the Net You Need.
