It's not just that easy, you stillhave to ream the new guides fr the valves... Thing is, it's not a lot of money for bronze inserts, last seta of SBC heads I had done (abouyt 8 months ago) was 70 bucks. Anyways, I'm not an old fart...just a spry 48, but I've had a few sets knurled in my day, and after about a year of running (roughly 10-15K miles) you could notice a decrease is performance...kinda a "miss", and when the heads were eventually pulled (as alluded to before by an earlier post) the knurkling was about gone, the valves were sloppy in the guides again, 1/2 of the valves had poor facing on them, and couldn't be reground. FWIW...if I was on a shoestring budget, and with the miles posted he'll be running, I'd bolt them on and go...but if I had some spare coin AND since the heads are sitting in my lap, I'd probably take them in and have some inserts put in, and make sure they hard hardened seats...if not, put them in as well on the exhaust seats. The thing is with the good positive Teflon seals as what was posted before, the valve guide boss needs to be machines to fit it, it's not just the same as plopping in an "umbrella" seal. Another thing....what the heck does loose valve guides have to do with a "puff at start up"...when you're alking about umbrella seals, teflaon seals...ect? SUre if the "soon-to-be-brittle-and-break" oring seals provided by GM on the stems go to hell, oil willwick down the valve stems and puff up, but that has nothing to dowith the guides...heck, if you don't beileve me, put a resh motor together, leave them seals out and stand behind it when you fire it up.
Hey Mike. The low lift of the cam you are going to run will put less side loading on the valves. If you decide to redo the heads I would start looking for a set of cheap valves right now with oversize stems. You ream the guides and do a valve job. I bought a set of intake and exhaust valves for my 352 FE engine for $35.00, I just keep my eyes open for good deals. Or, you could ream and install liners...depending on if your original stems are not worn oval.. I am on a budget also... Best wishes on whatever you do. Richard.
Properly done knurled guides are as good as new guides . Been doing them for 50 years and never had a problem. Some new guides come pre knurled. A properly rolled knurl will last.
I wouldn't guess that most home shops are equipped to install NEW guides. And I don't know exactly how much you'd have to invest in tools to even just knurl your own guides. And if you do either one you'll be in for a valve grind afterward. IF the heads were in fact properly rebuilt I'd probably run them as is for this relatively "light duty" usage. But I'd still want to take them apart first, make sure the valve grind looked right and check the valve stem clearances just to make sure. Might be a good time to check the valve springs too. If they just had the stock Chevy o-ring valve seals I'd upgrade to some umbrella seals while things were apart. If you're working on a budget I think it makes perfect sense to put a better Teflon umbrella type seal on the intakes only. If you get a little smoke at idle or during decelleration it's due to oil being drawn, by vacuum, past the intake valve stems only. The exhaust stems should only see pressure, actually trying to push any oil back into the valve cover area. It seemed to be pretty common on some engines to use stock, or cheaper all rubber umbrella seals on the exhausts and the more expensive umbrella seals with a Nylon or Teflon insert on the intakes only. Don't know what the availability is these days, but there used to be some decent umbrella seals out there that didn't require any additional machining to fit, at least for some styles of heads.
Mike Morand; The option here, that you have, is they are already there, and in tolerance. I would consider it silly to punch out perfectly good valve guides for the 'bling' of having new ones. Knurling is a time-honored technique, with no documented downside that I have ever known about. From what I've heard from people that had it done, they all liked it. Personally I had it done on only one motor, a Y-block in my '56 sedan (1967, drove it for five years and sold it, never had a problem). Hearing they don't last, but from people that can't even specify what head they had it done on, or how long they actually lasted, I take that advice with a grain of salt. Fact is, many people I know are of the opinion there is absolutely no difference in longevity. Never, have I heard anybody with actual experience at it complain that they didn't last. I hear machine shops diss them because they want to sell their "current" skills,(don't even know how to knurl). I'm still waiting for somebody that had it done and they can tell me what the downside is, gleaned from FIRSTHAND experience. I suggest that you don't fall for the; "cheap assed repair", "on a budget", etc. unless somebody can back it up.
Don't work on many SBC's and forgot about the integral guides. 455 Buicks for me. Anyway, I have the cutting tool for Teflon seals. I do those, but the rest I'd leave to a shop. As seldom as I would do a head, it wouldn't make good sense to buy the additional tooling to do guides - knurled or not. Interestng discussion nevertheless....
