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So, it ran last Fall, but not well, and now it won't start.

 

There would be a lot of 'tune-up' type items along with fuel supply that I would investigate before I pulled the head.  It should start and idle even with 25# compression, especially if you give it a shot of Ether. 

 

Didn't see your results for the wet cylinder compression check. 

 

Just one man's opinion, if it were mine, pulling the head would be way down the list if it ran last Fall.

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Jerry thank you I have sent Olsens an email.

 

Brian thanks for info, do you think it should still fire with only 25lbs compression ?

Funny I get same reading on all four cylinders 25lbs.

Wet test it only went up 30 max 35 lbs.

 

Im going to borrow another gauge before I pull the head.

 

The only thing I remember was last  time i drove it on the way back it did seem to begin to lose power.

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Did you remove all the spark plugs when you did the compression test? it will rev faster without them and you may get a higher reading.

 

Disassembly won't find an electrical, timing or fuel problem. It is not the next step. It will result in a lot of money being spent, however,.

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The fact that the wet compression wasn't much better than the dry means the loss of compression is due to the valves. Leaky exhaust valves or leaky rings, the car might start, but leaky intake valves, the car won't even try to start because there will be no vacuum pulling fuel in.

 

Needs a valve job.

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1 hour ago, Morgan Wright said:

but leaky intake valves, the car won't even try to start because there will be no vacuum pulling fuel in.

You might have to explain this. It seems contradictory to me.

 

If the EXHAUST valves leak, compression will be poor and the low pressure will pull "air" in from the exhaust. If the INLET valves leak, compression will be poor and you might find it popping through the carb when it tries to run? The low pressure is created by the piston going down and the mixture comes in through the inlet valve so if it leaks mixture will still get in.

 

But yes, it might need a valve job. But it should still start as it is.

 

So, you have spark. Is it at the right time in the right place? i.e. near TDC on the compression stroke? You have probably pulled a lead to examine the spark; are the plugs actually sparking?

 

Is it getting fuel? Are the plugs wet after an attempt to start?

 

Is the spark hot enough? What is the voltage at the coil during cranking? My Studebaker was hard to start and it turned out the coil only had 2.2 V. Every terminal is zinc on brass on a steel bolt and washer and nut - a wee galvanic cell everywhere. Zinc oxide doesn't conduct much. Clean terminals fixed that.

 

Edited by Spinneyhill (see edit history)
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1 hour ago, Spinneyhill said:

 

 

If the EXHAUST valves leak, compression will be poor and the low pressure will pull "air" in from the exhaust.

 

 

No, the compression is poor but the pressure is still greater than the exhaust, which at this point is atmospheric, there is no back pressure because the engine isn't running yet. Leaky exhaust valves during compression just lowers compression. Leaky intake valves during compression pumps air into the intake manifold.

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4 hours ago, Spinneyhill said:

The low pressure is created by the piston going down and the mixture comes in through the inlet valve so if it leaks mixture will still get in.
 

 

When the piston is going down the intake valve is open anyway so it can't be "leaky". The only time valves can be leaky is during the compression stroke.

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  • 4 weeks later...

 

 

 

 

This attachment is from the 1923 4 cyl. owners manual.   

 

Check to be sure that the distributor  is not 180 degrees out of time.    

 

I would pull a spark plug and with the plug wire on it and the plug grounded to the engine see if the plug sparks.  If no spark try sliding a point file between the points.  Just one pull should do it.  You do not have to file them.

 

After you time the engine and crank it a few times.   If the timing changes and it is out of time, it is probably a bad timing gear.

 

Before you pull the spark plug to check for spark, crank the engine with the choke out several times.   Then pull the plug and  smell it to see if gas is getting to the cylinders.

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