When is rains it pours

[Will]

To get ready for another assisted living show tomorrow morning I drove the T over to the gas station to fill up, I pulled up in front of the store and went in to pay for my gas and out of nowhere I got one of Florida's famous ten minuet deluge. After it was done I dried out the plug dips and started the car. It idled just great but when I went to move it, it was missing on more than one plug. I babied it home and It took it most of the way home to dry out enough to run on all 4. As long as I didn't give it very much gas it would run kinda smooth. What bugs me is I have a modern coil box kit plus I put neoprene washers on all the contact surfaces between the ceramic tubes and the plastic coil box backing so I'm not sure how the water got in. I do my very best to not get caught in the rain but once in a while its unavoidable. I wonder if I put some spray foam around the ceramic tube and the firewall it would seal out any weather. I wonder if maybe water got inside the timer somehow? Any ideas?

[TXGOAT2]

Sometimes a radiator core can collect a lot of water. When you start the car, the fan will pull water out of the core and blow it over the engine. Very high humidity might cause problems even if the surfaces don't actually look wet. This is especially true if any dust is present. I'd look for any indication that water is getting on the inside of the firewall behind the coil box, and look for any sign that bugs, lint, or spiders have accumulated there.

Another possibility: If you do not have a heat pipe on the carburetor, high humidity can cause similar symptoms when the engine is started by allowing condensate moisture to collect in the carburetor and intake manifold. Under some conditions, frost can form. It will clear up after the car runs for a few blocks. This can occur in warm, humid weather well above freezing.

[TXGOAT2]

I think that one of the service bulletins mentioned adding some kind of gutter or shield to the firewall to divert rainwater that got under the back of the hood away from the firewall area and plug wires. I don't remember where I saw it or exactly what it consisted of or what year cars were affected. I believe it was a small, simple, sheet metal item.

[Erik Johnson]

Water might be getting between the firewall and the body.

From the factory, I believe there originally was a rubber gasket, similar to a flat piece of inner tube, along the top of the wooden firewall between the firewall and the body.

When my dad replaced the original factory firewall on his 1917 touring approximately 75 years ago, he put a new piece of rubber between the firewall and body.

More recently, we when replaced the firewall again with one that was more correct to the factory original, instead of a rubber gasket, we installed foam rubber weatherstripping between firewall and body. Refer to this thread and scroll down to my second post:

https://www.mtfca.com/discus/messages/1 ... 1294979916

Note that in 1917, the metal cap/trim on the perimeter of the firewall did not include a drip edge/gutter to divert water away from the engine compartment side of the firewall. The revised firewall cap with the gutter was introduced later.

[TRDxB2]

To get ready for another assisted living show tomorrow morning I drove the T over to the gas station to fill up, I pulled up in front of the store and went in to pay for my gas and out of nowhere I got one of Florida's famous ten minuet deluge. After it was done I dried out the plug dips and started the car. It idled just great but when I went to move it, it was missing on more than one plug. I babied it home and It took it most of the way home to dry out enough to run on all 4. As long as I didn't give it very much gas it would run kinda smooth. What bugs me is I have a modern coil box kit plus I put neoprene washers on all the contact surfaces between the ceramic tubes and the plastic coil box backing so I'm not sure how the water got in. I do my very best to not get caught in the rain but once in a while its unavoidable. I wonder if I put some spray foam around the ceramic tube and the firewall it would seal out any weather. I wonder if maybe water got inside the timer somehow? Any ideas?

How about rubber grommets inserted into the holes & around the insulators instead of foam ? The size for OD, slot thickness & ID

[Oldav8tor]

The rain gutters for wood firewalls were not available until 1919...I have a 1917 but installed one anyway. They show up now and then at swap meets. Below is a Vowell drawing showing the arrangement. The arrow points at the gutter.

Originally they used felt to seal between the body and firewall. Any suitable weatherstripping is probably a good idea.

You want to be careful plugging the holes that the ceramic insulators pass through. You will want to be able to remove the coilbox for service.

I did not block the insulator holes at all, but I did install a plastic coilbox kit. I've driven in heavy rain and my engine has never missed a lick. I suppose you might put some sealant on the seams between the box and the plastic back board. It would seal it but not be visible.