Tip #7
Is There A Fire In The Hole?
On Pontiacs equipped with four-tube headers, a heat gun (put one in your travel toolbox) is an excellent diagnostic tool to quickly determine which cylinder(s) isn't contributing its fair share of work. There will be a slight variation in temperature at idle due to camshaft overlap and intake manifold distribution, so look for a drastic change between bores. A misfiring cylinder will be substantially cooler than the others, while a burned valve or late timing might increase the header temperature. Take your reading from each primary tube about one inch from its cylinder head's exhaust port.
Tip #8
Take A Look Inside
The spark plug is a window into the engine. A very dark color on the center insulator shows either a rich mixture or a cylinder that isn't firing. A very white insulator tip and nose means a lack of fuel. If all of the plugs look fouled, the problem is most likely carburetor related. If only one plug is fouled and it's unique to that cylinder, it can be an ignition wire (carbon deposits) or an internal engine problem (oil deposits).
Tip #9
Compression Without A Gauge
No compression gauge in your toolbox? No problem! Disconnect the coil wire and ground it. Then, with the engine cold enough to touch without burning your finger, place your digit over the spark plug hole, have a helper crank the engine over and check the pressure on each cylinder. If the problem is bad enough to cause the engine to run poorly, you won't need a gauge to determine it-your finger will tell you when one cylinder provides much less pressure than the others. If you find a weak cylinder, don't think the worst. Pull the rocker cover and look for a broken valvespring. The problem is most likely there and not a piston or ring.
Tip #10
Let It Bleed!
Even the best filtration system may allow some dirt to get into the carburetor and plug an air bleed. If the engine refuses to idle, doesn't have a massive vacuum leak and is nonresponsive to the mixture screws, it most likely has a plugged air bleed. Raise the rpm up and slowly choke the carburetor with your hand, removing it just prior to the engine stalling. The increase in suction is often enough to dislodge the foreign matter and allow the engine to run perfectly.
Tip #11
Know Your Car
As with any procedure, data obtained such as exhaust temperature, compression, etc. when the engine is running properly will be invaluable when trying to diagnose a roadside problem. You can't know what looks bad if you don't know what looks good. A smart Pontiac owner is intimate with the engine and knows the normal readings. Don't wait for a problem to occur to do your research.