TR4/4A Some Help with Setting Distributor

[bammons]

I have been chasing things that may be causing a lack of high-end power. I found some things in the carb linkage and carbs that I have fixed but nothing seems to have changed much on the lack of power. So, I looked at my distributor and noticed the rotor was not pointing at #1 spark plug when at TDC. I will note that the distributor was rebuilt by Advanced Distributor, and I had installed a narrow belt pulley system and as such there was no hole in the pulley. I built the motor but had a mechanic finalize some things and it was him that marked the pulley for TDC. So, after realizing that the rotor was off position I thought I would have to move the distributor a tooth over. To make sure it was at TDC I turned the pulley counter-clockwise which lined up the rotor/slot straight at spark plug #1. I am using a instruction sheet from Ottawa Valley Triumph Club and they say to have both valves on #1 closed and that could be determined by slight movement at both rockers while both on #4 are tight and won't move. When I rotated the pulley CCW I achieve this but it also seemed to do it at the marked position on the pulley. Looking at the picture showing the pulley rotated you can see the marks are way off and of course my timing would have been way off - correct? I did not pull anything other than the base so my question is: should I assume the TDC mark was incorrect and drop my distributor back in and make a new mark? Pictures are from start to where I am now. You can barely see two red dots on the pulley one for TDC and one for 8 degrees. First two pics are when red pulley mark shows TDC second two are after moving the pulley CCW. Bruce

 

[charleyf]

I do not know if this would help but here are two pics of my TR4 dist. at TDC and the @ 8degrees BTDC.
Have you put an electronic timing light on the engine? I am questioning that maybe the advance weights in the dist may not be working properly.
Charley

 

[Sarastro]

First, whenever you turn the engine over, go in the clockwise direction, as viewed from the front. The timing chain will have a little slack in it, which will make the position of the camshaft uncertain if you turn it CCW.

Also, the distributor position does not matter, as long as there is room to adjust timing and for all the wires and lines to reach where they need to. It is a common misconception that timing will be off if the distributor is not precisely in the position shown in the shop manual. All that matters is that the rotor be in position for the #1 plug wire at TDC on cylinder 1's compression stroke.

Now, forget about the distributor and find TDC on the compression stroke. If you don't trust the new timing marks, you can remove the #1 spark plug and feel the piston position. (There are a number of tricks people use; do a search.) At TDC on the compression stroke, both valves should be fully shut. If they are not, they will move a little as you rotate the crank. Then you are on the exhaust stroke and need to turn the crank one more full turn. As long as your mechanic is halfway competent, I'll bet you find that the new timing marks are OK.

Now you can install the distributor. If it is not precisely in the shop-manual position, that doesn't matter as long as there is room to move it for timing adjustment. If you absolutely must have it in the standard position, you will have to move the distributor drive. That is tricky, as you have to get the end of the drive shaft into the slot in the oil pump as well. You can turn the oil pump with a long screwdriver, try the installation, and after a few tries you should get it.

 

[bammons]

Charley - The distributor was rebuilt by Advanced Distributor. Steve - I was sorta thinking this through when I posted. You stated what I need to do: find true TDC without a pulley mark. That way I will know if it is marked correctly (or not). According to the Ottawa Triumph site when both valves for #1 are closed they will have a slight movement and the valves at #4 will be in the same position but with no play. That is what I am using to doubt the present marking. I will google how to see or feel into the #1 cylinder, but I don't think my fat finger is going to fit. Using the Ottawa method it does seem that I can get the stated position over a small range of movement. I would prefer more precise. Should I use a dial indicator/mag base on the valves until I get the same height? Bruce

 

[mctriumph]

IMHO you are barking up the wrong tree. Loss of power in the upper range is more likely fuel related.
Timing will be across the board power loss. Who jetted the carbs/selected the needles? Incorrect
needles can make a motor impossible to tune.
Mad dog

 

[karls59tr]

Would a mark that is 3/8" BTDC on the crank pulley be 4 degrees BTDC or 8 degrees BTDC?

