Draft tube, oil leak, cracked end cap, pulled engine
 

I have a 261 cubic inch straight six out of a 1959 Chevy. What options are there to eliminating the road draft tube? I've heard about using a grommet and a modern PCV valve with tubing to the intake manifold, but worry that the small tubing may create back pressure on the engine. Thoughts?

Re: Eliminate draft tube options
 

Back pressure on the engine? Explain this please, as I am not understanding how that is possible when you get away from the guys at the spit and whittle club.

The way you mentioned is how Deve's Technical network shows http://devestechnet.com/Home/PCVInstall

The second shot is from this 2014 thread. One of the members wanted a road draft tube that had been set up for PCV. This is similar to how I have done a couple over the past 50 years. Cut the road draft tube off about an inch or so out from the upright part, Either put in your grommet for the pcv valve or set it up for a fitting to connect the hose to and hook it up. You can get a PCV valve that will either screw into the intake with or without an adapter or one that connects to the road draft tube either with a grommet or to a fitting that is in the end of that tube like the photo shows. https://67-72chevytrucks.com/vboard/...d.php?t=635148 I'm wondering if any of those guys have even been on the board lately. Checking, Midlifer is the only one who is still active on the board and Newfisher was last on here in 2022.

You have to change the oil cap for a breather cap so air can go in. if it has a regular oil filler cap.

This diagram is a V8 but shows that you want air flowing in, through the crank case and flowing out through the PCV valve into the intake to be burned and flow out the tailpipe. That usually eliminates the blowby from flowing out from under the truck in a cloud as you are trying to impress the hottie in the sporty car in the next lane with your cool truck.
https://hosting.photobucket.com/albu...720&fit=bounds

Re: Eliminate draft tube options
 

are you trying to get rid of the tube for aesthetics or are you trying to be nore eco friendly?
if using the original draft tube with a pcv valve in it you could plug the end at the bottom with a frost plug that has a small valve in it so you can drain out any residue that collects down there. it would look kinda stock still except for the vac line and pcv valve inserted further up the tube. that way the oil that comes out with the air will drop out in the tube and collect at the bottom for you to drain out. if there is a way for you to install some course stainless steel wool in the tube, before the pcv valve, that would also catch some oil but you would need a screen so it doesn't start to get sucked into the pcv valve.
mr48 prolly knows more about it than me cuz I usually just keave them stock or upgrade them to a modern engine rather than rebuilding etc.

Re: Eliminate draft tube options
 

Considering your motor is supercharged, a common pcv set up likely won’t be able to handle the volume of fumes.
You should look into a pan evacuation system.
Like this one.

https://www.moroso.com/crankcase-eva...n-system25900/

Re: Eliminate draft tube options
 

oh right, I forgot there is a cool old superchrger on this one.
rethink that pcv system.
are you wanting to eliminate the draft tube because it doesn't work, it's messy or you want to upgrade for some reason?

Re: Eliminate draft tube options
 

ok, here is the full story. A year ago I did see the article on Deve's website and bought his kit with a grommet, PCV, and stainless steel tubing over to my intake manifold. It enters the manifold at a tee fitting. The other side of the Tee fitting is a vacuum/boost sensor since I need to monitor that for the supercharger. Another sensor is affixed to the fuel pressure regulator to ensure that fuel pressure increases as normal vacuum at idle increases to boost pressure when the supercharger engages in higher rpm modes.

As I started test driving the truck, I was looking for any leaks given all the work done to the engine, transmission, brakes, and quick change differential. I noticed a drop here or there, which I would address but nothing major. Idling in the garage and/or the driveway produced no oil spotting (which make my wife happy) until I parked it overnight, then I noticed not a drip, but a puddle under the front of the engine.

I'll spare you all the details of where and how I looked for the source of the leak, but I traced it to coming from behind the crank pulley. Given all the customization that's been done under the hood of this truck, that entailed removing the drivers side outer and inner fenders, the alternator and AC compressor, to get the radiator out so that I could get to the crank pulley/balancer. Luckily I hadn't yet installed the grille.

