Lack of power

[millerliteliker]

I have noticed a definite lack of power (top speed) in my 49 F1 flathead.

What I have done:

Change fuel filter.
New fuel pump.
Remove fuel tank and clean / coat.
Previous - new Dennis Carpenter carburetor

The engine runs great. No issues at all. Does not smoke or sound like anything is wrong.

I guess the next step would be to run a compression test on the cylinders, but I really don't expect any issues.

The puzzling part is that the inline fuel filter is never full, but the glass sediment bowl on the fuel pump is always full.

Any ideas?

[Ken/Alabama]

See If you start easing out on the choke knob if the engine picks up. If so I'd be looking at the fuel pump or an obstruction in the fuel line somewhere.

[Seth Swoboda]

Have you checked the engine timing lately?

[Bob C]

Bad vacuum advance.

Bob

[drolston]

How about a few diagnostic clues?

Gradual or sudden onset of loss of power?
Does it miss or stumble as you reach full throttle, or, it just won't pull?
Are the wheels/brakes all staying cool?

When you run the compression test, also report on the plug color.

[DD931]

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I'm with Bob C. Bad distributor vacuum advance.

[flatjack9]

I agree with checking the advance. Those inline filters are never full. Nothing to worry about.

[Kurt in NJ]

Just5 checking the advance diaphram for "leaks" it the first step, then the advance should be checked to see that it advances properly at the specified vacuum, and if not the springs adjusted ---this makes a lot of difference

[millerliteliker]

Update: I went ahead and ordered a new vacuum advance diaphragm. Took the distributor out and made the quick change - no big help.

I got my old timing light out (not my newer digital one) and tried to use it - just too dim on the 6v system. I went ahead and loosened up the distributor and turned it CLOCKWISE. The truck was even more sluggish.

I went COUNTERCLOCKWISE and the result was instantaneous - the engine ran great and I easily got over 70 mph with good acceleration.

Thanks for the advice on the timing - that definitely did the trick.

Now - two questions:

1. Did I end up advancing or retarding the timing (turned the distributor counterclockwise).
2. Where can one find a 6 volt timing light in this day and age?

thanks for all the help and advice.

[Capt Kirk]

I think you can hook a 12v timing light to a spare 12 volt battery (not attached to the car) and run your test. As I was reading this thread I was also thinking a good check would be a vacuum gauge.

[D. Jones]

"Where can one find a 6 volt timing light in this day and age?"

In the past I used an extra 12 volt battery to run my digital timing light for my 6 volt system, now I use a 120 ac to 12 dc volt power supply intended to run 12 volt CB radios and such on house current. I picked it up at a yard sale for three dollars. Works great and only weighs a couple of pounds.

[flatjack9]

The distributor turns clockwise, so you advanced the timing when you rotated it ccw.