Keith Craft Inc.- We service what we sell!!! Check out our Cobra engines!!! We build high performance racing engines and components for the fast pace strip racing industry as well as daily drivers who want to be FIRST!!!
Whenever we have engine failures there is always angst over the event and the repair / restoration process. Your video of the loose valve in the guide is way more than 0.003 to 0.004" clearance. It is more than any worn guide I have ever seen.
Without being there to inspect the pieces I can't say much more about the poor fit. It is possible that incorrect guides or valves were assembled together. As several people have already observed, the guide that stands above the spring seat looks shorter than it ought to be and certainly shorter than any guide I have ever seen.
The fact that the finished head is the result of multiple visits to multiple shops does not play to your advantage. At this time the short road home is new guides, depending on the condition of the valves very likely new valves and a fresh valve job. I recommend you have all the work done at a single shop.
Whoever the "racing engine specialist" was that you visited, I would not go back to him. He misinformed you on multiple issues which the other guys have already tagged many of. My first two choices for you to get the heads squared away properly would be Brent at Lykins Motorsports (I think I did that right) or Lance at Craft. Both are very good my preference would be Brent
It is decidedly to your advantage to use a single engine builder for all your engine's build needs. When you begin to shop around parts and services from multiple sources you are building a receipe for failure. I know it doesn't seem like you ought to but that is the way it usually plays out.
Wish you the best on the rebuild — single source your labor and parts, you'll be glad you did.
Ed
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Ok, I'm going to address a couple of different people here:
Ed, I built this engine.....9-10 years ago. There is nothing wrong with how the guide looks in that photo. The spring locator looks to be a beehive spring locator and there is ample room above the locator for a valve seal. Everything there looks completely normal. What you don't see is the shouldered part of the guide that bottoms out against the floor of the cylinder head. It's hidden by the spring locator.
Olivier, I'm sorry you're having trouble, I really am, but this is not an assembly issue or wrong component selection issue. Just like every other FE builder in the US, I buy bare cylinder heads and assemble them with the valve springs and components to match the camshaft. Everything is checked, including spring pressures, coil bind clearances, etc., and if you have your build sheet, that information will be on there.
If you don't know how heads are assembled, bare castings have the guides fitted. The guides are ordered to fit the heads. The guides are then diamond honed to fit the valves. A valve job is completed. Then the heads are assembled with the correct components. I simply can't fathom how many sets of CNC ported Edelbrock heads went through Keith Craft's shop back around this time period. I would say literally thousands of pairs. Since only so many shops in the US have CNC machines to port heads, I have bought many sets of Edelbrock/Pond heads from Keith over the years.
I don't know what caused your issue. I have never seen anything like that before. The only thing I can come up with is some kind of hardness problem with the guides, where they were softer than they should have been? Other than that, I don't know how this engine has been treated over the past 9 years, how the car has been driven, etc.
It may seem strange to the customer, but there are things that sometimes happen that are not the builder's fault. We don't make the parts, all we can do is measure, check, blueprint, and assemble to the best of our ability.
My advice is to put new guides and valves in the heads and that's simply all I can advise being this far away and not having seen this engine for the past 9-10 years.
Whenever we have engine failures there is always angst over the event and the repair / restoration process. Your video of the loose valve in the guide is way more than 0.003 to 0.004" clearance. It is more than any worn guide I have ever seen.
Without being there to inspect the pieces I can't say much more about the poor fit. It is possible that incorrect guides or valves were assembled together. As several people have already observed, the guide that stands above the spring seat looks shorter than it ought to be and certainly shorter than any guide I have ever seen.
The fact that the finished head is the result of multiple visits to multiple shops does not play to your advantage. At this time the short road home is new guides, depending on the condition of the valves very likely new valves and a fresh valve job. I recommend you have all the work done at a single shop.
Whoever the "racing engine specialist" was that you visited, I would not go back to him. He misinformed you on multiple issues which the other guys have already tagged many of. My first two choices for you to get the heads squared away properly would be Brent at Lykins Motorsports (I think I did that right) or Lance at Craft. Both are very good my preference would be Brent
It is decidedly to your advantage to use a single engine builder for all your engine's build needs. When you begin to shop around parts and services from multiple sources you are building a receipe for failure. I know it doesn't seem like you ought to but that is the way it usually plays out.
