ET: Engine (Twin) Push rod tubes

paulgoodson

New Forum User
VOC Member
Thanks gents. I’m not talented enough to make Mr Watson’s excellent tool so I soaked the top end in penetrating oil, removed the rockers and used a soft, wide flat punch to tap it out. Don’t appear to have done any damage so that counts as a success!
 

vibrac

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VOC Member
where can you buy the Grey Flash push rod tube Assy
Colin Taylor makes them, but watch the included angle, if you have packing under the cylinders as it wont do angles that stray away from standard unlike the normal tubes. I have a couple of them waiting for a cylinder height I can use them on
I also have taken off miriad standard tubes and like Bill I have just gently tapped around the top of the tube inside the cap with a long flat end punch once clear of the head jobs done.
 

Cyborg

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VOC Member
While you can’t get the same sort of grip as Robert’s modified vice grips and you have to remove any traces of oil, these can help. You can usually grip the tube enough to turn it and then slowly work it down. Not ideal, but you can’t do any damage either. Might mean cleaning the tube thoroughly and perhaps even some belt dressing on the rubber strap. No guarantees that it’ll work in every case.
( it’s a small version of the strap wrench)

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greg brillus

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VOC Member
Vincent pushrod tubes like everything on a Vincent........preparation is the key........how to stop this problem for the next time.........Ok.........Lets start with the size of the flange at the top of the tube.......make sure it slides easily into the head, sometimes they are a very snug fit.......this will cause problems, and so will the sealing washer immediately under the flange, this too needs to be a nice slip fit into the head. I place a lower seal washer on the tube hard up against the flange, then linish both down slightly so it slides easily into the head. i don't use the original lower seals anymore, they are too inconsistent in size, I use 3 mm "O" rings backed up with a 2.5 mm upper one to act as a packer, and it helps hold the gland nut where I want it. Make sure the top flange is flat and check them for cracks, the lower tube should be 0.750" in diameter or close to it........custom fabricated ones that are larger in ID than that are a pain, as they can jam down the crankcase hole. All the available parts from the VOC spares co work well (except the lower seals) all other types of seals, nylon type packers etc are a pain and cause grief as they generally melt from the heat, or the over tightening of the gland nut crushes them so much they become almost welded to the head, and then the tubes are difficult to remove. On final assembly use a small bead of sealant on the top of the flange, and a tiny smear around the bottom of the tube taper, this will help the tube slide into the "O" rings in the case. I have done many engines this way now with no real issues with leaks, and you should not need to overtighten the gland nuts, unless there is a problem you may have overlooked..........Always take the time to pre fit things before assembly, it makes the final assembly much less stressful and you tend to get good results. I use this method for many things on these bikes............
 

vibrac

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VOC Member
i don't use the original lower seals anymore, they are too inconsistent in size, I use 3 mm "O" rings
So Greg I think I will try this 3/4" ID O rings 3mm cross section with some silicone gloop or dry?
Ah! metric! should I use 19mm ID?
 

oexing

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VOC Member
Yes, get o-rings for this place. The great thing is with these, you don´t need to push down the pushrod tubes , the o-rings enable the tubes to move about in angle positions. So just unscrew the gland nuts , lower them to half height and pull off the head. The pushrod tubes can be moved about to clear the head recess. You´d have to shorten the tubes possibly so they don´t enter the smaller bore in the case recess. But then , no use for extra long tubes, just long enough for having the o-ring on them. Unless you have to revert to compression plates sometime later, so then you´d get new longer tubes - no big deal.
I made me alu pushrods 10 mm o.d. so had to have excentric o-ring adapters to get clearance in the engine case as the tube recesses in the case don´t align the positions of the rod ball cups in the followers. In consequence I cannot push down the tubes due to offset o-ring adapter but don´t have to do this. I can fit the heads even so as the tubes can move about angle-wise.

Vic

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greg brillus

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Always love your work Vic........On standard cases and tubes, use a 3 mm "O" ring i can't remember the exact specs, but you want the O ring to be a snug fit into the case recess, then with a tiny smear of sealant or similar, you should be able to push the tube down into the o ring and feel it compressing the sides of the O ring and form a good seal........generally you will end up with a gap at the top on account of the O ring being much smaller than the original seal.......this is where I also use a slightly smaller section O ring 2.5 mm in section above the other one and this acts as a "Packer" thus filling the gap and stopping crud filling the area. It also helps with the installation as it will hold the gland nut up and out of the way until the head/barrel are fully home on the studs. Using a small amount of sealant not only helps the tube seal against the O ring, it helps the tube to slide nicely into the O ring without it causing the O ring to "roll" or twist as the tube enters through it. Once you are happy and have successfully started the gland nuts into the head and the nuts nipped up, you can massage the other O ring down the tubes and into the case using a small flat screwdriver blade. I have never had any come loose or slip out of the recess, so I don't see any need for special machined holders or similar. The tubes need to be able to move sideways as the head/barrel settle into place, the O rings are perfect for this.
 

oexing

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VOC Member
Greg,
the reason for having these o-ring adapters (grooved) is to move the pushrod tubes one millimeter sideways more in line with the cups in the followers. I made 10mm alu pushrods and these would be very close to the smaller bore in engine case where you push down the tubes normally. So I shortened the tubes so as not to enter the smaller bore and have them sit one mm offset as shown in pictures. No real use to have longer tubes except for packing plates under the cylinder and still have a seal on the tubes. So I cannot push down the tubes for disassembling due to 1 mm offset - but I don´t have to ! I just screw down the gland nut and can lift the head as the tubes can change their angle in the 2mm o-rings below, no troubles. And yes, no collected mud on top of the tube seals here I hope.

Vic
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