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TR2/3/3A Engine revs up and down

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RonR

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Folks,

I have tried everything short of selling the car as a project TR3A.

The car starts, but revs up and down on its own. If I push on the gas pedal to have it idle at say, 2500 rpm, it revs up and down from there without me doing anything.

Recent work:
Replaced fuel lines
Removed gas tank and removed debris and gravel (See picture; I need a locking gas cap)
Set the points and timing
Replaced spark plugs (non resistor type since the car uses points)
Set the carbs (balanced air suction and air/fuel mixture)
Checked carb float levels
Verified Gross jets operate

Any suggestions will be greatly appreciated.

Ron
 

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  • 05-28-24 - TR3 Fuel Tank Debris.jpg
    05-28-24 - TR3 Fuel Tank Debris.jpg
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Surging is a sign of a very lean mixture. How low does it idle, and how much is the surge when Idling? Also, empty dashpots can cause a lean surge.
 
Hi,

Try checking the mechanical advance springs in the distributer. Pop the cap off and twist the rotor. It should snap back to were it was. If not, its probably advancing or retarding on its own. That will increase or decrease the RPM.

I had that problem when I first fired up my TR-3a.

Good luck, Roy
 
Can you get the basic idle down to 1000? How high and low does the surge go? If you hold the linkage closed by hand, is the surge still there at same severity.
Bob
 
Intake leaking air into the manifold, Spray some carb cleaner in the suspect areas.
This will confirm. Usually the "pig" that sets on the underside manifold studs is out of position
and not getting pressure on the manifolds.
Mad dog
 
The revving was around 2000 rpm up and down, regardless of the starting point.

I rechecked the timing and all seem fine.
I rechecked the air/fuel mixture, and it was a bit lean, as CJD suggested, so I made the necessary adjustments.

For now, all seems right when just driving it up and down my very short block.
I will go for a longer drive this evening or tomorrow and see what happens.

Thanks everyone for your comments.
Ron
 
I think the problem is in the distributor springs or the vacuum advance eyelet has came unhook in the dizy and the timing is floating round causing the the engine idle to go up and down, like Roy said
 
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