Received a PM this morning in regards to this thread. Thought I would try to offer some information in regards to the guides.
Yes we did have an issue previously with guides. This goes back some time now as all of the current heads and guides we use now are from a different manufacturer.
We had been using a different manufacturer previously for the guides. We had used them for quite some time without any issues. It was not until we ran into issues last year with oil consumption that we thought that something was not right and there was a possible issue with the guides. After going through the parts we had still on the shelf and doing some analysis we determined that there was a batch of guides we had received that were out of spec. Some of this had to do with the guide bore concentricity. (The location of the ID of the guide hole in relation to the OD of the guide) We spec a tolerance for this concentricity measurement and found on this batch of guides that they were either right at the top of the spec tolerance or just outside the spec tolerance.
The second issue we found with this batch of guides was the material composition of the guide seemed to be incorrect as the hardness and durability of the guides were lower than they should have been. Upon finding these issues with the guides we determined that they were unusable. At the time we had already been using a different guide manufacturer for other high end guides for some of the more racing oriented only heads. We decided to switch over all of our guides to this manufacturer.
For any heads that did get built using the guides that came from the faulty batch we will fix, repair or replace these heads at no charge. While we were unable to get any form of compensation from the company that produced the faulty guides in the end we understand that as a customer of Livernois the responsibility for standing behind that product falls solely on Livernois.
The manufacturer we switched to using for the guides is a leading supplier of bronze guides and supplies NHRA, IRL, SCCA and NASCAR. We initially started using them for the higher end racing level builds we were doing and had great success with their components. We transitioned to using their guides for all of our heads based on this and have had excellent success over the past couple of years. We are confident that the guides they supply us with are the best in the industry.
In relation to this I thought I would explain briefly some of the factors that come into play in specific to the 3 Valve cylinder head and guides. In a more conventional engine where larger stem diameters are used like 5/16 and 3/8 the total contact area the guide has with the valve is much greater than the smaller 7mm (2V & 4V) and even worse on the 6mm stuff (3 valve & 5.0). The small head diameter also means a small contact area between the seat and the valve as well.
The problem created by having a very small area of contact is heat. Excessive heat will kill the guides. As the power level rises and the specific output go up we are faced with an issue of trying to remove this excess heat so that it does not damage components. With the 3 valve cylinder head we are faced with another issue that hurts heat transfer as well. This is that the guides themselves are very short due to the design of the head. This makes the contact area between the OD of the guide and the ID of the cylinder head guide bore very small. That contact area is critical since the area surrounding the guide boss in the cylinder head houses the coolant jacket where water is used to remove heat.
When you take a 3 valve engine and push double, triple or quadruple the stock output you place a very high heat load on the components. The only way the valve can cool itself is through transferring heat to the cylinder head and having the cooling system remove that heat. This means the small contact area between the valve to seat and also the area between the valveguide and valvestem are where all of this transfer must take place. If you can't transfer enough heat quickly enough you will damage the valves and guides.
I agree and you guys did an awesome job on my heads.
Given all of these issues we spent a fairly considerable time testing guide designs and manufacturers out to try and ensure that the parts we use would offer enough durability. We tested on some very high specific power output engines (1200+ HP) and worked with the manufacturer to come up with the needed design to ensure that the components would never be pushed near that failure point.
I wanted to share that just to try and offer insight as to what job the guides must do and what considerations must be made when it comes to design and use as it relates to the 3 valve cylinder head.
It's frustrating for us to have run into this issue with these guides as we feel we are always trying to ensure we offer the best products available. Unfortunately we cannot manufacturer all the components in-house that are necessary to build the entire engine and must rely on outside companies to do this for us. In the event of having an issue like this the best we can hope to do is work with any customer affected by this and try and quickly fix the problem and get them taken care of. If someone has issues with their heads and needs assistance please contact me and I will work on getting you setup to handle this.
Thanks
