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Volva Penta 8.1L cam info needed

General engine tech -- Drag Racing to Circle Track

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Pappy
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Volva Penta 8.1L cam info needed

Post by Pappy »

What type of cam does Volvo use in a 2008 Penta 8.1/496 GXi? It is the 420hp engine and has stamped rockers. The mechanic found one was cracked.
They want $80 for one rocker and $1,900 to do the job. They also want to charge $600 for the "Volvo" spark plugs, plus labor.

This is my son's boat and we didn't think we wanted to take the time to do this ourselves, but now we are reconsidering. They wanted $6,000 to replace all 16 rockers, $1,000 of that for the stamped rockers. I'm fairly certain they are GM rockers. I've also read that these engines have a reputation for weak valve springs. I think we would like to do that ourselves as well, with better springs. I just need to know what we have so we can get the right parts.

After much research on the internet I have not been able to find cam specs, or even whether it is a roller or flat tappet cam. I found a picture of a cam that appears to be a flat tappet by the look of the lobes. Hopefully someone here can help.

Eric
Chris_Hamilton
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Re: Volva Penta 8.1L cam info needed

Post by Chris_Hamilton »

I believe that the Volvo is the same motor as in several other makes such as Mercruiser and Crusader, and I'm pretty sure it's a BBC. So anything that would fit a BBC should work for you. Rockers, camshaft, spark plugs, etc.

For $8400 you can get a complete re-manned ready to drop in engine assembly with a 1 year warranty. Everything including the harness pulleys alternator etc. Complete EFI and controller. Looks to be everything needed to drop in and go.

https://www.michiganmotorz.com/pdf_data ... ts_id=3919

This place sells cam and roller rocker packages. They could probably point you in the right direction on a camshaft. They have a "stage 1" cam and roller rocker kit for under $1000.

https://www.raylarengineering.com/496ma ... parts.html
BillK
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Re: Volva Penta 8.1L cam info needed

Post by BillK »

496 should be roller. Go over to the OSO forum and ask in the General Tech section. Those guys will know the answers you need. I dont think there is anything different about the rockers compared to the truck engines. If you cant find the info over there PM me the engine serial number and I can find out next week.

https://www.offshoreonly.com/forums/general-q-20/
Bill Koustenis
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motormonkey
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Re: Volva Penta 8.1L cam info needed

Post by motormonkey »

Sent you a pm. Hope it helps you out.
cfm
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Re: Volva Penta 8.1L cam info needed

Post by cfm »

Here are the reg 8.1 (375hp) specs and Mercruisers 8.1 425hp specs:

https://www.offshoreonly.com/forums/gen ... o-cam.html
Kenova
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Re: Volva Penta 8.1L cam info needed

Post by Kenova »

https://www.raylarengineering.com/496ma ... parts.html

When I saw the torque curve for some of their engine packages I started giggling like a little school girl. :lol:
Good luck getting something like that to hook up on the street.

Ken
Over the hill but still learning!
Retaining it is the hard part.
jred
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Re: Volva Penta 8.1L cam info needed

Post by jred »

redid an 8.1 for a marine app all the threads are metric,, arp makes a rocker stud kit for it
changed to roller rocker arms and adjustable valve train if I remember right I had to order in some special guide plates for this change over,,
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