buffalo6262
New member
"Hi All,
I've looked th
"Hi All,
I've looked through previous topics here and haven't found anything that seems to match up with my problem.
My boat is an '87 Searay 250 Sundancer with an Alpha 1.
I have a factory new Barr EDM (built by Indmar for Barr) GM vortec roller 350 with a Holley 4150 carb (new, came with the motor, set up by Indmar), and a Delco EST igntion system (new with the motor), and full fresh water cooling (Seakamp--also new, installed when the motor was).
The motor was installed professionally in my boat late last season; I got about 3 hours on it late last year before winterizing it.
It started and ran great all three times out in the fall.
About 4 weeks ago, I dewinterized it and then took it out for another break in run (needs 7 hours total). The fuel tank had been filled with fresh mid grade (89 octane) and Startron (stabilizer, E10 fuel separation preventer) in the fall.
It started and ran beautifully (as it did the first three times)--out of the no wake zone, up on plane without a problem, sounded great the whole time. Good oil pressure (40 PSI @idle, about 55 PSI on plane @3500), good temperature (stable around 170F, with a 160F thermostat).
Ran on plane about 40 minutes, then dropped back to idle for some extended no wake zone running.
At this point, my passenger and I noticed a stumble/roughness in the idle that hadn't been there before.
Then, while I was maneuvering around a dock, it stalled. I restarted the motor and noticed that it was idling about 125 RPM low (575 vs 700 where it had been).
A this point, I headed back to the dock and took it home.
Restarted it on the hose and let it warm up @1200 RPM to about 150F (never gets much warmer than this on the hose) then dropped it back to idle.
Still, we had the rough idle (vibration that hadn't been there previously)
After much checking, we heard what sounded like a whistling noise at idle after warmup, so we swapped out the sandwich style 1/2" carb spacer for a solid phenolic one with new gaskets, thinking there might've been a carb base gasket leak, but no change in symptoms after we did this.
Next, we pulled all the plugs and checked wires (wires are also new). The factory plugs are AC platinums. All looked light tan except the rear and next to rear port plugs, which were darker (reddish deposits) than the rest (but not fouled).
Then, we found a slice in one of the starboard plug wires, where it had rubbed against a bracket on the block.
Replaced the sliced wire and checked the plug (1 up from the starboard rear--it was clean, light tan, not fouled) and restarted. Most of the roughness/shake was gone at idle. BUT: we notice now that after about 25 minutes or so of warming up on the hose, the idle will get progressively slower, dropping off about 100 RPM to 600 and sounding *very* slightly like it's surging.
If we adjust the idle up to 700 compensate, it'll hold at the new setting, sometimes dropping off a bit (25-50 RPM). Blipping the throttle will set it back up, but then slowly, it'll drop back to an uneven idle again.
What we've tried so far to elimate this:
1) replace carb spacer and gaskets, torque to 5 Ft/lbs (edelbrock says finger tighten, then give the nuts 1/4 turn more, which we discovered with a torque wrench works out to ~5 FT/LBS)
2) replace sliced plug wire (haven't found any damage on the others (which again were NEW with the motor).
3) retorqued the intake manifold, exhaust manifold and the risers (found some bolts had loosened a bit, but nothing huge).
4) Checked manifold vacuum. It's mostly steady around 19 (very slight slow wander of about 1-2).
5) Removed plugs, checked gaps (.30, as spec'd by Indmar), then reinstalled the plugs. Again, as mentioned above, 6 looked indentical (light tan) and 2 (farthest port rear and next to rear are darker/red colored, but don't appear to be fouled).
6) Oil looks good and clean
7) not losing any coolant.
8) distributor cap looks good
9) PCV valve was making a buzzing noise at idle, so we replaced it. No buzz out of the new one.
Next Steps/Questions:
1) Check timing. Barr specs 8 deg before TDC, and Indmar specs 10; I plan on checking with Indmar to confirm which number they prefer (since it's their motor).
2) Check compression. BUT: I have no documentation on the Delco Voyager EST ignition--how do I safely disable that so that I don't damage it while checking compression?
Assuming timing and compression look OK, I'm not sure where to go with this next.
1) Arbitrarily change all plugs/wires?
2) seal carb base gaskets and spacer with RTV?
3) try swapping out my Holley for a friend's spare to see if it has the problem with both carbs?
Any ideas/hints/pointers/suggestions welcome--I'm really hoping to get this resolved so I can get on with using my boat!
