Sprint troubles under 3000 rpm
-
HolgerS
Sprint troubles under 3000 rpm
I drove my Sprint this year approx. 3500 miles so far. Most of it was trouble free but since the last 300 miles it nearly do not cold start anymore and drives like a Kangaroo under 3000 rpm. I have changed most of the ignition stuff recently (new cables & connectors from Malc, new sparks, new condensor & points) and have installed the club build alloy carb mounts. I have adjusted the ignition timing off course and the standard SU carbs are running equal and their needles have not been changed. Any ideas as I am running out of those as well as out of time to get the car ready for the summer vacation in Belgium?
-
USASPRINTMAN
It sounds like a fuel problem.
Take off the carb float bowl covers and make sure that the needles and seats are in good condition.
Look on the bottom of the float bowl and see if there is a lot of crud from the gas tank down there.
If there is, you can clean it out easily by using a shop vacuum to suck it dry.
Next, check the mixture by pulling the choke out while you are driving the car. If it acclerates, you are running to lean.
Check the oil in the carbs.
And check your vacuum advance and retard system in the dizzy.
These things should help you find the problem.
Poor running when cold and bad idle sounds like fuel system to me.
Cheers,
Richard Truett
Take off the carb float bowl covers and make sure that the needles and seats are in good condition.
Look on the bottom of the float bowl and see if there is a lot of crud from the gas tank down there.
If there is, you can clean it out easily by using a shop vacuum to suck it dry.
Next, check the mixture by pulling the choke out while you are driving the car. If it acclerates, you are running to lean.
Check the oil in the carbs.
And check your vacuum advance and retard system in the dizzy.
These things should help you find the problem.
Poor running when cold and bad idle sounds like fuel system to me.
Cheers,
Richard Truett
Spluttering
Have you checked the fuel delivery to the carbs at idle? One of the float needle valves sticking?
As the old saying goes, 90% of problems with SUs are electrical.
Have you checked the resistance of the LT path from the coil 'earth' lead, through the points, throught the base plate, via the earth strap, through the dizzy mounting to the engine block to the body? This whole path ideally should be less than 0.2 ohms. If it is more than about 2 ohms you will have a problem similar to the one you are experiencing. Is the kangarooing slightly less when the engine is cold when on choke?
Best of luck and hope you find your problem soon.
As the old saying goes, 90% of problems with SUs are electrical.
Have you checked the resistance of the LT path from the coil 'earth' lead, through the points, throught the base plate, via the earth strap, through the dizzy mounting to the engine block to the body? This whole path ideally should be less than 0.2 ohms. If it is more than about 2 ohms you will have a problem similar to the one you are experiencing. Is the kangarooing slightly less when the engine is cold when on choke?
Best of luck and hope you find your problem soon.
Mark.
-
HolgerS
Only 58 hours before my planned 2000 miles trip and the problem is not fixed yet...... 
Today I rechecked everything but it is obvious that the problem is related to the ignition. I hadn't checked the distributor in detail so far because I knew it wasn't worn out and I had installed a new point, a new condensor, a new distributor finger and a new silicone cable set from the TDC stock. When I removed the cap today I found out that the cable in the middle coming from the ignition coil had melted the whole cap until there was a big crack towards the inner side
At least I have two spare caps here and will get a couple of feet of new cable by tomorrow morning but I still have no clue how this can happen with new parts nearly everywhere (except the distributor cap and the coil which worked perfect before exchanging the rest) and the Sprint has covered only one hundred miles with the new parts. Any ideas?
Please help to get my Sprint reliable in the upcoming 48h ....
Today I rechecked everything but it is obvious that the problem is related to the ignition. I hadn't checked the distributor in detail so far because I knew it wasn't worn out and I had installed a new point, a new condensor, a new distributor finger and a new silicone cable set from the TDC stock. When I removed the cap today I found out that the cable in the middle coming from the ignition coil had melted the whole cap until there was a big crack towards the inner side
At least I have two spare caps here and will get a couple of feet of new cable by tomorrow morning but I still have no clue how this can happen with new parts nearly everywhere (except the distributor cap and the coil which worked perfect before exchanging the rest) and the Sprint has covered only one hundred miles with the new parts. Any ideas?
