What makes the best material for valve guides and why?

Gerald Morris

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Respectful greetings to ye Seasoned Moparian Gearheads! The more I research the matter of refurbishing cast iron heads, the greater my self confidence grows toward making the effort at home, except for a sonograph, magnaflux hot bath and if necessary minimal planing the mating surface with the cylinder block. Getting my two Little Darwinian Imps into some educational institutions should free me to do MUCH of the more menial, time consuming tasks in my Shade-cactus barrio hovel workshop. With shop time now exceeding $100/hr, I'm willing to devote myself to plenty time carefully rehabilitating some of my cast iron cylinder heads. I now possess plenty specialty tools for such work, and am willing to invest in the last few needed.

So, my question for this morning is the thread title. I see iron, stainless steel, and bronze + (modern metal) alloy for valve guides. I admit ASSUMING I will NEED to replace or insert anew some sort of valve guides i these heads, though I plan to rigorously examine the guides as they are before committing resources to obtaining insertable guides or a knurling tool if that particular course of action commends itself over inserting ANY separate guide. ONLY if the cast iron body of the head has never previously been knurled and/or valve action hasn't inordinately worn out the cast iron portion of the head will I commit to knurling valve guides. I suspect inserting more specialized metal guides, especially made for that sole purpose would be the Prudent Course, but I hope to be wrong about this suspicion.

So, what is the Best Valve Guide for a resourceful but impoverished old junky looking to optimally rehabilitate some closed-quench cylinder heads meant for a 383? Should I use bronze alloy, iron alloy or the native cast iron suitably machined?

I eagerly await your enlightening responses
 

MEV

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These days debit card plastic makes the best valve guide material. However, back in the day bronze was considered the way to go.
 

CBODY67

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To me, the bronze heli-coil guide inserts are alleged to be the best. I found one article which stated that bronze and chromed steel make an excellent interface for longevity.

When I did them on my 906s at my late machine shop operative's shop, the heads were placed in the drill press and secured as needed. After an initial pass of the drill bit, then the internal area was grooved for the insertion of the bronze heli-coil guide insert. After it was inserted and secured in the grooves, with a long straight shaft, then the final sizing was performed and cleaned. Then the valve seats were touched with the respective valve seat stones. Cleaning, reassembly, and its done.

To me, this makes "a forever guide" as when they wear too much, then a new bronze heli-coil can be inserted and you're ready to go again.

Knurling was the old way to do things. Just screw the tool into the valve guide, which gives raised areas of metal to be resized for the valve stem diameter. Which, under a microscope, will reveal little jagged edges of metal that might not play too well with a new valve stem's surface. BUT this method works pretty well for a good repair . . . as it was either that or machine the heads for some sort of "knock-in" guide, where the "joint" might result in a heat barrier that might not let the valves heat be fully transferred into the cyl head heat sink of things.

Others might have other orientations, which I respect.

Enjoy!
CBODY67
 

Gerald Morris

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To me, the bronze heli-coil guide inserts are alleged to be the best. I found one article which stated that bronze and chromed steel make an excellent interface for longevity.

When I did them on my 906s at my late machine shop operative's shop, the heads were placed in the drill press and secured as needed. After an initial pass of the drill bit, then the internal area was grooved for the insertion of the bronze heli-coil guide insert. After it was inserted and secured in the grooves, with a long straight shaft, then the final sizing was performed and cleaned. Then the valve seats were touched with the respective valve seat stones. Cleaning, reassembly, and its done.

To me, this makes "a forever guide" as when they wear too much, then a new bronze heli-coil can be inserted and you're ready to go again.

Knurling was the old way to do things. Just screw the tool into the valve guide, which gives raised areas of metal to be resized for the valve stem diameter. Which, under a microscope, will reveal little jagged edges of metal that might not play too well with a new valve stem's surface. BUT this method works pretty well for a good repair . . . as it was either that or machine the heads for some sort of "knock-in" guide, where the "joint" might result in a heat barrier that might not let the valves heat be fully transferred into the cyl head heat sink of things.

Others might have other orientations, which I respect.

Enjoy!
CBODY67

Thank you for an INTERESTING reply, giving me a new perspective on this matter I'd not yet found or considered. I've yet to see any bronze helicoil type of guide inserts, but just "knock-ins" I've noticed some rather exotic looking bronze alloys in my net surfing thus far. Another consideration would be to use oversized shafted valves, which I have seen for the purpose of working with worn guides in the head. All this stuff about DIY head refurbishing is EXCITING, precisely because I CAN DO THIS STUFF! I WILL have to have the heads checked out in the beginning though, for sure.

