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302 Casting, Hardened Valve Seats


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20 replies to this topic

#1 mjf1212 (converted)

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Posted September 20, 2004 at 07:25 pm

Hi,

A few articles that I've read (notably the Paul Pitcher stuff ) recommend porting these ('302) heads and installing the bigger 360 size valves. Will the seat grinding for the larger valves destroy the induction hardening of the exhaust seat or can you get away with this without needing a new seat insert ?

Who might a person hire to do the porting as Pitcher describes and what would it cost ? I've got a set of '89 302 heads that i'm thinking of doing.

Thanks,

MJF

#2 Mr.LH

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Posted September 21, 2004 at 06:48 pm

Hughes charges 600/set for a port-polish with oversize valves

#3 Webslinger60

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Posted September 22, 2004 at 02:58 am

Im interested in this question too.

First: Exaclty how do they "harden" the valve seats?
I imagine all heads since 1975 had this done at the factory, to cope with the hotter burn of unleaded fuel.

Second: If the seat is cut for larger valves, then the "hardened" area is also gone, correct? Or does the process penetrate a few millimeters into the steel?
Would it have to be hardened again?

Im looking to buy a reman engine that comes with #302's upgraded to 1.88's
but the machininst never brought up this point? And I remember there was concern for a problem with pre-75 cars running no-lead. (although I owned several pre 75 cars in the 80s after leaded fuel was outlawed, and never noticed a problem?)
Is "hardening" even neccesary?

Edited by Webslinger60, September 22, 2004 at 03:00 am.


#4 moper

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Posted September 22, 2004 at 02:18 pm

In terms of materials, the exh seats are "induction hardened"..This treats the metal only to a depth of .015 or so. When a valve job is done, usually some of the hardness is removed, but some remains. When oversized valves are installed, new seats must be pressed in on the exh side. These are hardened all the way thru. As far as porting, many shops offer this, however, getting a "budget" job, will not result in large gains, and in many cases, will hurt output levels. Your best thing would be to ask around the local tracks, and find out who the good porters are, and ask to see some examples of the work. If you find a shop with a flowbench its a good bet they do good work. They should be able to provide you with before and after porting flow numbers to show increases also.

#5 moper

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Posted September 22, 2004 at 02:21 pm

Sorry, after re-reading, I noticed that you are also asking about the intake valves. These can be enlarged without installing seats, because the seats are only cast iron(the head material), so cutting away material doesn't hurt anything.

B)

#6 dana44

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Posted September 24, 2004 at 12:03 pm

Intakes don't require hardened seats, so cut away. The exhaust seats don't need to be altered because the ehxuast valves are large enough for street use and rpm below 7000rpm. Use a stainless intake and all will be fine. Problem of the early heads was that the intake valves (SBC and Ford especially) were not hardened or stainless, thus they sunk and burned without the lead in gas. Mopars always had a better quality material to start with and rarely had these problems.

#7 wittsend

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Posted September 26, 2004 at 09:52 am

The exhaust seats don't need to be altered because the ehxuast valves are large enough for street use and rpm below 7000rpm.


Dana 44,
Are you saying that for street use under 7,000 RPM the Intake should be changed to 1.88, but that the Exhaust can stay at 1.50? Or, if one sticks with the 1.50 Exhaust that the Intakes could (or should) remain at 1.78?
When I go to the 302 heads I want to do as much as is practical, but nothing more than is needed (I'll likely be well under the 7,000 RPM limit).
Thanks, Tom

P.S. I'm glad this question of the seat hardness was asked. I just assumed since everyone was recommending the larger valves (but made no mention of the seat depth hardness) that there was sufficent hardness to cut the existing seats.

#8 gearhead

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Posted September 26, 2004 at 11:46 am

Mopars always had a better quality material to start with and rarely had these problems.

<{POST_SNAPBACK}>

Got any engineering data/metalurigical analysis to back that statement up? Bashing the "opposition" with personal opinions, misinformation, or outright lies to make your choice of brand seem superior partially negates any argument for it's superiority.

#9 moper

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Posted September 26, 2004 at 06:59 pm

Having worked in the machine shop area for a while, and having owned and disassembled LOTS of mopar engines, I can say, they have no metalurgical advantage over GM or Ford. The valve material is also not important, unless is is under hard abuse..Even motor homes used standard steel valves, though they were sodium filled, and had special cooling ares around the seats. Street use denotes a lower rpm range..probably no higher than 5500 except certain circumstances. My street/race engines havent had to go near 7000 either, for that matter. Except when I missed a shift...lol... :huh:

#10 mjf1212 (converted)

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Posted September 27, 2004 at 02:34 pm

Hughes charges 600/set for a port-polish with oversize valves

<{POST_SNAPBACK}>



Where are they (Hughes) located ? Would this price include new hardened exhaust valve seat inserts ?

