915 Head Rebuild vs New Stealth Head

So.. time to figure out what head for my 67 440HP. Basically stock rebuild and the car is going to be a driver not a track car. 480ish cam, 2355 pistons, holley SD intake, HP manifolds. I would like the stock straight spark plug configuration which makes me lean toward stealth heads but I have heard you should take your new stealth heads to a machine shop and have them go over everything. So basically your $1000 plus shipping stealth heads probably will cost you $1500 when you are done, yes? So would rebuilding my 1.74 valve 915HP heads with exhaust seats be cheaper and give the same performance? What would you do? Thanks.

I bought a set of stealth heads and put them on my race car back in 2008/09. I took them out of the box and bolted them on. My engine is a mild race engine compared to most, was 10:1 with a .533 mopar cam. I later put a .557 solid cam in and changed the valve locks from 7 degree to the 10 degree ones. I ran the heads for 5 years before having someone do some hand porting on them (didn't make a different in my combo). I did end up putting new valve springs on then as well since I had 2 or 3 broken inner springs I shifted the engine at 6000, would go thru the traps at 6500. Most will tell you to have things checked over, but for a street car, I wouldn't have a problem just bolting them right on, but that's just me. If you have to buy new valves and springs for your steel heads, I'd think your going to have just as much in them as the alum heads.

I just bought a set of sheaths and installed them on a customers car. They are my first set. My machine shop advised me to surface them right out of the box. He has had issues with some aluminum heads and especially the stealths in not being flat in the middle. He blew a head gasket on the dyno his first set. Sure enough, these were .004 low between the middle chambers on BOTH heads. I’m glad I listened. I cleaned up the bowls, hand lapped the valve to check the seal and bolted them on. Everything has worked well and them run great. Customer wanted higher compression and they work at 10:1 just fine. I’m happy. The only thing I will do on my next set differently is enlarge the oil drain back hole in the heads and make a slight groove from the gasket rail to the hole for better drain back. I’m having trouble getting a gasket to seal with all the oil that stays in the head.

My opinion- If a closed chamber OEM head will make the power you want AND if the cost to refurbish them comes in at say $900 then go this route. Its recommended that every aftermarket head whether its an el cheapo whatever all the way up to big time $$ great brand heads that you pay to have a shop completely check them out and correct everything. For $900 to have your heads redone you know they correct and ready at time of pick up.

I bought a set of Stealths to improve the flow and avoid replacing the seats, springs and valve guides on a set of 1965 615 heads. The intake seat on the Stealth heads is small and it will require a valve job to it up and get close to the advertised 290 CFM flow out of the box. The valve guides and springs worked with my application but the spring seats were "too thick" for the spring compressed height with a fairly mild cam.

I ended up paying for the valve job and different spring seats, so yes, you can expect to spend around $1500 to have a set of decent flowing heads for your application. I figured that a valve job, seats, bronze guides and certainly springs would have run about $850. With my cam I flow around 270 CFM vs 210 CFM with the 516s.

My 383 (390, .040 over) made 480hp/460tq with an Eddy 1407 carb, Performer 383 intake and 2" dyno headers with around 10:1 compression. It could have been richened up some and would probably have made a little more. Certainly more with a better carb and intake. Cam is a custom Bullet .485/.490, .227/.234 at .050. Those heads make a difference and yes I would do it again.

Here's a link to the flow sheet.

440 Source flow after a valve job

The Stealths certainly don’t need $500 worth of labor done to them to be run.
For around $550 you could have a proper valve job done, back cut valves, skim cut the decks....... and have the bowls blended and a flow test done.
But they certainly don’t “need” all that be done to them.

The ootb flow is nowhere near 290. It’s high 250’s/low 260’s.
After recutting the seats and blending the bowls it’s about 280.

If someone wanted to run them ootb, I wouldn’t argue too hard against that.

At my shop, it’s unlikely you’d be able to have a set of 915’s gone through completely, all new parts, hardened ex seats, all new guides, valve job, flat mill, etc, for any less than what you’d have in the Stealths.