The oil wasn't coming from the seal around the crank as I had surmised, instead it was coming from the bottom of the timing cover. Turns out, one of the bolts holding the bottom of the cover was stripped and the oil was coming out of the bolt hole. In the end, I used a tap to enlarge the hole one bolt size (fine thread) and eventually taped both of the holes of the timing cover and block. They are now held securely with Grade 8 - 7/16 bolts instead of the 3/8 that were there.

I told this story to a good friend about the oil leak and before I could finish my thought, he asked me "did you try to rig up a PCV instead of the road draft tube". When I answered yes, he told me a story about doing something similar to an old Merc engine and that the amount of blowby coming out of the draft tube opening created a problem with some of the seals on his engine creating an oil leak.

This is what got me thinking about setting up an alternative arrangement to the one I installed from Deve.

Re: Eliminate draft tube options
 

to be honest, my reasoning should have been to be more eco friendly, but alas it was to be less messy and an eyesore driving down the street.

Re: Eliminate draft tube options
 

After a morning and partial afternoons work, I can assuredly say that the draft tube setup isn't even partially responsible for the oil leak and neither were the two stripped bolts at the bottom of the timing cover........

After reassembling all the parts that I had to take off the truck in order to get to the timing cover, I started the truck up and a constant drip was coming under the front engine mount. I'm not sure how the stock engine was mounted, but this engine is mounted to the front cross member under the front center of the engine. The front of the oil pan just clears this mounting point by about 1/2 inch. I can see that no oil is coming from the oil pan edges (front or sides) but the drip starts at the back edge of this front motor mounting point.

Given that the radiator and crank pulley are reinstalled, its hard to completely see the timing cover, but the source of the oil doesn't appear to be from the front of the engine, although until I find the source, anything is possible.

The photo below shows the drip. If I run the engine enough and there is enough dripping oil, it will also seep through the motor mount bolts that are illustrated too.

Attachment 2321064

Re: Eliminate draft tube options
 

Maybe you could try some UV leak detector.


https://www.amazon.ca/ACDelco-10-504...80abc7e3263622

Re: Eliminate draft tube options
 

Thank you. Not a bad idea.

This afternoon, I backed the truck up from the shop to get it on the four post lift so I'd have a better view. I even fashioned a diaper for it to keep it from dripping. Needless to say, the diaper was not successful. The truck appears to be leaking more oil than before I worked on the timing cover bolts. I probably lost 1/2 quart just backing it out and pulling onto the four post lift. I have quite a mess to clean up......

Re: Eliminate draft tube options
 

Because I know that no one here is shy about expressing an opinion, I'm going to suggest my next moves and see what folks think.

I'm reluctant to take the entire front of the truck apart again unless I absolutely have to. So my thought is to unbolt the engine mount bolts, then use a bottle jack with a pieces of 2 x 4 on it under the front of the oil pan to lift the engine an inch or so, so that I can attempt to see where the oil is coming from. I've already ordered the dye and have a black light flashlight to attempt to spot the leak location.

1) put dye in the oil
2) start and run engine until I see the drip.
3) stop engine and unbolt the motor mount bolts
4) use the bottle jack and 2x4 to lift the engine under the oil pan
5) once the engine is clear of the mount, use the black light o look for the leak location.

Thoughts? Alternatives?