Thanks in advance for any/all replies..."
I've looked th
"Hi All,
I've looked through previous topics here and haven't found anything that seems to match up with my problem.
My boat is an '87 Searay 250 Sundancer with an Alpha 1.
I have a factory new Barr EDM (built by Indmar for Barr) GM vortec roller 350 with a Holley 4150 carb (new, came with the motor, set up by Indmar), and a Delco EST igntion system (new with the motor), and full fresh water cooling (Seakamp--also new, installed when the motor was).
The motor was installed professionally in my boat late last season; I got about 3 hours on it late last year before winterizing it.
It started and ran great all three times out in the fall.
About 4 weeks ago, I dewinterized it and then took it out for another break in run (needs 7 hours total). The fuel tank had been filled with fresh mid grade (89 octane) and Startron (stabilizer, E10 fuel separation preventer) in the fall.
It started and ran beautifully (as it did the first three times)--out of the no wake zone, up on plane without a problem, sounded great the whole time. Good oil pressure (40 PSI @idle, about 55 PSI on plane @3500), good temperature (stable around 170F, with a 160F thermostat).
Ran on plane about 40 minutes, then dropped back to idle for some extended no wake zone running.
At this point, my passenger and I noticed a stumble/roughness in the idle that hadn't been there before.
Then, while I was maneuvering around a dock, it stalled. I restarted the motor and noticed that it was idling about 125 RPM low (575 vs 700 where it had been).
A this point, I headed back to the dock and took it home.
Restarted it on the hose and let it warm up @1200 RPM to about 150F (never gets much warmer than this on the hose) then dropped it back to idle.
Still, we had the rough idle (vibration that hadn't been there previously)
After much checking, we heard what sounded like a whistling noise at idle after warmup, so we swapped out the sandwich style 1/2" carb spacer for a solid phenolic one with new gaskets, thinking there might've been a carb base gasket leak, but no change in symptoms after we did this.
Next, we pulled all the plugs and checked wires (wires are also new). The factory plugs are AC platinums. All looked light tan except the rear and next to rear port plugs, which were darker (reddish deposits) than the rest (but not fouled).
Then, we found a slice in one of the starboard plug wires, where it had rubbed against a bracket on the block.
Replaced the sliced wire and checked the plug (1 up from the starboard rear--it was clean, light tan, not fouled) and restarted. Most of the roughness/shake was gone at idle. BUT: we notice now that after about 25 minutes or so of warming up on the hose, the idle will get progressively slower, dropping off about 100 RPM to 600 and sounding *very* slightly like it's surging.
If we adjust the idle up to 700 compensate, it'll hold at the new setting, sometimes dropping off a bit (25-50 RPM). Blipping the throttle will set it back up, but then slowly, it'll drop back to an uneven idle again.
What we've tried so far to elimate this:
1) replace carb spacer and gaskets, torque to 5 Ft/lbs (edelbrock says finger tighten, then give the nuts 1/4 turn more, which we discovered with a torque wrench works out to ~5 FT/LBS)
2) replace sliced plug wire (haven't found any damage on the others (which again were NEW with the motor).
3) retorqued the intake manifold, exhaust manifold and the risers (found some bolts had loosened a bit, but nothing huge).
4) Checked manifold vacuum. It's mostly steady around 19 (very slight slow wander of about 1-2).
5) Removed plugs, checked gaps (.30, as spec'd by Indmar), then reinstalled the plugs. Again, as mentioned above, 6 looked indentical (light tan) and 2 (farthest port rear and next to rear are darker/red colored, but don't appear to be fouled).
6) Oil looks good and clean
7) not losing any coolant.
8) distributor cap looks good
9) PCV valve was making a buzzing noise at idle, so we replaced it. No buzz out of the new one.
Next Steps/Questions:
1) Check timing. Barr specs 8 deg before TDC, and Indmar specs 10; I plan on checking with Indmar to confirm which number they prefer (since it's their motor).
2) Check compression. BUT: I have no documentation on the Delco Voyager EST ignition--how do I safely disable that so that I don't damage it while checking compression?
Assuming timing and compression look OK, I'm not sure where to go with this next.
1) Arbitrarily change all plugs/wires?
2) seal carb base gaskets and spacer with RTV?
3) try swapping out my Holley for a friend's spare to see if it has the problem with both carbs?
Any ideas/hints/pointers/suggestions welcome--I'm really hoping to get this resolved so I can get on with using my boat!
Thanks in advance for any/all replies..."
