Sending 8.1 heads to the shop.
 

I have a stock 8.1L Volvo Penta turning a jackshaft connected to a VP DP-E drive on a Carolina Classic 25 (think heavy boat for its size; 8500 pounds). I'm not looking to race the thing but would like to see if I can squeeze some power from the heads when I sent to the machine shop to refresh. Anything I should consider? SSmarine exhaust manifolds and risers will be used to fix the water reversion problem that caused the 2 center valves and ports to get eaten away. The manifolds will be part of the FWC this time. Still good compressions on all holes.

Thanks

Which 8.1? GI or GXi?

Gi-BF

Without a picture its hard to say but if the ports actually did get "eaten away" I think I would look for a replacement set of heads. Your machine shop should be able to tell you for sure. Those heads shouldnt be too hard to find used. Plenty of them in Chevy trucks. Dart had a cast iron version but I dont think they are available.

https://cimg1.ibsrv.net/gimg/www.off...cbdcb6793.jpeg
https://cimg2.ibsrv.net/gimg/www.off...a31ab06ea.jpeg

Yep, there's a bunch for sale on ebay. Probably could go the car-part.com route as well.

Wow,
Those are junk. I would not waste a second on them. I have done a lot of marine heads and I dont think I have ever seen anything that bad :( :(

The bare heads are still available new from GM Not sure why but the right hand one is almost 3 times as much as the LH one

RH 12581476
LH 12581477

looks like the acid water destroyed them

I’m glad I posted here. I was actually contemplating installing the new SS Marine set on them. Thanks for the advise.


Do machine shops have remans on the shelf? I’ll want the bronze guides installed as well.

I’m assuming I’ll need new head bolts. Any suggestions on brand for a stock application?

I’ll grab new intake and head gaskets as well. The exhaust manifolds will come with their own.

Probably not for those. Unless you are in a terrible rush I would either find a good used set to start with or a pair of new ones from GM. There really is not any reason to put bronze guides in. The factory guides are fine.

I dont know where you are located but I would try and find a machine shop that is familiar with Marine or Performance heads. They are not that different but just need to be set up right. If you are going to try and get a set of remans then see if you can find a marine dealer that has them.

Stock head bolts are fine. Either from GM or Fel Pro if they have them. Fel Pro marine gaskets have always worked fine for me but you really dont even need them because those engines are fresh water cooled so the stock truck gaskets are fine. Thats all that came on them from Volvo.