 

[Rick_Thompson]

There is a great way to set igintion timing using a vacuum gauge. I too changed out pulleys to billet ones, and consequently have no timing marks. I was becoming frustrated with getting a proper adjustment done when I stumbled across this procedure.

Using Vacuum Gauge to Set Timing (and adjust the carbs) : TR6 Tech Forum : The Triumph Experience

Thinking of using a vacuum gauge to set timing - and seeking advice on 1> attachment ( eg. disconnect brake servo to manifold hose at servo - and attach gauge); 2> process (loosen and rotate distributor and lock at max vacuum - or perhaps a couple of lbs less); and

www.triumphexp.com

 

[bobhustead]

If the valves for a cylinder are not showing lash at or about TDC for that cylinder, that cylinder is not on the compression stroke. Both valves are designed to be closed at the beginning of and throughout the compression stroke. That is what enables compresson to happen. The spark comes very near the top of compression and if a valve is open, you get no power; instead you get a backfire. Thus, the Ottawa club advice is correct. Use Steve's suggestion to find TDC when the valves are closed. Put a slender screw driver in the spark plug hole and feel for piston direction change while you rotate the engine by hand. The turn the engine back until you just feel the piston start to move down. This will be close enough to set the distributor shaft so that the rotor is pointing mostly toward the #1 plug wire and the points are just breaking open against the lobe on the shaft. The car will run at this point. Actual timing, as called for in the manual, is set by ear. Turn the dist body so you get the highest idle. The retard the timing so as to scrub off about 100 RPM. This will be very close to right. Final adjustment is to be by driving at 35 or so in 4th and punching the throttle while listening for valve noise. They call it ping. When you adjust the ping out, you have satisfied the requirements of the manual.
Bob
PS The procedure for initial setup I have described is the functional equivalent of the vacuum gauge procedure suggested by Rick, but requires less equipmeent and fewer spare vacuum ports to hook the gauge to (you don't have a spare port)

 

[bammons]

Mad Dog - I may be barking up the wrong tree. I started with the carbs and corrected a new bellcrank from Moss that I had to grind down on one side to match a original. Checked needles they are TW which is correct. Checked float levels which were incorrect and flipped the "stop" from contacting on the top to contact on the bottom as it is supposed to be. Also found the pedal lever on the pedal shaft was wallowed out and had maybe 3/4" slop at the linkage point which I fixed. Currently the jets are screwed down 14 flats which seems excessive, but I have had to have them even more. The valve clearances were incorrect. The disappointing thing is I had a mechanic finalize the engine settings and he also said he rebuilt the carbs. I have a street cam and now I am wondering if it may have been set incorrectly. The mechanic told me I had set it wrong but he had corrected it. He gave me the car back running decent but with a lack of power. I am going to find TDC and probably figure out how to reset the gear at the bottom of the distributor (a job I don't want to do). There is nobody for me to take it to so it is on me to fix. I love my BC's!! Bruce

 

[bammons]

Bob- you posted while I was writing the above. Going out to the garage to find TDC for sure and reset the distributor. With the effort I have made already I just need things to be right to track down my problem. Bruce

 

[sp53]

Does your distributor have the knurled nut on the back side of the vacuum advance so you can advance or retard timing there? You said the valves were out of adjustment how did you fix that? If the car starts relatively easy, your distributor is probably on the correct tooth and installed correctly.

I would probably pull all the plugs so the engine turns over easily remove the valve cover and then watch the push rods and valve move. Set number # 1 so both valves are closed and look at the marks on the pulley they should line up. Not a difficult job and that is probably how it was done

MD makes a good point on fuel delivery because when fuel delivery is poor there is no top end power. What kind of fuel pump are you using?

Steve

 

[Sarastro]

You cannot tell TDC precisely by the valves. They will tell you only if you are at TDC on the compression or exhaust stroke. On the compression stroke, both valves are closed and slight movement of the crank will not change that; on the exhaust stroke, the exhaust valve is closing and the intake is opening, so both will be open a little.

Bob's suggested method will get you close enough to TDC to install the distributor. It doesn't have to be exact.

