Spitfire 1500 running problems
Discussion
Hey all,
Very occasional poster here because the poor old Spit just doesn't get much use these days. One of the reasons for that is that it has not been running well for years. Basically it runs very well until hot and then it spits and stutters until it conks out and won't start again until it has cooled down a bit. So just when the weather is convertible friendly you can't be sure of a decent run.
Anyway, I've decided to take it to the Le Mans Classic this July, partly because it's first long run after restoration in 1999 was Le Mans and partly because it will mean I have to get it running properly.
So previously I had replaced coil, capacitor, points, condenser, dizzy cap, leads, plugs. All that because I thought maybe the issue was electrical. That made little difference so today I decided to replace the waxstat jets with standard ones. Used a kit from Moss and, while definitely a fiddly two hour job, it all fitted fine and the carbs appear to be operating as they should.
Unfortunately, the car now runs on three cylinders!! No idea what has happened here. If I remove the plug lead from the third cylinder back it makes no difference to running so that's the problem one. I removed the spark plug and tested it with the engine running and it is sparking well so it doesn't seem to be an electrical problem. I went through the process of resetting the jets so mixture should be OK. I also tried rotating the distributor a little to see if it picked up but made no difference.
It's almost like cylinder 3 (I think you count from the front) isn't getting fuel but with a twin carb setup surely if cylinder 4 is getting fuel then C3 with be as well?
No idea where to go from here. I'm even contemplating giving it to a local garage who I know are good on classic stuff. But of course I'd much rather understand what's wrong with it and try to fix it myself.
Any thoughts?
Al.
Very occasional poster here because the poor old Spit just doesn't get much use these days. One of the reasons for that is that it has not been running well for years. Basically it runs very well until hot and then it spits and stutters until it conks out and won't start again until it has cooled down a bit. So just when the weather is convertible friendly you can't be sure of a decent run.
Anyway, I've decided to take it to the Le Mans Classic this July, partly because it's first long run after restoration in 1999 was Le Mans and partly because it will mean I have to get it running properly.
So previously I had replaced coil, capacitor, points, condenser, dizzy cap, leads, plugs. All that because I thought maybe the issue was electrical. That made little difference so today I decided to replace the waxstat jets with standard ones. Used a kit from Moss and, while definitely a fiddly two hour job, it all fitted fine and the carbs appear to be operating as they should.
Unfortunately, the car now runs on three cylinders!! No idea what has happened here. If I remove the plug lead from the third cylinder back it makes no difference to running so that's the problem one. I removed the spark plug and tested it with the engine running and it is sparking well so it doesn't seem to be an electrical problem. I went through the process of resetting the jets so mixture should be OK. I also tried rotating the distributor a little to see if it picked up but made no difference.
It's almost like cylinder 3 (I think you count from the front) isn't getting fuel but with a twin carb setup surely if cylinder 4 is getting fuel then C3 with be as well?
No idea where to go from here. I'm even contemplating giving it to a local garage who I know are good on classic stuff. But of course I'd much rather understand what's wrong with it and try to fix it myself.
Any thoughts?
Al.
might help, dont take for granted things are working. ive had problems with spark plugs would spark outside but didnt under presure, found out eventualy with a colour tune, took me days before i eventualy tried out off frustration. didnt everthing carb, timing belt, timing etc. something simple and overlooked. are you sure the mixture is ok.
geof
geof
With your original symptoms in a 1500 I'd have gone straight to the fuel system and the Waxstat jets as it's a bit of a classic issue.
For your new problem:
1. Plugs out, car in fourth gear and rocker cover off. On level ground release the hand brake and roll the car forward. Make sure all the valves are opening and closing properly, especially those on cylinder #3. If you're getting fuel to #4 you should be getting fuel to #3 too but it's possible you could have a snapped inlet rocker arm on #3 inlet, so it not opening to let any fuel/air in or a stuck exhaust valve letting it all straight back out. Unlikely but you should be able to rule it out with this test.
