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-   General Boating Discussion (https://www.offshoreonly.com/forums/general-boating-discussion-51/)
-   -   496 vs 502 (https://www.offshoreonly.com/forums/general-boating-discussion/364240-496-vs-502-a.html)

PARASAIL941 12-19-2019 10:45 PM
Does it have 502 Mag Mpi , or carbed motor . What type of exhaust? Good luck!!!

BUP 12-20-2019 10:44 AM
Originally Posted by Dukemastiff (Post 4719158)
I'm thinking about keeping the boat original with the 502s. Since it has one still there. Just missing the one. Although I have no issues with the stock 8.1 in my mud truck. It's running 54 inch boggers with rockwell axles and breaks the tires loose. May be a bit different from the marine app.
Many systems are different for the truck 8.1 to the marine 8.1. The complete fuel system is different and operates at different fuel pressure. The cooling set up is different. The ecm for the truck uses O 2 sensors and other EFI differences as well. The ecm program for the truck is nothing like the marine calibration. The cam is different especially for preventing water reversion / valve overlap.. Just a jist of info as I can go on with it..

Dukemastiff 12-21-2019 11:57 AM
Originally Posted by PARASAIL941 (Post 4719162)
Does it have 502 Mag Mpi , or carbed motor . What type of exhaust? Good luck!!!
it's carbed. Looks like the old school gm Quadra jet carb. The exhaust is stock. Has the quiet option or thru hull.

Dukemastiff 12-21-2019 11:58 AM
Originally Posted by BUP (Post 4719224)
Many systems are different for the truck 8.1 to the marine 8.1. The complete fuel system is different and operates at different fuel pressure. The cooling set up is different. The ecm for the truck uses O 2 sensors and other EFI differences as well. The ecm program for the truck is nothing like the marine calibration. The cam is different especially for preventing water reversion / valve overlap.. Just a jist of info as I can go on with it..
that's what I was wondering. Thanks for the info

Eddienel 05-10-2020 08:40 PM
Interesting thread. I havent thought much about the 502. Ill have to start looking for them.

victorketch 06-21-2020 07:03 PM
have a 2008 boat with twin mercruiser 496 smartcraft engines. I have concerns about age of my manifolds I believe they are the dry manifold system with stainless risers. The boat has only about 180 hours on it.The manifolds are about 12 years old now. Boat is used in salt water but always flushed out with salt away. I had a marine mechanic pull one of the manifolds and riser off to the change a bad starter. The manifolds appear to look good inside. How long do these manifolds last? I'm looking for someone who really knows what they're talking about. I have read peoples opinions on replacing after 5 yrs but looking for a experienced mercruiser mechanics answer. Boat runs fine temperatures 170 ish. What happens when manifolds go bad? How do you inspect? Can water get in engine with the dry system if they go bad or do they just start increasing engine exhaust temperatures as they rust and clog up?


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