TR2/3/3A Rad installed = TR3A no run

[Bainesy]

Just started up the '57 TR3A engine yesterday after it had been sitting for almost 32 years. Points set, good spark, it started up easily using the push button on the dash, and it idled nicely; we gravity-fed fuel to the carbs from a bottle (didn't want to bother with what may be in the tank or if the fuel pump works, yet). Gauges indicated it was charging and the oil pressure was about 20 when idling and up to 50 when revving up to 4000 rpm.

This was without the rad installed, and we had a garden hose putting some water through.

Today we installed a rad and filled it, and the engine initially started up no problem, then died after running for a minute and we couldn't get it going again. The carbs need a rebuild and the plugs were pretty wet (with gas), but it seemed to be more than flooding.

As we had only changed one thing from yesterday, we took the rad off and it started up right away. We hadn't greased the water pump, but it wasn't making any noise and the belt is pretty loose anyway. I don't think it's the head gasket, maybe it's an electrical issue when the rad is installed? Maybe the engine is flooding with gas and the rad being installed was just coincidental?

Any ideas appreciated.

 

[mrv8q]

Sparking plugs.

 

[tdskip]

Let's hope it is just a coincidence.

 

[sp53]

If you gravity feed the fuel with too large of reservoir from too high of altitude this will make too much fuel pressure and flood the engine and foul the plugs. These cars only need 2psi from the pump.

 

[Bainesy]

Thanks sp53, that fits. We had put a larger bottle on yesterday, which, come to think of it, we took down while we took the rad off. The learning curve is steep right now...

I appreciate the replies.

 

[TR3driver]

The size of the reservoir makes no difference to the pressure. And to get even 2 psi, the top of the fuel (in the reservoir) would have to be over 6 feet above the carb bowls. Since those carbs should be able to hold back 4 psi (12 feet), I doubt that is the problem. Of course, you could still have a leaky float valve, but even that doesn't fit well with it running for a minute and then dying.

I think the radiator is probably coincidence. I'd put it back, start the engine again, and then when it dies, try to troubleshoot then. You didn't mention having to use the choke to start it, which makes me think maybe the carbs are just running way rich for whatever reason (are the jets up against the mixture nuts?) and as it warmed up the extra fuel made it too rich to run.

Only 20 psi on a cold start would worry me, too. Not necessarily a show-stopper, but something isn't right. And if the crankshaft needs to be reground, it's probably better to find that out now, rather than after the car is put back together.

 

[Bainesy]

Randall, thanks. I'm going to start reading up on rebuilding and setting up the carbs. Could low dashpot oil account/contribute to the problem?

 

[TR3driver]

Could low dashpot oil account/contribute to the problem?

I doubt it. The dashpot oil acts kind of like the accelerator pump on a more conventional carb; it provides a slightly richer mixture just as the throttle is opened (since otherwise the mixture would go lean just at that point).

But the effect is fairly small, the engine should run without any oil at all (except it might stumble and die if you open the throttle suddenly).

 

[sp53]

I still recommend hooking up a gas tank to limit the amount of fuel pressure. My experience was I hook up a temporary gas tank which was basically a large funnel up about six feet on the wall of my shop and it keep flooding and fouling out the plugs. When I hooked the gas tank up, things improved. This system is feed by a 2 psi fuel pump and vacuum sealed and there is nothing like an accelerator pump in there. The oil in the dash pot is used to keep a constant vacuum.
Steve