| parrish | -- 08-08-2011 @ 8:18 PM |
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The valves in my 37 flathead allowed so much wiggle that I investigated and was able to remove the valves REAL fast by just pulling the horseshoe clip out and "boing"...out the top popped the entire valve assembly! Question: does this indicate that the bores have been honed or did the guides actually wear down that much?
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| 37RAGTOPMAN | -- 08-09-2011 @ 5:38 AM |
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I would try a new guide in the bore, and see if it is sloppy also,[or measure the ones removed and compare to a new ones ] if tight you can replace them.I have not heard of the bore wearing, the guide do not move normally,so I am assuming the guides are replacements made not correctly.lets hope so,,, check into it and let us know, hope this helps 37RAGTOPMAN
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| flatheadfan | -- 08-14-2011 @ 5:15 AM |
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Parrish- I wouldn't be surprised if the bores have been honed over the years. If you are worried about leakage around the guides one thing you can do is use later model one-piece valves with solid guides AND have a provision for an oil seal. The seal itself is like an O-ring which fits into a grove in the guide. This seals off an potential leakage. Unfortunately, it also makes valve assemblies more challenging to remove after the engine has some miles on it. Tom Tom
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| supereal | -- 08-14-2011 @ 10:06 AM |
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We also machine an extra seal groove on the one piece guides, as some bores are either loose or damaged. It is likely that someone did hone the bores after having a hard time getting the guides out so they could just drop them in at reassembly.
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| parrish | -- 08-17-2011 @ 7:47 AM |
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thanks...I ordered a solid valve guide from Kyle over at C&G as a test and will give it a try shortly. I also ordered the seals which are packaged in a set of 8, so I assume the exhaust guides get too hot to use a seal?
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| parrish | -- 08-17-2011 @ 8:00 AM |
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After re-reading the replies, I'm questioning if the new solid guides money would be well spent. The mushroom valves would need to be replaced with the straight stem as well. With the kind of looseness I found on the split guides, wouldn't there be severe oil blow by? (This engine has not been fired up in a long time and is still in the discovery phase)
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| supereal | -- 08-17-2011 @ 8:33 AM |
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We use solid guides and stainless valves and, of course, adjustable lifters. We assume that, since a real rebuild isn't cheap, using the best components is required. One piece guides were used on the last of the flatheads because of better stem sealing and longer life. You can still grind the stems for clearance, but adjustable lifters allow resetting if any valves develop clatter later. We also install new valve seats to allow better valve sealing. Many old engines have insufficient seats. They not only leak, they allow valve burning because there is limited heat transfer to the block as the valve head closes. There are no shortcuts to a quality rebuild.
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| parrish | -- 08-20-2011 @ 7:39 AM |
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I received the test one piece valve guide and seal from C&G and it is a VERY tight fit in the bore...and this is after the old 2 piece literally popped out of the bore! Was the old 2 piece THAT worn? Or are the one piece guides different? The valve guide is so tight that trying to get the o-ring type seal on at the same time is going to be problematic...
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| TomO | -- 08-20-2011 @ 7:59 AM |
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The one piece guides have the same outside diameter as the split guides. The guide should not move in the bore, so if the split guide was the correct diameter, there would be no wear on the outer diameter. Your guides must have been undersized. Use a micrometer to measure the guides and the bores. I don't have the exact dimensions, but more than .002 would be too loose IMHO. The easiest solution is to order new split guides, have the valves and seats ground and re-install the valves. Because the loose guides allowed the valve assembly to wobble, you need to ensure that the valves and seats will match up with the new guides. If you want better oil control, go with the straight valves and 1 piece guides. Have the machinist check the valve stems and guide for correct clearance. If there is not enough clearance you will have problems with sticky valves. Tom
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| supereal | -- 08-20-2011 @ 8:38 AM |
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To get the one piece guides into the bore, first be sure the bore is absolutely clean and free of carbon deposits. Lubricate the exterior of the guide and the seal. We use Vaseline for that purpose. Don't enlarge the bores. The tighter the guides fit, the better.
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| rlh37ford | -- 08-20-2011 @ 6:05 PM |
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supereal: When you write "you can still grind the stems for clearance”, are you referring to "fine tuning” of the fit of the valve stem in the guides, or are you talking about grinding off the mushrooms of the Ford valves in order to use solid guides? Obviously, this question reveals how little I know about these engines as compare to you guys who’ve been at this for decades. But, even though I’ll have my engine rebuilt by a knowledgeable flathead builder, I’d like to know in advance what parts I should be buying. In this thread it sounds like straight valve stems and solid guides are preferred over mushroom valves and original NOS split guides. While I’m at it, I must as well ask where you get SS valves, and what type of adjustable tappets are preferred. THANKS
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| TomO | -- 08-21-2011 @ 10:27 AM |
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I think Supereal was referring to grinding the stems to give clearance to the non-adjustable lifters in a stock engine. In my experience there is little difference in performance between the one piece guide / straight stem valves and the 2 piece guide and mushroom valves. The one piece guides control the oil better due to the valve seals on the intake valves, but are more prone to sticking valves. My car burns about 1 quart in 1,000 miles if I let it go that long between changes with the split guides. Stainless steel valves last longer than some of the poor quality aftermarket valves, but the Ford script exhaust valves will give you very good service for many thousands of miles. Adjustable lifters are the preferred lifters because there are few shops that want to take the time to grind the valves for correct clearance. My advice is to look at your budget and decide which you prefer and can afford. Tom
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| supereal | -- 08-21-2011 @ 11:39 AM |
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Yes, I was referring to grinding the stems of straight valves, if you don't plan to replace the lifters with adjustables. We don't recommend that, however. We get lifters from C&G. They aren't cheap, but nothing good is. TomO is correct about geneuine Ford valves, but the foreign made repros should be avoided. The stainless valves we use are actually Chevy valves. We do lots of Chevy engines, and have those valves by the boxfull. We haven't had problems with sticking valves, probably because of using the stainless, and the care taken for stem clearance in the guides. We prefer the one piece guides for oil control. They are also a bit less expensive than the split variety. In either case, it is important to replace all valve springs and forks. There is nothing wrong with staying with the "mushroom" valves, but grinding them for correct clearance takes a lot of experience, something that is rare today. It can be complicated if the valve seats are worn. We replace all valve seats to ensure that they are sufficient both for sealing and valve cooling. As Tom said, the extent of your engine rebuild can be dependent on how much you can afford, as well as how you plan to use the vehicle.
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