It doesn't look like there's very much room for the inserts in the 302's heart shaped chamber, but I'm not a machinist...

I wonder how much more for bronze guides.

Thanks,

MJF

#11 SpecialK

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Posted September 27, 2004 at 08:58 pm

Mopar themselves took a stock 318 swirl head in the late 80's and installed larger 360 size valves in them. I don't believe they ever re-induction hardened the seats after they cut them for larger valves. And I know for a fact that they never installed hardened seat inserts either. Talk to Hughes first and verify, but I think all you need to do is machine the head for the 360 valve sizes, and do a mild porting in the bowl area and you should be good to go.

#12 Mr.LH

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Posted September 28, 2004 at 01:17 am

www.hughesengines.com

mopar only shop. i've heard good things about them. i plan on getting a lot of my stuff from them.

#13 cavemanmoron

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Posted September 28, 2004 at 05:26 am

i took my "302" heads to my local Napa machine shop.

They installed bronze valve guides,and did a normal valve jobs,
i asked the machinist about putting larger valves in,
he asked what cam do you plan on using?

I told him the Mopar Performance .430/.450 lift,he said the stock valves were more than enough.

They also installed the new valve guidesseals,and the new valve springs
that I bought,that were recommended for the cam.

#14 dana44

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Posted September 28, 2004 at 10:40 am

Got any engineering data/metalurigical analysis to back that statement up? Bashing the "opposition" with personal opinions, misinformation, or outright lies to make your choice of brand seem superior partially negates any argument for it's superiority.

<{POST_SNAPBACK}>


You can check the metalurgical values just as well as I can. The difference between a high nickel steel one piece valve has a better life expectancy than a two piece heat fused valve any day. Early Mopars always had one piece valves, blocks (especially early big blocks) had a much higher chromoly content and aged longer before machining than their counterparts, a set of stock 318 rods are beefier than a set of Chevy Pink rods, things like that. It is a pretty big list when compared. As an overall package, Mopars all the way through the mid 70s and earlier had better quality metal components than their counterparts. After mid 70s, bean counters started getting more involved in pinching pennies, but overall the quality of the metal is still equal to or better than their counterparts.

As far as the bigger exhaust valves go, why worry about increasing the exaust size to 1.60 over 1.50. The exhale is less than 6percent difference, and opening the bowl and raising the roof of the exhaust port will more than accomplish the desired results.

#15 Webslinger60

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Posted September 28, 2004 at 10:49 am

i took my "302" heads to my local Napa machine shop.  i asked the machinist about putting larger valves in, he asked what cam do you plan on using?
I told him the Mopar Performance .430/.450 lift,he said the stock valves were more than enough.

<{POST_SNAPBACK}>


I had a post last year, also questioning the neccesity of using the larger 1.88 valves, if a warmer cam would hold them open longer anyway. Dana44 responded with a detailed explaination why the 1.88's work so well, and Allpar moved oure dialog to the performance upgrade section. (but I cant find it now??)

As for the Napa machinist, you should have insisted on the larger valves.
In my experience, some craftsmen, after awhile loose enthusiasm for this hobby, and will discourage certain jobs, only because they, themselves dont want to do it.
"why do you want to do that?" "aw, ya dont need that" "we're too busy this week"
"Ok I can do it, but it'll cost $1000 & take 6 months"

More people than not, highly recommend the 1.88" upgrade, so It's got to be worth the effort. I'd return to Napa, see the owner of the franchise, say "I really wanted this upgrade" and refuse to pay twice. Or I'd find another shop, before you put the heads on.

#16 dana44

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Posted September 28, 2004 at 02:33 pm

I had a post last year, also questioning the neccesity of using the larger 1.88 valves, if a warmer cam would hold them open longer anyway. Dana44 responded with a detailed explaination why the 1.88's work so well, and Allpar moved oure dialog to the performance upgrade section. (but I cant find it now??)

As for the Napa machinist, you should have insisted on the larger valves.
In my experience, some craftsmen, after awhile loose enthusiasm for this hobby, and will discourage certain jobs, only because they, themselves dont want to do it.
"why do you want to do that?" "aw, ya dont need that" "we're too busy this week"
"Ok I can do it, but it'll cost $1000 & take 6 months"

More people than not, highly recommend the 1.88" upgrade, so It's got to be worth the effort. I'd return to Napa, see the owner of the franchise, say "I really wanted this upgrade" and refuse to pay twice. Or I'd find another shop, before you put the heads on.