2. While the plugs are out run a compression test. If you have a compression tester, use it. If you don't just press your thumb over #3 spark plug hole and roll the car again. You should feel the compression stroke forcing air out past your thumb. That would also rule out major leaks, including down past the piston (though I'd expect that to be forcing oil up out the dip stick tube too).
3. If you have an old spark plug and lead from the last time you changed them (always useful to keep 1 old plug and the longest lead in the boot as spares) swap them for the ones on #3. If you don't have spares swap the plugs and leads between say #3 and #4 (remembering to swap them at thedizzy end too). If it's a plug or lead question these tests should either rule it out or tell you by moving the problem to #4. It's quite possible to have a plug or lead fail in a way that only shows when it's tightened in to the cylinder/hanging the specific way it does when fitted to the engine.
For your new problem:
1. Plugs out, car in fourth gear and rocker cover off. On level ground release the hand brake and roll the car forward. Make sure all the valves are opening and closing properly, especially those on cylinder #3. If you're getting fuel to #4 you should be getting fuel to #3 too but it's possible you could have a snapped inlet rocker arm on #3 inlet, so it not opening to let any fuel/air in or a stuck exhaust valve letting it all straight back out. Unlikely but you should be able to rule it out with this test.
2. While the plugs are out run a compression test. If you have a compression tester, use it. If you don't just press your thumb over #3 spark plug hole and roll the car again. You should feel the compression stroke forcing air out past your thumb. That would also rule out major leaks, including down past the piston (though I'd expect that to be forcing oil up out the dip stick tube too).
3. If you have an old spark plug and lead from the last time you changed them (always useful to keep 1 old plug and the longest lead in the boot as spares) swap them for the ones on #3. If you don't have spares swap the plugs and leads between say #3 and #4 (remembering to swap them at thedizzy end too). If it's a plug or lead question these tests should either rule it out or tell you by moving the problem to #4. It's quite possible to have a plug or lead fail in a way that only shows when it's tightened in to the cylinder/hanging the specific way it does when fitted to the engine.
Flat 6,
Where will you be at CLM? The TSSC and Spitfire community will be at Tertres Rouges, so if you need advice/help while there you know where to come. And there are a number of Triumph convoys going. I think you're brave to start fixing a badly running car so close to the date - you might like to join one of the groups going, for mutual support.
Look on the TSSC site for your local area group, that may have a convoy going.
John
Where will you be at CLM? The TSSC and Spitfire community will be at Tertres Rouges, so if you need advice/help while there you know where to come. And there are a number of Triumph convoys going. I think you're brave to start fixing a badly running car so close to the date - you might like to join one of the groups going, for mutual support.
Look on the TSSC site for your local area group, that may have a convoy going.
John
Thanks all for advice - I'll try all that. Does seem bizarre that the engine would go off one cylinder just because of changed carb jets!
John - ref CLM, many thanks for your suggestion. I am coming from N.Ireland but travelling via England to meet up with some old Le Mans pals. We are well used to the challenges of taking old classics to La Sarthe - although I have been going in various 911s for the last 20 odd years so the poor Spitfire has been neglected.
I won't take the Spitfire unless it has been reliable in the run-up which is why I'm starting prep now (this is early for me!!). The 911 is reserve but to be honest I'm getting a bit bored taking it.
Will report progress.
Thanks all,
Al.
John - ref CLM, many thanks for your suggestion. I am coming from N.Ireland but travelling via England to meet up with some old Le Mans pals. We are well used to the challenges of taking old classics to La Sarthe - although I have been going in various 911s for the last 20 odd years so the poor Spitfire has been neglected.
I won't take the Spitfire unless it has been reliable in the run-up which is why I'm starting prep now (this is early for me!!). The 911 is reserve but to be honest I'm getting a bit bored taking it.
Will report progress.
Thanks all,
Al.
OK, so I have swapped the lead and plug from C4 to C3 and it has made no difference.
I then removed the rocker cover and turned the engine over on the starter - all valves running well.
When I removed the plug from C3 it smelled of petrol. So presumably that means that the spark is not strong enough to ignite the petrol? Looks like I need to replace the plugs and leads and see where that gets us....