Re: Eliminate draft tube options
 

ok, as a journeyman heavy duty mechanic, I have seen my share of hard to find oil leaks. I have used the dye and several other methods of detection but here is what I would suggest to do after jacking it up and setting it on stands at the same angle it normally sits at when it is on the ground. this is going to assume you have already checked for an internal engine venting problem, the oil level is correct when hot, the oil grade is correct and not diluted, doesn't have a gassey odor like it is diluted, the fuel pump has been checked for any leakage at the vent hole and gasket, the water pump weap home is dry, all the hose clamps for coolant etc are tight and don't show signs of weaping, etc etc
-1- start the engine and warm it up to get the oil warm and as thin as it is gonna get
-2-let it sit for a bit to give any oil sitting in a seal lip or anything like that some time to finish finding its way out.
-3- if you have any loose paint or rust in the area scrape that off as sometimes it can hold the old moisture behind it. I use an old wood chisel for this and it works pretty well. wire brush the area if you can access it.
-4-check all the gaskets to ensure there isn't one that has a missing piece or has been overtightened and is squished out. look at the front crank seal as good as you can to see if there are any "clean" spots where the oil leak has washed away everything. also check the oil pan and front cover for wet spots that re-appear after wiping off. these can be caused from pin holes rusted through from the inside.
-5- spray copious amounts of brake cleaner on the area and blow it all dry starting at the top and working down from there. ensure to clean out any blind bolt holes etc. if you have any damp areas respray those. do the area around the crank pulley and any gasket surfaces as good as you can. keep an eye out for any spots that seem to re-wet themselves as those can be where the problem is.
-6-get some good lighting set up. personally I use a small LED penlight that is super bright and can fit into tight spots. have an inspection mirror handy and set yourself up to be able to crawl around under the truck. if you have a hoist, awesome. set it low enough so you can see up as far as possible on the engine
-7- start it up and let it run for a few minutes, long enough to show up any oil leaks, then shut it off and get under there with your light and mirror. if you find a leak keep working your way up until the wet spot dissappears and then check very carefully in that area.
-8- if still having trouble you can try sealing up the obvious leak spots, like the oil filler or vent cap and then apply a slight pressure with compressed air (and an air pressure regulator) through the dipstick tube. then recheck as above.
-9- I have used the dye as a last resort because I find once the dye is outta the leak it seems to spread all over along gasket surfaces and casting bumps and you spend more time cleaning the area and positioning the blacklight that you do actually looking. I mean, sometimes it is obvious, but for those hard to find leaks I always do the other way first.

if you have the engine jacked up be carefull starting it as sometimes the fan can interfere with the rad or hoses or wiring or a fuel line can get stretched etc.

Re: Eliminate draft tube options
 

there is a pressure feed to the nozzle that oils cam gear, it passes through the front plate/engine mount and is a common source of leaks between the plate and block

Re: Eliminate draft tube options
 

This is an awesome check list of things to do. Honestly, I've already done some of them, but not all. I will be using this list to guide me in my search. Thank you very much!

Re: Eliminate draft tube options
 

I've been scratching my head for several days culminating in today trying to find the source of the leak. Here is my dilemma that your post seems to address.

The front of the timing cover is dry (no obvious oil leaks). When I had the crank pulley/harmonic balancer off, the crank seal was moist but not a source of the leak and I think I would have seen a track of oil down the timing cover from that seal. So the front of the engine looks clean.

From under the car, the oil pan gasket is solid and show no leaks or weeping anywhere along its circumference.

The oil drip is coming from the center mounted engine mount, just below the front of the oil pan, yet the RTV that was generously applied to the front edge of the oil pan also is dry. I have touched paper towels to it and get no oil residue.

The leak seems to be coming from somewhere between the front face of the block and the back edge of the block where the front/center motor mount is (see my photo in a post above). Could this be where the nozzle that you mention passes through? How do I check that, let alone get to where it is located? Thank you for the idea.

Re: Eliminate draft tube options
 

There are two causes for engine oil leaks where the oil isn't under pressure from the oil pump. Something wrong with the gasket's sealing or excess pressure in the crankcase and internal spaces of the engine connected to the crank case such as timing cover and valve cover.

When I built my T bucket in Texas I put two breather caps on the valve covers and no pcv valve. = all the race cars had two breathers. Even with a fresh re-ring job on the 283 there was always some signs of oil around the breathers. Worse if I was driving at highway speeds for a distance and I drove it to school and work every day in good weather that summer. When I needed an engine in my 48 we pulled the 283 out of the T and sold the T and I put it in the 48. It ran like a bandit in the 48 and 80 mph was 3000 rpm. The engine always had oil coming out of the breathers and I had removed and plugged the road draft tube on the 61 engine. Dumb move by a 28 year old who should have known better but didn't figure it out until he read an article in a magazine about running a pcv valve system to alleviate the exact same issue I was having. 6 bucks worth of parts later I was in business and my oil mess went down a ton.

