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351C Oil Pump - Melling M84-A

Printed From: The Ford Torino Page
Category: Powertrain Specific Forum
Forum Name: 335 Series Engine Forum
Forum Description: 351C, 351M and 400 engines
URL: http://forum.grantorinosport.org/forum_posts.asp?TID=19204
Printed Date: 22-January-2021 at 10:42AM
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: 351C Oil Pump - Melling M84-A
Posted By: texanrebel
Subject: 351C Oil Pump - Melling M84-A
Date Posted: 02-November-2020 at 1:52AM
Is there a way to remove the welsh cap/plug to enable access to the relief spring to install a shim? Removed the pin...and I don't see anyway of removing it without damage & replacing.

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1972 Montego GT
1977 Mercury Monarch
1988 Ford Thunderbird Turbo Coupe



Replies:
Posted By: Rockatansky
Date Posted: 02-November-2020 at 10:49AM
the usual suggestion is to run a self tapping screw into the plug and work it out however you can. yes the pug will need to be repaired with weld to close the hole or replaced. they say the plug is reverse taper and can be hard to source replacements. IIRC i think i've seen people post that they've used a regular taper plug. some just push the original plug in farther and shim up to 1/8" max, and some say it makes no difference after the engine warms up the pressure will be about the same. makes sense because the spring controls a safety blow-off valve, not a regulator in the traditional sense. once the oil reached temp and thins out, the valve usually doesn't open again because the viscosity has thinned out. here's a thread from the old forum, use the search there to find many more. oiling is a big topic

https://www.tapatalk.com/groups/clevelands/viewtopic.php?p=15290#p15290" rel="nofollow - https://www.tapatalk.com/groups/clevelands/viewtopic.php?p=15290#p15290

i know for sure the size & part number for a reverse plug is in that old forum somewhere


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72 GT Ute
   


Posted By: Rockatansky
Date Posted: 02-November-2020 at 11:58AM
plug gets destroyed
http://www.tapatalk.com/groups/clevelands/viewtopic.php?p=152445#p152445" rel="nofollow - https://www.tapatalk.com/groups/clevelands/viewtopic.php?p=152445#p152445

Super Roo gives the size ... but verify it yourself!
http://www.tapatalk.com/groups/clevelands/viewtopic.php?p=21352#p21352" rel="nofollow - https://www.tapatalk.com/groups/clevelands/viewtopic.php?p=21352#p21352

listings for std taper plugs, concave or flat bottom
http://www.boltproducts.com/expansion-plugs.html" rel="nofollow - https://www.boltproducts.com/expansion-plugs.html

this might be it? but verify yourself!
http://www.summitracing.com/parts/mel-mpc-156" rel="nofollow - https://www.summitracing.com/parts/mel-mpc-156




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72 GT Ute
   


Posted By: texanrebel
Date Posted: 02-November-2020 at 2:26PM
Thanks Rock, I did a quick check on Tap Talk but had to go offline so didn't get much of a chance to look around. I figured it would be the drill hole & install screw route.
Once again, thanks for the info.

Billy


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1972 Montego GT
1977 Mercury Monarch
1988 Ford Thunderbird Turbo Coupe


Posted By: texanrebel
Date Posted: 04-November-2020 at 10:55PM
The Melling plug MEL-MPC-156 is a perfect fit. Just have to get something a little more robust to insert in the pin hole to secure. In the link the guy suggested a piece of solid fence wire.




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1972 Montego GT
1977 Mercury Monarch
1988 Ford Thunderbird Turbo Coupe


Posted By: texanrebel
Date Posted: 04-November-2020 at 10:57PM
To clarify...meaning the pin hole in the pump housing. I placed the old plug (with hole I drilled to extract) next to the new one for comparison.

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1972 Montego GT
1977 Mercury Monarch
1988 Ford Thunderbird Turbo Coupe


Posted By: Rockatansky
Date Posted: 05-November-2020 at 4:25PM
sounds a little redneck to me?

i've also heard of drilling the hole larger to fit a roll pin but thinking about it engine vibration & harmonics could cause any type of pin that's not mechanically trapped to walk out. never heard of the standard cotter pin failing either though


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72 GT Ute
   


Posted By: texanrebel
Date Posted: 06-November-2020 at 1:10AM
Agree, I just kept the original cotter pin

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1972 Montego GT
1977 Mercury Monarch
1988 Ford Thunderbird Turbo Coupe



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