Knurling appeals if things aren't too bad, but I plan to search for the helicoil inserts....
 

Big_John

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Guide knurling was the cheap alternative to doing it right, or in other words, getting the engine running well enough and into someone else's hands. It wore out fast, and things were worse when all was said and done. It also gave a wonderful path for oil to channel down into the combustion chamber. I seriously doubt if anyone is even doing guide knurling anymore.

Honestly, I haven't seen the "heli-coil" type guide repair done for many years. The good shops I knew always used a press in guide. As I understand it, the "heli-coil" type guide also wasn't good at oil control. I know it was popular some years ago, but I think that it was a replacement for knurling the guides and any small shop could do them. Personally, I always looked at them as a lot better than knurling, but not anywhere near as good as a press-in guide.

The best choice for me, and I know the choice of the shops I've dealt with, has been a good bronze guide replacement. It has to be done by someone that knows what they are doing though... Correct press fit and then correct valve stem clearance when done.

The other alternative, and it would depend completely on availability and how bad the guides are worn, is to use an over-size valve stem.

In my experiences, on the 440s with some mileage, the exhaust valve guides were usually worn to about .010+ with some of that wear in the valve. Often the intake was close to being in spec, or at least the intake valve was still usable. You could pretty much figure on tossing the exhausts.

Of course, before I would invest too much in a set of old cast heads, I'd look into some of the new aluminum pieces. You can run higher compression without necessarily higher octane fuel because of how the aluminum retains less heat etc. It might be cost effective. Yes, I know they are off shore sourced, but so is about everything else.
 

MEV

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"Of course, before I would invest too much in a set of old cast heads, I'd look into some of the new 00 pieces. You can run higher compression without necessarily higher octane fuel because of how the aluminum retains less heat etc. It might be cost effective. Yes, I know they are off shore sourced, but so is about everything else."


My thoughts exactly about debit card plastic making the best valve guides.]
 

Gerald Morris

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Guide knurling was the cheap alternative to doing it right, or in other words, getting the engine running well enough and into someone else's hands. It wore out fast, and things were worse when all was said and done. It also gave a wonderful path for oil to channel down into the combustion chamber. I seriously doubt if anyone is even doing guide knurling anymore.

GOOD WARNING! I wondered when first presented with that method whether removing iron from the original cast guide was a good idea, and could see plainly that even if one could create ridges in the inner circumference of the old body the question of how well they would wear arose. The technique came to my attention because I'm researching methods I CAN DO AT HOME. But wrecking a good cast iron head doesn't figure on my list of goals.

Honestly, I haven't seen the "heli-coil" type guide repair done for many years. The good shops I knew always used a press in guide. As I understand it, the "heli-coil" type guide also wasn't good at oil control. I know it was popular some years ago, but I think that it was a replacement for knurling the guides and any small shop could do them. Personally, I always looked at them as a lot better than knurling, but not anywhere near as good as a press-in guide.

But this method would be FEASIBLE to my shade-cactus shop. Mind you, I own a 20 ton press now, but suspect what's truly needed for pressing inserts are PRECISION MACHINE TOOLS, not brute force for that particular task.

The best choice for me, and I know the choice of the shops I've dealt with, has been a good bronze guide replacement. It has to be done by someone that knows what they are doing though... Correct press fit and then correct valve stem clearance when done.

Here we get to needful precision again. IFF I'm well informed or supervised, I have no problem with exacting dimensions or tolerances. I soldered under a microscope on some NASA equipment in college on a circuitboard I drafted, then photo-etched, cut, cleaned, installed, tested et al. Mind you, this was rough, crude stuff meant just for liquid nitrogen operation, NOT liquid helium! I reckon LN2 still might be a cheap way to make metal insets contract enough to expedite pressing them into sundry holes prepared for them. Read somewhere some folk use it to place valve seats. THAT matter for my next thread probably.....

The other alternative, and it would depend completely on availability and how bad the guides are worn, is to use an over-size valve stem.

I LIKE this idea! Yes, I've seen the availability of such valves too, though none yet with the 4 grooves the exhaust valves from the Golden Age used w their keepers.

....
Of course, before I would invest too much in a set of old cast heads, I'd look into some of the new aluminum pieces. You can run higher compression without necessarily higher octane fuel because of how the aluminum retains less heat etc. It might be cost effective. Yes, I know they are off shore sourced, but so is about everything else.