<{POST_SNAPBACK}>


The 1.88s work well because of the bore and stroke. Punching them all the way out to the 2.02s, although capable, is overkill for the street. The main problem is that the 1.78s flow fine up to the 4000 or so rpm, then peter out. A larger cam with greater lift takes that up to around 5000rpm before the peter out, but that is just when the horsepower starts kicking in and the limitation then becomes the valve size, so the 1.88 is the cheapest answer with the least amount of machining. Cheapest because it is a stock 360 intake valve so is really common, fits exactly, and just a little bit of bowl work is required. Taking a tenth of an inch plunge cut is not too hard on equipment, then cut the seat, all is well. I do agree 6 months and $1000 is way out to lunch for this job, which should be in the neighborhood of say $300-400, being not that labor intensive.

#17 gearhead

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Posted September 28, 2004 at 06:19 pm

You can check the metalurgical values just as well as I can. The difference between a high nickel steel one piece valve has a better life expectancy than a two piece heat fused valve any day. Early Mopars always had one piece valves, blocks (especially early big blocks) had a much higher chromoly content and aged longer before machining than their counterparts, a set of stock 318 rods are beefier than a set of Chevy Pink rods, things like that. It is a pretty big list when compared. As an overall package, Mopars all the way through the mid 70s and earlier had better quality metal components than their counterparts. After mid 70s, bean counters started getting more involved in pinching pennies, but overall the quality of the metal is still equal to or better than their counterparts.

As far as the bigger exhaust valves go, why worry about increasing the exaust size to 1.60 over 1.50. The exhale is less than 6percent difference, and opening the bowl and raising the roof of the exhaust port will more than accomplish the desired results.

<{POST_SNAPBACK}>

So the short answer is that you don't have any engineering data/metalurigical analysis to back that statement up. OK

#18 cavemanmoron

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Posted September 28, 2004 at 07:40 pm

I had a post last year, also questioning the neccesity of using the larger 1.88 valves, if a warmer cam would hold them open longer anyway. Dana44 responded with a detailed explaination why the 1.88's work so well, and Allpar moved oure dialog to the performance upgrade section. (but I cant find it now??)

As for the Napa machinist, you should have insisted on the larger valves.
In my experience, some craftsmen, after awhile loose enthusiasm for this hobby, and will discourage certain jobs, only because they, themselves dont want to do it.
"why do you want to do that?" "aw, ya dont need that" "we're too busy this week"
"Ok I can do it, but it'll cost $1000 & take 6 months"

More people than not, highly recommend the 1.88" upgrade, so It's got to be worth the effort. I'd return to Napa, see the owner of the franchise, say "I really wanted this upgrade" and refuse to pay twice. Or I'd find another shop, before you put the heads on.

<{POST_SNAPBACK}>



Heads are on the running engine already,
also on a 273 you can't go to larger valves,unless you notch the block.
or if it is bored out a lot. ;)


If the car ,like mine is going to be street driven,95% of the time,and
like my useage,have decided to use the stock exhaust manifolds,
why go with high rpm stuff?

I did go to true dual exhaust,but at this time can't afford a set of Dougs headers,
which list for $940, + shipping,and thats is Not "coated";so the stock
exhaust is my limiting factor,nit 1.78 vs 1.88 valves,LOL.

1967 and newer car owners have the luxury of being able to buy very,Very inexpensive headers.

$100 or less uncoated from Summit.

If the 1.88 valve upgrade is for a 318,or 340/360 go for it,
the "302" casting # heads have a smaller combustion chamber,
than the 360 heads,and thus have better compression. :)

you will prob want to Not use 87 octane gas,which I don't anyways. ;)

#19 dana44

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Posted September 29, 2004 at 10:31 am

So the short answer is that you don't have any engineering data/metalurigical analysis to back that statement up. OK

<{POST_SNAPBACK}>


Restated, not on me, but I have in the past done the comparison and stick to my analysis that the statement was proven to be true.

#20 gearhead

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Posted September 29, 2004 at 10:56 am

You can check the metalurgical values just as well as I can. The difference between a high nickel steel one piece valve has a better life expectancy than a two piece heat fused valve any day. Early Chevys always had one piece valves, blocks (especially early big blocks) had a much higher chromoly content and aged longer before machining than their counterparts, a set of stock 327 rods are beefier than a set of Mopar Performance rods, things like that. It is a pretty big list when compared. As an overall package, Chevys all the way through the mid 70s and earlier had better quality metal components than their counterparts. After mid 70s, bean counters started getting more involved in pinching pennies, but overall the quality of the metal is still equal to or better than their counterparts.

You can check the metalurgical values just as well as I can to verify or dispute this. Restated, not on me, but I have in the past done the comparison and stick to my analysis that theabove statement has proven to be true.


The above statement is just as valid as your original statement, until someone proves one or both incorrect with valid references. (With no references to engineering data/metalurigical analysis to back either statement up, their both personal opinions.)


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