Wish you the best on the rebuild — single source your labor and parts, you'll be glad you did.
Ed
I agree with you Ed. Too much people working on an engine is not a good solution at all !!! Rebuild will be done by myself only !!
As I live in France it's impossible to send heads to Brent or KC but we have good machine shop here so that won't be a problem to replace guides / do a valve job / etc...
The racing engine specialist talk to me about all possibles issues but for him it's a valve guide problem or a too high valve lift causing premature guides failure.
Ok, I'm going to address a couple of different people here:
Ed, I built this engine.....9-10 years ago. There is nothing wrong with how the guide looks in that photo. The spring locator looks to be a beehive spring locator and there is ample room above the locator for a valve seal. Everything there looks completely normal. What you don't see is the shouldered part of the guide that bottoms out against the floor of the cylinder head. It's hidden by the spring locator.
Olivier, I'm sorry you're having trouble, I really am, but this is not an assembly issue or wrong component selection issue. Just like every other FE builder in the US, I buy bare cylinder heads and assemble them with the valve springs and components to match the camshaft. Everything is checked, including spring pressures, coil bind clearances, etc., and if you have your build sheet, that information will be on there.
If you don't know how heads are assembled, bare castings have the guides fitted. The guides are ordered to fit the heads. The guides are then diamond honed to fit the valves. A valve job is completed. Then the heads are assembled with the correct components. I simply can't fathom how many sets of CNC ported Edelbrock heads went through Keith Craft's shop back around this time period. I would say literally thousands of pairs. Since only so many shops in the US have CNC machines to port heads, I have bought many sets of Edelbrock/Pond heads from Keith over the years.
I don't know what caused your issue. I have never seen anything like that before. The only thing I can come up with is some kind of hardness problem with the guides, where they were softer than they should have been? Other than that, I don't know how this engine has been treated over the past 9 years, how the car has been driven, etc.
It may seem strange to the customer, but there are things that sometimes happen that are not the builder's fault. We don't make the parts, all we can do is measure, check, blueprint, and assemble to the best of our ability.
My advice is to put new guides and valves in the heads and that's simply all I can advise being this far away and not having seen this engine for the past 9-10 years.
Brent as you told me when I bought the engine to you I always let it warm slowly. I never raced it just use it on the roads. Always use 10w40 or 10w50 oil with Zddp additive every year (or 5000 miles). Never open the engine until 3 weeks ago.
Location: Virginia Beach, Va & Port Charlotte, Fl.,
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It also would be a good idea to have the heads "hot tanked" after disassembly. That'll get rid if all the oil and combustion deposits in the chambers. You may have already planned to do so.
The best of luck to you with your rebuild. The FE has a lot of not well known idiosyncrasies that need to be dealt with during the build. If one doesn't know them one can get into problems that'll cost a lot of time and money. Personally, I wouldn't even hire a well know and very reliable machine shop to do a rebuild if they didn't have a good bit of FE experience.
...
The racing engine specialist talk to me about all possibles issues but for him it's a valve guide problem or a too high valve lift causing premature guides failure.
This is one example of the questionable information / guidance the engine specialist is providing you OliveR.
Lift will not wear guides. A valve stem and a guide are a linear bearing. Small displacements or large displacements have no lateral thrust in a linear bearing. Too much lift can bind springs or introduce spring retainer to guide interference but importantly, it does not put a side load on the valve stem. Side loading comes from incorrect rockers, poorly installed rockers, just bad rocker geometry in general or wrong length pushrods to hit the most common contributors. All of those contributors can individually put a side load on a valve stem that will accelerate guide wear but importantly, lift will not.
I suspect your engine specialist while presumably well intentioned is unknowingly providing you an inaccurate analysis of why what has transpired, transpired. As well intentioned as he might be, I doubt he will be able to either solve or fix the problem, primarily because he does not understand the origins of the problem.
There was a popular Indiana Jones movie a number of years ago where Indy was searching for the Holy Grail. He and the bad guy find it almost simultaneously. The problem is, it is only one of a number of Grails on a table before them. The bad guy chooses the grail he believes to be the True Grail and fills it from a water source in the cave and drinks the water from the grail. He promptly dies and turns to dust on the floor of the cave before everyone's eyes.
