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Need Help With Stromberg Carbs

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bravenrace

bravenrace

Jedi Hopeful
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Hi,
I'm new here and new to British cars, although I use to be a professional mechanic, so I'm pretty good with cars in general.
I recently bought a '74 TVR 2500M. I'm sure you all know that this car has the Triumph TR6 engine in it. It currently barely runs, and I haven't spent much time at all on it to correct that. I'd like to educated a little more before I do.
Here's the symptoms. You have to crank it forever to get any fire at all. Starting fluid doesn't seem to help. The colder it is, the harder it is to start. Once it starts to try to fire, it still takes many tries to finally get it to start. Once it starts it sputters, occasionally backfires, and occasionally revs smoothly and freely for brief periods of time, then it goes back to sputtering. The misses are bad enough that you can't really drive the car at all.
I did take it out on the road the first day I had it. I warmed it up for a long time before taking it out (it does run better when it's warm, and the choke on each carb is working). I drove it down the road about 1/8 mile and it died like I had turned the key off. It wouldn't restart. I checked for spark and it seemed like it wasn't getting any. It also seemed like the carbs might not be getting gas, so I put some more in. After that it kicked a couple times, but still wouldn't restart. So we towed it back to my house.
I had my son spray starting fluid in while I tried to start it, and it would fire and then die once it burned all the starting fluid. I checked the spark again with a tool that is installed inline in the coil wire and is clear. There was an arc, but (at least compared to other cars I've seen) it looked very weak.
That's as far as I've gone with it. You might notice that these symptoms seem to vary with the situation, and you are right. Its also seems unlikely to me that it has boht ignition and fuel problems, but not impossible. So before I spend a lot of time on this, I thought I'd pick your brains in case there are any common reasons for this problem or peculiarities with this engine that might call for special troubleshooting procedures. The reason I've titled this post as needing help with the Stroms is that according to the previous owner, two separate British car repair facilities told him that there was something wrong with the front carb, but he didn't know what.
Any ideas? Sorry for the long post.
Jim
 
Jim, where to start, the carbs need oil, lift the black plastic knob on the top, (unscrew) and add some thin weight oil, if there is none in it. If that is OK, undo the four screws on the top dome and check out the rubber diapham for brakes or cracks. As for the air leaks in the hoses from the emissions, it's hard to tell without a picture how the DPO (d... Previaus Owner) had things hooked up. This should atleast get you started. As for the spark, if you still have the points setup, they tend to oxidize, so run a fine file or sandpaper through them and set to .015. There is a small wire running inside the distrubtor inside a cloth cover, (very fine wire), check it's not broken. Now see what happens. Wayne
 
[ QUOTE ]
Jim, where to start, the carbs need oil, lift the black plastic knob on the top, (unscrew) and add some thin weight oil, if there is none in it. If that is OK, undo the four screws on the top dome and check out the rubber diapham for brakes or cracks. As for the air leaks in the hoses from the emissions, it's hard to tell without a picture how the DPO (d... Previaus Owner) had things hooked up. This should atleast get you started. As for the spark, if you still have the points setup, they tend to oxidize, so run a fine file or sandpaper through them and set to .015. There is a small wire running inside the distrubtor inside a cloth cover, (very fine wire), check it's not broken. Now see what happens. Wayne

[/ QUOTE ]

Thanks Wayne! There is oil in the carbs, but how do I know it's the correct level? Seems like to check the diaphram I would have to emply the oil - If so, what kind of oil is it?
It appears that most of the emissions equipment has been disconnected. If I suspect a vacuum leak, I usually disconnect everything that isn't necessary to eliminate it anyway. I did notice that the vacuum advance isn't hooked up on the distributor. While I'm sure this isn't helping anything, am I correct that it's likely not the cause of this problem?
I've seen a couple electronic ignition kits for these engines. I don't really care for points, so I was thinking about buying one of the kits. I have a Pertronix on my '65 Mustang, but I also see that Crane has one. What do you think of these - Good, bad, which one?
The wire in the distributor - What's it for?
Thanks again for your help,
Jim
 
Jim, The oil level is 1/4 inch from the top of the inter circle that you see. The top comes off with the four screw and the oil chamber stays put, so don't worry about dumping oil all over the place unless it's way to full. The wire is a gound for the points plate. AS for electronic ignition, I have had no trouble with the Crane 700, but they both are good. Your vacuum hose on the distributor is for retard only on your later model, (say what), yeh, I know. Wayne
 
This is not even $0.02 of value but i think your problem is about 97% ignition related, not carbs. If you can not get the motor to fire with starting fluid, you do not have spark at the plugs. Even if you don't care for the points, try what you were advised about the clean up and gap setting for the points.

P.S. I favor electronic ignition too.
 
After you take the top of the carbs off you will remove a spring and a piston with the diaphram on it. On the bottom of the piston there is a very thin mixture needle. You need to be careful when you pull the piston out, as to not bend the needle. Phil
 
Tracking down a problem like this is really a matter of eliminating possibilities one by one until you solve it.

First I would change the carb diaphragms as they are very delicate and notoriously troublesome. Check that the fuel filter is not blocked, replace it if there is any appearance of dirt or rust particles. Disconnect coil to prevent sparks then remove the gas line feed to the carbs and crank the motor briefly to see if gas spurts out. (Try to catch most of it in a container.)

Since you don't know the maintenance history of the car I would start by replacing all the plugs and ignition wires, the points and condensor, and maybe even the coil. If that doesn't solve the problem you have eliminated a lot of potential problems and are closer to the solution.

Check all the nut6s on the inlet and exhaust manifold are done up tight and test for leaks, which mess up the mixture.

If none of this helps you need someone clevere than me (or is that I?)
Good luck!
Simon.
 
If you have a Lucas coil, check to see if the male spade connectors are braded (riveted) to the coil. Sometimes these are loose and will cause a poor connection at the coil. Drove me nuts on my TR6 one time. The car would run and then just quit without warning. The TVR is a neat car, enjoy!
 
I would replace the conderser first, and check that the fuel pump is delivering fuel. If the car has been sitting any length of time over the years, it is not impossible for the tiny passages in the chokes themselves to become plugged up. You can remove the chokes from the carbs, and inspect and clean as required. As posted above, check the diaphragms very carefully. Carb cleaner is really hard on the rubber, so if you choose to clean anything up, remove the diaphragms first. (note they have alignment tabs....)
 
What is the VIN of the TVR. My shop owned 2547TM for a while, and it was sold to a guy in ohio. Just curious.
 
Mine is 3106TM.
 
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