ONE reason for my preference to do the grunt work at home is to minimize that $100+/hr shop time. With cast iron heads, I CAN do a fair bit with them, even with my current arrangement and accoutrements. I also enjoy LEARNING as I work. I have a spare 915 head fwiw, and a spare 516; this odd couple having been on an old 440 some kiddo dropped into a Roadrunner about 40 yrs ago. These "spares" look decent enough to the eye, though I would INSIST on a more thorough examination before doing aught w them.

I really don't give a dead hamster's scrotum about where car parts get made, so long as they get made WELL. Many members of this very forum predicted that the Cardone 843817 I purchased 3 yrs ago would spectacularly fail about 2 yrs and 9 months ago, but it continues to baffle these latter day doom-mongers by functioning perfectly well. Be this as it may, such an exception occurs because the workers in the Taiwanese plant which manufactures these are relatively well paid, well instructed, motivated and supervised. Asia does NOT abound in workers of such good quality. Sadly, this continent lacks them now too. Real Triumph of the Swill now, Global Crapitalism, eh?
 

Big_John

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But this method would be FEASIBLE to my shade-cactus shop. Mind you, I own a 20 ton press now, but suspect what's truly needed for pressing inserts are PRECISION MACHINE TOOLS, not brute force for that particular task.

By the time you purchase the tooling to do a "heli-coil" type insert, you could have a shop do a "heli-coil" type insert.

Honestly, I don't even know if you can buy the tooling or new inserts. Offhand, the tooling is probably out there on the "used" (read junk) market, but getting the new inserts might be tough.

Here we get to needful precision again. IFF I'm well informed or supervised, I have no problem with exacting dimensions or tolerances. I soldered under a microscope on some NASA equipment in college on a circuitboard I drafted, then photo-etched, cut, cleaned, installed, tested et al. Mind you, this was rough, crude stuff meant just for liquid nitrogen operation, NOT liquid helium! I reckon LN2 still might be a cheap way to make metal insets contract enough to expedite pressing them into sundry holes prepared for them. Read somewhere some folk use it to place valve seats. THAT matter for my next thread probably.....

Well... I've measured gage blocks, getting into sub-millionths of an inch as a Metrologist and I've also done a lot of machine work as a Journeyman Tool & Diemaker. Been around enough automotive machine shops to know that machining cast iron is nasty and there is a skill set required to bring the nasty cast iron, filthy parts and precision machining/work together. Only a chosen few are really good at it.

Having a press is only a small part of the equation.

The guides need to be bored out at the correct angle to the valve seat and head. Simple drilling and reaming... well, yea, maybe, but it's a half assed ( technical term) way. Any drill/ream will follow the existing worn hole. Probably not a huge issue with the intake, but the exhaust is going to be harder to keep it right so the valve seats square to the existing seat. They also need to be sized correctly so the new guides press in tightly, but not so tight as to crack the existing and now thinner guide. Then the guide has to be honed to size. It all adds up to one thing... The cost of the tooling to do it correctly adds up to more than having the service done by a pro that's done them a zillion times.

I have seen some "off hand" type guide installation kits where the guide is installed using hand tools. A friend once asked me to try to use one years ago... While I was successful, I can't say I was really impressed with the final results. A good shop wouldn't use that type of tooling... This was a rough and ready shop and he was looking to cut some corners on a money losing project that no one cared about.
 
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70bigblockdodge

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If you put guides in it use smaller stem valves. The 3/8 stem is too big anyway. The stock guide is huge and needs cut down for performance dual spring sets, not that you are doing any of that. No need to worry about making stock guide too thin. Stock valves have a horrible emissions lip on them, this kills flow at low lift, less than .300", when the valve is close to the seat. Uncle Tony did a video about removing the lip with a drill press and a file, I have done it with a drill in a vice and a stone or file. If you get new valves because of size changes or just to eliminate the 2 piece valve that's 55+ years old I would go to thinner stems.
 

detmatt

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This is a mountain I personally would not climb. I could easily earn much more then it would cost to pay a pro in the time it would take me to do it myself, forget about finding and buying the right tools. I do respect anyone who wants to try it though!
 

CBODY67

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In the realm of aluminum heads and increased compression ratio and "no clatter" . . . I found that to not be quite as true as I suspected and read it might. When I was getting ready to build my 350 Chevy V-8 for my '77 Camaro, I got some of the first '86-production Corvette aluminum heads for it. $550.00 for the pair, at that time. Got a matching piston and discovered it was a generic '71 spec 350 piston, so that was easy to find them then. For an assembled CR of about 9.5, which I hoped to be able to use normal unleaded fuel with.

