Marine sbc 305 exhaust valves

[apprentice1]

Hi all,
Have a Volvo Penta 5.0 GXI-F engine to rebuild. This is basically a 1996-2000 "vortec" 305, rated at 270 hp. Fuel-injected, entirely stock rebuild.
Looking for exhaust valves. No part numbers on the old ones, I am wondering if these were just factory truck valves, or if i need to order something special. Volvo penta part number is 3855808.
Looking to save $ over factory marine parts if possible

Thanks for the help,
Chris

[superpursuit]

More than likely they will be stainless for a marine engine.

Allan.

[rfoll]

likely 3/8 stem. I think all of the newer stuff is stainless

[ProPower engines]

No don't use a regular stainless exhaust valve they tulip from heat under load.
the correct material is inconel. They can be had from your favorite valve manufacture like Manley Ferria and REV to name
a few. The vortec head uses a 11/32 stem which equates to the super duty valve option from the above suppliers.

Now that is if your are not in a DYI repair situation that needs warranty. You could use a stock vortec single groove valve
with a hard chromed stem regardless of guide material as you will get the better valve that way but keep the seat at
least.020" from the valve face edge for greater margin strength.

[apprentice1]

Now that is if your are not in a DYI repair situation that needs warranty.

ProPower I am not sure i understand which way you are recommending with the above sentence. It is for a customer so there would be a warranty period. The Volvo Penta exhaust valve is apparently a gm # RM102174. I can't seem to interchange these numbers into the aftermarket but was wondering if these are just factory vortec truck valves at marine prices...

The inconel valves would work fine on the factory valve seats?

Thanks everyone for replying

[BillK]

Chris,
I have been using the Eloy 01807S on both 350 and 305 Vortec marine heads and have had absolutely no problems. It is a Stellite faced single groove valve. I don't think I have ever seen a 3/8" stem exhaust in the Vortec heads, only in the earlier heads.

[ProPower engines]

If you call Manley or talk to Brian at dakota parts they can both suggest what they have available based on the application.
While the marine internals are based on OE GM manufacturing both Mercury Marine and Volvo-Penta both spec parts
based on what they want. The newer true vortec engines are 11/32" stem on the exhaust but they have a better material
but as I mentioned the heads have hard seats installed so after machining any valve will be compatible with the seat
material. The main thing here is the stem coating has to be hard chromed to with stand the destructive nature of the
wet environment to avoid rust from coolant water exiting the exhaust as you know they get wet to a point.

The valve head material must stand up to high exhaust temps seen during hard running and not deform like a common stock or stainless valve will when its glowing red most of the time during operation.

The warranty issue I was referring to has to do with ending up with a econo 2 piece flash chromed stem valve.

The material you are using for a replacement valve guide must also be compatible with the stem to prevent premature
galling and sticking a valve IE: Stainless valve in a stock cast valve guide as the temps will cause fast wear and galling creating more warranty work.

Most " Super Duty " exhaust valves are available in inconel material as I mentioned contact your favorite valve manufacture's rep/tech and have a chat to be sure you are getting the best option to keep your customer happy by not having and valve/seat issues part way through next years boating season.