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Originally Posted by Steve H
(Post 4926994)
I suspect I'm getting a miss from each bank—at least, that's how it feels. It's hard to test by pulling plug wires because the exhaust exits below the waterline at idle, causing a lot of bubbles to smack the bottom of the boat. This makes it difficult to tell whether the sound is just water turbulence or an actual engine miss.
Pulling plug wires is your #1 troubleshooting process for this type of problem. Eliminating a poor combustion event and offending cyl. Otherwise, engine stethescopes or even Doc stethescopes work well to isolate and home in on problem locations. |
What are you running for spring pressures? The ZZ502 factory rollers don't like a lot of seat pressure. Anything at or above 150# can cause issues.
From your description, it sounds like a collapsed lifter that never recovered. But you set the lash @ 1/2 turn with no noticable issues. |
Originally Posted by Tartilla
(Post 4927201)
These were factory assembled plug wires? Or custom assembled??
Thanks
Originally Posted by Tartilla
(Post 4927204)
So how do you know there is a problem at all??
Pulling plug wires is your #1 troubleshooting process for this type of problem. Eliminating a poor combustion event and offending cyl. Otherwise, engine stethescopes or even Doc stethescopes work well to isolate and home in on problem locations.
Originally Posted by Tartilla
(Post 4927207)
What are you running for spring pressures? The ZZ502 factory rollers don't like a lot of seat pressure. Anything at or above 150# can cause issues.
From your description, it sounds like a collapsed lifter that never recovered. But you set the lash @ 1/2 turn with no noticable issues. Thanks for the replies!!!! |
Originally Posted by Steve H
(Post 4927237)
Sierra Marine Wires Both Engines. They were installed new with engines
I think it is a random missfire @ idle, then turns into a hard miss when getting on plane, then runs perfect over 1500 RPM I don't remember pressures. AFR used specs provided by Teague Marine to match their springs to Teagues cams Thanks for the replies!!!! Inside the box of prescribed use, the GM roller lifters were relatively reliable. The AFR 265 BBC Heads baseline Hyd Roll springs start at 175lb seat. PAC-1940 469/in rate. Puts it around 430lbs for a 0.550" lift. As you mentioned, Teague may have spec'd the springs, to a more suitable rate for their cam. ***ZZ502 springs setup for 140lb seat for crate eng. |
Originally Posted by Tartilla
(Post 4927201)
These were factory assembled plug wires? Or custom assembled??
Thanks |
Steve H, what ECM's are you running...... so this engine has never ran well ?
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No, this engine has never ran well. Running Holley HP ECUs. I forgot to mention above that I did swap ECUs with no change in port engine.
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Originally Posted by Steve H
(Post 4927253)
No, this engine has never ran well. Running Holley HP ECUs. I forgot to mention above that I did swap ECUs with no change in port engine.
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have you pulled the plugs right after the mis?almost sounds like reversion.sure you don't have any exhaust leaks?
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Sounds like a vac leak to me. Maybe an "internal vac leak"??
Could connect a vac gauge to verify. |
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