Road draft tubes work but they only work when there is a decent air flow going past the end of the tube and the end of the tube is meeting that air flow just right, that is using venturi effect to draw the fumes through and out the engine into the air stream but does nothing when the vehicle is sitting at a stand still except let fumes if they are being pushed out by blow by drift up around the front of the car. Older guys always can remember that car in town that had a cloud of oil smoke around the front of it at every stop light.

I'm not well versed in dealing with crank case pressure on a blower motor. I'm not sure the one guy that I know or knew is still alive or able to tell you. He drove a 29 Model A with a small block Chev with a 671 on the street and towed a camp trailer with it. He also crewed a AA fuel dragster at major meets.

Re: Eliminate draft tube options
 

Interesting reading here that might help. https://www.hotrodders.com/threads/p...or-not.445290/

Re: Eliminate draft tube options
 

Can't tell from the picture from underneath.
I think your engine will have this plate on it that is between block and timing cover, that is also the motor mount?
Arrow points to the plate
red circle is approximate location of oil squirter that sprays the cam gears, where it passes through the plate to the block can be a leak, runs down between plate and block.

Attachment 2321129

Re: Eliminate draft tube options
 

I think a normal PVC valve will seal under pressure - like from backfire, so it will probably be fine with some amount of boost and not pressurize the engine.

Even if the PVC lets boost pressure into the block, unless it badly overwhelms the breather I don't see there being enough pressure to blow out a seal or gasket, but if it allowed the supercharger to pump an air fuel mix into the block and that popped anything is possible.

Re: Eliminate draft tube options
 

when you had the front pulley off did you change the seal? sometimes hammering a new seal in can dislodge the tension spring on the seal lips and you don't see it unless you actually look inside there.
if I were you I would do all the check points and go from there. you may need to jack the engine up off the front mount so you can see the whole area.

Re: Eliminate draft tube options
 

Lots of good thoughts in all the posts above. I'll tell you what I know at this point. When running the engine yesterday (all while it was leaking) I removed the rubber hose that connects the Deve PCV kit that I installed where it connects to my intake manifold. Of course I had to plug the manifold port due to vacuum loss (and at idle and about 2000 RPM, the vacuum was substantial). With my thumb over the stainless steel tube from the PCV there wasn't a very noticeable amount of pressure. Given the vacuum at the manifold, I suspect there is a very good flow from the PCV to the manifold via suction rather than actual PCV induced pressure.

The supercharger runs in two modes, low idle and then there is a kick down switch at about 75% throttle that engages an electric clutch on the pulley to provide significantly more boost. At this point, I've rarely had the supercharger into high boost mode, all the leaking is occurring at idle or somewhat faster RPM, but not at high boost.

Lee's photo is very similar to my engine's timing cover (the shape of the cover is the same) and I do have the plate he is referencing and at least from what I can see up front, there is no leak, but it is directly behind that plate towards the middle of the engine that the oil seems to be coming from.

As for the pulley/balancer, I didn't pound it back on, I used a pulley/harmonic balancer installation tool along with my impact wrench to slowly drive the pulley onto the crankshaft. The timing cover and its seal went untouched and both are new in the past year as I was rebuilding much of this truck.

The wife and went to a Christmas party last night, that combined with my depression at having such a leak yesterday, I've decide to not work on the truck today while I summon up the energy and courage to get back out there tomorrow. My plan is to use my bore scope to probe around the places I can't see well (an idea friend at the party gave me), install some of the oil dye (on Tuesday when it arrives) run for a short while to circulate the oil and build up any pressure necessary to start the leaking, then jack up the engine an inch or so, and then use the bore scope and black light to search for the source of the leaking.

@leegreen I suspect that the fix, if it is that nozzle behind the timing cover, will require that I re-disassemble the front part of the truck to get to the timing cover, removed the timing cover and see if the nozzle passing though the plate attached to the block needs fixed/replaced. Is that the idea?

