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| Joined: | 03-14-2005 |
| Location: | Atlanta, Georgia USA |
| Posts: | 406 |
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Upon assembling that engine I set the Exhaust on the high side of .012" and the Intake to the high side of .007" dry. Same thing I do on all my engines before putting it through the paces. I'm pretty sure I logged 200-300 miles (about 12-15 hours) before Ron took delivery. I take great pride in knowing every engine I deliver is "slightly used". That engine should be ready to run right out of the box.
During break-in things do settle in, but also keep in mind tools vary in tolerance, and the measuring technique isn't an exact science. In my opinion, what you are observing is 'normal' when taking into account all of these factors.
Intake valves don't burn. Howver, a VERY common problem with the 907 is Exhaust valves buring. People never check their clearance and the Exhaust valves tighten up to the point where the valve can't seat long enough to cool and they eventually burn. You'll be driving down the road one day and magically you'll lose a cylinder (or two) like a friend of mine this weekend!
Should you worry? My aforementioned friend NEVER checked his valves since building that engine 80,000 miles and almost ten years ago. Of course now he needs a complete head-job, but one could argue he certainly got his money's worth out of that rebuild! By comparison over the Winter I check the clearance on my 907/910 hybrid built about 4 years ago terrified I'd be dropping a valve any day now. To my surprise all of the valves had shifted only about .003"-.004".
The exhaust is most irritating to do when the engine is in the car. Intake is easy and rarely ever presents itself as a problem. I'd say install the engine and check things after a few thousand miles. If you do want to adjust the intakes, adjust ALL of them to the high side of .007", but that is no guarantee.
On another note, I remember suggesting you change the Exhaust to a 107 grind. If you do change that cam then go ahead and re-shim the Exhaust to the high side of .012".
Keep in touch,
Judson