As it so happens, right now I have two sets of Evolution cylinder heads in my shop that I have seen before. Both of them were previously ported by me. What make this worth mentioning is the "when" that I last saw them. One set has a porting job which I performed in 1994; 20 years ago. It was the 131st set of heads that I had ported. You may wonder how I can be so sure about work that I completed so long ago, but its simple. I stamp an ID number into the heads I port and keep records.
Now, I don't know much about the life this particular set of head lived in the intervening years, but it was ready for new valves and guides. Not totally shot, unusable junk; just out of spec on the valve to guide clearance and stem taper. The present owner is not the one who I did the work for originally, and since another local shop brought them to me to freshen up, I don't know how many miles or owners they have gone through since '94.
16 year old porting
The second set of heads received my porting work a scant 16 years ago. They were the 273rd set of heads that I ported. I have a little more info on this set due to the fact that I count the owner as an old friend, though I suppose that he would point out that it would be more accurate to say that I am
his old friend, since I am about 10 years his senior. This set has gone in excess of 100,000 miles, many with sidecar attached, since I last saw them. The rest of the motor is quite worn out, to the point of needing a new crankcase pinion race, oil pump, and even an oversize breather gear due to the amount of debris that has passed through it. Somewhat surprisingly the guides did not need replacement on this set of heads, which is a testament to the design of the Evolution valve train.
guides still good - seats after valve job
1 comment:
I also just had a set of heads return. They were EVO heads that I ported back in the 90's as well. other than race customers, this is the second time I have had heads that I have ported return years later, the first set were from a Ford 289 that I did for a street racer. In both cases the new owners did not know that I did the work the first time around, so it was interesting to hear what they were doing now and the new owners liked to hear what they did the first time around.
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