Hey guys, this may sound amatuerish, but hear goes......
I put my 89 2556 5.7/omc in the water for a little fishing trip. After getting up on plane and pulling back to about 3600rpm we are cruising nicely when we start loosing rpm. And i mean alot of rpm, continues to drop till its only at 2200. I let out of it thinking maybe a clogged fuel filter and it would catch back up. No such luck. Temperature isnt high, plenty of fuel. I shut it down and we decided to fish where we stopped. Upon restarting, i notice a miss. After pulling wires at cap, i see its missing on number 5 and 7. Changed those plugs and we start back. Still a definate miss. Barely get 2200rpm out of it.
I bought this boat with very little hours on it (under 100) and before i put it back in service i did the usual for a boat that sits up that long. IE cap,rotor,plugs,points,condenser,wires,carb rebuild,timing,fuel system cleaning,oil change. Distributor advances correctly and base timing is correct.
After getting it home i did a compression test and i notice 0psi on 5 and 7. So off comes the valve cover to see if maybe it bent some push rods. Both intake valves were too tight. I adjust them and my compression returns to 160psi! I put it back together and double check timing and now its purring like a sbc should.
Here are my questions; 1. How did they get so far off, and why at 97 hours? Ive built many 5.7 sbc's and normaly after getting up to temp once or twice you adjust the valves and your good to go for a while. It seems odd that they tightened up the way they did. The po who owned this boat was a good freind and he only cruised the chesapeake bay for a short while before he and his admiral were caught in a storm. She wouldnt go out anymore and he dry stored it. He never abused it, had all the maint done at the dealership(he was a bayliner salesman). I cant get my head around it...
2.My secondaries never opened on the way back. I figured this could have been because the valve problem, but they still wont open. Are they adjustable on marine carbs? I remember adjusting the spring tension on these on my hot rod. Hopefully its a little too tight and the engine vacuum cant overcome it. It is a qjet btw.
I will be taking it out monday i hope, and plan on doing a fuel pressure test and playing with the secondaries then. I'll post as i go and learn more.....:hypnotysed:
I put my 89 2556 5.7/omc in the water for a little fishing trip. After getting up on plane and pulling back to about 3600rpm we are cruising nicely when we start loosing rpm. And i mean alot of rpm, continues to drop till its only at 2200. I let out of it thinking maybe a clogged fuel filter and it would catch back up. No such luck. Temperature isnt high, plenty of fuel. I shut it down and we decided to fish where we stopped. Upon restarting, i notice a miss. After pulling wires at cap, i see its missing on number 5 and 7. Changed those plugs and we start back. Still a definate miss. Barely get 2200rpm out of it.
I bought this boat with very little hours on it (under 100) and before i put it back in service i did the usual for a boat that sits up that long. IE cap,rotor,plugs,points,condenser,wires,carb rebuild,timing,fuel system cleaning,oil change. Distributor advances correctly and base timing is correct.
After getting it home i did a compression test and i notice 0psi on 5 and 7. So off comes the valve cover to see if maybe it bent some push rods. Both intake valves were too tight. I adjust them and my compression returns to 160psi! I put it back together and double check timing and now its purring like a sbc should.
Here are my questions; 1. How did they get so far off, and why at 97 hours? Ive built many 5.7 sbc's and normaly after getting up to temp once or twice you adjust the valves and your good to go for a while. It seems odd that they tightened up the way they did. The po who owned this boat was a good freind and he only cruised the chesapeake bay for a short while before he and his admiral were caught in a storm. She wouldnt go out anymore and he dry stored it. He never abused it, had all the maint done at the dealership(he was a bayliner salesman). I cant get my head around it...
2.My secondaries never opened on the way back. I figured this could have been because the valve problem, but they still wont open. Are they adjustable on marine carbs? I remember adjusting the spring tension on these on my hot rod. Hopefully its a little too tight and the engine vacuum cant overcome it. It is a qjet btw.
I will be taking it out monday i hope, and plan on doing a fuel pressure test and playing with the secondaries then. I'll post as i go and learn more.....:hypnotysed:
rod
Comment