View Full Version : Carb secondary diaphram

08-28-2003, 08:35 PM
I had a sudden loss of rpm at hole shot and Wide Open Throttle. With 2 guys(470 lbs) the WOT is 4020 (Perfect Pass & Analog Tachs). The secondary butterfly took a long time to open and then it only opened about 1/10 of an inch. We manually opened the secondary butterfly and WOT is 4150. Do I have a vacuum leak in the secondary diaphram? Do I need to change the spring - what color? Top speed with OJ 13 x 13 3 blade is 40 mph. I have a 3 blade Acme on order #541. Just replaced Prestolite breakerless ignition module and set gap to .010, new coil, tightened cam on throttle cable. Boat is 1997 Outback with Ford PCM 5.8 800 hours, (260 hp I think). Holley carb rebuilt at 330 hours and now has 800 hrs. Slalom ski only at 34 mph -so top end is not a concern. It is taking a longer time to get boat up to speed before entering slalom course. Thanks for any advice. Boat runs great at idle and once it is up to speed at 34 mph. Timing sounds great looks like 10 degree BTDC. Any suggestions appreciated.

09-03-2003, 10:16 AM
Advanced timing to 10 degrees BTDC - it was at 7 degrees and gained some WOT.

Added new Acme 3 blade prop number 541 13 x 12 to replace 13 x 13 OJ Legend. The boat is better than new. WOT is now 4160 and the holeshot is much better. www.propellersonline.com and www.schnitzskis.com had best prices on prop.