I got a set of 57 Chevy 283 heads dirt cheap from a local car club guy. He had them rebuilt 20 years ago but never used them. They were still in bags with a tag on them and had new valves, springs, etc. I took them to a machine shop to get them checked out since they had been sitting so long and they said the only problem found was that the guides had been knurled which they said was a quick fix to tighten up the valves. I asked how long they thought they would last but they couldn't or wouldn't say. This 283 is going in a 32 roadster that may get driven 2500 miles a year. Could I expect to get any life out of these or am I waisting my time. I'm working on a budget and I don't plan on pushing this engine hard.
Use them. They should be fine for the miles you are planning, epsecially if your budget is tight. Down the orad, you can update them if you need to. Hopefully when the budget is there for it. r
The machine shop I used to work at back in the 70's wouldn't knurle guides, my boss at the time figured they were only good for about 10k miles. Keep in mind when the guides are worn the valve do not seat the same every time they close which accelerates the wear on the valve face and seat.
Tried and true method, some old timers actually claim knurled guides are better because of the tiny channels holding lube better, I don't know about all that but I say you should get plenty of years use out of them!
I have knurled guides in the 355 chevy in my 39 Buick,fouled a spark plug at 48,000 miles. Replaced the o-ring seals with umbrella type seals and no more fouled plugs and 1 quart of oil between changes .The car has112.000 miles on it now. I`d say your good for a long time.
i rebuilt thousands of heads in the early 70s at a machine shop i worked at and if the guides were not worn too bad, they generally were knurled. ramco seals on top of the guide. we didn't have many comebacks.
I would like to add something else in regards to knurled guides. There is more than one method of knurling valve guides. In the machine shop I ran, we used 2 different methods of knurling guides. First there is the standard or "quick knurl" method where a tool is driven through the guide and threads are cut into the guide. The other, more prefered method, is the UTP method where the thread is rolled into the guide to raise the metal. The UTP method does last longer since metal isn't removed from the guide like the quick knurl method. We all know rolled threads are stronger than cut threads, and the same is true with valve guides. One thing that should be done on every engine build, but usually isn't, is to make sure the valve train geometry is correct. This will make the valve guides last considerably longer whichever method was used. I hope this helps.
i'll go against the grain here and say have new guides installed now. i have always felt that knurling is a poor fix...do it right while it's apart and easy to do. then you don't have to worry about it
so...the the conclusion here is if you don't plan on driving you car much it is OK to do a half ass repair? that's great...i'm with that now , i will save a lot of money in the future on new brake shoes , brake hoses , wheel bearing and seals , u-joints etc. i was crazy to replace parts that still had a few miles left in them. now i will just dig in the scrap pile for them
Trying to save a buck has never worked that well for me... and I tried most of these "fixes" when I was young & broke. How much were new guides? Can you install them yourself?
A little puff of smoke now and then is a whole lot different than a safety issue like brakes or wheel bearings. Why would you take the time to type such a rediculous response. I appreciate most everyone's input on the knurling question but I could have done without 36-3window's comments. It was just a simple question. I'm not a cheap skate, I just don't want to waist money. Thanks again to all the sincere replys. And by the way I have new brakes, tires, wheel bearings etc.
Knurling guides is not a half-ass fix! Might not be the most correct fix but will definatly run for years. Hell if you must do it right then you would want to buy a set of new heads at every rebuild.
Run em...you'll be fine. Someone above mentioned that some old timers preferred knurled guides because they hold lubrication, and there is truth in that. When I worked at a perf. machine shop in the mid-90's, we had some problems with stainless steel valves seizing in guides, especially when using teflon seals and bronze guides. The fix? At the request of the valve maker we replaced the bronze guides with pre-knurled cast iron replacement guides...and it worked...
mike , my response was sincere....you asked for opinions on knurling and i gave you my honest answer, sorry it doesn't go along with everyone else's. i don't consider my response ridiculous , i was exaggerating to make a point. i still say install new guides now while it's apart, but it's you engine and you can do as you please. remember , this is all free advice and worth every penny you paid for it
36-3window thanks for the second response. I realize knurling is probably not the best way but I am serious when I say this engine won't see a lot of use. I just wanted a ball park figure on how many miles I can expect to get before they loosen up again. I've got less than $150 in these heads and if they work they will be the only thing on this project that came in under budget.