I was a GM trained master technician and taught to knurl the guides on a engine overhaul. I've never had a problem with wear or oil smoke. I have installed new guides and had them wear faster than the knurled ones. But each to his own method , both have their merits, neither way is wrong.
Hey dude.......I'm a professional and I do knurling...........but its what the individual wants. 1.if your gonna drive it every-once-in-a-while, you can get by cheap by knurling. 2.If you want to do it right and have 70 to 100 extra dollars, get the guides sleeved with the bronze inserts.........they hold oil longer, also will wear 3 times better than cast to steel....... Knurling has it time and place..........when things get too wore out.......no amount of knurling will help.........you'll have to pay to have the replacement guidesput in....
I knurled a set on my 327 heads and put 150,000 on the and never had any problems with them, /i would say you should be good to go.
Good to hear from somebody with firsthand knowledge. Would you offer your opinion on the comparable difference with; (replacing all of the guides with new including reaming them) vs. (knurling them)? Which brings another question to mind regarding the process; Did you run a reamer thru after knurling?
I don't think I would knurled ones that have guides I would just knock out the old guides and replace them with new Bronz sleaves but then again im not a big fan of valve guides sleaves anyhow. All my race heads when the guides get to loose they fine new homes or put on something that don't require 300 lbs on the seat. Bud
29 nash, you ream a knurled guide to get 1/2 the factory clearance. So if the factory clearance is say .002 then you want .001 the oil in the grooves alow you to run tighter clearance.
Are there any cast iron head V-8 OHV engines with guides that can be replaced? I figured they are all pretty much one piece with the head
The old Desoto Hemi heads have guides that are pressed in. I am with Nash,,,use them if you have them,,,(Knurled guides that are in good shape),,,just my opinion. They will last for years.
Run 'em. The only reason you don't see knurled guides much these days is that it is quick and easy to do bronze. When they wear out drop me a note and I'll hook you up with the right tools to do bronze guides in your own garage/living room. But I wouldn't be afraid to run knurled guides, I've done so a lot in the past.
Here is my 2 cents worth . I have done many valve jobs back in the early 70's and I use to knurl guide too . Did many and never had a problem . IT'S NOT 1/2 ASS EITHER ! They were done that way and if you weren't building a drag car there is nothing wrong with them . Chev so called valve guides suck anyway ! If you have 3 or 4 bad guides then drill them and put new guides in them . I would also use the Ford style valve seals . There are some good one out there and aren't much . Easy to install too . You will be hard to find 2 machinist to agree on the same thing plus they want your money !!!! Yes new guides will last a lot longer but knurled guides work very well . Enjoy your hot rod & drive it ! RetroJim
Well then it's settled then! All factory, aftermarket and machine shops should just knurl guides due to the superior performance and longevity. Case closed ! (he says with tongue in cheek)
kNURLING USED TO BE THE STANDARD FOR TIGHTENING UP THE GUIDES. i THINK THAT SINCE THEY ARE OFF I WOULD GET NEW GUIDES INTALLED.
"Most shops now use a bronze wall insert to repair guides. When properly done. It offers the best results for the money. This insert also has a knurl of sorts (interrupted spiral) internally and holds oil for superior lube of the valve stem. " Good advise! If the seats are machined already then leave it as it is otherwise you will be cutting the seats again and losing seat material. Go with what your machine shop advises. This why you took them to the machine shop in the first place. If they are OK with it then move forward. When they wear out you can replace them with K-D liners or cast guides. Bronze guides are only necessary in a race motor. The surface speed of cast iron is fine but you don't want to break one. Bronze has a better chance of bending instead of breaking.
It amazes me with the new generation, can't sort out the options, everything has to be either/or, can't fathom the option of working with what you got. Sarcasim? Accompanied by a whole bunch of misstatements. Knurled guides have a proven record of use in all aspects of motor operation, never limited to 'economy' or 'low performance', 'bandaid', etc. Yes, knurling is a repair in some cases, but is/was NOT always a repair, used in many new applications as well.
I believe you are onto something here. The truth is there is no definitive right way to do it. I have a certain way that I do things they work for me. But to say that my way is the only correct way to do it would be absolutely wrong. BTW I have torn down a ton of engines in my time. Some that I know for a fact had never had a head off and I have found knurled guides from the factory, among other short cuts to make it run.
