Pushrod engagement

BillyKnight

Forum User
Non-VOC Member
Hello Vincent people,
I am fiddling about with my newly acquired 54 Comet, you may have seen my other post wanting one, well I succeeded!!
How do you make sure the pushrods are engaged on the followers? Its all a bit tight in there at the top, but not at the bottom!!
I had a nightmare today and managed to successfully ruin the inlet push rod after I put it back in, seemed OK then just turned the motor over and it made an odd noise. I could not fish it out, it all ended up tangled in the camshaft, fortunately only damaging the push rod and not the cam.
I had to open up the timing chest and remove the plate gizmo to get it out. All back together now, except for the push rod, but I do not want to repeat this calamity..
I removed the push rod initially because there was about 3 or 4 thou slop in the tappet but I could not rotate the rod, wanted to check all OK before just tightening it up. Maybe it was slightly bent before I attacked it, no doubt now. Toast!
On a postive note everyting in there looked perfect, so at least I feel confident in the machine, if not my own mechanics!!
Advice gladly received.
Billy.
 

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david bowen

Well Known and Active Forum User
Non-VOC Member
Push rods

Put rods in before you put the T cover on you can just see the followers behind the cam wheel with a good light
 
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Tom Gaynor

Well Known and Active Forum User
VOC Member
Pushrods

I rode my newly rebuilt twin about 80 miles before it became clear that, while it was still FAF (fast as ...) something was wrong. What was wrong was that the front inlet pushrod had jumped when the inlet valve hesitated, and had wedged where 1) it did no damage - a miracle, I later thought, and 2) the front pot still worked, albeit not very well because the inlet valve was stuck partially open. When I fixed the problem, I discovered what Vincent's did. EFTF. Even faster than...
My suggestion is that when you think everything is OK, observe through the rocker caps that it really is when turning SLOWLY over on the kickstart. Then take it for a blatt, and observe again.
I make no great point here, in fact I'm not even sure this isn't superstitious nonsense, but am now wary of fitting new pushrods to old followers and rockers.They may need courtship time before full intimacy...

Tom (just a romantic at heart)
 

BlackLightning998

Well Known and Active Forum User
VOC Member
Some thoughts...

I rode my newly rebuilt twin about 80 miles before it became clear that, while it was still FAF (fast as ...) something was wrong. What was wrong was that the front inlet pushrod had jumped when the inlet valve hesitated, and had wedged where 1) it did no damage - a miracle, I later thought, and 2) the front pot still worked, albeit not very well because the inlet valve was stuck partially open. When I fixed the problem, I discovered what Vincent's did. EFTF. Even faster than...
My suggestion is that when you think everything is OK, observe through the rocker caps that it really is when turning SLOWLY over on the kickstart. Then take it for a blatt, and observe again.
I make no great point here, in fact I'm not even sure this isn't superstitious nonsense, but am now wary of fitting new pushrods to old followers and rockers.They may need courtship time before full intimacy...

Tom (just a romantic at heart)

I'm no expert as members will know, but have had a little experience of some of the problems that a Twin can develop with pushrods. I had a "stuck" pushrod (would not rotate with fingers) and there were two camps of thought - one was to leave it and ride the bike, the other to open up the timing chest and have a look. I opted for the former, I pulled the pushrod and mounted it in an electric drill and polished the end with fine emery paper and t-cut/solvol mixture - it slotted back into the follower nicely and all was well. Apparently the pushrods are intended to "work harden" as I understand it and this can lead to the head splaying slightly and becoming snug or tight in the follower cup. However, mine actually was because the cams and followers were in the process of eating each other, getting good and hot in the process and it was this heat that was distorting the follower cup and trapping the pushrod end.

So - the good news is that you've opened it up and had a look. Keep an eye out is what I'd say and enjoy riding the bike. As for fitting them and making sure they seat with the timing chest shut up - well I used care, a penlight torch, a magnifying glass and several attempts to "feel" it up and down into the seat.

Best of luck and look forward to meeting up at some event and seeing you on the road.

Cheers
 

Tom Gaynor

Well Known and Active Forum User
VOC Member
Pushrods

If we meet, be it not by the side of the road, with one of us on their knees.
Stainless steel pushrods work harden. Later silver steel ones, don't. Once hardened, they're as hard as they'll ever be. (Heat to cherry-red, and quench in water. As for clutch pushrods.)
However, your original rockers and cam followers will have been formed, to some extent, by the pushrods they mated with (just like humans, really) so changing partners is a potentially fraught business. Just like...
Tell the difference with a magnet: if it fails to pick up, you've got stainless. I now have a mix. I guess that once they've "settled in" there's no difference. Just like...


Tom
 

david bowen

Well Known and Active Forum User
Non-VOC Member
Ouch

Billy I was telling my wife about your problem and what I had said, she said tell him to get a Dentist mirror I said why she said how do you think the Dentist gets the drill into the hole in your tooth.
 

BillyKnight

Forum User
Non-VOC Member
Thanks everyone for the response, I can see that a dentists mirror could be handy!
I think I will order two new push rods, plus a timing cover gasket. I'll pull the cover off, double check its all clean etc in there the fit the new rods so I can see them engage properly with the followers.
Then I shall re-assemble very carefully and see how it goes, turning it over slowly and re-checking the clearance etc before I start it properly.
Not such a drama. The old push rods can be picked up on a magnet so I guess they are not the original stainless ones.
Thanks again, also looking forward to meeting you lot. Lets hope its not by the side of the road!
Billy.
 

john998

Well Known and Active Forum User
VOC Member
Push Rods

Hello,
Just a thought, some stainless steels are magnetic, not sure which Vincent use. Only have one unemployed push rod to test, it looks like stainless, it is magnetic, and is sadly chewed.
Second thought, why use gaskets carefully used modern sealants are much better. The only gasket on my machines is on the cylinder base.
John.
 

BillyKnight

Forum User
Non-VOC Member
It sounds like we have a matching pair of chewed up push rods! I can see your point with the modern sealants too. I'll give it some thought.
Main thing is to get it back together, I feel terrible!
 
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