Al.
I then removed the rocker cover and turned the engine over on the starter - all valves running well.
When I removed the plug from C3 it smelled of petrol. So presumably that means that the spark is not strong enough to ignite the petrol? Looks like I need to replace the plugs and leads and see where that gets us....
Al.
If it smells of petrol that suggests the fuel side's all working.
If swapping the plug/lead didn't help that suggests it's not the plug/lead but maybe the earthing of the plug to the block? No circuit would mean no spark. Maybe get a small wire brush and run it around the spark plug threads in the block?
I'd also recommend asking on one of the Triumph club forums, either the TSSC or Club Triumph.
If swapping the plug/lead didn't help that suggests it's not the plug/lead but maybe the earthing of the plug to the block? No circuit would mean no spark. Maybe get a small wire brush and run it around the spark plug threads in the block?
I'd also recommend asking on one of the Triumph club forums, either the TSSC or Club Triumph.
Black I think.
I have an accuspark fitted as well but that shouldn't be the cause of the poor running.
I noticed today that the coil has leaked some oil. It is a '71 car so has a capacitor setup so I'm surprised if it has cooked itself. Anyway, I've ordered a new high performance one with new leads and plugs..I'll fit the coil first to see if that was the problem.
A.
I have an accuspark fitted as well but that shouldn't be the cause of the poor running.
I noticed today that the coil has leaked some oil. It is a '71 car so has a capacitor setup so I'm surprised if it has cooked itself. Anyway, I've ordered a new high performance one with new leads and plugs..I'll fit the coil first to see if that was the problem.
A.
FLAT 6 said:
Black I think.
I have an accuspark fitted as well but that shouldn't be the cause of the poor running.
I noticed today that the coil has leaked some oil. It is a '71 car so has a capacitor setup so I'm surprised if it has cooked itself. Anyway, I've ordered a new high performance one with new leads and plugs..I'll fit the coil first to see if that was the problem.
A.
I had a Pertronix/Aldon fail on one cylinder. I think one of the magnets had failed following a nasty over rev incident. I popped the points i had in the boot back on and all wad well. Ha e just stayed with points since although i will probably return to electronic in future. I have an accuspark fitted as well but that shouldn't be the cause of the poor running.
I noticed today that the coil has leaked some oil. It is a '71 car so has a capacitor setup so I'm surprised if it has cooked itself. Anyway, I've ordered a new high performance one with new leads and plugs..I'll fit the coil first to see if that was the problem.
A.
Also you dont mention dizzy cap. Put your old dizzy cap back on too. New components are s
t these days, especially the black rotor arms. If you are buying ignition components, powerspark are better than the pretend Lucas rubbish.
FLAT 6 said:
Black I think.
I have an accuspark fitted as well but that shouldn't be the cause of the poor running.
I noticed today that the coil has leaked some oil. It is a '71 car so has a capacitor setup so I'm surprised if it has cooked itself. Anyway, I've ordered a new high performance one with new leads and plugs..I'll fit the coil first to see if that was the problem.
A.
Does it have a rivet in it?I have an accuspark fitted as well but that shouldn't be the cause of the poor running.
I noticed today that the coil has leaked some oil. It is a '71 car so has a capacitor setup so I'm surprised if it has cooked itself. Anyway, I've ordered a new high performance one with new leads and plugs..I'll fit the coil first to see if that was the problem.
A.
This seems to be a very common cause of these difficult-to-trace running issues.
Of course it might be something else entirely.
So new coil, leads and plugs made no difference. Neither did fitting old dizzy cap. Have ordered a red rocker arm. Am also fitting new electric fuel pump under petrol tank just in case it is fuel pressure issue.
As to why changing jets would result in any of this remains a mystery...
And my '75 Landie has failed it's MOT. Wouldn't even need one if I didn't live in N.Ireland. Times like these I wish I'd stuck with sailing as a pastime...
As to why changing jets would result in any of this remains a mystery...
And my '75 Landie has failed it's MOT. Wouldn't even need one if I didn't live in N.Ireland. Times like these I wish I'd stuck with sailing as a pastime...
