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TR2/3/3A Hesitation during acceleration

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GTP1960

GTP1960

Jedi Knight
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I probably have created my on problem, but before I take it into the "real guy" I would appreciate opinions.

Background:
just getting it back on the road after replacing crank fan with dampened narrow belt pulley ( losing TDC mark in process.) though I did mark the new pulley based on the old ones position , I can't spot my mark with a timing light.
So I'm pretty much just setting the timing by ear and feel.

new petronix flame thrower III distributor & 45k coil

new facet electric fuel pump.
(fresh 93 pure gas)

starts right up & idles smoothly.
(i have the idle set at about 1000.)
bumps a little while revving.

hesitates & lurches slightly during acceleration while running thru the gears, but once up to running RPM /speed, seems to run well.

Any opinions & advice appreciated.
 
Start with the basics. Have you checked the oil level in your carbs? Your symptoms are what happens when the oil level is low.
Charley
 
Thanks Charley,
i'll check that.

BTW: what oil do you recommend?
John Twist recommends 90weight, but I think the manual says 30.

Some of the guys in our club use that marvel mystery oil.

I've been using 30

Guy
 
90w is too thick. If you need that much you are compensating for a vacuum leak somewhere!
 
IIRC, I'm using 20W in my SUs. Ever since being rebuilt 4-5 years ago, haven't had to add any oil upon checking.
Oil level would be the first thing I'd check... Good luck!
 
I made a study on my TR3A some years ago. 20W was my preference; but there doesn't seem to be much difference between that and 20W50 (which is a lot easier to buy in stores and is also what I use in the crankcase).

FWIW, because of the (deliberately) different rating methods, 90 weight is actually about the same as 40 weight; which is what the manual recommends for temperatures over 70F.
 
So, tell me....if you use to much oil in the carb chamber , will it leak into the combustion chambers and cause impressive smoke?
i kind of hope so...
 
It will eventually find it's way into the engine; in fact I believe that is why the early owner's manual says to overfill them slightly every 6000 miles (so the excess can lubricate the sliding rod as it leaks down the carb throat).

But I don't know about the "impressive smoke" part. I suspect the vent passage is too small and substantial overfilling will just cause the engine to run poorly until it leaks out enough to let the piston rise as far as it needs to.
 
Guy, one thing to check is the linkage on the carbs. If one is getting the gas a bit early there is a little stumble in the acceleration. Getting the linkage right is a big part of the art of carb tuning.

Wayne
 
I would advance the timing. If that fixes the hesitation slowly bring the timing back until the car idles the best you can get it. My experience is that the timing, too fast of idle, fuel grade, acceleration, all have a connection and have to be balanced out by driving-plus no carbon on the plugs. I look at the plugs while I am playing around finding that sweet spot, and again mine shuts right off and does not pre-ignite from deposits on the plugs.
 
balanced out by driving-plus no carbon on the plugs. I look at the plugs while I am playing around finding that sweet spot, and again mine shuts right off and does not pre-ignite from deposits on the plugs.
Click to expand...

i pulled #1 plug to find TDC. The plug was pretty black with carbon. They are the new high output needle point plugs
(ndk, I think).

But on the brighter side, I'm not having any pre-ignition problems. And she starts pretty well.

but I think my term "hesitation" was wrong. After driving a little more I believe she is missing, under load, but seems to level off when the accelerator is static.(2000-3000 rpm)
i'm going to check for vac. Leaks today & ck the rest of the plugs. I believe I have her timing pretty close, now that I have re established TDC.

thanks for the all the input!
 
FWIW - I tried the NDK plugs in my TR3A a couple of years ago and experienced the same missing under load - changed back to Champions and my problems went away - will never use anything but Champions again.
 
You have the point less ignition or I would maintain to get the point gap correct before timing. In your case, I would check to see if the choke is returning, so that the jet bottoms out on the brass nut on both carbs. One other thing I look for is how much choke I need to start it cold in the morning? If they do not need a choke, then something is wrong. They seem to run a little better slightly lean also.
 
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