Pin holes in rocker cups

[CAP'N BOB]

I have a 1947 FL that has always had a leaking problem at the top end. I am trying to fix that. I've looked at a number of posts, one or two of which mention pinholes in the intake rocker cups. I pulled my front rockers to look at the front intake cup, and there is not a pin hole there. GEDC4787.jpgHave not taken the rear apart yet, but am fairly certain there is not a pin hole in that one, either.

Is the pin hole a fix that some of you have found to help and you have made the hole, yourselves? If you have made the holes yourselves, what size do the pin holes need to be and where should they be located? I saw a photo from Fabe dated 3/4/2014 and I think I see the pin hole, but must be honest and say, I'm not sure I see it, so can use the guidance.

Thank you.

Bob

[knuckleheadtim]

The pinholes were factory, and are about.055" in diameter. The front intake and rear exhaust tins are the same stamping, but the intake has the pinhole and the exhaust has a noticeably longer tube on it the keep it away from the exhaust pipe so the oil doesn't bake in it. It's not uncommon to see them switched, or the wrong ones installed. Some early rear exhaust tins may not have had the long tube, or they were intakes and not drilled. The rear intake cup is drilled
similarly.

IMG_2910-001.JPG

The one you show is a rear exhaust judging by the long tube, and someone drilled the hole in the wrong place.

[gharper]

I drilled small, maybe 1/16" holes on all 4 covers, each at the highest point of the cover, about centered lengthwise. The purpose is to break any vacuum that may occur in the "sealed up" cover. This will allow oil to return down the pushrod tubes easier and keep the oil level from getting too high in the cups. It helped considerably on my 39.

[CAP'N BOB]

That partially explains why this has always leaked and smoked from the oil burning off. I've never had cause to take the heads apart, so these were this way when I bought the engine way back when and put it in a frame.

Silly question, but I'm going to ask, anyway, do you recommend I take the heads off, dismantle them, put the tins where they belong (or even new tins), or just drill the .055 hole? I guess it sounds lazy to do the half-way approach, but, it seems to me taking the valves loose and/or out gives me the need, or at least potential need, to have the valve seats worked, etc. That is probably the best approach, but I do not have the ability to grind valves or install guides, and that. I can put things together once the work is done.

Ah, crap, I cannot leave it wrong, now that I know. I'll just bite the bullet and take the heads off and have them rebuilt by someone competent to do the work, if needed. Any recommendations for me on what to be careful of, since this is wrong, now? And, any potential in your experience that I may be able to dismantle the heads and get them back together without new valves, guides, etc? Any recommendations of competent knuck head re-builders, if it comes to that? Would you trust S&S to rebuild them?

Oh, the spot that looks like hole, center rear, is a bit of sealant, as it turns out, which I have now removed.

Thank both of you for your help, on this.

Bob

[knuckleheadtim]

You definitely want someone intimately familiar with Knuckle heads, as there is a multitude of things that can be done wrong on them. Valve height, travel, and guide clearance are all critical, and severe damage can result if they aren't right.

I like the Kibblewhite nitrided valves and cast iron guides. Stock seats are Stellite, and don't need to be replaced unless they're cut down too far. I run .0015" clearance on the intake guides and .003" on the exhaust with a valve stem height at 1.560. A nice upgrade is Kibblewhite OS intake valves and Sportster seats, but they're a little pricey.

[CAP'N BOB]

Have the rear intake tin cover off, and sure enough, there is a nice little hole in the cup, just where you show it to be.

One of the people responding said they had put a pin hole in each cup. I was taking the heads off, but the rear head "nuts" came off the studs on 4 of the 5 bolts/studs. That's when I decided to take the cover off the rear intake to see if the hole was there. I can try to jam nut the studs and get them out, then pull the head, but what do I gain if it is ok to have the hole in the rear exhaust cup? I know the oil line is too long, but if it works, it works, and has for at least the last 20 plus years, though with top oil leaks. If I continue on with removing the studs and head (may not have any choice, since this engine is in a 1958 frame that I had to modify the seat post on to get it to fit, so it is VERY close) and find the hole but do not want to pull the valves, am I going to cause myself trouble down the road?