Re: Eliminate draft tube options
 

Sorry to hear you're down in the dumps because of your luck with the truck. Dont worry, its fixable. It sounds like what LG is describing may be your issue if you cant find another reason. Unfortunately taking it apart again means some redo of what you just did, by the sounds of it, but it will be easier this time because you've already been there so you know where all the fasteners are and what has to come off first etc.
I know where you are coming from. I just dabbed some sheet metal parts for a window surround. Some really hard angles and tedious labour. It turned out great but it is 1/16" to wide. Gotta redo that. Wife says it's only me who will know. I said yup. Gonna redo it.

Re: Eliminate draft tube options
 

Thanks. Yep, it's depressing to do, re-do, then re-do again the same tasks. As I tell my wife, no job is ever done until I've done it twice.....this will be third time.

I know what you mean about re-doing tasks that only you will see, as I've said before I have Automotive CDO (that's OCD in alphabetical order). If I know something isn't right it will bug the hell out of me until I fix it properly.

Re: Eliminate draft tube options
 

Found this video which illustrates what everything under the timing cover looks like, including the nozzle (squirter he calls it). I don't know if this view makes me feel better or worse given some of the things that he talks about that could produce a leak. The engine was completely rebuilt long before I acquired the truck, but it hadn't been run very much (if at all) since the rebuild.

https://www.youtube.com/watch?v=p2RAiCRke1I

Re: Eliminate draft tube options
 

it has probably close on 40 years since I have had one of those apart, but I think this is the gasket and that slot you see is pressurized oil for the nozzle

Attachment 2321291

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When I saw this, I went through the metric ton of gaskets that were in a box that came along with the truck and I found these. My question is, to replace the gasket behind that plate, won't I need to remove the timing gears from the crank and cam? That sounds like brain surgery to me, although several of the tasks I've undertaken in the past 18 months have also appeared that way. As it is said "what doesn't kill me, makes me stronger"

Attachment 2321296

Re: Eliminate draft tube options
 

probably the gears have to come off, its been a long time

you could remove front mount and spin the pump with a drill down distributor hole to help confirm the source

I think the front mount bolts through block would have originally had nuts inside the block, and threading the holes was a common shortcut to allow easier removal of the mount plate. you said that you retapped for larger bolts,
and it sounds like the leak has gotten worse since you started working on it....maybe some thread locker for sealant on those 2 bolts before ripping it all apart again?

Re: Eliminate draft tube options
 

Lee you may be onto something. I clearly had a leak, but not a fountain of oil, prior to my work on the bolts at the bottom of the timing cover. I just watched another video from the guy's that I posted above and saw the nuts that you are referring to in his video, what a dumb ass way to secure those bolts! Clearly the bolt that were previously used didn't have the nuts on them, which is highly likely given the previous owners rebuild that he had done.

When I tapped to the next larger bolt size, I did put a fair amount of RTV on the bolts as I installed them. I've been thinking that when I tightened them down I may have over tightened them, creating a larger leak if that plate is loose at all.

My plan is still to insert the dye, run for a few moments until I see the drip start, then look closer for a source. In my mind, I have already reconciled that I'm going to be disassembling the radiator, alternator, compressor, etc. to get to the timing cover. It's a mindless chore that I don't enjoy all that much, but its absolutely going to be necessary.

Thank you for all the input.

Re: Eliminate draft tube options
 

if it leaks from the cover, do yourself a favor and take it apart. fix it right and be done. clean all the surfaces properly, use the gaskets if they are good and replace them with new if they are not. use a little gasket eliminator on the gaskets if you want. rtv is the bain od most good mechanics as it is a bandaid fix usually and will eventually come off and leak. "the right stuff" silicone sealer is the ONLY silicone I will use now. too many come backs over the years to be bothered with any of the other rtv silicones. even then I only use it when I can't get a gasket or if the gasket needs a dab in a corner, etc. yes, maybe this will be a big job in your eyes, but better than never parking in a friends driveway because of the embarrassing spot left behind, or always cleaning up that spot in your own parking area, or having a really nice kinda one of a kind rig that has an unrepaired oil leak.
if those gaskets are in the box of stuff left over then it would seem the previous owner didn't take the time to redo that part properly. might as well just fix it right and carry on.

