• Welcome to the website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Hon. Editor and Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this website.

    If you have previously registered to use this forum, you should log in now. CLICK HERE.

    If you have never registered to use this website before, please CLICK HERE.

ET: Engine (Twin) Fogging for Mosquitos; Valve Guide Issues and Solutions

timetraveller

Well Known and Active Website User
VOC Member
Steven, if you search these pages back a few weeks you will see that Chris Tilley from South Wales had a similar problem. I have also had the same problem as had one of my local chums. The solution was that I designed a part which fits between the top of the lower guide and the bottom of the top guide and this prevents the lower valve guide from ever starting to work itself loose. I sent drawings to Chris and he got a local machinist to make two very nice items which also allowed him to use the oil seal on top of the lower guide. I am prepared to get a batch of these made if the interest is there and although the two I had made originally were made of steel I would probably use 7075 aluminium alloy for these as it has proved its worth and strength in the aluminium John Emmanuel steering heads I have had made. It will have to be a batch. The reason is that the chaps who do the CNC work for me do not really want to make less than ten off of any item. When I try to get one (or four offs) I run into trouble with people fitting the work in. E.G. I have been waiting eight weeks for some minor stainless steel parts to be made to fit an alternator kit to an open 'D'. Have a look at the Chris Tilley correspondence, which does include a drawing so you can make your own if you have the skills, and then let us see whether there is enough interest to make it possible to get a batch made.
 

clevtrev

Well Known and Active Website User
VOC Member
Well personal circumstance didn't allow me to tear into the motor and find the cause of the problem. So I have resurrected this thread to bring everyone up to date. In another thread I mentioned I had purchased the new extended rockers to install when I figured out what was going on with the sudden smoking. Well over the Easter weekend I pulled the heads. Bur first I started the Shadow to see if by some miracle it had healed itself. Not. So I made a by pass on the oil line to the heads and rockers. That stopped the smoking and lead me to believe that the cause was an worn guide allowing excess oil into the cylinder and/or exhaust causing the smoking. When I removed the muffler/silencer I heard a rattle. I thought it was the baffle loose inside. Until a little something fell out. At first glance it appeared to be a lump of carbon. Closer inspection revealed it was metal. In fact it had a curve to it. I looked up the inlets and exhausts of both heads and could see the top of all the valve guides, except the front exhaust. I could see the valve guide retainers, except the front exhaust. This did not bode well. With both heads off, I removed the valves from the front head. The lower guide is completely gone. The little bit of shrapnel I found in the exhaust is all that remains. The threads for the guide retainer are completely fretted away, only the retainer remains.
Now I have to decide whether to repair the head by the methods I have seen on the forum of making an insert to retain the lower guide or purchase a new head. But first I must determine if the hole for the lower guide has been worn excessively or not. Does anyone know the standard o.d. of a lower guide?
Of interest the upper guide appears to have been sufficient to keep the valve aligned as there doesn't appear to be any damage to the valve or head in the seat area.
Steven
It would not have been the upper guide controlling the valve, it was the rocker arm, and if you look in the combustion chamber you will see where the head of the valve has been seating, you will notice that it has been seating more on the same side as the lot in the rocker arm.
The lower guide diameter was 9/16". Exhaust that, Inlet is 1/2".
 

chankly bore

Well Known and Active Website User
Non-VOC Member
Exhaust guide standard o.d. is .563", lockring thread is 7/8"x 20 t.p.i. Whitworth form. Maughans can probably reclaim it.
 

ClassicBiker

Well Known and Active Website User
VOC Member
TT, that is the thread and repair I was referring too. While I feel confident I could make the item myself, why re-invent wheel? If you were not considering having a batch made, I would under take making myself a set. Now that Clevtrev has kindly supplied the o.d.s (Thank you Clevtrev) I will get my telescoping gauges out and see if the bore of the missing valve guide is in any condition to take a standard or over sized guide, or if there are other issues as a result of the guide calling it quits.
Chankly Bore popped up while I was typing this.
I had not considered them. They (Maughans ) would definitely be less than a new head or two. I will have to see if the guide bore or valve seat is severely damaged. After reading what Clevtrev says about the valve seating to one side based on the slot in the rocker arm.
Thanks for the input and suggestions. I will update as I find out more.
Steven
 

timetraveller

Well Known and Active Website User
VOC Member
I got a price this morning from the CNC chaps. £45 each for ten off and a bit cheaper for 20 off. This is more than I expected so if any of the engineers in the Club feel like making a batch at a better price than that please talk to me on enw07@btinternet.com . Over to you guys.
 

ClassicBiker

Well Known and Active Website User
VOC Member
Just rang Maughans. They can reclaim the threads and do no-lead valve seats but they are so loaded up with work they are not currently taking any more on. Their suggestion was to call Conways and see if they would take it on. Thoughts?
Steven
 

Bill Thomas

Well Known and Active Website User
VOC Member
Have the threads been damaged Steven ?.
The Spares Company sold oversize lower guides, Last time I looked, Some years ago ?.
Good luck, Bill.
 

ClassicBiker

Well Known and Active Website User
VOC Member
Hi Bill, unfortunately the threads are completely gone. If it weren't for the fact that I know there should be threads there and the lock ring was floating about, you couldn't convince that there were ever threads there.:eek:
Steven
 

Bill Thomas

Well Known and Active Website User
VOC Member
If you could sort out an oversize lower guide, I would have thought someone near you could put a bigger thread and make you a special thread ring ?, Just a thought. Cheers Bill.
 

roy the mechanic

Well Known and Active Website User
VOC Member
Steven, first off you do not need no-lead valve seats. The originals in my rap have done the best part of 300000 miles and the tappets rarely need adjustments . I have visited Conways , they have a comprehensive machine shop. The only thing that would concern me is shipping parts for many thousands of miles, not only will they get there, but will they get back, having paid for the work. Whatever you decide, be lucky. Roy.
 

