View Full Version : TR6 69 TR6 tune up tips

06-05-2006, 11:03 PM
It finally stopped raining and I get to take my car out for my second real drive. What a rush! No windsheild yet, but bugs don't seem to hurt too bad until I get over 50 MPH. In any case, my car is noicably sluggish when I drive through town. I don't know if it is a fuel problem or ignition problem. When I am at a stop, I have to have the choke pulled out. I have never tuned a British sports car before. I read my books (I forgot my CD at work) and I am ovewhelmed on what to do first. I put in new plugs, rotor, cap and points. I disconnected the vacuum hose and set it at 10 BTDC. The tachometer shows 1,000rpm at idle. I had bought a carb kit from VB a few months ago, but after the posts on carb rebuilding, I am reluctanct to do that now. Any advice?
Thanks, Kevin

06-05-2006, 11:36 PM
Kevin, make sure you have plenty of oil in the dash-pots. A low level was enough to make mine run bad and I also had to pull the choke out while idling or even turning a corner at low rpm. Just an idea.


06-06-2006, 12:40 AM
I looked up the correct level in my Bentley manual, and it is not clear to me how full to fill it. How far from the top should it be filled? I have heard that overfilling also causes a problem.

06-06-2006, 04:09 AM
it's debatable if overfilling could harm your carb/intake system. I used to take care not to overfill then I read on the forum that the excess just flows to the other side of the plunger not causing any harm. I think the manual states that you should feel resistance from the oil level when you push the plunger down and feel resistance 1/4" from the bottom of the cap to the base of the carb. But it shouldn't be this tedious so just put a little motor oil in there and try it out. I was using a blend of AT fluid and Marvel Mystery oil but have returned to 10w40 and find it runs better.


06-06-2006, 05:26 AM
Brother Kev,
No windshield?! I hope you are not driving with just a windshield frame and no glass. Why, you ask? Safety concerns. The purpose of the windshield glass is also to keep your head inside the car. I know this sounds morbid but your description of driving without a windshield brought back a terrible memory to me from 1964. A friend was test-driving his LBC without the glass, only a frame. A very, very low-speed bump caused him to go through the empty frame and when he whip-lashed back, horrid as this sounds, broke his neck. Didn't make it. Sorry for such a negative story, dude, but had to say it. Please put a glass in (even with belts on) unless there is no frame in place yet.


06-06-2006, 07:01 AM
Some things to look at that would cause poor engine performance.
Make sure your diaphragms don't have holes in them. Check for vaccuum leaks causing the carbs to run lean. Old gas. Our modern gasoline does not have a very good self life. If the car sat for an extended period of time, make sure they are clean inside and not full of lacquer. If the carbs are not balanced, the engine performance will suffer.
If you have played with the richness, put it back to where it had been. Fuel adjustment seems to be the first thing people attack, but seldom is the problem. Unless of course you have made it a problem by playing with it.
The first things I would look at are the vaccuum leak and diaphragms.

06-06-2006, 09:18 AM
Yes Bill, I did drive the car without a windsheild. I checked, and it is legal. Even though it is legal, I didn't think about your point. I guess I was a little anxious. I have some repairs I still want to do anyway, so I will wait until summer to put the windsheild in and drive it.

Thanks for the carb tips. I replaced the vacuum lines and fittings. I have not adjusted anything because 1)the car was at least running, and 2) I didn't know what I was doing.
If I take apart the carbs and need to replace the diphragms, will I just need to rebuild the rest of the carbs too? I have not rebuilt one of these before. I purchased a rebuild kit and needles from VB. I have no idea of the qulity of this kit. I am afraid of rebuilding it and making it worse.

06-06-2006, 09:43 AM
You can replace the diaphragms without touching anything else.
Replacing the diaphragm is quite simple. You will notice there is a tab on the underside of the outer circumferance of the rubber . That fits into the slot on the carb body.
Just make certain that the diaphragm is fitted the whole way around.
Before removing the dashpots, you should see a line molded into the metal of the dashpot that continues down into the carb body. Those should always line up at assembly.

