Stag engines

Just to add to my junk, I've just bought a Triumph Stag for two hundred quid. It's in the condition you'd expect for that sort of money, but does have a genuine Stag engine in it. One that's pretty dead, admittedly, but it's complete, fairly clean and not seized. I managed to get it running for a few seconds on what sounded like one bank of cylinders, then spent a couple of hours checking the carbs and electrics (it has a complicated looking Newtronic electronic ignition fitted, but working OK). It didn't improve, so I started wondering if the timing chain had jumped a cog or two on one side. No clues when I had a look under the rocker covers. The timing chains didn't look particularly loose. The cams were rather worn and pitted around some of the lobes, but I can't see why that would stop it running. There are no nasty noises when turning the engine over, though it seems to turn a little too easily as if compression's down, which would back up my thoughts about a timing chain problem. I reckon the engine will fetch a reasonable sum on eBay, even in its current state, but it'd be nice if I could get it running without spending anything on it. Anyone know how to check the cam's timing on one of these? And also, how to get an idea whether the valves have clobbered the pistons? Or any other thoughts at all about it?

Reply to
Willy Eckerslyke
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When these things stand for any length of time the valves stick and stay open. (Rings seem to dry as well,) You could pull the covers off the cams and check the clearance off the back of the cam. I think off hand 015"

It will not be the timing chains.

The cams do pit which is not a problem. I have never known the valves to clip. on any of this family of engines.

Make sure that there are no air leaks in the inlet side. Hoses or rubber caps off.

What happens if you place a few squirts of oil down each cylinder? ( to seal the rings) and when you remove the plugs to put the oil in check what colour they've been.

Would say, you may be pulling the heads off - what a bugger! with them sloping studs - which could also be seized in the head.

The water pump may also be dry and will leak. check the slot in the block for leaks.

rm

Reply to
Rob

That's good to know. Thanks Rob. I was going from a somewhat biased webpage which claimed that the chains stretch with age and "jump", though couldn't really see how they could.

Again, that's good news!

The air cleaner was in the back of the car and some of the breather (?) pipework was hanging loose with at least one elbow missing, so I'm not at all sure I put it all back on correctly. There could well be an air leak or two... Reckon it'd do any harm if I just blanked them all off to see if it'll start?

Haven't tried that yet.

They're all too new to tell me anything. They're a bit black, suggesting the engine's been run since they were changed. And they match on both sides of the engine. Someone's replaced the plugs, the distributor cap and rotor arm very recently. I don't think the car's been standing for long if at all. Someone's clearly tried to get it going, given up and hauled it to the scrapyard - where I found it. The diaphragms on the Stromberg carbs didn't look too healthy, indicating that whoever's been there before didn't know all that much about what they were doing.

I did ponder on that, then decided I'd be better off selling the engine as-is on eBay with an honest description. Bodywork is totally shot and it has been officially recorded as scrap, so is only good for parts, but there's enough there for me to make a decent profit.

I didn't see any signs of leaks when I looked yesterday. One bit of bad news is the total lack of any anti-freeze in the coolant, but it might not have been like that for long enough to cause any damage, assuming the system was filled when the last person fiddled with it.

Incidentally, is it normal for the power steering pump to be on the same side as the battery, preventing it from being lifted out?

Reply to
Willy Eckerslyke

In news: snipped-for-privacy@mid.individual.net, Willy Eckerslyke wittered on forthwith;

Throw a nice Rover engine in :-)

Reply to
Pete M

Yes, the battery is on the same side as the power steering pump!

ken

1974 Slag auto 1976 Dolly Auto 1981 TR7 Manual 2003 Mini Auto 2006 Rover 75 CDTI Auto
Reply to
Ken Forrest

Usual things on these engines are points, carb diaphragms and sundry air hoses or air leaks. Before looking for anything more complicated. If the electronic ignition is ok that's one less thing to worry about.

Reply to
Dave Plowman (News)

Hehe! For real irony value, I was half tempted to get the Stag engine running then fit it into my P6.

Out of interest, how did folk mate the Rover engine to the Triumph gearbox? Or did they just use the Rover 'box along with the engine?

Reply to
Willy Eckerslyke

Thanks, that had me puzzled. So do you normally have to move the pump to swap batteries? On this one, there's no way it'd fit past, but perhaps the engine's dropped a bit on its mounts or something.

Reply to
Willy Eckerslyke

I had another quick look at the air hoses last night and I'm not convinced that there's enough wrong to prevent it starting. I won't have time until the weekend to investigate further, but have decided to finally buy a compression tester. Then at least I'll know whether it's worth spending any more time on the engine.

Luckily the original box with instructions for the electronic ignition kit was in the car - and it included details of how to test it. It had me worried because there was also a second, identical kit that had clearly been used, suggesting someone's been having problems with it in the past. Also, there were too many leads to the coil (about 5), some with insulation that was well past its best. Removing all of the old leads and using a live feed from the battery should have eliminated any trouble there. The original distributor parts are also in the car, so I could swap it all back if I have to.