ClassicBiker

Well Known and Active Website User
VOC Member
If you could sort out an oversize lower guide, I would have thought someone near you could put a bigger thread and make you a special thread ring ?, Just a thought. Cheers Bill.
Bill,
Funny you should write that. I was just seeing what material is used for the valve guides, 630 bronze seems to be it. I'm waffling back and forth with whether to make up the slide in cup device TT suggests or get the threads repaired back to original size, or over size. I was also thinking that if I sent it out for repair I would get no-lead valve seats installed. But the valve seats look reasonable, so I might pass on that. The club does sell over size guides, I have to see if I need them or not, or an over size outside of their range. I see I can easily buy a tap in larger sizes and making a ring is not an issue. I think I talking myself into doing myself.
Stay tuned.
 

Bill Thomas

Well Known and Active Website User
VOC Member
Most of us have to send stuff out at some time, But If I can do it, I will have a go.
Last month in the Vintage Club, There was a Bloke who sent a Vin' Cylinder Head away for repair, It was gone for 3 years !!, He had to take Legal advise, To get it back, They told him, If the stuff is away for more than 6 years, It's not yours anymore !!.
He does not say who he sent it to.
I don't think there are many cases like that, But it makes you think.
Cheers Bill.
 

timetraveller

Well Known and Active Website User
VOC Member
If you use my modification you do not need a lock ring. You just have to ensure that the new part fits tightly on top of the flange around the guide. It just holds it down.
 

ClassicBiker

Well Known and Active Website User
VOC Member
Bill, That was what I was a little afraid of. The head disappearing into big wide world, never to be seen again.

TT, your mod it was I'm going with. Upon closer inspection, where the lock ring would engage the threads of the head has been worn away to such an extent it is nearly the same size as the major diameter where the rocker works. So no chance of going up a thread size. I've been looking at my choices of 7075 and I can easily obtain 7075-T6 in 1-1/4" diameter. I'm going to measure the valve guide bores and see if I need oversize or standard size guides. If I cannot get a suitably sized guide to replace the AWOL guide, I can buy C630 bronze to make my own. If all else fails my fall back plan is new heads.
Stay tuned.
Steven
 

timetraveller

Well Known and Active Website User
VOC Member
Steven, if you make guides with a flange, like the original but larger, then my modification can be made so that it sits directly on that flange. The protruding part at the bottom of the new part can be made to sit within the damaged space where the lock ring was and it can even be machined to take an oil seal. If it is difficult to get the ring exactly the correct length to exert a force on the top of the guide then a shim on top of my mod would ensure that there cannot be any movement of the replacement guide
 

Bill Thomas

Well Known and Active Website User
VOC Member
Can't remember if you have to keep the bottom guide short for Mk2 Cams ?, Is it Exhaust your problem ?
Good Luck. Bill.
 

ClassicBiker

Well Known and Active Website User
VOC Member
Bill, I replaced my Mk2 cams with Mk1 a couple of years back as the cams and the rockers were very badly worn. I had originally thought that perhaps when my father had rebuilt the bike back in the late 70s early 80s that he had neglected to shorten the guides, but when I was replacing the cams, I could clearly see the top of the guides were all nearly flush with the top of the lock rings. Now that I have the heads apart I can see the three remaining guide tops are not damaged in anyway. Which leads me to believe the guide self destructing is just the luck of the draw.

TT, I had intended to replace all the guides and lock rings with the new type that take the oil seal. I had also read in the other thread where you posted the dimensions that someone had managed to fit an oil seal to your modified part, so I was going to do the same. But shimming it to make sure that pressure is exerted had not occurred to me.
Steven
 

Bill Thomas

Well Known and Active Website User
VOC Member
I think it's how deep the valve seats are cut, New valve seats would make the collar come nearer to the top of the guide ?. Cheers Bill.
 

ClassicBiker

Well Known and Active Website User
VOC Member
Bill, I suspect you are absolutely correct. The valve seats appear to be about middle of the road. Nothing is pocketed and therefore masked nor are the valve faces extremely proud. I would suspect that if the collars were hitting the guides there would be witness marks on the collars. What I find confusing is I haven't found a piece of the shoulder of the guide that would have been trapped by the retaining ring. I'm also pleasantly surprised by the lack of damage. Except for the small length of cylindrical body of the guide the rest is gone. As if it turned to dust and disappeared and this piece just slipped out the exhaust port.
Steven
 

Bill Thomas

Well Known and Active Website User
VOC Member
We have been told of this before, As you say, Strange.
I have looked up the Exhaust hole on one of my bikes, And can see a lot of oil Running down ! But as long as it still goes, That's good enough for me, I don't go far !!, Joke.
I have a lot of respect for OUR Trev', But if the top guide was not there, I would think the valve would be all over the place ?.
I remember dear old Dave Dock at a Sprint, His Bike was not going well, He stripped it out in the padock,
And found the valve seat had been going up and down, Resting on the valve head !.
Cheers Bill.
 

Latest Forum Threads

Can't Find What You Need?

Buyer Beware: Fake or Real?


Top