[70ra455]

I have a set of 093 heads being rebuilt and when I inquired about putting hardened seats on them I was told that Pontiac heads don't take them well because the valve chambers are too close together?

I never heard that ... can someone help me?

And what is a fair cost for a triple valve job, new springs, cleaning, and taking all warping of the heads out (with and w/o doing the hardened valve seats)?

Thanks

Phil

[Deadhead]

I had them put in my 092s. Driven thousands of miles with no issues.

You will have to run octane booster with 92-93 gas with those 093s. Not sure how much the car will be driven, but that might be an issue.

[MescaBug]

Without hardened seats, a complete rebuild including stock type valves and springs is somewhere between 650$ and 800$. That's what I pay.

Magnaflux, cleaning, valve seats job, new guides, mill/square surfaces, freeze plugs, heater nipple and re-assembly.

[70ra455]

Does anyone know if the 093's came with "double springs"???

Anyone else on the hardened seats issue?

MescaBug thanks for the info ... do you get hardened seats ... if not ... why? Thanks for the help ...

[MescaBug]

Originally Posted by 70ra455

MescaBug thanks for the info ... do you get hardened seats ... if not ... why? Thanks for the help ...

No hardened seats. Most of the heads I had rebuilt were running when removed and in good condition or already had hardened seats (from 74?). Seats were not eroded to the point where it needs replacing.

I say, dont replace the seats unless you really have to. Its a good-to-have, but not a necessity.

Its a fairly common practice though. Hardened seats are installed on 2.11/1.77 heads. And there is not a lot of meat between the I and E seats.

[70ra455]

Maybe it is that lack of "meat" between the I and E seats that he is referring to. Also the 093 heads were used on GTO 389 or 421 with tripower only so I wonder if there is less space with larger chambers?

[Engine-Ear]

Originally Posted by 70ra455

Does anyone know if the 093's came with "double springs"???

Anyone else on the hardened seats issue?

MescaBug thanks for the info ... do you get hardened seats ... if not ... why? Thanks for the help ...

The pair of 093s I owned had two springs per valve.

Also, I had bronze-wall guides, hardened exhaust seats and stainless valves in my rebuild. A lot of people much smarter than I am have said that a street driven (non-raced, non-trailer-pulling) 389 doesn't really need that, especially if you run dished pistons for a pump-gas C.R. and have the dizzy re-curved.

Good luck!

[rohrt]

I did a search in the archives on hardened seats. There was several post about how Pontiac heads did not need them due to the metal they used. Different story for others like Ford and Chevy.

[70ra455]

What does the two springs per valve do? More compression?

[tharkun8]

Originally Posted by 70ra455

What does the two springs per valve do? More compression?

I'll yield to those more knowledgeable but I think the double springs are intended to
keep the valves stable and not moving during heavy operation.. springs get to loose
and/or wobbly and it can affect the opening and closing events a bit.. i believe.

I expect someone will confirm or deny shortly...

John

[70ra455]

and the 093 heads come with 2 springs per valve?

[b-man]

Nearly all Pontiac heads are fitted with dual valve springs, different springs with more tension were used on the performance heads like the 093.

Stiffer valve springs are necessary to keep the lifter in contact with the cam lobe during high-RPM operation, also to keep the valve from bouncing off the seat. You must control the valve with enough spring pressure for the operating conditions, pure and simple.

[jdh421]

I put Hardened exhaust seats in every set of early heads I use. I have never had a problem with premium unleaded fuel. I believe the factory switched to hardened seats in 71 or 72 with the advent of unleaded fuel.

[Ragtop Man]

The second conical spring is really more of a damper than a true valve spring, used to prevent unpleasant and potentially destructive harmonics at higher RPM. Preventing float is equally as important.

One thing worth noting: In Mark Donohue's "Unfair Advantage," he talks about the practice of making sure that all the Trans Am Camaro short-blocks were well broken in before the race, sometimes swapping them into the transporter to get miles on them before the race.

Then, with all the parts happy and clearanced, they would swap the heads for a fresh set with new springs and a new valve job, and immediately pick up 30-40 horsepower.

They found that breaking in the engine got all the critical surfaces properly lapped; the new heads put a seal on the engine that would go away rather rapidly. Can't recall where I read it, but some engine builders used to sort through used valve springs, so they could get ones that had already stabilized at close to their final rates; fresh springs can lose a lot of their rating in the first 100 miles, depending on heat and how fast they cycle.

If you've ever seen the ultra-slow-motion of a typical conical spring on youtube, it is amazing the darn things run at all. The 'bounce' of the spring as the valve closes, and the flex of both the rocker and shaft (assume the pushrod is getting its due in the other shots!) are really surprising.

[70ra455]

Thanks guys ... I have the heads being done by someone who comes highly recommended as a GM guy. I'll pick them up and let you know what we did (or he did!)

[mike nixon]

GM guy, That smells like Chevy to me!

I had hardened seats put in the G/P's heads due to the fact I had enough miles on the engine that it pulled two exhaust vales thru the head itself. Installed larger exhaust valves at that time also.

Mike

[63gpman]

To Mr Nixon's point, are you already purchasing valves? If so, now is the time to step up. And if you are having hardened seats put in or any real seat work done, your labor should not be much if any different.
-
A standard valve job around here with taking the heads in off the engine that include taking them appart, cleaning, magnaflux, surfacing, 3 angle and putting them back together is right around $225. Price goes up for seats, bowl work and parts needed.

[Ragtop Man]

Get the screw in studs, too.

[geeteeohguy]

My experience with running '65 and '66 389s: all the '77' and '093' heads are GTO heads and big car 421 heads, regardless of intake system. There is no difference in the head between tripower and 4bbl application. Only in the intake and camshaft. No block differences except for the stamped number. All of the '77' and '093' heads I've owned were double valve spring heads. I have been told by more than one machinist that hardened seats were only preferred on Pontiacs (which had/have pretty hard seats to begin with...much harder than Chevy or Ford) on vehicles that were under constant high load conditions, such as pulling a trailer or sustained high speeds above 3000 rpm....more like 3500 and up. I did not install hardened seats in my '77' heads on my '65 GTO when I had them done in 1981, and that was 33 years and 50,000 hard miles ago. No problems with them still. And I'm running a pretty big cam in that car, too. So, hardened (unleaded spec) seats are preferred if you are towing a boat, car, etc, or are buzzing cross country at 3500 rpm with a 3.90 rear gear. Otherwise, IME, not really necessary.