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TR2/3/3A TR3 replacing rings how to?

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Re: 110,130,125,125

Jim Lee said:
On the advice of the Forum I did a cold compression test to see if I needed new rings. Cylinders 1 to 4 tested as
100 - 1
130 - 2
125 - 3
125 - 4
Click to expand...
Jim, before you do a tear-down, you might want to run this test again with the engine WARMED UP, rather than cold. Also, if you didn't, it's often best to do this with all plugs out and throttle held wide open. I wouldn't exepct the results to change all that much, but one never knows....

Yes, that one cylinder is low, although not hideously so. If the same relative results are achieved with the above method, you might try one more time on that cylinder after dribbling a bit of motor oil in through the spark plug hole. If the number increases, chances are rings (and/or bores ???) are worn in that cylinder. If they don't change, there might be a problem elsewhere, such as valves?
 
Re: 110,130,125,125

:iagree: But note that the oil will always make a small increase in reading by displacing some of the combustion chamber volume. A large increase indicates problems with the rings. How much depends on how much oil you use too, so use about the same amount in each cylinder. If you have a pump-type oil can, two pumps is about right.
 
Re: 110,130,125,125

I used the ridge reamer he liked, https://mgaguru.com/mgtech/tools/ts311.htm
, and it always worked very well. Plus you can use it on the liners while they are being held in place with washers and sockets.
 
Re: 110,130,125,125

Hi all,
I am just getting back into full time TR3'ing.
1959 TR3a with recently rebuilt head.
Wondering if it is time to replace the rings.

Just did a warmed up compression test so now I have:

Cold - Warm - Difference

1 - 110 - 145 +35rel
2 - 130 - 130 0
3 - 125 - 155 +30
4 - 125 - 160 +35

#2 cylinder seems the strangest to me with no difference.

Are the +30's considered normal? I am going to do a leak down test as soon as I can get a homegrown tester together.

Another question on a totally different subject. The engine runs great but I have what feels to me like a large dead spot on initial acceleration. It is really bad when dead cold, like to stall out if I am not very careful, but is still there after it is fully warmed up. It is most noticeable when slowing down to make a 90 degree turn either way. I have to make sure that I keep the revs up or it is a while before I can accelerate out of a turn. I don't expect it to respond like a fuel injected car but I know that it has done better than what it is doing now.

Does this have to do with the SU damper oil doing its thing? There was definitely some in them as I could feel the resistance screwing the top in. It might have been a little bit low but not much. Have not given it a test ride since I topped it up. The lighter the oil the quicker the carb response right? I have Marvel Mystery Oil in there now but thinking about putting motor oil in there to see if it makes a difference. I am wondering if the Marvel Mystery oil is too light so that the carb is getting too much air and fuel at the same time. It feels like it has to 'catch its breath' when I get on the pedal too quickly

Could this also be a problem with the timing? Other than this dead spot the engine seems to run really well. Nothing close to a backfire or lugging. I am also wondering if I have the dreaded throttle spindle wear? I can actually bring the rpms down low enough that the car will stop running by standing at the engine and pushing up the linkage without too much force. It appears to have another fraction of an inch that it will sometimes go back to and if I am driving and the car is not warmed up it will stall. I have sprayed carb cleaner on both side of both carbs and not heard any difference in idle so I am kind of puzzled on this. It will be idling fine at about 11 or 1200 rpm and then all of a sudden I will come to a stop and the idle will drop way low...low enough to shut the engine down. I am also wondering if my floats needs adjusting as the shut downs usually happen when I am braking hard and/or pointing down hill. Is there a rule of thumb for where the floats should be?

Thanks to all and happy motoring.

Jim Lee
 
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