FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: fairlaniac on May 27, 2019, 04:13:18 PM
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I have a ‘66 center Oiler block cast as a side Oiler. Is there a list or diagram of Welch plug locations to modify for 1/4 NPT plug? How many? Also understand to leave the plug behind the distributor a Welch plug.
Thanks!
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I tap all of them, even the one behind the distributor.
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I tap them all too. 7/16 drill bit for 1/4"NPT. I tap the hole behind the distributor for a 1/2"-20 set screw. Just be careful not to tap too deep for the set screw or it'll be into the lifter bore.
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Is there a 66 center Oiler, I thought they were 63 and 64.
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After about somewhere in 1965 or so they went to the "side oiler" casting, but many non-auto applications (marine and industrial) were drilled as top oilers. Have seen some marine blocks machined on the side for mount clearance where the machining cuts some of the casting away where the side oiler passages would be.
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I tap them all too. 7/16 drill bit for 1/4"NPT. I tap the hole behind the distributor for a 1/2"-20 set screw. Just be careful not to tap too deep for the set screw or it'll be into the lifter bore.
Keep in mind that a straight thread won’t seal. I tap with a 1/4” NPT behind the dist and use the same plug as everywhere else. You will poke through the lifter bore but I run a hone through all the lifter bores anyway.
Whatever goes in that hole behind the dist has to go deep enough to not snag the dist when you drop it in.
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I tap behind the distributor for a pipe thread also, but I don't see a big issue with a straight thread in this location. The amount of leakage past the threads is going to be pretty small, and its internal leakage, so you'll never notice it. It might be easier to tap the straight thread in this location; usually with the pipe thread I have to go in a couple times and then test fit the plug to make sure the distributor drops in. Once, a long time ago, I installed the pipe plug without checking for distributor clearance. Silly me ::) Another one of those FE lessons...
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I tap them all too. 7/16 drill bit for 1/4"NPT. I tap the hole behind the distributor for a 1/2"-20 set screw. Just be careful not to tap too deep for the set screw or it'll be into the lifter bore.
Keep in mind that a straight thread won’t seal. I tap with a 1/4” NPT behind the dist and use the same plug as everywhere else. You will poke through the lifter bore but I run a hone through all the lifter bores anyway.
Whatever goes in that hole behind the dist has to go deep enough to not snag the dist when you drop it in.
Yessir, I am aware. Done a couple that way. I don't tap all the way through, obviously so the taper on the unfinished thread provides a little bit of a "stop" for the set screw. I put red loctite on it. I figure when it cures and solidifies, it will seal.... I also touch up the edge of that hole in the lifter bore afterwards.
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I tap behind the distributor for a pipe thread also, but I don't see a big issue with a straight thread in this location. The amount of leakage past the threads is going to be pretty small, and its internal leakage, so you'll never notice it. It might be easier to tap the straight thread in this location; usually with the pipe thread I have to go in a couple times and then test fit the plug to make sure the distributor drops in. Once, a long time ago, I installed the pipe plug without checking for distributor clearance. Silly me ::) Another one of those FE lessons...
I'd have to sit and think about that one some more. The whole engine is a situation of controlled leaks, but a lifter bore with oil pressure behind it will shoot out quite a bit of oil. Should be able to check it with a priming tool and the distributor out, I suppose.
The passenger side cam thrust plate bolt is a straight thread going into the lifter bore but it seems like a set screw would leak more than a bolt with a head on it......IDK???
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If the NPT tap is a bit long for getting into the lifter bore, get a 2nd and grind the end way down. Start with a regular tap, then go back with the shorty. Done that in other applications where a plug had to be just so, but not more so and work room was limited.
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I used Brent's method this time and it worked well. Although with my tap combo I had to open up the access hole a bit. Worked great though
I do think you could go one size smaller NPT, but having one size for all passages is convenient too.
As far as the set screw, I think it would work great too. Drill only deep enough to leave a small step and then finish with a bottoming tap. It would tighten against the step and seal as well as NPT.
However, in the end, Brent's method was real easy and worked well.
As a side, prior to doing that one, I used to double freeze plugs there, not sure if it added insurance, but it made me feel better :)
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Is this a 427 Center Oiler or a 390
Weren't 427's cept 68 all Solid lifter blocks = no hole behind Dist.
I'd be careful with threading that center main in the back since the relief valve is so close under it, could crack the wall between them with NPT if not REAL careful.
When I did my '62' 406 a couple yrs back I just went with the Welch plugs and staked them with sealant. Seemed to be more trouble than it would be worth to me. Oh I did tap the front of the main since you really can't mess too much up.....JMO
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I bought a 1/4nptf pulley tap for the hole behind the distrubitor. Makes easy work out of hard to get to hole. Bought it off ebay used American made in great shape for like $10. ebay can be great for hard to find or odd tooling. Also have a 1/2" bottoming pulley tap that is awesome for head bolts, can remove a bolt chase the thread even if the head is still on.
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When I was observing work in Roush's Prototype Shop, it was the practice inside the distributor hole to straight thread it and use a plug made from a cut-off bolt with a saw kerf on the cut end to be able to put just a bit of 'oof' into turning it tight. Worked like a charm.
KS
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I had a 65 top oiler it had four bolt motor mounts not sure when the side oiler came out.