I'm in the middle of preparing my 390 block. What is the proper size to tap the offshoot passages that go from the main gallery to the lifter galleries? I'm doing this just in case I run a solid (mechanical) lifter cam later.

As I understand it there are three opinions on this topic from what I consider reliable sources:

1) Steve Christ's book says something vague about a 7/16" tap, and shows same thread size for the new (deep) plug and the (shallow) one that replaces the soft plug.

2) On this site, I've seen someone recommend 3/8-24 set screws.

3) I need to clarify this, but I think Dennis at DSC Motorsport recommends 1/8" pipe plugs for those.

Are there advantages to either combination? How deep do you run the tap if you used a tapered pipe tap? What did thread size did FORD use originally on the 427 blocks?

Thanks in advance!

--Matt

1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108

 

Anyone?

1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108

 

I don't know exactly but just give it time. I know of a few here who can answer that question.

 

I just got a little more info. According to Dennis at DSC you're supposed to use 1/4-NPT threads. That seems pretty reasonable.

I read once (wish I remember where) that if you use the shell-type solid lifters you don't need to block the oil offshoots to the lifter galleries. But if you use the traditional "dumb-bell" -type you need to block them.

I'm using the Erson shell-type solid lifters from DSC.

So, I have questions on that:
Do I really need to block the offshoot passages at all? What is the downside of not doing it?
Will the cam lobes get better oil if I don't block them?

I'm hoping that DF and others will chime in with their experiences in this area, too.

Thanks in advance.

--Matt


1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108

 

I agree with you about the shell type solid lifters. But, plugging the oil galleries is so simple and so cheap and easy, you should do it. I use a drill bit to measure the hole and pick a pipe tap and plug size based on that. 1/4 sounds right but someone may have redrilled the galleries for improved oiling. I have been using tiny casting plugs to restrict oil to the cylinder heads. I don't see why these would not work in the lifter galleries and would be a lot easier to do. Just squeez them so they are a bit out of round and tap them into the gallerie with a flat punch.
William in Atlanta

 

 

Tap the small hole to 1/8NPT and the outer hole to 1/4 NPT but I dont know if this is rare or whatnot m but my larger holes were drilled to 17/32 from FORD so the tap woulnt work. I am now going to have to put in a setscre type of plug and not so shure of how it will hold up. Hopefully your will work with the 1/4 NPT tap. If you hav any more ?s let me know.

 

With the set screw type of plug, just use a bit of Loc tite. Should not back out. Also if you only tap it just a bit past the passage you are blocking. you should be a able to bottom out the screw. That will also help to keep it from backing out.


Scotty

 

That set-screw idea sounds interesting, but what did the original Fords use?

The combination of 1/8-NPT for the lower hole and 1/4-NPT for the upper sounds interesting, too.

Will it hurt anything if I don't block them at all?
I'm using shell-type lifters.

What did the original factory Fords use?

--Matt


1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108