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| Joined: | 06-23-2013 |
| Location: | Mission Viejo, California USA |
| Posts: | 90 |
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Many thanks for your wonderfully detailed response. The HG let go last December with the drive up to Willow Springs for an Extreme Speed event. I ended up with about a pint of oil in the top of the radiator when I finally realized that the coolant hoses had started sweating oil. Now here we are and its June 2022 and the 907 is all apart and have discovered that a PO had replaced one of the original Mk1 pistons and rod assemblies with a Mk2 which is slightly different in the area of the wrist pin. So the 12 lb fly wheel was not a happy time trying to run it this way. So I have procured a new used set of Mk2 pistons and rods from eBay. The 12 lb flywheel, with new pressure plate, along with the crank and pistons and rods are at West Coast Balancing this week.
11602 is at 92,187 miles now and the cylinders are looking good and the head is now lapped and the valve seats are re-cut with a Neway seat cutter tool. To your jetting recommendation I shall have to take this on as my wide band O2 had stopped working shortly after I had been running it only to find the sensor-head was terribly fouled with a lot of carbon. So probably oil bubbling past my exhaust valve guides as 4 of the seals had come apart where the spring grips the seal to close in on the valve stem. However, prior to that happening the air fuel ratio was looking pretty good for most all of the throttle plate positions and under various load and over run conditions.
I think most of my 15MPG is because I mash the accelerator more than I ever hold it steady when I drive this car. The run up to Willow springs did produce 18.46 MPG as that was the drive up there from Orange County to the track and then three sessions on the track with a lot of WOT for a total of 216 miles on the tank full. The return home netted 223 miles on the next fill up but was partial so never got the correct mileage. If things get well settled after the rebuild I'll take a good look at messing the idle jetting as I think the air screw turns I have would indicate that I need to change things a bit.
Again Tim, always appreciate your input and your immense head knowledge on this engine and chassis.