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1999 VLX Valve Covers


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Baggerlance

Newbie here. I picked up a project boat a few months ago. It had 545 hours on a Indmar fuel injected 365 HP Hammerhead. My understanding from digging around on this forum and other searches this is the Vortec 5700 L31 engine with GM high performance heads and cam. The boat is mechanically solid and I have most of the history since new, but it's cosmetically rough. It was rode hard and put away wet on a covered ski lift for years. It has deteriorating center bolt chrome valve covers and there is chrome flake all over the engine bay. I guess my question is - is there anything different about the valve covers for GM high performance heads vs standard monsoon cylinder heads for this era boat?

 

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Edited by Baggerlance
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Here is my 1999 Monsoon II 5.7L.  As far as I know, the valve covers should be the same since it is basically the same engine that was bored and stroked about 30 more cubic inches.

If you need a better photo of the valve covers, I can do that for you later.

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Baggerlance

Thank for the offer JustGary. Mines also a 5.7L, but the heads are different in my version. Its basically your engine with GM high performance heads/cam. Malibu also called this the "hammerhead" option even though its not the 383 block. Not sure if the stock covers will fit or not.

Eagleboy I've done some searching on Summit Racing site and there is a ton of options there. Thx.

I guess I could pull them and run down to the Napa parts store to compare with others. Not sure if these were added by Indmar as OEM or aftermarket from a previous owner.

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They're standard GM covers. The ones on your boat might not be OEM. Indmar used composite covers on the Monsoon and Hammerhead IIRC. Definitely on the monsoon anyways. 

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Baggerlance

Thanks for the responses folks. It's still a mystery to me if these came stock for the 5.7L hammerhead 365HP option, but even if I could find the OEM replacement I doubt I'd use it. The chrome flaking is unacceptable. The closest I could find on the summit site is https://www.summitracing.com/parts/trd-6992 but it doesn't have the breathers plus the oil fill hole. Lots of good options on that site. Polished aluminum makes sense. Michigan Boarder your color combos look great. Nice engine!

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Here is an option:  https://www.summitracing.com/parts/ems-ms108-40p

I have ones with breather holes and no oil fill hole, I simply use the breather hole as an oil fill, skinny funnel works great.  Looks to me that that particular valve cover style has bounced around the suppler group, many moons ago it was a Summitt branded one.

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Baggerlance

Thanks Woodski - (cool handle by the way - sudden flash back to my old taperflex ski). Hadn't thought of filling through one of the breather holes.

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Michigan boarder
2 hours ago, Woodski said:

Here is an option:  https://www.summitracing.com/parts/ems-ms108-40p

I have ones with breather holes and no oil fill hole, I simply use the breather hole as an oil fill, skinny funnel works great.  Looks to me that that particular valve cover style has bounced around the suppler group, many moons ago it was a Summitt branded one.

Same with me, oil fill takes a little longer but I only do it once a year anyway.

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@Baggerlance - Are the heads on your engine aluminum and do they have a GM Performance engraving on either end?  If they are and do, those are probably GM Fast Burn heads, which have larger valves than the stock Vortecs.  Although looking at the exhaust manifolds they don't seem like they would match the exhaust port shape of the Fast Burn heads.  My guess the cam is a ZZ4 which means that combo will have good midrange power and is pretty sporty.

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Baggerlance

Woodski - Pretty sure they are bowtie last I looked, but I'll check later this week with a magnet. The original 1999 bill of sale from the dealer specifies the "hammerhead 365HP" upgrade.

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Baggerlance
Posted (edited)

I emailed Indmar and they responded back in a day. Great customer service!

GM Fast-burn heads P/N 12464298. Cam was GM P/N 10185071. 

Valve covers were possibly plastic covers from the GM LT-1 engine P/N 12552322.

Edited by Baggerlance
removed direct quote from Indmar rep
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Baggerlance

Just when I thought I had aftermarket covers, I ran across this 98 VLX with the 365HP option for sale. Looks like Indmar/Malibu did slap these on to differentiate.

I'm going to go with polished aluminum bowtie covers and call it a day.

 

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Baggerlance

So I checked out the heads today. They are stamped with the GMPP insignia and no reaction from the magnet.

The heads must have been painted black at some point unless GMPP ran a batch that were painted. In any case, I ordered a set of GMPP polished aluminum covers, gaskets, and oil filler cap from Summit today. Looking forward to making things right with the old girl. Will have to see if any inner lip trimming is needed to make the new covers fit.

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Baggerlance

Closing this thread as I've installed new covers. I only had to reroute the PVC valve to the rear of the intake manifold. Easy install and not too difficult to get the covers on and off past the manifolds. These are 1/4 taller than standard. Had to take off the injector pigtails and bolt holding the distributor coil to the engine lift bracket. No big deal. The original gasket and valve cover interior were in surprisingly good shape. Interior of old covers are stamped M/S but no part number.  I replaced with GMPP #12497978 valve covers, GMPP #10046089 gaskets (identical to the one I took off), and GMPP #12341993 oil cap. Thanks for the comments folks! Not the best photo but what looks like scratches are just reflections. Covers are pristine.

 

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