Couple of suggestions:
1. Fuel vapourisation? Is the original heat shield by the carbs still present?
2. Are you running the original air filter box with the flexible pipes to capture cool air from the front of the bonnet or have you changed that in favour of pancakes taking under bonnet air. When I had a 1500 in mid '80s and I thought I would do away with the original set up in favour of unboxed K&Ns. When things got hot under the bonnet it would barely run until things cooled down. Reverting to the original setup cured that.
1. Fuel vapourisation? Is the original heat shield by the carbs still present?
2. Are you running the original air filter box with the flexible pipes to capture cool air from the front of the bonnet or have you changed that in favour of pancakes taking under bonnet air. When I had a 1500 in mid '80s and I thought I would do away with the original set up in favour of unboxed K&Ns. When things got hot under the bonnet it would barely run until things cooled down. Reverting to the original setup cured that.
Thanks Oldbenz, there is a heat shield in place. I have been running the car with a 4-branch manifold, K&Ns and richer needles since the late 90's. In that setup the car has been over the Alps into Italy, to Le Mans and even both John O'Groats and Lands End (not on the same trip!).
So the running problems over the last few years have always been a bit of a mystery. I did that '1p' fix of the waxstat jets some years ago but they have never really been right so that's why this project is really about going back to standard red SU jets.
So, update after a very frustrating day. I have fitted an electric fuel pump (Spitfire 1500 rated) and have completely bypassed the front carb and fed fuel directly to the rear carb. I even found an old float top for the fuel chamber. None of that made any difference. Tested spark with my new coil, leads and spark plug - v.strong against the head.
Was just knocking it on the head for the night about 15 mins ago and had a thought - I have some cold start spray that you spray into the air inlet on winter mornings to give the starting process a boost. Got the wife to crank while I sprayed this directly into the rear carb...hey-presto, she fired!
So, the issue appears to be no fuel getting through the rear carb...which might mean a faulty new jet. There is plenty of fuel in the side chamber so for some reason it not getting up past the needle.
The only other thing I haven't tested is compression. Presumably it's the downstroke of the piston that sucks the fuel into the cylinder so if there is leakage around the rings the suck is reduced to the extent that fuel is not drawn in? I think a trip to Halfords and a new compression tester is on the cards for the morning. Of course if that turns out to be the problem then the poor old Spit will not be visiting Le Mans...
Al.
So the running problems over the last few years have always been a bit of a mystery. I did that '1p' fix of the waxstat jets some years ago but they have never really been right so that's why this project is really about going back to standard red SU jets.
So, update after a very frustrating day. I have fitted an electric fuel pump (Spitfire 1500 rated) and have completely bypassed the front carb and fed fuel directly to the rear carb. I even found an old float top for the fuel chamber. None of that made any difference. Tested spark with my new coil, leads and spark plug - v.strong against the head.
Was just knocking it on the head for the night about 15 mins ago and had a thought - I have some cold start spray that you spray into the air inlet on winter mornings to give the starting process a boost. Got the wife to crank while I sprayed this directly into the rear carb...hey-presto, she fired!
So, the issue appears to be no fuel getting through the rear carb...which might mean a faulty new jet. There is plenty of fuel in the side chamber so for some reason it not getting up past the needle.
The only other thing I haven't tested is compression. Presumably it's the downstroke of the piston that sucks the fuel into the cylinder so if there is leakage around the rings the suck is reduced to the extent that fuel is not drawn in? I think a trip to Halfords and a new compression tester is on the cards for the morning. Of course if that turns out to be the problem then the poor old Spit will not be visiting Le Mans...
Al.
And I've ordered a new high quality red rotor.
At this rate I may as well just order a new engine...Maybe not such a bad investment after 27 years of ownership. It's a MkIV with a 1500 engine and I've always fancied putting in the freeer revving 1300 with some Triumph Tune Fast Road mods to give it some pep.
Al.
At this rate I may as well just order a new engine...Maybe not such a bad investment after 27 years of ownership. It's a MkIV with a 1500 engine and I've always fancied putting in the freeer revving 1300 with some Triumph Tune Fast Road mods to give it some pep.