I’ve been running Ootb Stealths for about 10 years, and that’s with .027 Cometic MLS gaskets! Even though everyone says don’t do it. I lightly sprayed copper seal on all layers of the gaskets.
When I say ootb I mean in terms of machining.....no machining. I did Lapp the valves and replace the locks with 10 degree locks.

I see as of 3-2-2021 the Stealth heads are $1000 per pair. I didn't realize they could be purchased at so low a price. However- in the rare event those 54 year old 915 castings need MINIMAL work to be ready to run they are still an option but my mind is shifting toward the Stealths.

Fast68 is correct. Good machine work is not cheap. I know some cheaper shops but their equipment is worn out and they do poor work. These builds take too much time and money to take a chance anymore. He talked me into the Stealth heads and sold me a cam that works perfectly for my combination.

A wonderful question to ask after 50 years of iron heads!

915 67 big valve heads are top of the 440 tree in my mind.
906’s are very over rated and 452’s are better...

But it’s 2021 and aluminium is king now!

Better ports, less weight and affordable.

Me I would spend 100 hours porting each 915 head and be very, very happy to do so...

Do I need hardened seats, not for the 1/4 miles I do lol...
Do they need a skim every time I take them off?
Not really...

Had a pair of 452 MP aluminium heads to repair and they were Awful.
One head was bowed 0.020 thou that’s 0.5mm...

The work needed to put it right was crazy...

I had a set of 915's rebuilt in 2016 I think. I bought them for $200 & had $700+ in machining/parts/paint if I recall correctly. The iron heads were cheaper than Stealths, contrary to popular belief. Plus, I employed a local machinist & the money stayed in my local economy rather than sending a cut to China, if you care about that sort of thing.

While I don’t really have anything against the Stealth heads, I like to buy American if possible.

There is only a $149 price difference between the Stealths and some E streets, and the E streets ship for free.

The stock look of the Stealth is worth zero to me......... so the E streets are what I’d use(and they flow better ootb).

Funny, these are the Edelbrock Performer RPM's (save for straight spark plugs) that everyone raves about being so good and "Made in U.S.A!"

I'll follow along. I only have used the old Stealth heads on the 1969 Coronet 505" stroker engine,
I bought those along time ago, so I have no idea how they compare to the current castings?
My castings were nice quality, but I never run heads out of the box. Needed to change springs and retainers for the hydraulic roller cam, so also did some mild porting and valve job while they were apart.
Didn't need to surface my heads?

Originally, I wanted to use them for the more stock look, with manifolds, but I kept making changes to the engine with headers, EFI and such, so now the "original" look is a non-factor, and I though about going with a head with better spark plug placement (in the chamber.)

I haven't used the Edelbrock E-Street heads, but they look decent on paper, and have a slightly smaller chamber volume for more compression.

The aluminum heads use reduced wrenching head bolts, so figure the bolt hardware into the cost of the aluminum heads.

The 915's could be re-built at less cost, and you could re-use the original head bolts. For the $1,000 cost of the aluminum heads, you could put the larger stainless valves in, and hardened exhaust seats in the 915's, and maybe even some mild porting?

Anyhow, if you want more originality or lower cost, I would likely rebuild the 915's with the larger valves and some porting.

If you want performance, the aluminum heads might be a better starting point?

Aren't the E-street heads and overseas casting assembled in the USA?

They are the same exact castings as the RPM heads.
Cast at the Edelbrock foundry in California.

I wonder if all the 915 proponents use the same line of thinking with other items in their lives.
Like daily driver cars that are 50 years old, music in the home on an 8 track player, old black and white tv with rabbit ears, rotary dial telephones, etc.

classic false equivalence fallacy

Perhaps....... if you care to interpret it that way.

The point was, as things wear out...... the owners are presented with a choice.
Repair it, or replace it.
Whether it’s a furnace, a refrigerator, washing machine, computer, a vehicle ...... or parts for your car.

There is a whole industry that exists because there are enough people who elect to replace their cylinder heads with new and improved pieces instead of refurbishing their old ones.

