Question: I restored a 1966 Austin Healey 13 years ago. I was pleased with the results except for two frustrating quirks. First, when the engine is cold it bucks, coughs and backfires through the carburetors. Once it’s warmed up, all is well. Second, if I shut the engine off when it’s hot and re-start it a few minutes later the engine acts as if it's running on fewer cylinders. Once again, within a short distance, all is well. Any ideas?
Answer: There is one common denominator that can cause both the hot and cold problems you're having, and that's the carburetors.
The cold problem that you describe could be caused by an improperly adjusted or malfunctioning carburetor or choke, or both. Or, it could be caused by carburetors that are not properly synchronized, but I don't think that's it because the problem goes away when the car warms up.
The problems that you're having when the car is shut off hot, and then re-started could also be caused by one or both carburetors being improperly adjusted. In this case I suspect that when you start the engine, one or more cylinders are flooded with gas, or are flooding with gas when you start it. This gas has to be pumped out of the flooded cylinder(s) before the spark plugs in those cylinders can begin firing again.
I think that if you check to be sure the carburetors are operating properly (including the choke), and are properly synchronized, your problems will go away.
Motor mount problems:
Question: I am the proud owner of a 1985 Buick Regal 3.8L with 63,000 miles. The drivers side motor mount has just broken for the third time. I think the torque of the engine is causing this to occur. Is there a new mount I can purchase to fix this problem so it won't happen again?
Answer: I would look at things that might be causing the motor mount to weaken. One possibility is an exhaust leak that is leaking hot exhaust gases onto the mount. Another might be something like a brake fluid or power steering fluid leak that could be softening the mount.
If you can't find a cause, it is possible that the motor mount can't stand up to the torque, particularly if they are a poor quality aftermarket product. In that case you can attach a steel cable, or “torque strap” from a point on the engine block to a point on the frame. Ideally you can use the mounting points for the motor mount on both the engine block and frame. Allow enough cable for a small amount of flex. You can have a cable made or you can buy a aftermarket one.
Question: I have a 1970 Oldsmobile Cutlass Convertible with a Rocket 350 engine. The engine was rebuilt last year at a cost of $6,000.00 using only high quality parts…at least that’s what I was told. If I’m doing 60MPH and I floor the accelerator I get a “gurgling” sound from the engine. The same thing happens if I drop it into 2nd gear at about the same speed. It sounds like marbles in a plastic tube. I’ve had 3 different “good mechanics” look at it. One tried adjusting the timing but it just made the engine hard to start. Another said “It’s your gaskets and the motor isn’t breathing correctly.” The last one said I should live with it. Any ideas?
Answer: Since you had 3 "good mechanics" look at it, I'm going to have to assume that all of the basics were checked.
I think the timing may be an issue, but not in the manner you're checking it. It’s possible that the distributor may be set up so that the timing is advancing too far / too soon. This is controlled by any combination of weights, springs, and vacuum. The weights and springs come in an assortment of sizes so that the distributor’s performance can be optimized.
The other possibility is that the engine is running lean, which would cause these symptoms. This can be caused by anything from a carburetor that's too small to a vacuum leak in a place such as the carburetor base gasket, or intake manifold gasket.
I would check the distributor first (a good speed shop can do this), and then I would check for a vacuum leak.
Classic auto tip A broken motor mount is more than an inconvenience. Besides causing cosmetic damage to the hood, and broken fan shrouds from movement of the engine, it can also create safety issues, such as binding throttle linkages. GM had just such a problem in the late 1960s and their recall solution was to loosely strap the engine to the frame with a “torque strap.”
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