Tappet Clearances & Non running

[AlanBartlett]

As the Weasel has been becoming more and more reliable, using it for commuting to and from work on sunny days and weekends. I decided this morning I would check out a few things ie the tappet clearances. However this evening I am a bit puzzled by its now rather poor running to which I've spent most of the day scratching my head so here I am.

So I went around all the tappets checking them for their 2 thou clearance as specified. The ones on the passenger side hadn't moved so untouched from when I last did them. The Drivers side under the hellish steering column were 8 thou on the inlet and about 6 thou on the exhaust. So I removed the column to gain a better access.

I reset them both back down to 2 thou. I then went to restart the car and here is where the trouble started. It would only fire on one cylinder (The non adjusted passenger side) So I retraced my steps re adjusted the D/S valves up to 6 thou to try and see if that would get it running. It ran however still favouring the Passenger side. I then adjusted the exhaust down to 2 thou, and left the inlet at 6, to which it ran but still not as well as it should. So here comes head scratching bit.

What would cause this?

Perhaps sticky valve? Valve moving I can turn it on the tappet nuts a full 360 degrees You can also see it moving with push rod.

Could the valve not be seating properly, but why would it work with different valve clearances?

When I put in 6 thou feeler into the tappet gap, the engine will stop firing on the cylinder, and then cut in when take it back out.

Could it be a leaky valve, not seating properly, again with different gaps how would that effect this?

I'm off to grab another kitkat to have a ponder this evening, before possible head removal tomorrow. These Jowetts certainly give you plenty to think about don't they!

[Tony Fearn]

Well here's a to do!
I haven't a clue, so can't really advise, but before you remove the cylinder head, and in no particular order:-
1. Did you set the D/S tappets when their opposite tappets were at the top of their reach? - I suppose you did.
2. Crud builds up on the stem of the valve just before the valve head, so it might be sticking.
3. Are the tappet guides firmly fixed?
4. Give the valve stems a good squirt with WD40, and later use the oil can on them.
5. Introduce a thin-bladed screwdriver between the end of the tappet and the tappet nut on the valve and send the valve further into the cylinder and
see if it comes back to where it was.
6. Were you resetting the tappets when they were warm? They need to be set cold.

Tappet and valve.jpg

Can't think of anything else, unless the valve seats are burned.
Happy fettling.
Tony.

[Forumadmin]

Can you do a compression test?

[BarryCambs]

I had exactly this on mine before the engine rebuild. It was a sticking exhaust valve which I managed to free off temporarily. Can the heads come off the Weasel with the engine in the car?

[AlanBartlett]

I spent the day checking over things, I took the head off, and inspected the suspect valve, there was a small amount of carbon around the stem, cleaned off, and cleaned out the valve guide. How ever on inspection of the valve guide there is movement up and down which looks like there is wear in the valve guides. The valve was sitting nicely in its seat and not proud in anyway.

In an attempt to see if there was a leaky valve I lapped in both valves with nice seats again, although they were not horrendous when I took them out. I put everything back together this afternoon and tried again. Still not happy with the 2 thou gap, I got it down to a tight 6 in the end. Not a job I'm looking forward to having to do. Taking the cylinder off in the car, yes it can be done, but I don't fancy my chances of not breaking rings!

[Tony Fearn]

Last night I wondered if it was something else that's bothering that driver's side cylinder.
Is there a crack in the dizzy cap?
Is there continuity between the dizzy and the spark plug end for that cylinder?
I've noticed that when I took a plug out of a cylinder, and didn't replace the sealing washer, even though the plug was tightened down securely, when I squirted a bit of WD40 around the plug base, bubbles arose meaning the plug wasn't seated properly and compression must have been lost.

'Still not happy with the 2 thou gap, I got it down to a tight 6 in the end'.
I can't understand what you mean with this.
Tony.
P.S. George G, where are you when we need you.

[Tony Fearn]

Alan,

viewtopic.php?f=3&t=2720&p=14525#p14525

Stephen aka Splitpin has replied to my half shaft query, but I remembered that he had put the above post on JowettTalk because of a sticky Bradford valve.
It may be of interest.
Tony.

[AlanBartlett]

Hi Tony,

I was referring to the cylinder running with a 6 thou gap and the not so happy running with a 2 thou gap.

Having more of a thought last night why would it only run on that cylinder with a larger gap. Thinking more along the lines of timing, what if it would run on a larger gap because it would slightly delay the opening of the cylinder?

I checked the timing out last night it appears I may be a tooth out on the ignition timing as the inlet valve looks to be opening before tdc. I remember putting this right sometime last year, but I think I may still be out, well quite obviously by looking when the inlet starts to open in relation to tdc. How did it run at all.

That will be this evenings investigations!

[BarryCambs]

More modern engines can have inlets opening BTDC, but the Pre War Service Specs say all the twins open TDC.

http://jowett.org/jowettnet/dt/tech/jti/pw.pdf

If you're going to be looking at the valve timing, it might be worth ignoring any timing marks (mine doesn't have any anyway) and setting it up as described in the service spec. It can be a pain, but well worth checking. I've always thought the big differences in the performance between identical pre-war Jowett cars is probably down to poor cam timing. I didn't check mine before strip down, but the power probably increased at least 100% after the engine rebuild, far more than I'd expect just by bringing the compression back up.

Barry

[AlanBartlett]

So a bit of an update. Two evenings later! I checked out the gear timing. I was a tooth out. I set all the tappets to 6 thou as recommended and followed through the book to reset it all up, watching and feeling when tappet was opening. I reset them back to 2thou, adjusted the distributor so now I am pleased to report it is firing on both cylinders.

I refitted the radiator this evening, put the bonnet back on and got out for a short run over to the next village and back. There is definitely improvement, seemingly reaching 40 quicker, and holding on to the gear for longer without having the change as much. I hope to take it on another run in the morning to work and back so see how it fairs. Fingers crossed for a better performing car. All that because the tappet wouldn't adjust up! What a palaver!

[StevenGray]

Alan,

viewtopic.php?f=3&t=2720&p=14525#p14525

Stephen aka Splitpin has replied to my half shaft query, but I remembered that he had put the above post on JowettTalk because of a sticky Bradford valve.
It may be of interest.
Tony.

Doesn't seem like 8 1/2 years since I posted that.

[Forumadmin]

Yes Alan, valve timing is quite important