Type 4 engine rebuild: take 3

[RWK]

No, you have to drill it larger so it does not move into the lifter hole, it shouldn't because pressure will push it away, but I would feel better if it didn't move.
Sorry, hole is 10mm you could use 11mm- 7/16 plug.
Alternately you could tap 1/4 npt past the rod hole,7/16 drill or 1/4 pipe reamer and put in a 1/4 NPT plug, if you already have the 3/8 NPT hole, that should guide a 1/4 npt pipe reamer and tap perfectly, you can do all by hand.
Any machine job shop or tool and die could do very easy also, 5 minute cut, half hour set up. Hole has to be reamed or the Oring won't seal, if you choose that method. IMHO the amount of threads that one has in that situ is not enough, you may get lucky maybe not, really not anyway to test before assembly.
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73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[orwell84]

Ok, I think I get it now.

The o-ring plug is not the best option because it won’t let the gallery plug thread deep enough.

You are suggesting ream and tap the end of the oil gallery. Put in 1/4 npt plug. The put in the 3/8 plug in the original gallery plug hole.

OR

Tap each end of the 10mm pushrod bore either 11mm or 7/16 tap and put in an 11mm or 7/16 plug, grub screw whatever...

Tapping each end of the pushrod bore seems like it would be the easiest.

Thank you

[RWK]

Here is a quick sketch, you can see you have plenty of room past bushing hole to plug or tap, If you have a 1/4 npt tap and reamer you can do it!
As far as tapping bushing hole,you can use a cover plate and gasket on pump side, don't see a need for anything on cam side if you block oil galley, and leakage will go to sump with spent cam oil.

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73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[raygreenwood]

[orwell84]

Thanks. I actually understood both responses.

I think I was confused by the npt measurements.

M11 is kind of an oddball size and actually don’t have a hand reamer or an non metric taps.

I may just farm this one out.

[raygreenwood]

[orwell84]

[raygreenwood]

[orwell84]

I decided to tap each end of the oil pump pushrod bore with a 7/16-20” tap and put in 1/2” long set screws at each end. I’m going to screw them in with loctite 271. This should plug the lifter oil gallery. I can’t see how it could cause any problems. It’s probably the easiest way as it’s just straight tapping. I couldn’t find 7/16” set screws anywhere locally but McMaster Carr had them. Wish me luck with my tapping.

[orwell84]

Ok, I think so got this figured out. Definitely going to plug the cam side of the pushrod bore with a 7/16” set screw. It should be easy to tap.

The fuel pump side of the pushrod bore is different. It’s quite deep and a larger diameter, 12mm. It is hard to fit a tap in there. There is a step where the bore narrows.

I came up with this idea based on Raygreenwood’s drawing of the modified bolt.

I could use almost anything that was the right size to fit the hole in the fuel pump boss, a 2” piece of rod, a bolt shank, a stud etc. I could tap threads into the pump cover and secure the bolt with that. Or I could just use the cover plate to hold the bolt in place.

Even if it the oil gallery leaks a bit past the bolt, it would end up going to the sump. From what I have read there is not a lot of pressure at the end of the oil gallery. The bronze push rod tube doesn’t seem to be that much of a restriction since it only partially blocks the end of the oil gallery.

[RWK]

Why not just tap the cam galley as discussed before, less work more positive results. Put a cover plate and gasket on fuel pump side, nothing needed on cam side, I can loan you the 1/4 npt reamer and tap if you don't have.
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73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[orwell84]

[orwell84]

I tried tapping the case with what I had on hand. Looks like it should work. Figured if I botched it I could always do the second gallery plug.

Fuel pump side:

I just need an M12 set screw.

Cam side:

I used a 7/16� set screw. I think it will work ok.

[raygreenwood]

Nice work!

The reason I do not like just using plugs.....I would rather use a complete bolt with a reduced cross section in the middle.....just like both of our sketches......is because you will need to peen slightly around that set screw/plug on the cam journal side to prevent it from EVER moving forward/inward and contacting the cam. Yes....I spoke to someone years ago that this happened to. Destroyed the cam and dumped his oil pressure on hiw 914.
How much do you REALLY trust locktight? I really trust it on something that I can also torque down TIGHT in the first place.

But if you tapped that hole from the cam side and did not tap all the way through to the gallery....so you can make it up tight....and then peen it on the cam side so its forever captured PHYSICALLY.....then you are good.

If you tapped the pug hole all the way tjrough to the gallery.....peen the cam side....and reach through from the outside with a long skinny punch and peen the inside too.

Ray

[orwell84]

I tapped almost to the gallery...basically the length of the tap thread so I can bury it pretty far from the cam. But yeah, it doesn’t bite like a pipe plug.

A set screw backing out that far seems highly unlikely. One would have to be cosmically unlucky to encounter this possibility.

All the same, the thought crossed my mind and I pictured exactly what you described even before reading your last post. So yes, I will be peening it every which way.

[RWK]

https://www.mcmaster.com/8798A12/
https://www.mcmaster.com/2538A32/
You can use a short/std. tap also. Shank dia. (.562) on the ones I have here are the same as the tap dia. of the tap drill size that was used to make your larger 3/8 galley plug tap, so it will provide straight alignment with the existing hole,making hand reaming and tapping accurate, as you can see from the dims. the reamer small end is just about the dia. of the galley hole so you will be able to cut and enlarge the hole without drilling.
The short std. tap will limit your thread depth, why I show the long tap, however the long taps sometimes have a smaller shank, best to know what size shank, surprised Mc carr doesn't state it, but its an industry std. .562.
_________________
73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[raygreenwood]

[orwell84]

[RWK]

Guess it depends on how deep they drilled, based on my quick measurement you can tap (for 1/4 npt) up to 50mm deep before you get too close to lifter bore, I would not go deeper with 3/8 tap there may not be enough wall stock deeper in, idk, the boss on the outside IS big enough for 3/8. VW cast it so they could put there style plug there.
If your tap drilled hole is deeper then 25-30 mm then you could go deeper with tap and seal PAST the rod bore, but then you will lose your sealing at the outside, ( tap will oversize it there because it's taper gets larger as you go deeper) pipe taper sealing usually takes place on only a portion of the plugs length depending on how it was tapped.
I would say if they drilled it too deep you cannot go the 1/4 npt route, and leave it as it is.
I have used green sleeve retainer (the hi temp one) locktite to seal pipe plugs, fills the voids created by less then desirable tapping conditions, i.e hand drilled inaccurate holes, crooked tapping, unable to apply enough torque, ect. most of the teflon sealers will reduce friction allowing plug to over torque sometimes cracking the weak cast case.
_________________
73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[orwell84]