Re: Eliminate draft tube options
 

not sure on the gear removal thing but I think the crank gear gets to stay on because the steel plate has a big enough hole to get it past. the cam gear however.....
maybe just pull the cam.

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Pulling the cam.....oh my I wonder if I will sleep tonight...LOL. for me that is a big job, but if it is what is necessary then I guess I'll have to go there. I hope not, but guess I'll see.

As for the previous owner, who I didn't know, he had purchased several different boxes of gaskets for various projects that his wife just scooped up and sold with the truck. There are gaskets that aren't even for this truck in that box.

Gonna pick up some of "The Right Stuff" tomorrow, one way or the other. Thanks!

Re: Eliminate draft tube options
 

Dumb question. If I have to, can I pull the camshaft without taking the valve cover off, taking the rocker arms off ,and pull the lifters?

Re: Eliminate draft tube options
 

Pretty much gotta pull the valve cover to release the rocket arms and pull the pushrod so the lifters can be lifted up enough to get the cam lobes past the lifters. It may seem like a big overwhelming job but you just need to look at it as a bunch of little jobs placed back to back. Take stuff apart in sequence and place the parts in order of disassembly in cake pans, cookie sheets, cardboard boxes etc. Whatever you have that's clean and handy. I use a rag in the bottom so parts cant roll around and get mixed up. Remember that lifters wear to their cam lobe so keep those in order for sure. Same for pushrod in the lifter end and the rocker end so keep those oriented correctly and in order. Bolts are bolts but some may be specific lengths so always good to keep stuff set up in their order of disassembly. Have a large enough area set for storage so you can get the order of storage in sequence. Otherwise just think your way through and ask questions if you get stuck.
I still only use "the right stuff" sparingly. I also use a product called gasket eliminate which is made for a metal on metal seal. Still, if there is a gasket made I would rather use that. Cork gaskets are not high on my list of great items. Neoprene or formed silicone is good. Paper is usually better than cork in my book. Of course there will be those that disagree, lol.

Re: Eliminate draft tube options
 

it seems the increase in the leak coincides with retapping those bolts,

A couple ideas:
-drilling and retapping the block you might have pulled some metal between plate and block, now it won't pull tight

-did you tap the plate too? if both pate and block are threaded it wont pull tight


If you do have to pull it apart I'd give some serious thought to dropping the pan and putting nuts onto those bolts. 2 bolts on like 8" centres into 1950s cast iron holding the front of a 600 pound engine from flopping side to side. I'm think the factory may have had a good reason to go to the expense of machining a flat inside that hole for the nut to sit on rather than just threading the hole.

Re: Eliminate draft tube options
 

Lee, I hesitate to say that great minds think alike, because that would be giving me far too much credit. But as I lay awake last night going over the sequence of events that lead to the leak getting worse, I kept coming back to taping the holes in the cover/block. I realized that I was so concerned about getting shavings from the tapping into the oil pan that I may not have tapped deep enough and only ending up tapping the cover. While the bolt offered some resistance when going in, not an excessive amount.

Your thought that the tapped bolt into the block caused the two pieces, timing cover and block to not match up properly. Either from shavings and or as they threaded, they were not flush and that created more of a gap.

My plan is to put the florescent dye into the oil tomorrow when it arrives, run the engine to get a drip, then trace the drip and I highly suspect it will show around the bottom of the timing cover around one or both of those bolts. Then the disassembly can begin, including the balancer and timing cover. I may very well end up doing as your also suggest of pulling the oil pan. That will likely be a challenger as the previous owner used a cork gasket and what looks like two tubes of RTV to seal it tight.....oh boy can't wait...

