Author Topic: Valve Timing  (Read 9681 times)

cobbadog

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Re: Valve Timing
« Reply #15 on: 20 February, 2021, 09:51:28 pm »
I re-visited the dizzy again today. We found the other day the rotor button is a poor fit onto the shaft. By this I mean that there is sideways movement on the shaft. Hold the shaft in the vice and with the back edge of the rotor button aligned with one of the lugs around the perimeter of the dizzy body that aligns with the terminals inside the cap then I could mo ve the rotor to the right by around 1/3 the width of these lugs which is possibly around 2mm.
Now thinking back there was what looked like a bit of cloth inside the rotor button and I thought it was a crude fix for a piece of felt that usually is found stuck in the end of the shaft as an oil holder and slowly let oil feed down the shaft to the bob weights. Now I am thinking this was a very crude way to remove this slack. I think the rotor button is not the correct one for this dizzy and have looked for a replacement.
I measured the gap in the top of the shaft that locates the rotor button then had to think outside the box to be able to measure the drive lug inside the rotor. SO good old blue tack came to the rescue. I rolled a piece up, stuck it inside the rotor and used a screw driver to push it against the drive lug. There is a difference of around that 2mm I mentioned earlier. So in the interests of being 'rough' I also replaced the piece of old cloth with some brand new cloth and made it into a "U" shape and sat it into the groove in the shaft and fitted the rotor button. It is now a firm fit. So while the dizzy was out I again stripped it down and went one step further than before and removed the bob weights to ensure they are clean and free to move and porperly lubed at the moment with light machine oil. When I spin the shaft the weights obviously move out as I do see them return back as it slows down. I also noticed that the weights do not return fully back to touching in the stop position. If I touch it they do but at the moment they wont and there is nothing stopping them returning. The springs are good and have tension on them but I have no idea why this is happening.

Then another helpful tip was put forward, bent or stuck valve even a bent push rod. So with out removing any push rods at the moment I rotated the engine and as each cylinder came up to TDC I was able to spin the push rods and there was no obvious siiiign of them being bent but I do relaise they need to be rolled on a flat surface to ensure this. The last time the engine was running it was bloody rough and some huge back fires with flames up the chimney, not good. So once again I checked the valves and looking especially at exhaust valves. All were to spec on the gaps but this does not mean that one or more are seating. Having said that, visually all valves both inlet and exhaust 'look' to be sitting at the same height. I am now thinking of removing the head and make sure that all valves are seated properly and that none are sticking. Sounds drastic but for a bit of time I can then discover if this is the source of my nightmares.

Hi allisb,
Thanks for that suggestion and is yet another reason to lift the head, strip it down. When the engine was rebuilt all those years back I did not replace the springs so this is a big help to jolt my head into gear.

I appreciated any and all input that will help me resolve this.
Cheers, John & Dee. Coopernook. NSW.

allisb

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Re: Valve Timing
« Reply #16 on: 21 February, 2021, 09:24:47 am »
Hi, I could easily be wrong. As I was once, (but that was last century)

But jokes aside, there has to be a reason for all this.

Thinking, while the rocker cover is off, with the valves closed, can you depress the springs by hand? Try turning it over as if you are setting the valve clearances, and press down on each one when it is closed.

All the very best with it
Rx
I spend most of my pay on old tractors and engines, I tend to waste the rest

cobbadog

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Re: Valve Timing
« Reply #17 on: 21 February, 2021, 01:24:17 pm »
Cheers allisb,
I will check but when playing with both valves on #4 they are very hard to push down, to the point I had to use a screw driver to lever them down then pull it out quickly to get them to snap shut. Not the test you have asked for but will have ago at it tomorrow by trying just that. I cannot turn the engine over by hand at all with the spark plugs in so they come out first but very easy thing to do.

https://youtu.be/7Ec7MdevOyo

Above is a link to the video made today. No back firing or flames out the chimney, good start. Still has a flat spot from idle and this is as good as it gets at the moment and the air mixture is 3 turns out with very little if any black smoke at idle which is an improvement. After a lot of going back over what I have done  time and time again I did finally twig to a piece of cloth that was inside the rotor button. For years I thought this was suppose to be the missing piece of felt that sits in the centre of the shaft beneath the rotor button. Now I believe it was jammed in there to take up the slack between the drive lug and the groove in the top of the shaft. So I took the correct steps to fix this, made another bit of rag.  :o
It does centre the rotor to the groove and has removed that freeplay and since doing this it has stopped the back firing and flames. I am waiting for an answer about a new rotor button so will order it if it will be correct. Timing once again was set as a static timing to the "M" on the flywheel so next attempt will be rigging up the timing light to see what happens.
I am still very much considering to lift the head and check the valve faces and seats plus springs and look and feel for a sticky valve.
Cheers, John & Dee. Coopernook. NSW.

oldgoat

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Re: Valve Timing
« Reply #18 on: 21 February, 2021, 11:45:37 pm »
A compression test will save you dirty hands and the effort of undoing a lot of nuts. If the values aren't in spec then you can dismantle to your hearts content.