If a technological advance befits the user, it is worth considering. If it doesn't benefit the user, why go there? I know a lot of people who still have a flip phone because it does everything that they need it to do. If a cast iron head does everything the owner wants, why spend money on something else?

One example I think of are the newer refrigerators that have the see through door. Really? Now we are too lazy to open the door? And paid a premium for not having to open the door.

The way I see it is your butt dyno will never tell the difference between the two heads. If doesn't go to the track you'll never know the power difference. Do what you can afford.

I agree with this. I think the OP mentioned that his car is just a "street' car, so if it were me, I would just keep the 915 heads, and do a little work on them to work with the cam and intake. No reason to go overboard for a street car, a street/strip car that goes to the track often, or a full bracket car would be a different story obviously.

I like the fact that the stealths are aluminum and you can run 10:1 compression ratio and and it does not detonate. Can’t do that with iron heads and pump gas very easily.

With flow and all other things equal an aluminum head needs almost a point higher compression to equal the power of the iron heads.

Nice replies Guys.

Here in the ‘old country’ we is seen as dynosaurs with our 50+ year old cars.
I remember a guy in the 80’s asking me “why do you put engine management on a model T”?
That’s how he saw us back then and I hate think how they see us in 2021 lol...

So where are we now?

Building a 528ci hemi for a Moparmate and he is talking EFI at me...
I’m thinking iron heads or aluminium heads and he is thinking about engine management...

So what’s right and what’s wrong?

Neither, it’s all about what you is happy with.
Seen a lot of bowed and buggered aluminium heads as a lifelong engineer.
That’s not to say that iron doesn’t go outta shape too...

This extra one point of compression thing haunts me!

So you take off your open chamber 906 and put a closed chamber Eddy head and.

The engine sounds like a bag of nails and wrecks the piston skirts...

Been there done that and I think it’s Tosh (English for trash)...

Nope,,, with pump gas it really hurts the engine so I’m sticking with IRON...

Count me in the group that simply took my Stealths out of the box, changed the valvesprings to the ones that came with my cam. Also added 10* locks, and bolted them onto the car. Went a decade with Zero issues. Finally pulled them a couple of years ago and sent them to MCH for a full CNC port and prep. Everything with that process went great, now flow 320+ (according to MCH). I have never had an issue of any kind with mine.

Not true and if you have documented evidence to state otherwise I'd be happy to see it.

Hotrod ran a comparison of an AL head vs an FE head, they saw nothing to support any of the old wives tales about AL needing more compression, or FE being more sensitive to detonation.

https://www.hotrod.com/articles/ccrp-0602-iron-versus-aluminum-cylinder-heads-test/

What I think, and this is only supposition on my part, is that the reason AL heads got a rep for being more detonation tolerant, or even for making more power, than an iron head is that people were taking iron heads designed in the 50's, 60's or even 70's and comparing them to modern design heads that happened to be made of aluminum. I firmly believe that the combustion chamber design and port improvements account for the differences, not the materials chosen.

A good example of this is sbc vortec head[iron] much better flow and port design.

In NHRA Stock a lot of Mopars changed over to the acceptable aluminum replacements and were very disappointed. Some combos are factored higher with the original iron heads than the aluminum, the chamber CCs must remain the same. Back before all of the aftermarket heads became legal a well known BB Chev engine builder and Stock racer told me the iron heads are faster.

Building to race rules is a whole different animal. You have to meet their rules regardless if that is the most efficient setup. Also, anecdotal evidence, i.e. someone told me, is not documented evidence. I gave you a link to some relevant and documented testing, that is what I am looking for in this regard. Now if you had a dyno run that showed 915 heads made more power than Stealth heads, ALL ELSE being the same, then that would be interesting.

Years ago one of the big name aftermarket head makers ran an add showing something like 50hp gain with their heads over stock heads. If you read the tiny fine print it said compared to stock 305 heads on a 350. LOL, well no chit cherlock as my Dad would have said. Wonder how it compared to stock 350 heads on a 350?