Re: Eliminate draft tube options
 

before you start check availability of the required gaskets in a neoprene style for the pan, possibly a new front sels since it will have been disturbed a few times and they don't usually like that, pick up a small tube of "the right stuff" for the dabs in the corners, and then take it apart. before you install the pan get yourself some longer bolts the same size as the pan bolts and cut the heads off them, hacksaw a groove in the cut off end for a screwdriver to fit into and screw them into the 4 corners of the block so the pan can be slipped over them for good alignment. sometimes I use a stud actually so a nut can be screwed onto the end and the pan can hang there just below the gasket while you make sure everything is good first before pushing it up the last little bit. also, place the pan on a flat surface and use the round end of a ball pein hammer to sit over the bolt holes, then strike that gently with another hammer so the distroted area where the bolts have been sucked up can be made flat or slightly convex the other way. this helps to not cut the gasket in that area when the bolts are torqued down. I also use weatherstrip adhesive on the rubber end gaskets to hold them in place as i find the silicones and other liquid gasket type materials only seem to grease things up really good and then you never really know if the rubber part is intack or if it has squeezed out the one side or the other. it is like contact cement so it almost dries then you install it and the part stays put. some "right stuff" in the corners and good to go. sometimes I use the aviation form a gasket stuff along the block rails to hold those gaskets in place, it never really dries dut holds the gaskets pretty well for alignment, espcially if you have a few studs placed along to hold things where they should be.
LG could be exactly correct with his theory on your bolt holes. if you drilled or tapped the holes there is likely a burr on the inner edges of the flat steel part that is always left behind during these processes. it is likely not allowing the 2 parts to sit down flush against themselves.
when you get after it post up some pics of the leak found and also the tear down and repair. there is always somebody looking, now or later, that has the same questions or problems.

Re: Eliminate draft tube options
 

If you tapped the cover and the block you will never be able to pull it tight, you need to drill the cover slightly oversize so it can pull tight. Use a drill stop or eyeball it but that hole needs to be bigger than the threads on the bolt

Sounds like dropping the pan is going to be required one way or another. You could consider doing that first, properly tap those holes or just drill them out and put on nuts from inside. Then put the pan back and fire it up to check the leak. Worse case you have to drop the pan a second time if you go the nut route - can see why tapping the block is attractive.
But you have a hoist right? And a spacious clean shop if your pictures are accurate - I am green with jealousy!

There are some tricks you can use to try and keep all the threading swarf from falling into the hole. I'm not sure I'd be confident enough to risk it with a bypass filter or no filter at all? and a valuable engine.

Re: Eliminate draft tube options
 

Excellent input, I appreciate it.

The reason I'm even reluctant to drop the oil pan is this. When I first got the truck, I knew the engine had been fully rebuilt, but not run for years (other than an occasional crank or two). I wanted to see the bottom end of the engine and inspect the oil pickup. I took all the pan bolts out (kept the corners in but very very loose) and tried to get the pan off the engine. When I said the previous owner was generous with his RTV, I wasn't kidding. The pan seemed glued to the engine with an edge of cork gasket and plenty of RTV showing along the edges. In the end, I decided I really didn't need to take the pan off and ended up bolting it all back up.

Now of course if I need to take the pan off to get to nuts for the lower timing cover bolts, I have no choice but to wrestle that pan off. Any good tricks for getting it fully removed will be appreciated.

Re: Eliminate draft tube options
 

Given that it is a 1959 261 cu/in engine, it has full oil filtering with a spin-on filter.

When I tapped the holes, I coated the end of the tap with grease (my trick for getting the shavings to not fall into the pan)

The shop is indeed a clean one (epoxied floors) and boy did I have a mess when I backed it out of a parking spot on the shop floor and moved it onto the four post lift. Holy crap I used a lot of shop rags and towels......LOL

I'm going to need new gaskets for the timing cover and the oil pan. The ones I posted a pic of are very thin paper and that doesn't give me much comfort. The ones I have for the pan are old cork ones that I honestly don't trust. Where is a good place to find quality new ones?

Re: Eliminate draft tube options
 

Is Fel-Pro a good gasket brand/type for the timing cover and oil pan? The pan gasket looks to be cork with four rubber sections for the ends. The timing cover looks to be the same paper that I already have.