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Mercury racing 500HP valve adjustment

bocco

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I had a V-drive with log exhaust manifolds for a long time and it was easy to pop the valve the valve covers and adjust the hydraulic lifters with the motor running. My current boat has a 500HP that has IMCO exhaust and it looks like the only way to get the valve covers off is to remove the exhaust manifolds first. Am I correct that to adjust my valves I need to remove the exhaust manifolds and adjust with the engine off? Do I need to worry about the lifters bleeding down before I can finish the job?

Thanks

Gary
 

guest hs

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That engine should have a hydraulic roller cam shaft. Take them down to zero lash and then 3/4 tighter set them then forget them. You probably do have to remove the exhaust to remove the valve covers.
 

bocco

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That engine should have a hydraulic roller cam shaft. Take them down to zero lash and then 3/4 tighter set them then forget them. You probably do have to remove the exhaust to remove the valve covers.

It does have hydraulic rollers and I don't think the valves need adjusting at this time. I'm just collecting knowledge.

Thanks
 

28Eliminator

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That engine should have a hydraulic roller cam shaft. Take them down to zero lash and then 3/4 tighter set them then forget them. You probably do have to remove the exhaust to remove the valve covers.

X2. If you have to adjust hydraulic rollers, something is broken [emoji51].
 

farmo83

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I had to replace a lifter in mine last year and for the record you do NOT have to take the exhaust manifolds off, although having said that it may have been faster to pull them off as fishing all of that out of their was a huge pain in the ass.
 

bocco

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I had to replace a lifter in mine last year and for the record you do NOT have to take the exhaust manifolds off, although having said that it may have been faster to pull them off as fishing all of that out of their was a huge pain in the ass.

Looks like the lower valve cover screws would be a bitch to get at. I've read about these motors having valve spring problems so I might have to at least check the springs at some point. But for now it runs great.
 

racerden

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I had a V-drive with log exhaust manifolds for a long time and it was easy to pop the valve the valve covers and adjust the hydraulic lifters with the motor running. My current boat has a 500HP that has IMCO exhaust and it looks like the only way to get the valve covers off is to remove the exhaust manifolds first. Am I correct that to adjust my valves I need to remove the exhaust manifolds and adjust with the engine off? Do I need to worry about the lifters bleeding down before I can finish the job?

Thanks

Gary
If you thinks that's bad, try it on a TT Race Aero
 

Dalton

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Every hp500 I've disassembled had at least one bad rocker, just putting that out there
 

Carlson-jet

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In the old days it was easy to figure out a cam lobe or lifter was going bad, it was in the adjustments. Hydraulic Rollers do not give the same tell tale signs of flats. They slowly disintegrate and than erupt into catastrophic failure unless periodic inspections are made. Take that advice for what it is worth. Free :)
 
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