Hardened valve seats

[Kaiser2boy]

I heard a rumor that the 1953 Dodge flat head six 230 cu in standard engine came with hardened valve seats and is OK to run with no lead gas.
Is this true ?

[Tom Petroff]

Yes, Yes, and Yes.
Your Good to Go.
Tom

[Elwood]

The Plymouth/Dodge small block flathead six (displacements from 190 up to 230 cubic inches) was designed with hardened exhaust valve seats from its inception in 1933.

The intake valve seats are machined into the block, and do not have replaceable seat inserts, but inserts are available as an aftermarket item from places such as VPW. The block has to be machined to install them, however.

[Matt Wilson]

I've seen the hardened intake seats advertised. What situation would call for their use? Is it better to use them because of today's fuels, particularly with the rise of ethanol gas? Non-hardened intake sets never used to be a problem.

[Cheyenne Dave]

Matt,

It is not so much the addition of ethanol as the loss of lead. Lead was supposed to somewhat cushion the blow of the valve closing on the seat. Improper valve spring tension can also cause undue valve/seat/cam wear.

cd

[Matt Wilson]

Matt,

It is not so much the addition of ethanol as the loss of lead. Lead was supposed to somewhat cushion the blow of the valve closing on the seat. Improper valve spring tension can also cause undue valve/seat/cam wear.

cd

But for the intake valves? I've always read that there was never much issue with the intakes and low (or no) lead, because those valves an seats run so much cooler than the exhaust valves and seats. Everyone I've spoken to - flathead owners, machine shops, etc., - all say that the intakes haven't been a problem on no-lead fuel. And of course, the exhausts on the flatheads haven't been a problem because they are hardened. So it seems that something else is coming into play as the motivation for installing hardened intake valves and seats. Of course, I can always be wrong, but that's just what I've read and been told.

[DrPepper]

I thought it was the stem and guide that...

the Lead lubricated?
Years ago I had to have guide inserts installed on a 383 I built. Seems there was a controversy about the use of hardened steel vs. bronze alloy guides when lead went away. Did a google search found a bunch of info.
These were interesting:
http://www.enginebuildermag.com/2013...-seats-guides/
http://www.speedtalk.com/forum/viewtopic.php?f=1&t=9084

Interesting topic...subscribed..!
DrPepper

[Elwood]

I've yet to find any serious scientific research into the use of hardened seats for intake valves; it's probably out there, but lost in the swirl of conflicting opinions and "facts" on this subject.

Interesting that Dodge engineers specified the use of hardened exhaust seats back in 1933, even after tetraethyl lead had become widely accepted as a gasoline additive in the 1920s. But they didn't include hardened intake valves in the new engine design. Which suggests that the high heat of the exhaust valves was still a factor in valve durability.

For anyone contemplating some performance modifications to their flathead, such as significantly raising the compression ratio, perhaps the hardened intake valve seats would be a good idea?

[Charles Talbert]

Facts we have found that stand the test of time

Those of you that know me and M Series Rebuild know the name of the game here is SIMPLY to turn out a product that is THE BEST IT CAN BE. After building many flat heads, this is our findings.
Concerning hardened exhaust valve seats; yes the originals were hardened, (30's technology) however when those "hardened" seats are compared to the superior quality high nickel alloy seats of today, as you might imagine, technology from the 30's is quickly "out the window." Enough on that subject.
Moving on to the intake seats, certainly they don't take the beating the exhaust seats take, BUT, in keeping with our aim to build engines the best they can be, we machine the deck and replace the intake seats right along with the exhaust seats. On a large part of the core engines we tear down for rebuild; it is blatantly obvious that the intake seats have been resurfaced several times due to prior service. After being cut several times, it becomes necessary to machine a counter bore and install a new seat, IF that newly rebuilt engine is to be in keeping with our standards of building an engine to the BEST it can be.
We don't always know the applications our rebuilt engines will be going into. Big question; if it is in a truck that will be driven little and never subjected to any hard running, that particular engine might do ok with a somewhat lesser degree of workmanship quality being applied during a rebuild. Many builders view these engines as just some old relic, and figure they would never be going into any type of situation that would even be remotely considered as stressful, so they don't put any extra effort into the build. That just isn't my view, the BEST it can be is always in the back of my mind. All our rebuilt engines will continue to get new seats on both the intake and exhaust sides.

[Matt Wilson]

Charles, I think I remember you mentioning this to me when we spoke. Thanks for the refresher.

