FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: djburton on March 11, 2024, 07:17:33 AM
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I'm prepping a mirror 105 block that has all screw in plugs except the one in the distributor hole. I knocked the cup plug out for cleaning and would like to put a screw in plug in that location. The factory drilled the hole,stopping about 1/16 inch from the lifter bore,leaving a ridge with the ID of the gallery bore. If I run a tap in there it will surely mess up that ridge. Should I go ahead and tap it as is,drill the hole all the way through with a 7/16 drill and tap...or leave it as is and stick another plug back in. It's a nice standard block and I don't want to screw it up.
Thanks!
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Personally, I usually leave that plug behind the distributor, a press in cup plug. Considering the challenge of tapping that hole correctly, without going in too deep and having the pipe plug protrude into the front lifter bore, or not deep enough , and it interferes with the distributor body, not to mention it is at the end of the lifter feed passage, so the oil pressure is likely lower there, I feel any potential benefit is outweighed by the potential problems. I can say that I have never had a properly installed cup plug in that location ever leak or fall out, in close to 50 years of playing with FEs.
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I'm prepping a mirror 105 block that has all screw in plugs except the one in the distributor hole. I knocked the cup plug out for cleaning and would like to put a screw in plug in that location. The factory drilled the hole,stopping about 1/16 inch from the lifter bore,leaving a ridge with the ID of the gallery bore. If I run a tap in there it will surely mess up that ridge. Should I go ahead and tap it as is,drill the hole all the way through with a 7/16 drill and tap...or leave it as is and stick another plug back in. It's a nice standard block and I don't want to screw it up.
Thanks!
Don't worry about the ridge, just run a 7/16" drill through to the lifter bore, tap it 1/4 NPT, then come back with a lifter bore hone and clean up where the drill came through.
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What Brent said, I went to change out my distributor in my 428 ,pulled the old one out and looked down and saw the plug sitting there, they all get tapped after that.
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I find you have to thin the dist hole side of the plug as well as dress the lifter bore.
Some plugs are longer than others so that makes a difference also in the depth of threads.
It requires a deep cut thread, be patient.
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A short Pioneer plug will do the trick without having to cut it/shorten it. Tap until it will sit below flush and roll on.
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The type of pipe plug that you will need, is called a "Dry Seal". Edit: The dry seal plugs, had a little different taper and that's why they don't go in as far.
In a critical area, you need to use a pipe plug thread gauge to be sure that the thread is deep enough but, as shallow as possible. The gauge has a flat on it, across 3 threads. When you reach those threads, the first is min, next is nominal and the last is max thread depth.
You may not need to drill all the way threw if, you use a pipe reamer. It tapers the hole the proper length for the thread.
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The type of pipe plug that you will need, is called a "Dry Seal". Edit: The dry seal plugs, had a little different taper and that's why they don't go in as far.
In a critical area, you need to use a pipe plug thread gauge to be sure that the thread is deep enough but, as shallow as possible. The gauge has a flat on it, across 3 threads. When you reach those threads, the first is min, next is nominal and the last is max thread depth.
You may not need to drill all the way threw if, you use a pipe reamer. It tapers the hole the proper length for the thread.
You don't want a "Dry Seal" plug. You want the plug to go in deeper in this area, not shallower.
Pioneer makes all kinds of different pipe plugs for engine scenarios. Tall, short, drilled, etc. The short Pioneer plug is the best choice here, don't have to cut them down, just tap the hole and screw them in.
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Brent, you apparently don't know what a dry seal plug is.
Your short Pioneer plug, is most likely a a dry seal.
A pipe plug thread gauge will keep a lot of people out of trouble in tapping for pipe plugs.
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Brent, you apparently don't know what a dry seal plug is.
Your short Pioneer plug, is most likely a a dry seal.
A pipe plug thread gauge will keep a lot of people out of trouble in tapping for pipe plugs.
They have different names, but I was going off of this description, that you typed in:
"The dry seal plugs, had a little different taper and that's why they don't go in as far."
You want them to go in further, not go in as deep.
Could be that we're talking around each other. Or maybe we're not. I really don't care either way.
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The type of pipe plug that you will need, is called a "Dry Seal". Edit: The dry seal plugs, had a little different taper and that's why they don't go in as far.
I may be wrong but as I recall the major difference between NPT vs. NPTF thread was at the root of the thread of the NPTF was of greater diameter (at any equivalent point in the length of thread) and flatter than that of the NPT thread, this to cause a crowding and displacement of material in crest/point the adjoining thread profile in the tightening this which provided a more effective "dry-sealing" characteristic. :-\
Of coarse, one is "suppose" to use the proper corresponding tap for the intention, NPT vs. NPTF. :)
Scott.
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I can testify to going slow and careful when you tap that hole behind the dist.
I forgot to drill thru first, so the tap bound up and I snapped the tap off in the hole when I did my 428. ::)
I can tell you I was sweating getting the broken tap out!
Near impossible to drill a broken tap!
Very limited room to work!
I did get it out but I buggered up the hole so that I had to go up to the next size.
I got it done but it was not a fun time. :( Lots of cussin' involved....
(read my sig)
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Some 1/4" pipe taps.
I like to use sharp ones. ;D
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By "The dry seal plugs, had a little different taper and that's why they don't go in as far." I was referring to the depth, not going so far.
Anyway you should use "Dry Seal" plugs for all gallery applications.
