I am having some minor moisture issues with my HP 500 clone.

Do Merc HP 500s use a PVC valve on the Dart intake? I have an OEM HP 500 intake and it has a grommet in the valley and a 1/4 NPT fitting below carb.

Do Merc HP 500s use a lifter valley pan (heat shield)?

THANKS!

yes and yes

The carbed 500HP's were prone to reversion due to the cam overlap and 110 lobe sep.
After the first year or two, Merc changed the Gil risers to help prevent the reversion.

JIMG
I cannot find the OEM HP500 PVC valve or parts available on the Mercury Marine or Doug Russell websight/parts illusturations???????

I have 18 in/Hg @ 1000 RPMs (in neutral). Will an automotive PVC valve work? Is it set up with a 1/4" (3/16"?)hose and brass nipple on the intake below the carb?

Griff
I have the standard Gil Offshore risers (Gil's late model tall ones will not fit under the hatch). Do any of the online retailers modify the inner exhaust tube on the Offshores (make it longer) to reduce reversion? Gils websight is down??????

THANKS for the replies!

Probably the best solution would be to change the cam to the 500efi cam or a Crane 731. Same power, a little better idle and no reversion issues.

This is an illustration for a HP500 ( never mind that
the intake in the picture looks like a dual plane though)
it shows the galley tray and pcv hardware

http://www.mercruiserparts.com/Show_...ND+FRONT+COVER

running a automotive one in my 500 works fine

Jaay and Ez
Thanks for the help. I'll order a PCV valve from Bam and compare it to an auto valve..

Giff
Do not want to change cams, short block is pretty fresh and I am using stock lifters and dog bones. I think I will try extending the Gil Offshore tail pipes a few inches to lessen the reversion. Engine purrs like a kitten (800rpm idle in gear) when warm BUT cold idle is awfull

THANKS for the replies!

thats weird, mine is fine hot or cold..no choke airhorn milled stock 800....what dist are running , how much initial timing ?

EZ
I cannot figure out the cold idle issue I have a lifter ticking so I am getting ready to set valve lash BUT #6 intake lifter does not want to pump up @ cranking speed.

On another post it was mentioned that all valve lash must be set exactly the same. I have not checked mine in 400 hours

Gen VI
169611
HP 500 Holley 800, 1/8" holes in primary throttle plate
MSD Ignition and Dist 18* initial
9.5 CR
111* Intake lobe centerline
Stock lifters and dog bones

I have a new 830 ready to run. If the lash and exhaust does not help I'll install it. BUT, I am considering Pro 1s. SOOOOOO I might do the whole top end.