pictures of lillie heads?

jay760

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Has any body got pictures of the lillie head with the porting and combustion chamber? or the Shell and Branch heads, would be nice to actually see them to compare them rather than read and guess at the differences.
 
Has any body got pictures of the lillie head with the porting and combustion chamber? or the Shell and Branch heads, would be nice to actually see them to compare them rather than read and guess at the differences.

I have some of the combustion chamber,valves and shot of the intake but can't show them. None of the photo's show any of the finer details of workmanship that could be of a useful guidance. As for the valves,I've mentioned it before many times,thick valve margins and a tulip shaped exhaust valve give positive gains and you'll gain this by cutting down virago 750 valves. I have a photo of an exhaust port by Bob Bertaut,that he sent me years ago,several in fact but unfortunately I lost a few of them. I 'll post the photo shortly.

Bob never would go into a lot of details how he worked the guide boss area and over the years I've change my ways of porting that particular area ,you gain a little extra port volume but with less resistance for a smoother flowing port.
 
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Since the stock ports are, if anything, too large to begin with, the actual amount of material that is removed by the Lillie head's CNC porting process is very minimal. No material is added to the ports before the CNC porting process. In fact, on both the intake and exhaust ports there are areas where the cutting tool doesn't alter the shape at all.
Also, we've learned that the head castings vary considerably, so there will be material removed from a given area in one head that is untouched in another.
The intake valve is a approx. 1mm larger and the exhaust is about 2mm. The model for the valve head shaping is the H-D XR750, and a standard racing three angle valve job is the seating spec.
Differences of as little .005" affect flow, and when you combine that with the subtle nature of the changes made, it is very difficult to visualize where the magic lies.
There is also some material removed and blending done around the value pockets. This is crucial, but once again subtle. An exception is around the guides where the modifications are obvious but straightforward.
The emphasis on the exhaust port is more related to reduction of turbulence and less upon more theoretical flow.
Again, looking at the completed head, which doesn't really look that much different than a stocker, the buyer might ask if they got their money's worth? Yet, when the two are compared on a high end, state of the art flow bench the Lillie head flows 56% better on the intake side and 27% more on the exhaust than the stock unit.
 
Jay, looking at your ports,there's still room for flow improvement around the guide boss of the intake and for the exhaust,you still have the protruding guide sticking in the air stream,a contributing factor for resistance = less flow and port velocity. The exhaust guide length needs to be cut down to intake guide length and tapered at the end. The roof,guide and boss area are the key to improving the flow and velocity of E/P.
 
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