One thing I wonder about is how much risk there is with doing this. With a competent machine shop, is there any greater risk to this than, say, boring the cylinders oversize, or any other operation? If I elect to do this, and it goes badly for some reason, then I believe the entire block would be trash after that. Not like many OHV engines, for which a replacement head can be readily sourced if it gets screwed up. I'm just trying to gage the situation. The cost is not an issue, as my machinist says he will do all the intakes for about $100 and all the exhausts for about the same.

[Charles Talbert]

Charles, I think I remember you mentioning this to me when we spoke. Thanks for the refresher.

One thing I wonder about is how much risk there is with doing this. With a competent machine shop, is there any greater risk to this than, say, boring the cylinders oversize, or any other operation? If I elect to do this, and it goes badly for some reason, then I believe the entire block would be trash after that. Not like many OHV engines, for which a replacement head can be readily sourced if it gets screwed up. I'm just trying to gage the situation. The cost is not an issue, as my machinist says he will do all the intakes for about $100 and all the exhausts for about the same.

Your question of risk is not something I can answer since I'm not the builder, that is a question for your machinist 100%. It is all in his knowledge, reliability, and quality of workmanship. If it were here, I'd do it for sure, it's just part of our normal operation. Like I said, we don't take short cuts; if you omit that step from the process, the engine is simply not as good as it could be. Short answer, not replacing all valve seats during a major engine rebuild process is over looking a major step is my personal opinion. If you don't trust your guy knows how to properly perform every step in the process, then I wouldn't hire him to do the job.

[Matt Wilson]

Your question of risk is not something I can answer since I'm not the builder, that is a question for your machinist 100%. It is all in his knowledge, reliability, and quality of workmanship. If it were here, I'd do it for sure, it's just part of our normal operation. Like I said, we don't take short cuts; if you omit that step from the process, the engine is simply not as good as it could be. Short answer, not replacing all valve seats during a major engine rebuild process is over looking a major step is my personal opinion. If you don't trust your guy knows how to properly perform every step in the process, then I wouldn't hire him to do the job.

Well, progress has been slow, but progress is happening. I went ahead and bought intake and exhaust seat inserts from VPW. They are SBI brand, which I had never heard of, but my machinist says SBI makes REALLY good stuff. In fact, he had some kind of SBI part in a box on his counter top when I walked into his shop today.

Charles, my machinist was mentioning risk with regard to the possibility of cutting into the block and finding a water passage, which as far as I can tell, has nothing to do with his knowledge, reliability and quality of workmanship. He says cutting into a water passage is rare, but does occasionally happen, although he is speaking about other engines, not the Chrysler/Dodge flatheads. He wanted me to be certain that this is the route I really want to take, as there are not just millions of these engine blocks laying around anymore, and cutting into a water passage would ruin the block. His main concern is if there happened to be a core shift during casting of the engine block, resulting in a water passage being closer to one of the intake seats than intended, then the cutter could break through into that passage.

I told him that the experts (such as yourself and VPW) have rebuilt hundreds of these engines with intake seats and never had a problem. By saying you've rebuilt hundreds of these engines, I might be exaggerating (or maybe not), but between you and VPW, I'll be that's true. I don't think VPW rebuilds them anymore, but in speaking with them, they have put plenty of intake seats in engines when they used to rebuild them, and they have sold plenty more to customers doing their own rebuilds and have never heard of this type of problem from these engines, and I assume it's the same with you. Based on that, my machinist felt more comfortable with doing this and I told him to go ahead with it. I hope I don't regret my decision, all in the pursuit of making things the best they can be, but it seems that the odds and other people's experience, are with me.

The other thing I wonder about is the fact that the intake and exhaust seats are so close together, as shown in the attached photo. When the intake seat area gets cut to take the insert, the remaining block material between the exhaust and intake inserts will be very thin, or perhaps non-existent for a short distance. That doesn't seem to be conducive to a good, tight fit of the two seats in their recesses. I guess it works, because people have been putting intake seats in these engines for decades, and it's even stated in the rebuild manuals, but it seems less than ideal in that regard.

Of course, the exhaust seats should be a non-issue. VPW says their inserts are direct drop-in replacements for the factory inserts (but made of better, harder material), so no cutting of the block required.

[Charles Talbert]

Anything is possible, especially with old castings. I can say we have never had an issue with any of the downside possibilities you have mentioned. I can't speak for anything pro or con concerning VPW's experience, although I would have confidence in information obtained from Matt concerning shop activities at Vintage.