I would like to point out a couple of things; 1) If the guide was not too worn, then knurling would be fine. Wouldn't a tear down and visual inspection determine this? 2) There is a diffrence between new guides and installing liners. Porknbeaner, I believe, is referring to a kit you can buy to ream the guides oversize then slip in a thin wall guide or liner and then use a tool to knurl the liner in place, then ream to fit the stem. Having seen this done and the great results I think it can't be beat and is a hole bunch cheaper than new guides. 3) The factory used the cast iron of the head casting for cost savings, but it must be mentioned that cast iron is a better conductor of heat than any of the alternatives. Therefore it is my thought that any of the alternatives would benefit from a slight knurl to hold a bit of lubricant. 4) The umbrella seals were used by GM starting in the mid to late 80's, and can be had over the counter very cheap, a great value. These shroud the guide enough to prevent smoking but do allow a slight bit of splash to lube the guide. 5) GM induction hardened the seats when they were manufactured, and as long as they haven't been cut much should be fine. Hardened exhaust valve seats should definetly be installed in anything that is going to be operated at 70% power for extended lengths of time. An application aproaching that can many times benefit from stainless exhaust valves. So; if the heads you have were properly done, and the car you are using them on is not real heavy or see a lot of hellashous use, then go for it!!!!!!
wow....there is definitely two schools of thought on this , some for and some against knurling. i agree with porknbeaner...do it the way that works for you for me it's new valve guides. when i said that originally i actually meant inserts. i just had it done to some 283 powerpack heads and looking at the bill it cost me $92.94...to me it is worth it and it is the way i want to do it. if knurling works for you, go for it. i also had hardened seats installed ..some will say that is a waist of time/money when you can put on 305 heads. again , that is the way i want to do it after reading all of this , i appears there is no right or wrong answer.....just what's right for you
Well I think it all comes to this How much money you got to spend if not much go down to napa and buy a knurleing kit for a few bucks then do it yourself,and if you have more take the heads to a shop and have new guides put in. now see how easy it is !!!
It amazes me too...see Ive been a lurker here on the HAMB for years, and always read your responses with amazement....you seem to like to defend things that you feel are right...look back and youll find yourself defending post about poor looking burped up welds, and you saying you cant determine the quality of the weld by its looks...or similar...Im assuming youre of age...so nothing anyone will say/so/provide evidence contrary to waht you believe will say your mind. Case in point...just in this thread, I posted my real world experiences with knurled guides...yet...you seemed to glaze over that post and defend/promote your opinion saying something like "Glad to see someone with real world experience....yaddda-yadda...as it pertained to YOUR way of thinking...now why didnt you say "Gee...here's a guy that has had bad luck with knurled guides and has seen some downside to them...." as I wrote about? I dunno, you talk about the "new generation" with disdain, even though I learned from my dad (who has long since passed and probably if still alive would rival/out-age you) and would still rather spend a CX-note on insert today, rather than a C-niote to get the guides knurled. I think you really need to open up your mind, realize it's not 1962 anymore, and there have been a few avances in technology in the automobile field that is much, much better than "The way we used to do it in the day".
Allsteel36, If you will go back and read post #49 , maybe you will understand what the others are talking about. I took offense to it,,but didn't want to get into a pissing contest. We all try to help the best we can. Tommy
I agree with you, I never said that knureld guides were "bad/half assed-or just bad pratice"...infact I even said that if the OP was on a budget, just run'em...but, if he had an extrav C-note in his pocket, then go with inserts...plain and simple....if youre here to tell a knurled set of guides will last longer then a setr of bronze inserts...you'll be talking out your wrong ear. If the "advancements" on knurling hav come sooooo far oiver the years, then why did "they" come up with a superior product...ala inserts? Ofcourse you re machinist, you get paid by the hour, so I'm guessing you'll defend your job +hours vs. the correct way to rebuild a head. Think about longevity, not a 1/4 mile at a time.
Longevity of valve guides. Takes two to tango! Worn valve stems - deep six 'em. Period. New valve stems - carefully inspect for imperfections - then high speed spin them in a drill press with 1200 grit oiled wet-or-dry abrasive paper to a mirror finish. Then do your clearance fit to the guide. This is especially critical on silicon-aluminum-bronze guides (carelessly called "bronze" guides) or liners. Remember, ANY imperfection on the valve stem will 'short-live' the guide. Also, both guide and stem must be surgically clean prior to assembly. Guide and stem must be completely coated with assembly lube during the assembling process.
The Jalopy Journal
