Intake Valve Seat Inserts

[Matt Wilson]

Hello all, I'm building up a 265 flathead for my Dodge Power Wagon, and I'm planning to have the machine shop install hardened intake seats, which I bought from Vintage Power Wagons.  I've talked to some folks who are of the opinion that these are better than the original cast iron seats that were machined into the block and should be installed for use with today's fuels, especially when doing a performance build, as I am doing (mild or moderate performance build, that is).  I don't doubt that they would last longer, being hardened, but I'm having second thoughts and wondering if the benefit warrants the risk.  By risk, I mean cutting into the block and possibly running into a water passage.  I know people have fitted these engines with intake seats, but you never know when you might have that block with a casting core shift.  Cutting into a water passage would ruin the block.

So with the above in mind, I'd like to ask how many miles you guys get out of your intake valves and seats before needing replacement.  Do you often find much wear of the seats when doing rebuilds?  Have you seen much difference do you see in performance engines or under hard use?

I suppose another question is how many of you have installed intake valve seats?  Did you or your machine shop run into any issues?

If I use the stock setup, I can always do a valve job later on, but I'd rather not have to rely on that, as it means I have to either take the block back out of the truck and to a shop, or find a portable valve grinder, or find a shop that has one and is willing to come to me.  I intend to keep this truck a long time (already had it 27 years, hopefully another 40 to go!), and I intend to drive it several thousand miles per year, so I want this to be a long-term rebuild.

Thanks,

Matt

[mechresto]

Hardened seats are the only way to go....as far as cutting yourself at a later date. ..no issues.

The probem of modern fuel with no cushion agent (lead) is eliminated as the seats won't pound out.

 

[Elwood]

My small block flathead (i.e. 230cid) is at the machinist's shop now, having hardened intake seats installed (along with the usual work for a rebuild).  I'd rather take the lesser risk now of discovering a problem with core shift, than later with intake valve seat wear into the block material.

[wallytoo]

the originals in the 25" blocks are hardened, according to a few sources.

 

dodgeb4ya will know for sure, though.

[Matt Wilson]

3 hours ago, wallytoo said:

the originals in the 25" blocks are hardened, according to a few sources.

 

dodgeb4ya will know for sure, though.

I think you may be talking about the exhaust seats.  Those were definitely hardened from the factory, but I don't think the intake seats were.

Edited July 17, 2017 by Matt Wilson

[Dodgeb4ya]

I have never seen a hardened intake seat in any Mopar flathead... even in the big Moly block engines.

I've had my 265 I rebuilt in 1974 running strong in my 1952 PU now all these years with never an issue. It does have sodium exhaust valves and bronze  exhaust guides.

The  iron  intake seats should last fine as long as they are not sunk in the block and are machined properly to the valve face width and location IMO.

I have never had one fail on any MoPar flathead car or truck

.Because of neglect and poor rebuild work yes bunrt valves and seats...hardened failures too..

Spring pressures are low too.

Edited July 17, 2017 by Dodgeb4ya
spell check

[Matt Wilson]

4 hours ago, Elwood said:

My small block flathead (i.e. 230cid) is at the machinist's shop now, having hardened intake seats installed (along with the usual work for a rebuild).  I'd rather take the lesser risk now of discovering a problem with core shift, than later with intake valve seat wear into the block material.

Thanks, Elwood.  Sounds like you are hedging your bets, like I am.   Intake valves and seats are not terribly susceptible to early wear, like the exhaust parts are, but I'd rather have that insurance as long as there's not a great deal of risk involved.  

Did your machinist make any comment about how close together the intake and exhaust seats are?  It seems that there would not be much block material remaining between the exhaust and intake seats after cutting the recesses for the intake seats.  Makes me wonder if the interference fit will be as good as it should be, and I want to be sure there's not going to be much of a risk of having a seat come loose later.  With all these questions, maybe I'm worrying over nothing, but these are the questions that come to mind.

[wallytoo]

1 hour ago, Matt Wilson said:

I think you may be talking about the exhaust seats.  Those were definitely hardened from the factory, but I don't think the intake seats were.

indeed, i was.  i should have read your post more carefully.

