Merc/CMI service bulletin

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04-01-2011, 08:19 AM

#21

redbud35

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Just spoke with Mercury Racing, they said to drill the top plug to 13/16". Easy enough!

04-01-2011, 08:19 AM

#22

thirdchildhood

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Quote:

Originally Posted by redbud35

I'm glad I came back to this thread. I used the supplied plugs to plug the end of the rail. (CMI supplied) them with the new headers. Then plugged the bottom side of the tail with a brass plug from ACE Hardware. The guys at CMI never said anything about a differant fitting for the jumper on the top of the tail.
I bought all the fittings on my 370 from ACE to convert. I guess I need the ported plugs changed?

Or drill the one out.

04-01-2011, 08:42 AM

#23

Dave M

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Quote:

Originally Posted by redbud35

Just spoke with Mercury Racing, they said to drill the top plug to 13/16". Easy enough!

You mean 13/32"? 13/16 is .8125"

04-01-2011, 08:46 AM

#24

Dave M

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Quote:

Originally Posted by redbud35

The old rail fitting with the bypass hose looks like this pic. The new one has the blue thumb screw but no outlet for the bypass hose.

Attached Thumbnails

04-01-2011, 09:44 AM

#25

thirdchildhood

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Quote:

Originally Posted by redbud35

Just spoke with Mercury Racing, they said to drill the top plug to 13/16". Easy enough!

Quote:

Originally Posted by Dave M

You mean 13/32"? 13/16 is .8125"

Yeah, the service bulletin says .406" (13/32) and Merc Racing told you 13/16"?

Undoubtedly a typo but I hope no one does it!!

Last edited by thirdchildhood; 04-01-2011 at 09:53 AM.

04-01-2011, 01:16 PM

#26

redbud35

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typo!

04-01-2011, 01:54 PM

#27

TWIN-SPINS

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looks like to me,,,if you used your wide band air/ fuel ratio sensor inside the header,,,you would be able to tell your getting water inside the header when the sensor fails,,,rather loose an o2 sensor,, than an engine

08-17-2011, 06:15 PM

#28

rsscoggins

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Quote:

Originally Posted by redbud35

You can buy the plugs anywhere. The header rail takes a 3/4" plug and the tail is a 1/2".

Are these standard plugs or NPT? Can I get them in the plumbing department? Brass or what?

I want to plug mine this weekend and drill out the starboard restrictor. I will order the bushing/reducer for the blue plug but I want to do this immediately since I am reading about all the bad things that can happen with the CMI headers.

I did check and I do have the "new" style with the cool collar.