06-06-2006, 09:53 AM
As far as rebuilding is concerned, if you take your time, do one carb at a time, and follow instructions, you should be fine. Depending on the mileage of your car, I would hold off on changing needles at first.
If your new kit has Grose Jets, you will have to adjust the float levels.
The main thing is to clean everything thoroughly. This can be done by comparing the jet body heights and adjusting the metal tab on the float accordingly. As you take something apart, look for the replacement gasket or O-ring to familiarize yourself with the set up.
If you mess up, you're on your own. You won't mess up. It's really quite easy, but a little time consuming.

06-06-2006, 10:03 AM
I learned to take only one side apart the hard way, but thanks for the reminder. This car has sat for a long time, although the previous owner did a good job of emptying gas from the lines before storage. I think I will do it the way you said and just replace the diaphragms and see what happens.

Thanks, Kevin

06-06-2006, 12:22 PM
Try advancing the timing a little. After you advance it, take it for a ride. If you hear pinging, retard the timing a little or put it back to the factory setting. If there is no pinging. Try running it at that setting for awhile.
Working on the carbs is not difficult. Follow the instructions, don't rush and be careful not to lose or damage any pieces.

06-08-2006, 01:09 AM
I am still stumped. I checked the diaphragms and checked the oil level in the carbs. The carbs seem to be fine on both accounts. The idle speed is supposed to be 800-850 RPM. I am not able to get it that low. If I rev the and take my foot off the gas pedal quickly, the engine stalls. The timing seems to be close, but it jumps around when I shine the timing light. I am frustrated on what to do. I can't tell if it is a carb problem or ignition problem. It seems like a vicious cycle since one effects the other. I am going to recheck my dwell tomorrow and recheck the timing. If I can not get it to idle properly, that may be a problem. Any further suggestions?

06-08-2006, 05:41 AM
You say you disconnected the vacuum hose. Did you plug the vacuum line on the carb. Since there really is no pollution stuff on the 69 engine, I think, was there a vacuum advance on the dizzy (a big bellow-looking device on the side)? Set the timing at 8 degrees BTDC and make certain that any and all vacuum lines are plugged (with a rubber cap) on the carbs. If the timing light is jumping around, are you sure that the bolt that holds the dizzy is tight? Leave the timing set at this. Getting the rpms to stay at 800-850 is not really that ideal. 1000 rpm at idle is really more like it.


06-08-2006, 09:54 AM
I can get the car to idle at 1,000, but it seems a little high. If the idle is too high, won't it affect the timing? I did not plug the vacuum lines. I thought I was just supposed to disconnect them when I used the timing light. I am still not sure what you mean by "dizzy". Are you refering to the two vacuum advance pieces on the distributer that the vacuum lines attach to? I'll try what you suggested tonight and let you know what happens. I will also check the dwell. I may end up doing my best, and then taking it in for a diagnostic if I can find a mechanic that is familiar with this car. If they get it running better than me, I'll just check the various settings to see what I missed. I hate having to go to a mechanic. (This will be the first time for this car.) I am about out of money, and I am already above what I agreed (with my wife) I would spend to get this car running. It looks like I will start having to hustle up money by selling stuff on Ebay.
Thanks for the suggestions.

06-08-2006, 11:21 AM
Dizzy = a nickname for the distributor.
Yes, any open vacuum line on a carb will cause
the engine to run very poorly. Usually there is only
one vacuum line. You don't have to plug the vacuum
line on the "dizzy" because it does nothing if there
is no vacuum to it. Just do it for neatness.
"most" TR6 engines are perfectly happy at 1000rpm idle.
What do you have the dwell set at? 35 is about right. Just set your points at factory settings according to the book, unless you are running a hot coil such as a Lucas Sport coil, where you could open the points a wee bit.

Hang in there.

You need to explain to your wife what the priorities in life are.


06-08-2006, 11:54 AM
Just a thought but are you attempting to adjust idle with or without the accelerator linkage attached. If the linkage is out of adjustment it could be preventing you from getting a good true idle. Try removing the linkage from the equation. Set the idle, then when you re-attach the linkage and it changes, there is your problem. If it persists with the linkage separated then you have just eliminated one more possibility.