Starboard Engine burning more fuel and can't get over 2800 RPM
Posted: Thu Jul 14, 2022 4:05 am
I hope this isn't a problem but I have a 1965 Shepherd Cruiser (Trojan bought Shepherd in the early 70's I think).
She has twin Crusader CH220's (Chevy small block 305's) from 1983 approx.
My fuel burn on the starboard engine is around double the port. I also can't get starboard engine over 2800 RPM.
I've been trying to diagnose it but I'm feeling a bit stuck. Leaving for desolation sound on the 24th of Aug and was hoping to have this more dialed in by then.
-Distributors are pertronix flame throwers. Springs seem good on them. Cleaned up contacts inside cap.
-Both idle vacuum at 18. At 2000 RPM under load port vacuum is 16 and starboard is 10.
- sprayed brake cleaner around intake manifold and bottom of carb but didn't cause any kind of revving. I was pretty sure I had a vacuum leak but it seems not.
- I advanced timing on starboard by 2 degrees and it inproved idle vacuum sigificantly but seems to have made no difference in vacuum under load. Going to change it back to originak timing mark
- next steps were going to be swapping carbs and ignition coils to see if problem followed either.
- props are a bit of a wild card. Port side is stamped 16x14, 16x15 and 16x16. Starboard is 16x14. The port side is a lighter bronze prop by unknown mfg and strbrd is heavier broze prop by Osborne. I had an extra set repoitched to 16x14 and tried to install them while on scuba but I'm going to need to heat up the props to get them off, prop puller did nothing. Hard to tell obviously but the props look like they are pitched the same when you line up by sight.
- those vacuum gauge guides say a steady vacuum reading of 10 is indicative of late valve timing. I don't really want to get into advancing the cam until I've crossed out all other possibilities.
Anything else you all suggest I try? I'm all ears.
She has twin Crusader CH220's (Chevy small block 305's) from 1983 approx.
My fuel burn on the starboard engine is around double the port. I also can't get starboard engine over 2800 RPM.
I've been trying to diagnose it but I'm feeling a bit stuck. Leaving for desolation sound on the 24th of Aug and was hoping to have this more dialed in by then.
-Distributors are pertronix flame throwers. Springs seem good on them. Cleaned up contacts inside cap.
-Both idle vacuum at 18. At 2000 RPM under load port vacuum is 16 and starboard is 10.
- sprayed brake cleaner around intake manifold and bottom of carb but didn't cause any kind of revving. I was pretty sure I had a vacuum leak but it seems not.
- I advanced timing on starboard by 2 degrees and it inproved idle vacuum sigificantly but seems to have made no difference in vacuum under load. Going to change it back to originak timing mark
- next steps were going to be swapping carbs and ignition coils to see if problem followed either.
- props are a bit of a wild card. Port side is stamped 16x14, 16x15 and 16x16. Starboard is 16x14. The port side is a lighter bronze prop by unknown mfg and strbrd is heavier broze prop by Osborne. I had an extra set repoitched to 16x14 and tried to install them while on scuba but I'm going to need to heat up the props to get them off, prop puller did nothing. Hard to tell obviously but the props look like they are pitched the same when you line up by sight.
- those vacuum gauge guides say a steady vacuum reading of 10 is indicative of late valve timing. I don't really want to get into advancing the cam until I've crossed out all other possibilities.
Anything else you all suggest I try? I'm all ears.