With the same distributor and initial timing, it clattered with even a 50-50 mix of super uneaded and mid-grade unleaded. So much for THAT theory, in this case. I also knew that the production engines used detonation limiters, too, fwiw.

As the heads were configured for an EFI engine, there is no heat crossover passage in them. No prob as the 4175 Holley has an electric choke. What I did like is how much quicker the heater worked in cold weather. Not having to heat the cast iron first, so quicker heat in the car.

The brand of valve guide tools we used to do my heads with was "Pioneer", which sells lots of aftermarket items for engines and such. Which also seems to be the brand that most machine shops around here use for valve job items. The valve seals were orange silicone Chevy 454 spec items, trimmed to "Chrysler length", rather than use the stock black ones.

Valve guide knurling was popular in the 1950s and such, as that was all that anybody could afford to do. It worked well back then, but that was all most machine shops would do for a stock valve job. It, like the bronze heli-coil guides, uses the existing valve "plane of things" so all orig architectural relationships are maintained. Whereas, with the knock-in/interferance fit guide, care must be used to maintain the orig angles and such of the valve stem in the head, which then also affects the valve seats. Competency is needed to do this operation and have good outcomes, just as when cutting the seats for hard seat inserts.

Just my experiences and thoughts,
CBODY67
 

70bigblockdodge

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This is a mountain I personally would not climb. I could easily earn much more then it would cost to pay a pro in the time it would take me to do it myself, forget about finding and buying the right tools. I do respect anyone who wants to try it though!
This is true!
I would like to do them myself, but I have excellent access to a shop with a Mopar racer.
 

Gerald Morris

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The consensus tends toward, DON'T do the valve guide work beneath the Shade Cactus then. Well and good! I won't mess with that or seats at the homestead. I need these heads to work WELL, reliably and for a good amount of time.

I'll consult the the local shop I've found which is the Most Moparian, according to the local Cognoscenti. BEFORE I so much as SCRATCH the least bit of iron on the pair of heads designated for this job, I will need to find out how much work, if any, a professional shop will permit me to do at home. I can easily run a carbide burr to cut some rough stuff down and out near intake ports, and am a fairly dab hand with such tools, but again, NOT A SCRATCH BEFORE CONSULTATION!!

As much as I LIKE doing my own work, I'm PAINFULLY AWARE of just how CRUDELY my situation impinges on any work I must do. Cylinder heads must contain repeated high pressure explosions after all, so I don't want to commit some idiotic mistake resulting in a valve sucked into a cylinder, with resultant piston shrapnel going the Devil Only Knows where....

AFTER obtaining my desired pair of heads, with new rockers, springs, push rods, lifters et al, I MAY then look at a SPARE with a more experimental eye.... Time will tell, and Budget.
 

Gerald Morris

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As nigh always, your thoughts merit careful reflection.

In the realm of aluminum heads and increased compression ratio and "no clatter" . . . ...For an assembled CR of about 9.5, which I hoped to be able to use normal unleaded fuel with.
/QUOTE]
I'm aiming for a CR from 9.2 to O higher than 9.5, tops! We can only get 91 octane "premium" in this valley, which is the stuff that makes Old Mathilda purr instead of hack up hairballs. I like the way these 2 barrel fed engines with closed quench heads work with tight gear ratios < 3:1.

I had a "Ladies Mach 1" a 1970 Mustang Grande with a 351 Cleveland equipped just so; closed chamber heads, big Motorcraft 2 barrel carb, tight arsed rear end, and that setup smoked a GREAT many putatively more powerful motors and cars of the ~3100-3300 lb class, including full up Mach 1s, Dodge Chargers with 340s, Plymouth Dusters with the same, sundry GM 283-350 equipped Camaro-Nova sorts of setups. Alas, 18 yr old monkeys REALLY shouldn't be ALLOWED ACCESS to so much mechanical power, and my determined emulation of Steve McQueen didn't do me any good at all, other than teaching me how to pray fervently. But ALL agreed, this was a VERY SPECIAL 'Stang, with that relatively rare luxury rod setup, and it SURPRISED many more experienced gear heads, even Wayback Then.

I'm foregoing the large 2 barrel carb in my plans for Mathilda though. The new Edelbrock AVS2 set for just 500 cfm looks to be a NICE little "Economizer" sort of 4 barrel which I think can be easily adapted for such a purpose.