[CAP'N BOB]

That makes it easy: No hole in rear exhaust, probably correct cup; Hole in rear intake, just visible in the photo; No hole in front intake; No hole in front exhaust. Was able to get the covers off without removing the heads, so no jam nut, this time. I should be able to get the head bolts torqued right.GEDC4789.jpgGEDC4790.jpgGEDC4791.jpgGEDC4792.jpg

Current plan, put the head bolts back on, AFTER get the tin covers back on the rockers. Drill a .055, or as close as I can get a drill bit, probably the 1/16" mentioned. Button the top end up. God willing, replace the oil pump shaft bushing and have it straight, put it all back together and running by Easter.

Always good to be optimistic! :-)

If any of this sounds unrealistic, Tim and anyone else, please let me know.

I will keep the info on valves, etc, Tim, in case I must pull this engine down in the future.

Thank you for your help, and standing by for further input from you, as you think I need, before I get too carried away with the sheer relief of what I just found!

Bob

[knuckleheadtim]

Give it a shot, it's not like you're doing anything irreversible!

[CAP'N BOB]

It's only time! And, I have the rest of my life. :-)

[rousseau]

Bob
Gharper was dead on. The tins must be "vented to atmoshphere" in order to drain. Also,make sure the push rod tube seals are installed proper and sealing good. A poor seal here will also cause the tins not to drain.

[Rubone]

The tins must be "vented to atmoshphere" in order to drain. Also,make sure the push rod tube seals are installed proper and sealing good. A poor seal here will also cause the tins not to drain.

Just to clarify something. The tins do not "drain". They are emptied by vacuum and the oil is drawn from the bottom of the tins to the rocker box and then down the pushrod tubes, tappet guides, and into the cam chest. All the related components must be air tight except the highest point of the tins.H-D only did the intakes since they were the highest and broke the hydraulic lock. So the tappet guide seal, the cam cover, the tin to head connection (often cracked), the return tube to tin cup connection (often loose) and the pushrod tubes must all be sealed in order for the system to work. Panheads drain, Knuckleheads suck...

[CAP'N BOB]

Thank you.

Have purchased new pushrod tubes, new corks, have the S&S breather gear they designed to provide more "suck", new bushings arrived for the oil pump shaft, last night, may get there.

Bob

[CAP'N BOB]

Thank you, Robbie.

The tins are old, so it is possible I will be back in here if they are cracked. As of right now, I will drill one hole in the front intake, no others (rear intake has its hole). Once I get the parts all back in their rightful places, I will start the bike using a gas bottle, not the tanks, so I can observe any leaking anywhere.

Will post results. And, more questions, of course!

Bob

[CAP'N BOB]

GEDC4794.JPG
Brand new .055" intake tin hole! I had a .055" drill bit and it worked. I tried to replicate the position of the exhaust intake tin hole, so it is just aft of the first screw hole. Hope I did not make it too low, but time will let me know that.

Rear head back on and torqued. Put new rocker arm oil seals on front and rear. New ones are thicker and tighter, came from V-Twin.

Froze the oil pump shaft bushing for 2 hours in a bath of dry ice and acetone. Drove it in with a piece of wood and hammer. Not easy, but it is there and "warming up" to the temp of the case. Seemed to go in straight, not cocked, this time. Reaming, as needed, coming up.

Off to put the front head back together, then ream and get the oil pump shaft smoothly turning and put the gears back in.

Thank all of you who have responded for your help. Tim, you have been very informative.

Will update progress when back together.

Bob

[CAP'N BOB]

GEDC4797.jpgGEDC4798.jpgGEDC4799.jpg

Plugged hole with drill, tap and set screw to help ensure it sucks!

Bushing in and shaft moves freely.

S&S bushing was .533 OD, .424 ID and 2.540 long, prior to freezing with dry ice and acetone for two hours and being pounded in with a hammer over a piece of oak. Did a little reaming, worked up to .423, which is interesting since the stated ID of the bushing is .424. The shaft is a righteous, measured several times, .4215, so the bushing is .0015 over but I feel good about that. No slop in the shaft. Have not put the pump on so do not know how that will be, but also do not feel bad if I need to ream to .424, since the bushing was originally that ID. That would put me at .0025 over and maybe that is too much. Better too loose than too tight, right? Or am I deluding myself? In any case, I'm done for today so if I'm way off base with any thoughts of reaming it more, please save me from myself! I DO NOT want to take this bushing out! :-)

Thank you, all, again, for your help and forbearance!

Bob