While the distributor is out, you might want to check the advance mechanism and make sure all is OK there. MD may well be right about a fuel problem, but I think that an advance problem could be a cause as well.

 

[bammons]

The mechanic had set the TDC mark correctly. I checked for it being on compression stroke and watched the piston rise and everything seemed to be correct. I got the distributor rebuilt (Advanced Dist) and had not checked points since installation but the point gap was too narrow, so I reset that. Waiting for the wife to get home with new spark plugs before driving the #1 plug has a thread that I don't like the looks of. Have set the timing at 10* (street cam). So now the only other timing thing would be the cam timing but I won't go there now. Now I wonder if MD may have a point. I started to rebuild the old fuel pump (and in fact have the rebuild kit) but could not get the two "vents" out that were peened in so I just ordered a new one from Moss and that is what is on there now. I am tired of getting inferior parts from them and I hope this is not another one. Waiting on a voltage stabilizer now to replace the Moss one that lasted 5 months. What is a good way to test the fuel pump? SP - I do have the knurled nut presently set in the middle. I reset the valve clearances to .014 and .016 (street cam) from the .010 that the mechanic had set them. Car has been starting easy. No pinging. Bruce

 

[charleyf]

When rebuilding the fuel pump, in my experience( 4+ pumps and no failures) I have not replaced the one way valves ( these are not vents). Just replace the diaphragm and gaskets. Your old pump may very likely be a better unit than the newer ones, even with the older valves .
To test the pump simply push the cam arm down and listen for the noise it will be making. You can also hold a finger over the outlet and feel the air while pushing the cam.
When you were working on the carb linkage did you verify that the butterflies of the carbs fully open with the linkage? This is done by looking down the throat of the carb while lifting the carb piston and needle with someone helping by depressing the pedal all of the way down. The butterfly should be flat or nearly flat.
Charley

 

[bammons]

Ok I lied a little. I was getting READY to go set the timing and went to do it and I noticed the rotor was turned the wrong direction. Ok lifted the distributor and turned the shaft and now the distributor will not settle into the slot. Turned around it just drops in. There is a groove on the distributor shaft but it does not seem to fit into anything. I can't see anything that would prevent it from dropping in. If I am at TDC then the slot is lined up where it should be and I should be able to drop the distributor in. Am I missing something? Charley - Can I check the "new" one on the car and what do I look for when on the car (fuel pump)? The butterflies are the first thing I noticed when looking for problems with low top end power and yes they were not opening all the way (see my 3rd post above about rearranging the linkage). I thought that was the source of the problem but so far no.

 

[sp53]

the slot on the bottom id offset

 

[sp53]

The distributor only goes in 1 way because of the peg on the bottom is just a little tiny bit offset. Either you are looking at it wrong or you moved something 180.

The knurled nut moves the timing either advanced or retarded. Each line of calibration next to the knob is supposed to be 4 degrees( i think 2 or3 ). So if you turn the knurled knob toward the A just one line it should advance the timing 4 degrees.

When you get it running, remember where the mark is next to the knurled knob so you can go back if needed. Now move the knob toward A with the engine running and the engine idle should rise. Some. The knurled knob is for fine tuning the timing. It will not effect the dwell.

Steve

 

[charleyf]

Bruce, to check a fuel pump on the car undo the hose at the carb. Put the hose end in a jar and either use the hand pump on the fuel pump or turn the engine over. Watch the hose end for fuel delivery. This is a yes or no fuel test.
Charley

 

[bobhustead]

A long straight slot screw driver will effortlessly turn the oil pump shaft. Insert in the slot at the top of the oil pump shaft. The dist shaft will fit into the oil pump shaft ony one way because as Steve said, the slot is offset from center. You can turn the oil pump shaft any amount (limited by the need for the drive teeth to fit the cam) to affect where the rotor will point.
Bob

 

[TFB]

TDc can also be obtained by putting the crankshaft pulley key at the the bottom center.This can obviously be compression or exhaust stroke but lets you mark the bare new pulley,with a TDc mark lined up to the pointer.
Tom