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Possible cause of my 29 Buick Carb Fires


Bill - 29 Buick

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As many of you know, I had two carb fires on the trip home from the BCA National this summer. It was brutally hot out (40+C / 100+F) and the first fire started immediately after I turned on the electric fuel pump when the car started to vapor lock. The second started after I'd stopped for a few minutes and needed to use the electric pump to restart a very hot car.

We couldn't find an apparent cause except perhaps the "regulator" installed in front of the occasionally used electric fuel pump decided not to regulate and too much gas was pushed into the carb bowl and out through the hole in the top of the carb bowl. This would have meant that the needle and seat (actually one Grosse-Jet and one needle and seat) on 2 carbs had to be faulty.

The Canadian 1929 McLaughlin Buicks have a Dole Primer pump installed for cold weather starting - these were standard on all 1929's sold in Canada. This pump sucks raw gas out of a connection in the gas line and pushes it into the intake manifold through a series of small pipes.

Today, we found something interesting. The rigid pipe connection between the fuel pump and the Dole pump valve in the gas line had simply worn smaller at the Dole pump valve - allowing gas to drip out with a new, low pressure electric pump, without the car running. As this valve is very close to the exhaust pipe it's not hard to imagine that gas squirting out this valve would catch fire.

In addition, the mechanical pump was likely sucking air in at this worn connection which may well have been the cause for some of my vapor lock problems - especially on very hot days.

FYI.

-- Bill McLaughlin --

Editor & Publisher - 1929 Silver Anniversary Buick Newsletter

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Bill :

Thanks for the update. I was wondering if you had found the culprit! Very feasable senario.

Again we are glad you were not injured (except emotionally about the damage done to the car).

How are the repairs coming. I am hoping to see you and your 29 in South Bend.

Larry DiBarry

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A few years ago I restored a Stewart Warner vacuum tank back to operation for a 1932 Hudson Eight Brougham. It is a medium blue wood wheeled dual sidemount car in Oklahoma or Nebraska now (I think). We threw away all the "improvements" including a pressure regulator between the vacuum tank and the carb! It's gravity feed. And we corrected the wiper vacuum supply so it didn't draw off the tank, too. Sometimes the updraft carb will leak a bit and if it spits back due to a lean mixture of the timing being off or the advance lever out of adjustment you can get a little fire going. I am overcautious; I start those cars with the hood open.

Bernie

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I'm glad you figured it out but I'm especially glad no one was hurt in the fire and that you were able to put it out. Another few minutes and it would have been a total loss. This is every old car owners nightmare. Call me crazy but I've got two fire extinguishers in the '28 now.

On the other hand it is remarkable how durable these things are. The engine catches on fire and you change out a few parts and your back on the road.

About the top getting torn while being transported on the roll back: As you recall it was so hot (100s) that week after the National meet and the '28 was getting vapor lock all over the place. There was no way I was going to make a 400 mile trip in that heat. So I rented a U-Haul truck and trailer for the trip home. It was an open trailer and my top pulled apart too. I guess they are not made for sustained 65mph winds.

Anyway it's good to hear you're back on the road.

Dave

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