Thanks Dave and everyone for your help, I'll keep you posted.

Reply to
Willy Eckerslyke

I doubt the Stag box would handle the torque for long.

Reply to
Dave Plowman (News)

By all means buy a compression tester. By going systematically through the tests in the instruction leaflet, it will tell you a lot about your engine.

But you can do a fairly simple test for no compression without one. Stick your thumb over a plug hole in the bank that does work and spin the engine on the starter. That will give you a feel for reasonable compression (which it must be for that bank to work). Then try each plug hole on the other bank in turn and see if they feel similar.

Also don't overlook the obvious. For an engine to run, you only need three things

  1. Fuel and air mixed in the right proportions
  2. Compression
  3. A decent spark at the right time.

If you work through systematically, you must eventually find what is wrong. You can assume the fuel and air are reasonable if the float chamber contains petrol and the piston moves when you try the lifting pin, provided the diaphragm isn't split.

You are about to try the compression - but it would be unusual if all four cylinders in the bank were without. That would suggest the valves are open at the wrong times, or were jammed open.

So don't make assumptions about the sparks. Four cylinders run, so use these as your starting point for checking the firing sequence. You have tested the electronic ignition, but it is worth checking that the distributor contact that the rotor arm points at is connected to the cylinder that is at TDC. Don't believe any lead numbering, and don't assume the previous owner knew which cylinder was numbered what. Shine a torch down the plug holes to look for the cylinder with the piston at the top, or feel for it with a bit of washer tubing (Don't use wood or metal to probe!). Then turn the crank to the next distributor connection for the dead bank until you are certain that the right positions go to the right plugs. And swap the plugs between the good bank and the dead one - you might have four dud plugs, and if you swap them, the dead bank will move with them.

Happy hunting. Jim

Reply to
Jim Warren

Thanks very much for the useful post Jim. I've printed it off for the weekend, so won't reply to it all right now.

I'd agree with that assumption if I knew the engine had been running healthily before. Unfortunately I don't, and as someone's been mucking about with it I'm a little dubious about the position of the jets. They look very low compared to the Stroms on my Vitesse. But these are the type that you can't adjust from below, so hopefully they've been left alone.

Working through it all systematically as you say has to be the key though. Happily it's all easily accessible.

Reply to
Willy Eckerslyke

SU Carbs? Usually what stops them from being of any use is a lack of oil in the dashpot.

Reply to
Conor

No, Strombergs. Damaged diaphragms can cause problems, but I've replaced these. And topped up the dashpots.

Reply to
Willy Eckerslyke

Same way they used a different gearbox in the Dolomite to the Sprint, They have an adaptor in between for the conversion.

Also the same way they use a 5 speed Toyota box behind a V8.

Also add to what Dave said that box on the Stag/Sprint/2500 is a very strong box and capible of taking far more power.

Reply to
Rob

The adjustments are through the top but you need a special tool to stop the piston turning whilst turning the allen key through the middle. You will more than likely tear the diaphragm if you haven't the tool.

Once they have been set usually stay fairly close to being in tune.

Tool is pictured here

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Its the Cat 1 picture.

rm

Reply to
Rob

This can happen, but is rare. Normally the left bank goes first (viewed from driving pos'n), normally due to binding jackshaft/water pump, causing chain stretch. There have also been issues with incorrectly hardened aftermarket crankshaft sprockets and weak chains that stretch rapidly, and incorrectly hardened water pump skew gears that cause jackshaft binding and failure. Another cause of rapid chain stretch is a binding cam in a head, this is usually caused by previous overheating. The stag engine has an unfair reputation - if looked after it's a fine engine of its time, but woe betide anyone who lets one overheat badly, the bills to fix correctly with no further issues can be huge.

It probably wouldn't.

If the valve timing has slipped, there will be almost zero compression on the bank affected.

If it's sat for a while, might be worth pulling the carbs apart and cleaning the float valves - if you haven't already confirmed fuel is getting to all cylinders. I *think* it's the same as the rover v8 in somuch as the left carb feeds the 2 middle cylinders on the right bank and the end cylinders on the left bank, the right carb feeding the other 4. depending what cylinders are firing (pull leads to see?) that would narrow it down to either fuel (outers on one bank, inners on the other) or mechanical (a complete bank down) before looking further.

Will check book tonight if I get a chance.

Do a compression check first. Badger.

Reply to
Badger

Nope, pump unbolts complete with its bracketry and gets tied up beside the washer bottle to enable battery removal! Better by design......... Badger.

Reply to
Badger

Stag box is different to the 2500 - looks identical on the outside but has much heavier bearings to cope with the extra poke from the v8. Stag box can cope with the power from a standard carb'd rover engine no probs - unless it's subject to very course use or is already well past its best! 2500 box won't last 3 weeks behind a rover v8! Badger.

Reply to
Badger

I've got one I hope to never have to use again (as I hope to never have Strombergs again) - Open to offers...

Somewhere I've even got a NOS diaphragm for a CD150, again, if I ever have a Stromberg to fit it to, I'll be using an SU instead..

Reply to
Stuffed

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