Rough Running ZZ502
05-30-2025 | 10:11 AM
#11
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Joined: Aug 2019
Posts: 1,226
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From: BC
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.
05-30-2025 | 10:30 AM
#12
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From: BC
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.
From your description, it sounds like a collapsed lifter that never recovered. But you set the lash @ 1/2 turn with no noticable issues.
05-30-2025 | 02:09 PM
#13
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artselectricinc.com
Joined: Dec 2000
Posts: 703
Likes: 27
From: Longview, WA, USA
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!!!!
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.
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.
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!!!!
05-30-2025 | 03:43 PM
#14
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Joined: Aug 2019
Posts: 1,226
Likes: 416
From: BC
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!!!!
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.
Last edited by Tartilla; 05-30-2025 at 03:50 PM.
05-30-2025 | 03:53 PM
#15
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From: Murrayville Georgia
05-30-2025 | 06:33 PM
#18
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Joined: Aug 2004
Posts: 4,788
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From: naples,florida
What brand distributor are you running ? Have you pulled it and inspected the drive teeth? Had a similar situation years ago with an engine