cobbadog

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Re: Valve Timing
« Reply #19 on: 22 February, 2021, 04:11:18 pm »
Did another compression test today on a cold engine and all came in at 65psi which I thought was a bit low. Then just now I remembered I did NOT open the throttle to full so will have another go tomorrow.
Bought a NOS dizzy cap genuine Lucas in box and a Bosch GL229 rotor button which suits this dizzy I have. Also found that the picture in the workshop manual is NOT one to suit the early 30C, must be to suit later models.
The DX4A and DZ4A were both original fitments to the 30C from 1949 - 1954 along with a long line of pommy cars Austin A90, Land Rover for just 2 years, grey fergy, Vanguard obviously Sunbeam one model and so on around a dozen vehicles all up.
Then when looking at it again today I saw this, the condensor wire which was running close to an earth and might be able to jump so I moved it 1/4 turn.
Cheers, John & Dee. Coopernook. NSW.

allisb

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Re: Valve Timing
« Reply #20 on: 22 February, 2021, 06:51:36 pm »
Sounds like the valve springs could be well ok. You may be on to it with the dizzy parts, especially if it has improved.
you?ll certainly expect better compression with the throttle open, but being all even is a good start. You may not have to lift the head.
You?re winning!
I spend most of my pay on old tractors and engines, I tend to waste the rest

cobbadog

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Re: Valve Timing
« Reply #21 on: 22 February, 2021, 08:58:41 pm »
Thanks for the support. It has been doing whats left of my brain in for ages and yes it does feel as if I am getting somewhere.
Cant wait to do the compression test again but properly as last time I thought it was in the high 70's then get the new parts.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: Valve Timing
« Reply #22 on: 04 March, 2021, 04:46:42 pm »
New cap arrived today and the rotor button I can pick up tomorrow and try to resolve this bugga once and for all over the weekend.
Cheers, John & Dee. Coopernook. NSW.

allisb

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Re: Valve Timing
« Reply #23 on: 04 March, 2021, 09:11:14 pm »
Fingers crosse for you
I spend most of my pay on old tractors and engines, I tend to waste the rest

cobbadog

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Re: Valve Timing
« Reply #24 on: 05 March, 2021, 09:13:34 pm »
Cheers, the rotor button arrived today so at some stage over the weekend I ill have yet another go at him. With all this rain and humidity the grass is taking over everything and neds mowing so it will be done with an industrial mower, then get more done on the mower deck off Husky then this engine.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: Valve Timing
« Reply #25 on: 06 March, 2021, 09:11:18 pm »
Well the new cap was fitted and the rotor  button is not correct. I believe they sent the wrong part so will check that out on Monday. Did a start up and ran it for a while before lifting the revs to maximum and back to idle after a brief run. Still sounds as if it is running on 3 cylinders sort of. So at idle again I started pulling the HT leads one at a time and seems that #1 is the missing pot. AS it was late in the day and I was stuffed from being hunched over the mower deck welding I gave it up and will get back to it tomorrow after more welding.
I will re-test the HT lead with the multi meter and try another spark plug and I have a lot of spare ones that I have been rotating about trying to find out what is wrong here. I was disappointed that the rotor button is wrong and I was hopeful that was going to be the problem, time will tell.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: Valve Timing
« Reply #26 on: 24 May, 2021, 04:15:55 pm »
Well for a very long time but only when I could I have been having fun trying to solve a problem with the 30C. Found a slight issue with the needle and seat in the carby and replaced the seals on the main shaft to ensure no vacuum leak there. Went over to the ignition and replaced everything from coil to plugs and everything in between and yet it still ran rough. Pulled the front off the engine to double check the cam timing and also double and triple checked the valve clearances. All of this has been done over many attempts as time has been available and last weekend I sat down with him with a carton of beer and we had a very long talk about why he was being so bad. We talked for a while and then I went inside for lunch and when I came back for no reason he started running like he used to. So I then got down to adjusting the air bleed/mixture screw and got rid of the small flat spot and allowed him to run for a fair while. I took him for a drive up and down the driveway and thought this is good. Next time I will just sit down with him again with a carton of beer have a a talk should he feel that he wants to be naughty.
So today I fitted the tinware back on and went for a drive around the block as he has Club rego, even stopped at the service station and fueled up. It felt good to have him back to his old self and then I noticed an issue, a fuel leak so back home to sort that out. The main thing is that he lives again, the fuel leak is from the tank somewhere so will look closely at that and I am now convinced as to what the problem was so if it happens again I know where to go.
Cheers, John & Dee. Coopernook. NSW.

ianoz

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Re: Valve Timing
« Reply #27 on: 24 May, 2021, 10:15:52 pm »
Come on Cobba , Tell the truth .Beer indeed . You slipped a shot of Bundy rum in the tank , didn't you  ;D.
Mate good to hear Davey Brown is back to old self .
fowler vf,david brown 30td,cat D24U,D47U,D47J,D46U,R4,D68U IH TD9,TD6 and many more
 Benaraby Central Queensland

cobbadog

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Re: Valve Timing
« Reply #28 on: 25 May, 2021, 09:27:11 pm »
Haven't had a Bundy for over 30 years. Many moons back in the hard drunking days Winter was supported  by Captain Morgan shots with around half of the 10 - 12 schooners just to keep the bugs out.
Even though the drive was short it was very pleasing with David demonstrating his torque in H range 3rd by pulling out of a corner and up hill with no worries at all. Throttle response was also brilliant with little time taken to reach governed speed. It does put a huge grin on ya dial when it runs like this and really is why I'm not pissed off about the fuel leak.
Cheers, John & Dee. Coopernook. NSW.

allisb

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Re: Valve Timing
« Reply #29 on: 26 May, 2021, 06:36:08 pm »
Hi, just logged on.
That?s terrific news. Good to hear that he is back on track, after all those hours of work. Enjoy!
I spend most of my pay on old tractors and engines, I tend to waste the rest