mercury 500 50HP water exhaust cover issue

[Walleye007]

Hello,everyone
I found my cover is litter bit different from others'. Compared to other cover, my cover blocks the cooling cavity.This motor has been running for more than 40 years.
Can someone help me figure out if my opinion is wrong,share your thought.

 

[racerone]

Why did you take the cover off ?----You are right the motor is 40 years old.----Likely that you are overthinking here.

 

[merc850]

Looks like an over sized bolt hole to me, maybe someone broke a bolt and drilled a new hole.

 

[Walleye007]

Looks like an over sized bolt hole to me, maybe someone broke a bolt and drilled a new hole.

No. the Left one is from another post. The right one is mine. My cover block the water channel.You can see the difference

 

[Walleye007]

Why did you take the cover off ?----You are right the motor is 40 years old.----Likely that you are overthinking here.

That is a long story. Only No.4 cylinder has a spark.So I removed the ignition cabel to open the distributor. But in order to remove the cable, I have to removed a bolt from exhaust cover. When I put everything back, I snapped that bolt. and broke a piece of water jacket.Now I have to pull the power head to shop to weld it . in this photo, the w channel should not be blocked.

 

[Faztbullet]

If it came from factory blocked ...leave it blocked.