Please help to get my Sprint reliable in the upcoming 48h ....
It does sound rather like the lead from the coil to the distributor (the "king lead"?) wasn't quite connected properly in the distributor cap. Since the electricity there is 10,000 volts it's possible that it was somehow arcing in the hole for the cable, and the air was getting so hot it melted the cap. Is the cable damaged?
-
HolgerS
Check the distributor advances if you suck on the pipe. Try it with the old condenser, points and leads.
Tinweevil
Tinweevil
1978 Pageant Sprint - the rustomite, 1972 Spitfire IV - sprintfire project, 1968 Valencia GT6 II - little Blue, 1980 Vermillion 1500HL - resting. 1974 Sienna 1500TC, Mrs Weevils big brown.
-
HolgerS
Checked the dwell angle including different angles, checked the ignition coild and double checked with another one, changed the distributor cap & finger again against new ones together with new cables and messured each individual through. Also checked the grounding lead/strap and the carbs which both are running mechanical fine, get enough fuel and are set equally. In addion I messured/checked all cables and contacts.
All this hasn't had any impact on the situation that the Sprint runs well in idle but does not like to rev up. From 2000-3000rpm it starts jerking already and from 4000rpm onwards it does not rev any higher.
Only thing I wondered is that the oil pressure instrument shows me that the pressure do not rise as fast anymore than before and I had the head skimmed in between. But this shouldn't havean impact on the higher revs or does it?
Funny thing is that with the old cables, condensor, etc. it doesn't run either anymore.
Any other ideas before I throw the whole thing out of the window?
All this hasn't had any impact on the situation that the Sprint runs well in idle but does not like to rev up. From 2000-3000rpm it starts jerking already and from 4000rpm onwards it does not rev any higher.
Only thing I wondered is that the oil pressure instrument shows me that the pressure do not rise as fast anymore than before and I had the head skimmed in between. But this shouldn't havean impact on the higher revs or does it?
Funny thing is that with the old cables, condensor, etc. it doesn't run either anymore.
Any other ideas before I throw the whole thing out of the window?
Still sounds like the advance mechanism isn't working. Check it with a strobe up to 3000, the advance figures are in the manual IIRC.
Tinweevil
Tinweevil
1978 Pageant Sprint - the rustomite, 1972 Spitfire IV - sprintfire project, 1968 Valencia GT6 II - little Blue, 1980 Vermillion 1500HL - resting. 1974 Sienna 1500TC, Mrs Weevils big brown.
-
HolgerS
Thanks for all your hints but the beast is not driveable anymore and I haven't find the problem but time is running out. Now I'm standing here frustrated with three not running Triumph's in the garage and 10 hours I'll start the journey. I never had so much trouble with the Triumphs and all the years enjoyed the cars very much for endless miles in the last ten years wit honly very minor problems. Seems that 2007 is not in favour with me..... So I will pack the daily driver now and leave the Sprint problem for the time after the two week vacation.
-
Jon Tilson
- Guest contributor
- Posts: 11179
- Joined: Tue Oct 03, 2006 9:45 pm
- Location: Middlesex
Blocked jet...
on one carb...
Seperate them on the trottle lionkage and rev them up individually...one wont rev.
Jonners
Seperate them on the trottle lionkage and rev them up individually...one wont rev.
Jonners
Note from Admin: sadly Jon passed away in February 2018 but his humour and wealth of knowledge will be fondly remembered by all. RIP Jonners.
-
HolgerS
Just want to let you know how the story ends. After searching a lot more the solution was exactly what Jonners mentioned at the end: the rear carb was not running at all even if I leveled them on idle. Unfortunitly this wasn't easy to sport as the engine was not starting at all as soon you tried to start it without the carb filters to check the carbs.
After dismantling the whole carbs and clean them and assemble them with a new overhaul set the Sprint worked perfect. Last weekend I drove 1300 miles in 3.5 days without any trouble and it was a real pleasure.
After dismantling the whole carbs and clean them and assemble them with a new overhaul set the Sprint worked perfect. Last weekend I drove 1300 miles in 3.5 days without any trouble and it was a real pleasure.