The brand of valve guide tools we used to do my heads with was "Pioneer", which sells lots of aftermarket items for engines and such. Which also seems to be the brand that most machine shops around here use for valve job items. The valve seals were orange silicone Chevy 454 spec items, trimmed to "Chrysler length", rather than use the stock black ones. ....
/QUOTE]

Is this the same Pioneer brand name I see for sundry drive train parts today? I LIKE the quality of the few items I've bought with that brand! Motor insulators, a few tranny and suspension rubbers and such. Their stuff lasts. I might try a search for the brand name for now, even though I pretty well think I'm persuaded NOT TO ATTEMPT GUIDE OR SEAT REPAIR OR INSERTION AT THE HOMESTEAD!

But I thak you all the same for every keystroke.
 

Gerald Morris

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By the time you purchase the tooling to do a "heli-coil" type insert, you could have a shop do a "heli-coil" type insert. ....

I have seen some "off hand" type guide installation kits where the guide is installed using hand tools. A friend once asked me to try to use one years ago... While I was successful, I can't say I was really impressed with the final results. A good shop wouldn't use that type of tooling... This was a rough and ready shop and he was looking to cut some corners on a money losing project that no one cared about.

Its getting late. I wish I had more time to answer your thoughts more fully, but for now, I want to THANK YOU especially for tipping my thoughts back to a saner assessment of my situation and what course offers the best remedy given what I have and can reasonably do here. My wife will thank you in this case doubly. Iron and cutting oil make for NASTY bedding!
 

detmatt

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This is true!
I would like to do them myself, but I have excellent access to a shop with a Mopar racer.
I can still get iron heads done up right for about the same cost as aluminum so long live the American made iron head!:usflag:
 

Big_John

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Its getting late. I wish I had more time to answer your thoughts more fully, but for now, I want to THANK YOU especially for tipping my thoughts back to a saner assessment of my situation and what course offers the best remedy given what I have and can reasonably do here. My wife will thank you in this case doubly. Iron and cutting oil make for NASTY bedding!
You really have to crunch the numbers and access the risk/reward when doing some projects.

I'm the guy that will do almost anything I can myself... I used to figure that even if buying the tools cost me as much as having the job done, the next time, those tools are paid for and the job is very low cost...

In this case though, the learning curve is high, the tools aren't cheap, and the chance of using said tools again is low.

I did some searching and it seems that low cost is $5 and high cost seems to be $10 each for a valve guide. So, between $80 - $160, but even if it was $200, once you figure the cost of buying the tools and the valve guides, it's more cost effective to have the shop do the work.

Another factor you have to think about... I have an old friend that owns an automotive machine shop. I've known him since he started in the business and worked for another friend of mine. If you walked into his shop with a bare head you took apart, he'd be OK with it... Walk in there with a head you did the valve guides yourself and he'd say "No". His reputation as an excellent shop is at stake for one and he knows that if you didn't do it right, it's going to cost him time (read $) to work it out. The chance of failure of parts he didn't work on is a risk he wouldn't take, knowing he could be blamed. He's a smart businessman. He knows when to say "no". Some other shop might not, but then do they do the level of quality you want?
 

Gerald Morris

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You really have to crunch the numbers and access the risk/reward when doing some projects.

I'm the guy that will do almost anything I can myself... I used to figure that even if buying the tools cost me as much as having the job done, the next time, those tools are paid for and the job is very low cost...

In this case though, the learning curve is high, the tools aren't cheap, and the chance of using said tools again is low.

I did some searching and it seems that low cost is $5 and high cost seems to be $10 each for a valve guide. So, between $80 - $160, but even if it was $200, once you figure the cost of buying the tools and the valve guides, it's more cost effective to have the shop do the work.

Another factor you have to think about... I have an old friend that owns an automotive machine shop. I've known him since he started in the business and worked for another friend of mine. If you walked into his shop with a bare head you took apart, he'd be OK with it... Walk in there with a head you did the valve guides yourself and he'd say "No". His reputation as an excellent shop is at stake for one and he knows that if you didn't do it right, it's going to cost him time (read $) to work it out. The chance of failure of parts he didn't work on is a risk he wouldn't take, knowing he could be blamed. He's a smart businessman. He knows when to say "no". Some other shop might not, but then do they do the level of quality you want?

I totally understand and agree! I don't like MY NAME going on work somebody else diddled up before me. I need two good heads for my Family transport, so in this case, I've decided ot to experiment.
 

Gerald Morris

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I can still get iron heads done up right for about the same cost as aluminum so long live the American made iron head!:usflag:

Right on! I may well have a go at totally re-doing some heads here, but ONLY after insuring that I have GOOD ONES installed and running in my driver first. THEN I can school myself a bit.
 
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