Thunderbolt500, 50hp #3173882. No power

Hi & please help,

It's a 1971 & hasn't run in years.
I've replaced lower end seals, impeller, cables, fuel lines & the latest rebuilt carbs.
Had enough power to get my 11yr olds up on skis, even with low high end power. Now with the rebuilt carbs the upper end power is less?
I've adjusted the idle mixture screw but don't have the confidence to address timing & synchronizing?
Any ideas are greatly appreciated!

Check engine compression, a sick engine won't ever run properly. Get a manual which will show you the ins-n-outs of getting the timing set properly. These are not extremely critical as long as you haven't messed with the belt timing, or moved the "spark advance" timing stop.

Make sure the distributor rotates to its timing stop, and the carburetors open fully when the throttle is advanced past that point.

A boat that's waterlogged or has problems with the hull structure can be the cause of poor overall performance. A propeller that's too large for the boat/load will bog the engine down. Your 50hp should run somewhere in the range of 5200-5500 rpm at wide-open-throttle with a light load.

Here's a posting with a bunch of general troubleshooting tips that you may find useful:

http://www.marineengine.com/boat-forum/showthread.php?433729-ignition-components-and-their-purpose

HTH........ed

Thanks for your reply, I'll start looking.
Could you recommend the best manual?
I've got a couple but not with great detail.