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You may not need to drill all the way threw if, you use a pipe reamer. It tapers the hole the proper length for the thread.
I'll second that on using a reamer. While not necessary in most instances with the stock FE blocks, it does make the job easier when tapping the holes. Just goes "smoother". I also found (with the holes by the lifter bores that get plugged or piped) that a reamer lets you know immediately if you are dealing with an overly large hole to begin with.
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I do like Rory - and just leave that one as a press in plug. Unlike others it cannot really go anywhere (distributor in in the way).
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I'm not sticking my head out on this one!! 8)
It seems that there isn't a bad answer here as long as you're methodical...
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Thanks gentlemen! That clears things up lol. Anyway, I guess I'm on a mission to do the screw in deal. I do have the Pioneer plugs and they are shorter and more flat on the end than the original plugs that were in the other holes. First thing,found my tap was too short,nobody in town ever heard of the extended reach variety. Ordered one online...they don't give them away. Update to follow...
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Theoretically the press-in plugs should work just fine; after all, in practice they seem to have worked for the O.E.M. just fine, with perhaps what would have to labeled only as rare instances where one might have blown out. But at this point in time as having to be replaced, I believe beyond the issues of not being installed correctly the probably bigger issue leading to failures is that the product being utilized is just not of the quality of that as originally. And therefore with the increased instances of failure (after the O.E.'s product has been replaced) this has caused the acceptance in the practice in the utilization of the screw-in fixturing types.
With that consideration, and the fact that once I had an FE that I was tearing down, in which the distributor was lose but just wouldn't pull up and out of the block; after an untold amount of time and effort trying to extricate it, as it turned out the pressed-in gallery plug behind the distributor had dislodged, which then proceeded to provide a blocking function for the removal of the distributor! >:( I thread all of them! ;)
Scott.
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While working on an engine at Roush's Prototype Shop, I learned that the common practice there was to make a plug from a cut-off fine thread bolt. The end of the bolt was finished to make full contant with the step and the outer end of the plug so fashioned was simply slotted so as to be inserted and tightened with a screwdriver.
To my mind, a threaded plug is superior since it can't be displaced by pressure. Why not be sure?
KS
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Thanks gentlemen! That clears things up lol. Anyway, I guess I'm on a mission to do the screw in deal. I do have the Pioneer plugs and they are shorter and more flat on the end than the original plugs that were in the other holes. First thing,found my tap was too short,nobody in town ever heard of the extended reach variety. Ordered one online...they don't give them away. Update to follow...
I enlarged the hole on the front of the block to allow using a 12pt socket with an extension on the reamer and tap. I did that after deciding that it wouldn't be detrimental to do so. With that being said, if my understanding of enlarging the hole on the front of the block is incorrect and anyone knows of any issues it could cause, please let us know.
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They make extended length taps so that you don’t have to do that. I have a nice sharp 6” 1/4NPT tap.
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Well I'm stumped. I can not find the tap and I did not drill the hole bigger.
I can not remember what the Geny looks like either. I must be getting demented. ::)
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They make extended length taps so that you don’t have to do that. I have a nice sharp 6” 1/4NPT tap.
Understood on the extended length taps. As the op had noted, they are more $$ and not as easy to obtain from a local store which led me to enlarging the hole since I had everything on hand to do that. I also liked the idea of being able to use a hex socket for removal and installation. I'll run with changing the size of the hole is of no consequence since nobody has stated otherwise.
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I've used a 1/2"-20 set screw before with success. Just go very slow with the tap/not all the way through, so there is a slight shoulder in the threads for the screw to stop at. A couple drops of red loctite for assurance. I do use a 1/4 NPT plug with the aforementioned extended length tap now. Works like a charm. I used the "NPT" tap with a extreme press. "NPTF" plug from McMaster Carr. Those plugs sit slightly further in than a "NPT" in the same hole. Plug seals just dandy as well.
(https://i.postimg.cc/4yypsJDD/20230827-132114.jpg) (https://postimages.org/)
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I used a 3/8 extension backvards on a regular lenght tap,
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Holy! I got the short end the stick for sure. The square end on my tap is 7/16 and the hole on the blocks were too small to fit that end of a 3/8 extension. :o
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RE tap too big for 3/8 drive:
Can you use use a 1/4 drive socket?
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Can you use use a 1/4 drive socket?
IIRC, no since the hole wasn't quite large enough for a 1/4 drive socket either. I have one other block that hasn't been touched. I would have to check the hole on it to be certain though.
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Success! You definitely have to go deeper with the tap than you would think. Half a turn at a time...not a whole lot of room for mistakes. The ridge has to come out as the tap extends into the lifter bore quite a bit. Deburr the hole and a couple turns with the hone in the bore and I'm done. Hey,if any of guys are inclined to do this and need a long tap,this one on eBay for 21 bucks. Fits perfect in the outside hole so always starts straight.
https://www.ebay.com/itm/313032873536
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Late to this game, but I also drill and use a long tap like Brent. In fact, he drove me to do it this way many years ago. The key though is a good quality tap and it'll cut like butter.
Although it feels spooky as you tap, there is plenty of depth there, you'd have to drive the end of the tap into the lifter port deeply to go too far. I just go a few turns, try the plug, and repeat until it looks good and I slide a distributor housing in to avoid surprises.
I also have not seen any common NPT plug that wouldn't work. There is plenty of depth to clear unless you have some sort of crazy plug I haven't seen.