Al.
OK, I think I've come to the end of my mechanical talent (assuming I ever had any).
I have bought a compression tester and the compression in each cylinder is exactly the same at 150 psi. That seems pretty strong. Certainly doesn't suggest compression is the problem here.
I've put my old jet back in again and that made no difference.
So I can see no physical reason why the car is not running. If the rocker arm was the issue then surely it wouldn't run on any cylinders?
So, over to my old-school mechanic and it's the 911 for Le Mans.
I'll report back when I've had a diagnosis. Thanks for all your suggestions.
Al.
I have bought a compression tester and the compression in each cylinder is exactly the same at 150 psi. That seems pretty strong. Certainly doesn't suggest compression is the problem here.
I've put my old jet back in again and that made no difference.
So I can see no physical reason why the car is not running. If the rocker arm was the issue then surely it wouldn't run on any cylinders?
So, over to my old-school mechanic and it's the 911 for Le Mans.
I'll report back when I've had a diagnosis. Thanks for all your suggestions.
Al.
OK, I think I've come to the end of my mechanical talent (assuming I ever had any).
I have bought a compression tester and the compression in each cylinder is exactly the same at 150 psi. That seems pretty strong. Certainly doesn't suggest compression is the problem here.
I've put my old jet back in again and that made no difference.
So I can see no physical reason why the car is not running. If the rocker arm was the issue then surely it wouldn't run on any cylinders?
So, over to my old-school mechanic and it's the 911 for Le Mans.
I'll report back when I've had a diagnosis. Thanks for all your suggestions.
Al.
I have bought a compression tester and the compression in each cylinder is exactly the same at 150 psi. That seems pretty strong. Certainly doesn't suggest compression is the problem here.
I've put my old jet back in again and that made no difference.
So I can see no physical reason why the car is not running. If the rocker arm was the issue then surely it wouldn't run on any cylinders?
So, over to my old-school mechanic and it's the 911 for Le Mans.
I'll report back when I've had a diagnosis. Thanks for all your suggestions.
Al.
If spraying cold start down the carb. throat brings it to life any you have fuel in the float chamber I wonder if you've had a bit of rubber or other detritus get in there and block either the float chamber exit or inside the carb lower body?
Start by taking the air box off, pulling the choke out and shoving your finger in there to lift the piston up and down a few times. In that set-up you should more or less get fuel pooring up out of the jet in to the carb throat. Certainly it should get damp looking.
Next whip the carb. off and give it a strip-down on the bench. SUs are quite simple, with just 2 valves on the fuel side - one in the float chamber lid that stops more fuel coming in when it's full and the other the needle filling and blocking off the jet stopping fuel being sucked in to the carb. throat. I've never had need to try this and wait to be corrected but with the piston out and float chamber lid off you should be able to easilly blow in to the top of the float chamber and have air come out in to the carb. throat.
Unscrew the jet pipe from the float chamber and I think you have a big hole, so should be easy to see if anything blocking/restricting that. And with the jet removed it's a big hole in the carb. body too. Then it's just blowing through the jet.
Start by taking the air box off, pulling the choke out and shoving your finger in there to lift the piston up and down a few times. In that set-up you should more or less get fuel pooring up out of the jet in to the carb throat. Certainly it should get damp looking.
Next whip the carb. off and give it a strip-down on the bench. SUs are quite simple, with just 2 valves on the fuel side - one in the float chamber lid that stops more fuel coming in when it's full and the other the needle filling and blocking off the jet stopping fuel being sucked in to the carb. throat. I've never had need to try this and wait to be corrected but with the piston out and float chamber lid off you should be able to easilly blow in to the top of the float chamber and have air come out in to the carb. throat.
Unscrew the jet pipe from the float chamber and I think you have a big hole, so should be easy to see if anything blocking/restricting that. And with the jet removed it's a big hole in the carb. body too. Then it's just blowing through the jet.
Gassing Station | Triumph | Top of Page | What's New | My Stuff