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Making Gravely Valve Guides
Posted: Sat Apr 21, 2007 9:24 am
I restore Gravely Two wheeled T-head tractors. Valve guides have gotton very expensive. Because of this I would Like to make my own. I have a complete machine shop so this would not be a problem. Goodson Engine Builders recommend that I use cast ductile steel. The tech felt the heat would probably be less of problem since the exhaust side of these blocks gets very Hot. They will glow a cherry red in the dark. I figure around 500 to 600 degrees. Does anyone know where I can purchase Ductile Cast steel? The guides OD will be finished to around .626/7. Ideally I would like to be able to purchase rounds that will finish to these diminsions any length is ok. I found gray Iron that Is 1.5 OD This woud be too costly. Any Ideas are welcome. Also I have been told the blocks and heads were built by studabaker. I am trying to find valves that will fit I can come close but there is always one important dimension that is out of wack You can e-mail me directly at firstname.lastname@example.org
Posted: Sat Apr 21, 2007 2:41 pm
I'm a little confused by your terminology. Are you asking about ductile iron? For the most part, all steel is ductile, where cast iron is not. Ductile iron is a fairly recent (50 years or so) process whereby cast gray iron is inoculated to alter the way graphite precipitates. Tiny spheres of graphite form instead of flat sheets, improving the tensile strength and ductility of the material considerably. It is the material that is commonly referenced as semi-steel. To be perfectly honest, I'm not sure I've ever heard a reference to cast ductile steel. although that doesn't mean the term doesn't exist. Sure creates confusion if it does.
Posted: Sat Apr 21, 2007 3:20 pm
The local machinist said I needed cast ductile steel. When I called goodson and talked to their tech he also stated that cast ductile steel is what I neeed. I do not care what is called do you know were I can get the material I need to make exhaust/intake valve guides. thanks gene
Posted: Sat Apr 21, 2007 6:48 pm
A good friend and long time restoration expert on the old Holt and Best crawler tractors shared with me one of his scecrets for replacement valve guides at an affordable cost.
After a machine shop botched the job on a head rebuild job, he picked up a scrap Cummins diesel engine camshaft of the correct diameter and material for his repairs. The lobes were ground to get through the flame hardened zone and then turned in his lathe to the proper dimensions. The high quality of ductile iron in the camshaft worked perfectly for his needs. It was of better quality than the original guide material ever was. One camshaft was long enough to make all the guides he needed and with material left over for more if needed in the future.
Many times the material we need is right there in front of us, just in a form we do not recognize as being suitable for our needs.
Re: Gravely Guides
Posted: Sun Apr 22, 2007 3:47 am
gene gullo wrote:The local machinist said I needed cast ductile steel. When I called goodson and talked to their tech he also stated that cast ductile steel is what I neeed. I do not care what is called do you know were I can get the material I need to make exhaust/intake valve guides. thanks gene
You may not care what it's called, but you must know the proper name to find what you want. The array of available alloys is staggering-----your chance of hitting on the right one without knowing what you want would be very small.
I have no clue where you can buy cast ductile steel. That's why I asked if your terminology was correct. I've been in the machining trade since '57 and I've never seen or machined it. Jorgensen's stock book doesn't show it either. Maybe that local machinist you spoke of can suggest a source.
Posted: Tue Jul 03, 2007 8:34 pm
I am sure you want ductile iron, not steel. I am like Harold, been in the trade since Oct. 1971 and I have never seen or heard of ductile steel.
When I had my 302 heads done, I had them install hardened cast iron sleeves. The price couldn't have gone up that much on them. Last time I bought some they were a little over $2 each. This was about 8 years ago.
Posted: Sat Jul 07, 2007 1:01 pm
Hi Thanks for your reply the correct terminology of what I am using is G-2 Continuous gray cast iron. This is a peralitic gray cast iron which contains graphite. I buy it oversize 5/8 x 6 foot lengths. I turn it down to .628 and 2.5 inch lenghts. According to the manufacturer this material can be used for both intake and exhaust valves on air cooled one cylinder engines. Have you had any experience with this material? What are your thoughts on using this material for the exhaust valve. thanks for your thoughts gene
Posted: Sat Jul 07, 2007 2:32 pm
I don't know that I've had any experience with that particular formulation, but being a pearlitic iron it should machine not as freely as a ferritic iron, but should have greater wear resistance. I would expect it to machine in the 75 sfpm range (with HSS). From your description, it is not ductile, but that may not be an issue. Shooting from the hip, It's possible you made a good choice. Ductile may not be necessary for valve guides, considering ductility plays no role in their performance.
Posted: Sat Jul 07, 2007 6:03 pm
Hi: How do think this material will react to the heat/exhaust side of the engine. The Valve stem is .340 I am honing these out to .343 The tech from Peerless steel said this would work fine. Below is a definition of this material taken from the companies home page thanks gene
Peerless steel said G-2 - Continuous Cast Gray Iron 40,000 P.S.I.
G-2 is a pearlitic gray iron containing type A graphite material made to this specification will have optimal strength, wear and hardness when compared to other gray iron grades.
Posted: Wed Feb 27, 2008 5:37 pm
Boy I see what you mean about price. I never dreamed they were going for $22.00 each now.
I don't have a Gravely guide here to measure but if memory serves me the OD is .627 & are just short of 2" long.
My father had an old "L" mod that the ex guide had came loose in the cylinder. If I am not mistaken I used a guide for a big block chevy (about $5.00) as the base material to make a new oversize guide. I do remember the ID was 3/8" & I reworked a stellite exhaust valve to fit the 3/8" guide. I don't remember if it was a BB chevy truck valve or if it was a Ford valve. I do remember having to grind the head a bit smaller. Then setting the stem up in a lathe & grinding the valve lock ring with a tool post grinder & shortening the stem to length. I used the original C clips for valve locks. Don't remember at all what I used for a valve spring retainer. Most likely just ground the .030 out with a die grinder & mounted stone.
I'm sure if you check with an automotive machine shop you can find some kind of automotive replacement valve guide to re-work. Although it's been 15 years since I was in the automotive machine shop business. I'm sure you can buy high quality universal replacement valve guides with a OD sized for press fit use in a .625 hole. I'm also fairly positive you can get 3/8" or 11/32" ID. All you would have to do is cut them to length. When I was buying them in bulk boxes of 100 they were costing me $0.85 cents each.