The Knight's Templar, Knight who has guarded the Grail for centuries turns to Indy and offers a simple admonishment, "Choose wisely. He did not!"
I am going to offer the same admonishment to you for your consideration. Choose wisely. You won't die if you do not but, your engine might.
Ed
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Last edited by eschaider; 09-18-2021 at 11:58 PM..
Reason: Spelling & Grammar
Cobra Make, Engine: ERA FIA 2158, ERA 427SC 649 sold
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if it was a thrusting issue, I would think there would be more play up and down (in line with the rocker arm) than side to side. It is also possible that the finish on the valve stems is just rough enough to be slightly abrasive to the bronze guides. At 3000 RPM the valves are opening and closing 25 times a second, 13,000 miles is a lot of cycles, it would not take much.
That certainly explains why the valve margins are clean in your post 23.
The valves have been kissing themselves.
Are all the valves like this, are they all the same, some worse than others, or some not worn at all?
I would find it hard to believe they are all like this. How on earth the engine ran at all without snapping valves off.
What valve stem seal was fitted?
Looks like it had a bad combination of valve guide material, and NO lubrication past a positive valve stem seal, which viton is very good at.
Ultimately the valve stem seals would have let oil through, the engine would have been a heavy smoker, since the seal would have pulled out of round while the engine was running.
It would come down to the cylinder head manufacturer's choice of guide material as the cause.
That certainly explains why the valve margins are clean in your post 23.
The valves have been kissing themselves.
Are all the valves like this, are they all the same, some worse than others, or some not worn at all?
I would find it hard to believe they are all like this. How on earth the engine ran at all without snapping valves off.
What valve stem seal was fitted?
Looks like it had a bad combination of valve guide material, and NO lubrication past a positive valve stem seal, which viton is very good at.
Ultimately the valve stem seals would have let oil through, the engine would have been a heavy smoker, since the seal would have pulled out of round while the engine was running.
It would come down to the cylinder head manufacturer's choice of guide material as the cause.
Gary
Hello Gary.
All valves are not like N°7 exhaust I show you in the video. 2 or 3 others are like that. All others have minimal wears but out of normal wear.
Every intake valves are full of burn oil and some exhaust too (but not all).
Viton valve stem seals were installed and when you look at them upper lips are damaged.
You're right.... my engine was smoking a bit before disassembled it but what I most found was excessive oil consumption.
Well what I'm going to do is to replace valve guides (#9704 Edelbrock ref - for FE heads), do a seat job. My machine shop is going to check valves and if they are ok he will do a valve job.
I am sure the Edelbrock family would like to know about this.
I don't see this as an assembly problem.
Considering not one other member here including one FE expert (Brent Lykins) has seen this happen with this type of guide, points to a metallurgy issue, when your guide batch was made.
Or perhaps number of cold starts versus run-time at operating temp.
The Edelbrock head out of the box is a very low performer, that's why we used to have them CNC ported. In addition, a 3/8" stem valve makes for a heavy valve that also obscures flow.
When specialty head shops provide CNC ported heads, they are ordered in bare castings so that the guides and valves can be custom fit for the application.
If you have 11/32" valves, *these are not Edelbrock guides*.
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
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Quote:
Originally Posted by Gaz64
Considering not one other member here including one FE expert (Brent Lykins) has seen this happen with this type of guide, points to a metallurgy issue, when your guide batch was made.
Or perhaps number of cold starts versus run-time at operating temp.
Oliver, is there a stamping on the outside of the valve guide that is visible? For instance, the Edelbrock guides (which it is said you do not have) often have the number 39-1119 on the outside. Of course the inside diameter of that particular Edelbrock guide is already too big for an 11/32" valve. But it would be interesting to know if your guides have an identifying stamp.
The Edelbrock head out of the box is a very low performer, that's why we used to have them CNC ported. In addition, a 3/8" stem valve makes for a heavy valve that also obscures flow.
When specialty head shops provide CNC ported heads, they are ordered in bare castings so that the guides and valves can be custom fit for the application.
If you have 11/32" valves, *these are not Edelbrock guides*.
+1 on what Brent said. This looks like an 11/32 valve stem in a ⅜ guide. This is very likely not a wear problem as much as it is a parts mismatch problem.
Ed
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