Tell tale location, 1975 70 hp

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Paddy60

Seaman Apprentice
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Jun 15, 2012
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I have reviewed the FAQ area and saw a how to add a tell tale. The photo shows drilling at the top of the head. I was replacing the thermostat and can see back in there. The wall thickness is pretty thick in the area show to drill. So thick, that I wonder if there is a port of some sort. Anyone drill there and recall if they had to drill about 3/4"? I can add photos if that would help

Patrick T
 
Chinewalker

Chinewalker

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Re: Tell tale location, 1975 70 hp

Telltale should be added to the top of the block, not the head.
 
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Paddy60

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40
Re: Tell tale location, 1975 70 hp

here are two photos. One is from the FAQ area and it's on the head. The second photo is a view from the T-stat opening. The T-stat view is a bit exaggerated, but the point is it is quite thick. Does anyone have a OMC 3 cyc head photo? I just want to see what behind. I don't have an issue with drilling through so much material. I figured I would drill an 1/8" hole through, then use the 11/32 drill just for the 1/8" NPT thread portion.

The head configuration has a head cover that appears to be just a water jacket. Circle path around each spark plug, it's about 1" thick. Then just behind is the head. It's the circled in red area and the head is about 1-1/4" thick. Then behind it is the block where the knock out plug is seen.

Patrick t
 

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Paddy60

Seaman Apprentice
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Messages
40
Re: Tell tale location, 1975 70 hp

All,

As a follow up; I added the fitting for the tell tale on the water jacket housing the T-stat. It's not on the head but on the head cover. I figure easy to replace if I really screwed up!

I had viewed photos of the head for a Ebay poster selling one that was my exact model number. From measurements I took with calipers, drilling a hole in the head would have been dangerously close to the sealing edje. At minimum, could weaken the structure of the head. going with the location on the cover just seamed safe. I could see where it was going to come through.

Thanks for your help,

Patrick T
 
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