Stumped

[BigDinOhio]

I have a 1978 270 weekender with 260 mercruiser, it starts and runs fine out of the water but under load it has no power and is popping through the carb. I have tried all tune-up possibilities including replacing points with mallory electronic replacement. I am stumped and not boating much, any help or suggestions would be greatly appreciated. Thanks in advance, Big D

 

[Quint4]

Check the timing. Also it may be running lean which will cause popping.

 

[BigDinOhio]

Thanks, will do. When I bought the boat it was under 3 feet of snow and ice, guy claimed it would go 35 mph, have not got it to go 8 yet. But I got a good deal on it and refuse to give up on such a nice boat. Appreciate the help.

 

[BigDinOhio]

Well, we figured it out no compression on 4,6 or 3,5 pulled the heads to find 2 bad headgaskets and one terrible machine shop job. The heads are not even the same casting or valve size, we are in the process of repair, thanks again for the help. BigD