As a modern mechanic, and a part time machinist, I would say for the money, have new guides installed, and never have to worry of it again! Knurling is a cheap and poor way of doing things, it's what you do if you want to "fix and sell", wich I have never understood why you would want to screw a fellow gear head. That being said, the older fellas will surely disagree, and say they've done it for years, and put 100K on sbc's and never had an issue, but these guy's are often mis-informed, uneducated on the matter or don't really care if there is blue smoke going out the tail pipe. If you want a nice clean running engine, change out the guides. Putting new style valve seals in, to me, is also a bad idea, and a "quick fix" to a smoking engine. The fact of the matter is, the exhaust valve nees to see oil in order to prevent it from burning up. Just telling you what I would do.
This may be ot or not but i do know areas that mate to each other its better to have a surface thats segmented for wear and lube rather than one large matting surface.The knurling only would leave very small bearing surfaces like small points.I have some heads i have been running that were knurled probably 20 years ago.
I don't know your engine building experience or expertise but knurling the guides was pretty standard procedure in a lot of shops in the 60's 70's and 80's. True there is a limit as to how loose the guide can be and safely be knurled but I had good luck with it and got good service out of the heads that I did. If he wants to have the machine shop replace the guides and regrind the seats so that he might get a bit longer service out of it that's fine too but the general consensus is that he will get his 2500 miles a year out of the heads the way they are for many years to come without having a problem. If he were planning on putting it in a daily driver to run 30,000 miles a year it might be prudent to go ahead and replace the guides. <input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">
News flash, its not the 60's, 70's and 80's anymore, its 2009! Just because it was considered acceptable back then, doesn't mean it's the right way to do things! That engine WILL smoke!, and it will do so within the first 2500 miles! But I guess if it's "traditional" to knurl, and flight attendents say it's ok because "that's what we used to do" well then that makes it ok.
I know that my father ran a 7-8k rpm smallblock chevy in the early 70's with knurled guides. He still has a set of those heads laying around. As someone here mentioned, the thought of the day was that oil would load up in the grooves giving extra lube at big rpm's. It never blew up or bent a valve so I wouldn't have a problem doing it today. Who cares if it used a tiny bit of oil, it was 1/4 mile at a time anyway.
Seem that if it was better to have a surface similar to a knurled one then they would come that way from the factory. I had a set of SBF heads done back in the 80s. Ran a mild Erson cam in it and never spun it past 5,500. The knurled guides lasted about 3 years and 20-25K. When it started to smoke I pulled a valve cover and found I could easily wiggle the damn things back and forth. Now maybe I got screwed and I don't know which method they used, all I know is that it's the only set of heads I've had to re-do that fast.
So what do we need to push the guides out and press in new ones? Seems like some home shops could do it. As well as grind the valves. Only holdup for me would be grinding the seats. As a side point, don't some race engine builders put Teflon guides on the intakes only?
Well, when I went to school 10 years ago they taught us knurling. Frankly the knurled guides were tighter than the new ones I had put in a set of heads. I figured those guys with years of rebuilding experience knew what they were doing.
Chevy small block guides cannot be simply pushed out and re installed. The guides are part of the casting and are drilled and sized in the casting. To repair chevy guides. The old guide must be drilled out and sized with a reamer. Then a proper sized insert is pressed in and sized to the valve. A really ambitious home builder with a mill and tooling could do it. Otherwise you take the heads to guys like myself and rely on my experience and your budget to rebuild your heads. I only knurl valve guides that have minimal wear. Knurling got a bad name because of shops that would knurl guides that should have been replaced. Many at customers request. Yes and some that were out to make a fast buck. 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.
Not to say that after the fact knurled valve guides are superior to factory machined valve guides, but don't EVER assume that, if some aspect of engine rebuiling was better, the factory would have done it that way. 99.99999 percent of the time, the factory does it the cheapest way they think they can get away with. Recalls? Those are the cheapouts they COULDN'T get away with!
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