[Matt Wilson]

9 hours ago, Dodgeb4ya said:

I have never seen a hardened intake seat in any Mopar flathead... even in the big Moly block engines.

I've had my 265 I rebuilt in 1974 running strong in my 1952 PU now all these years with never an issue. It does have sodium exhaust valves and bronze  exhaust guides.

The  iron  intake seats should last fine as long as they are not sunk in the block and are machined properly to the valve face width and location IMO.

I have never had one fail on any MoPar flathead car or truck

.Because of neglect and poor rebuild work yes bunrt valves and seats...hardened failures too..

Spring pressures are low too.

Good info.  How many miles would you say you've put on your 265 in all that time?  Thanks for the input!

[Dodgeb4ya]

About 45,000 miles

[Elwood]

19 hours ago, Matt Wilson said:

Thanks, Elwood.  Sounds like you are hedging your bets, like I am.   Intake valves and seats are not terribly susceptible to early wear, like the exhaust parts are, but I'd rather have that insurance as long as there's not a great deal of risk involved.  

Did your machinist make any comment about how close together the intake and exhaust seats are?  It seems that there would not be much block material remaining between the exhaust and intake seats after cutting the recesses for the intake seats.  Makes me wonder if the interference fit will be as good as it should be, and I want to be sure there's not going to be much of a risk of having a seat come loose later.  With all these questions, maybe I'm worrying over nothing, but these are the questions that come to mind.

As to the amount of material around the seats, and possible interference with the existing exhaust insert, my machinist didn't mention any concerns.  But I didn't specifically ask him about the issue, either.  I expect to be at the shop tomorrow, and will bring up the question, although he may have already done the work, in which case we'll know for sure.

The intake seats on my engine have to be re-cut.  I'm not a fan of cutting repeatedly into the original block material, and when possible I opt for replaceable wear components.  I know, I'm swimming against the tide in today's world, but who knows what the future will bring with regards to gasoline quality and mix, and I wanted hardened seats on all valves.

[Matt Wilson]

Thanks, I'll be interested in hearing what your machinist says.  Having said that, I also went by my machine shop yesterday afternoon and asked the machinist about this, amongst other things, and he said it's not uncommon for engines to have the valves and seats so close together, and not even uncommon for the seats to overlap some, requiring one of them to be cut to accommodate the other seat, and he said this doesn't cause a problem with the fit of the seats into their respective bores.

Unlike your seats, mine were in pretty decent shape, and probably could be re-machined, but I had the same thought as you, regarding the future of fuels.  I'm hoping better intake and exhaust seats installed now will prolong the usefulness of my engine as fuel chemistry and quality changes going forward.  Plus, the fact that I'm hopping up the engine somewhat seemed to warrant better seats.  I'm even getting the exhaust seats replaced with new seats that are supposed to be even harder than the already-hard originals that came in our engines.  

My valves and seats are made by SBI, which I had never heard of, but my machinist says they make really good products.   The valves are made of 21-4N, which has been around for a long time (since the 60's, I believe), but is still considered a fairly premium material for street engines.  I'm going to try to find out what material the seats are made of.

Edited July 18, 2017 by Matt Wilson

[John-T-53]

Like Dodgeb4ya says, the exhaust seats are already hardened. I don't think you need to change them unless they are damaged in a any way...I'd leave 'em alone if they look good, except for a recut if necessary. These engines were built with high quality materials. If you were working on a Chevy or Ford of the same era, perhaps new seats would be compulsory.

Even on my little 230 block they're hardened and were kind of a pain to recut with a stone because of the hardness...the stone had to be re-dressed twice or more on each seat.

I've put about 15-20k miles on it since the rebuild several years ago, and it had over 100k miles on it before then, and no abnormal seat wear was apparent. I have SBI valves and guides too, no complaints.

[Dodgeb4ya]

I'm more concerned more about the engine bearing materials than anything else.

That's where a problem will be a BIG problem if there is an issue.

Today's modern replacement parts  for the flatheads are inferior to the parts back in the 60's and 70's IMO.

Mostly offshore replacement parts are being used for rebuilds unless old stock HQ parts are being sourced..