Building to race rules is a whole different animal. You have to meet their rules regardless if that is the most efficient setup. Also, anecdotal evidence, i.e. someone told me, is not documented evidence. I gave you a link to some relevant and documented testing, that is what I am looking for in this regard. Now if you had a dyno run that showed 915 heads made more power than Stealth heads, ALL ELSE being the same, then that would be interesting.

Years ago one of the big name aftermarket head makers ran an add showing something like 50hp gain with their heads over stock heads. If you read the tiny fine print it said compared to stock 305 heads on a 350. LOL, well no chit cherlock as my Dad would have said. Wonder how it compared to stock 350 heads on a 350? [/quote] Here's a good example, A 69 Camaro 396/375 in Stock with auto which is the most popular, is rated at 412 HP with iron heads, the same car everything else equal with identical factory aluminum heads is rated at 405 HP. In NHRA Stock, it's common knowledge that 10K spent for a 3 hundredths gain is a good deal so with money being no object, they can't get the aluminum heads to equal the iron heads all other things being equal. The aluminum head car can run 56 lbs lighter but most guys pull the extra weight to run the iron heads. The same thing with the 62-67 383, 7 HP more for the iron heads and nobody is running the aluminums. That's an extra 80lbs for the 63 383 to pull in H/SA to run the iron heads. The combo's that show more HP for the aluminum heads on the Mopars are rarely built.

Unfortunately Motortrend stops us from viewing all the wonderful info by HotRod!

A great loss to us overseas wannabees...

So, I saw a vid from the man in Canada called Nick.

He did a back to back 'Iron versus Aluminum' hemi dyno run and the ALI heads didn't do very well at all...
Stock heads 'no porting' and both cast by Mother Mopar!

I bet the ALI heads needed 'MORE' compression lol...

Once a myth starts they is hard to break!

My greatest pleasure on my trips to the US of A, was watching MYTHBUSTERS!

Hopefully one day they will do some realtime-useful car stuff like ALI v IRON...

Best myth of ALL time 'BUSTED' by Brandon at 440 source...

Late model iron 440 blocks ARE THINWALL castings...

Why DID Mother Mopar write that in the BIBLE of Mopar Performance???

AND who would take the TAILGATE off the back of their pickups???
All your stuff falls out onto the FREEWAY you JACKASS...

ALTHOUGH i STILL BELIEVE THE 915 IN BOTH BIGBLOCK AND SMALLBLOCK ARE AS GOOD AS IT GETS...
(Oops wrote that with Caplock on)

I have taken the plunge and in the process of building a 413ci 1962 MAX-WEDGE, surely the KING off IRON>>>

Some ifs here to consider. "What ifs" actually. What if the guides in the iron 915 heads are still good? Possible but unlikely But if they are still good that saves about what $300 in machine shop costs? Its possible a good set of street heads can be made from a vintage set. I mean when were talking an honest 350-400 hp home build these heads are more than capable. Factor in a DIYer sensible porting job and you have some really great heads. Just things to at least point out.

If the steel heads don't need guides, and the valves are good to use, having the steel heads cleaned, lap the valves and install the springs needed for your cam is the way to go. If you can do all this yourself all the better, but to find a good set of steel heads is the key. If you have a bare set of heads, that need vales and than need guides, adds up quickly. I had $500 in a repairing of set steel heads I had on car. Broke the motor, bent 7 valves. Had a machine shop plain the heads to clean them up and install 2 guides. My dad did all the other work and installed new valve springs.

I remember reading somewhere, maybe here, maybe in one of the car mags that due to aluminum's ability to dissipate heat better than cast iron, you COULD run more compression. I don't think it said that you HAD to. I think it was said that you could run ABOUT one extra point of compression with the aluminum before you had the detonation issues that you would have had with the cast iron. And I may have misunderstood all of that and gotten it wrong.

I charge 100 for thin wall bronze bronze guides, parts and labor. 360 for clean and mag, guides, comp valve job and cleanup mill, any porting, flow testing or parts are extra. These heads are still worth using IMO.