I searched the threads and can't find the information that I'm looking for, maybe someone can offer some advice...
RV-9A with a factory fresh IO-320 from Van's with the Avstar fuel injection servo. The Van's stock cowling is attached and fits well, and I have the FAB attached to the servo and lined up to the cowling snout. I had to slightly elongate the six holes in the stock VA-131C Mounting Plate to get the proper alignment to the snout with the plan to remake from a blank sheet of aluminum if necessary.
So here are my questions:
1.) What is the acceptable clearance inside the cowling between the FAB and the cowling? As the location of the servo is biased to the left side of the sump, the clearance on this side is only about a half inch. I'm afraid that there could be contact with the cowl when the engine twists in the mounts. The fix seems to be a custom mounting plate with the hole for the servo offset a bit to the right. Is there a consensus on the acceptable amount of clearance?
2.) The mixture arm of the servo does contact the cowling. I'm not too alarmed by this as I've seen others have documented the same issue (thank you Mike Bullock at rvplane.com), and the fix seems easy enough with a cutout in the fiberglass, a build-up of some clay, and a few layers of fiberglass. My question on this one is with regard to overall cowl symmetry... does it matter?
3.) With the fiberglass and air box top plate mated for proper compression of the filter, the vertical alignment of the bottom (fiberglass part) of the FAB assembly to the snout of the cowling is about 3/8" high. While alignment of the top plate is achieved with a simple bend, I'm not sure how to address the bottom. I have seen pictures of other's work that shows a spacer installed between the servo and sump. While this would help with the vertical alignment of the FAB assembly to the cowl snout, I'm afraid that it would make matters worse for the interference of the mixture arm to the cowling. I'm thinking of two options. One would be to fabricate a spacer for between the servo and the FAB. Another would be slitting both sides of the fiberglass and repositioning just the forward portion it downward. I like the idea of tweaking the fiberglass better as this would also increase the opening of the FAB to better match the opening in the snout. Has anyone else worked through this one?
Thanks for your input, I appreciate it.
RV-9A with a factory fresh IO-320 from Van's with the Avstar fuel injection servo. The Van's stock cowling is attached and fits well, and I have the FAB attached to the servo and lined up to the cowling snout. I had to slightly elongate the six holes in the stock VA-131C Mounting Plate to get the proper alignment to the snout with the plan to remake from a blank sheet of aluminum if necessary.
So here are my questions:
1.) What is the acceptable clearance inside the cowling between the FAB and the cowling? As the location of the servo is biased to the left side of the sump, the clearance on this side is only about a half inch. I'm afraid that there could be contact with the cowl when the engine twists in the mounts. The fix seems to be a custom mounting plate with the hole for the servo offset a bit to the right. Is there a consensus on the acceptable amount of clearance?
2.) The mixture arm of the servo does contact the cowling. I'm not too alarmed by this as I've seen others have documented the same issue (thank you Mike Bullock at rvplane.com), and the fix seems easy enough with a cutout in the fiberglass, a build-up of some clay, and a few layers of fiberglass. My question on this one is with regard to overall cowl symmetry... does it matter?
3.) With the fiberglass and air box top plate mated for proper compression of the filter, the vertical alignment of the bottom (fiberglass part) of the FAB assembly to the snout of the cowling is about 3/8" high. While alignment of the top plate is achieved with a simple bend, I'm not sure how to address the bottom. I have seen pictures of other's work that shows a spacer installed between the servo and sump. While this would help with the vertical alignment of the FAB assembly to the cowl snout, I'm afraid that it would make matters worse for the interference of the mixture arm to the cowling. I'm thinking of two options. One would be to fabricate a spacer for between the servo and the FAB. Another would be slitting both sides of the fiberglass and repositioning just the forward portion it downward. I like the idea of tweaking the fiberglass better as this would also increase the opening of the FAB to better match the opening in the snout. Has anyone else worked through this one?
Thanks for your input, I appreciate it.