TR4/4A Some Help with Setting Distributor

[charleyf]

Ok did the fuel test using the key (starter) instead of the primer lever. I have a gear reduction starter so it spins faster than stock. This is about 6-7 seconds of pumping and yielded say 3 oz of gas. Much more than the primer lever method but is it what it should be? I will wait for answers before doing anything. Bruce

My opinion is that it is enough to show that the fuel pump is working okay.
BUT that does not mean that you do not have a supply problem going to the fuel pump. So at higher speeds if you have a restriction in the supply line you would not be getting enough fuel to the pump to maintain higher speeds.

I believe you need to now look at the line from the tank to the pump. It does not take much of a restriction (or in my case a bit of RTV gasket material ) to either plug or impede the fuel flow.
Try opening the fuel line prior to the pump and see how that flow is. Depending on how full the tank is the flow should be a 1 to 3" stream . I would also try some compressed air down that fuel line. Also look into your tank for anything floating on the bottom. This is all best done outside the garage as it gets messy and dangerous with the spilled fuel.
I ended up draining my brand new TR3 fuel tank to find and clear out some small bits that had totally stopped the fuel flow.
Charley

 

[bammons]

It is not the coil. I swapped out a distributor from a TR250 (which never has run since I have had it) but assuming it is good, no change. Took it for another ride after opening up the jets some more also. So on to the fuel line from the tank. Dreading pulling the line but I know I need to check it. I tried to see the fuel outlet using a flashlight and a mirror on a stick but the mirror was just slightly too large to go in the tank. I don't see anything obvious floating around in the tank where I can see. Bruce

 

[mctriumph]

There are at least 40 or 50 different needle sets for the SU carbs. each one has a different
profile to deliver a ration at a given throttle setting . I would guess you are going lean at the top
end.(rich would blubber).
Crude rascals have been known to put a needle in a drill and sand it(and mic it) to get more fuel
at a range of RPM.You may be able to order a better profile.This would be a great time to
go on a chassis dyno......
Mad dog

 

[charleyf]

There are at least 40 or 50 different needle sets for the SU carbs. each one has a different
profile to deliver a ration at a given throttle setting . I would guess you are going lean at the top
end.(rich would blubber).
Crude rascals have been known to put a needle in a drill and sand it(and mic it) to get more fuel
at a range of RPM.You may be able to order a better profile.This would be a great time to
go on a chassis dyno......
Mad dog

I recall that you are using a TW needle, which is the recommended one for the TR4A. I have TR4s and TR3A and use a SM needle. That is a slightly richer needle than the TW. I doubt the needle is the problem.
Charley

 

[sp53]

I have SU H6’s and use the SM needle. Your car looked like the carbs are Stromberg or something looking at the linkage.

I once had a blockage in the back carb body itself where the carburetor bowl feeds into the body. A piece of rubber dislodged from the rubber gasket. I found it by looking at the spark plugs and noticing the back carb spark plugs were running much cleaner and leaner than the front carb. It took me a month or two to find it. The problem was no high end power also. If SU are both pistons lifting up on the carbs.

Pull the plugs out and look close read the plugs and put clean ones in for the next test to see how the fuel is burning

When you get it running rough trying advancing the timing with the knurled nut, or even retard the timing and see what happens. I take it you replaced the condenser, right.

Steve

 

[bammons]

The distributor was rebuilt last year by Advanced Distributor. He uses the "good" red rotors. I pulled a plug after my drive and even though I am way down on the jets (I think at least 18 flats or more down the plug looked lean. Steve - the plugs have been looking the same so I would have to have blockage at both carbs but I am grasping at any straw here. I still think I have a fuel problem. I had some workmen here today so did not get the old fuel pump rebuilt and installed but tomorrow I will figure out how I can dis attach the line at the tank and drain some gas without a major incident and blow thru the line to the fuel filter. And put the old pump on. Are there any tips on properly engaging the cam lobe? Bruce

 

[NutmegCT]

Bruce - cam lobe: read the text I posted in #39.

 

[charleyf]

The distributor was rebuilt last year by Advanced Distributor. He uses the "good" red rotors. I pulled a plug after my drive and even though I am way down on the jets (I think at least 18 flats or more down the plug looked lean. Steve - the plugs have been looking the same so I would have to have blockage at both carbs but I am grasping at any straw here. I still think I have a fuel problem. I had some workmen here today so did not get the old fuel pump rebuilt and installed but tomorrow I will figure out how I can dis attach the line at the tank and drain some gas without a major incident and blow thru the line to the fuel filter. And put the old pump on. Are there any tips on properly engaging the cam lobe? Bruce

First to engage the cam lobe you only need to make sure the pump is offered up to the block horizontal or with the arm slightly up. Just do not point the pump arm down as it is unlikely but possible to slip that arm underneath the cam.
Bruce I would NOT recommend you trying to remove the fuel line from below the tank. At least not while it has anything over an inch or so of fuel.
Instead pull the fuel line apart at the rubber Junction just below the fuel pump. You can then add a hose and safely drain the tank into a container. Or what I did was to use a cheap siphon and take the fuel out of the gas cap hole and put it directly into a fuel can. Much safer and you can reuse the fuel. You may want to filter it before it goes back in.
Before siphoning the fuel try the test of getting fuel to the pump.
Have you removed the pump from the car yet? You can also use compressed air to blow the line back to the tank using the inlet end of the fuel line at the pump.
Lots of options. But I can not imagine being underneath the fuel tank and removing the fuel line with fuel in there.
Charley