Should I tie choke completely open when doing compression test?

What should my numbers be on a 61. 283/270hp in each cylinder?

Anything other than putting gauge adapter securely
In plug area and rolling car over with coil wire off so it don't fire?

Dave

 

Opening the throttle blades is generally accepted as the best way to get an accurate measurement. Personally I've not seen a difference in the readings.

David

 

I would secure the choke open all the way and the throttle as well. You want a clear air flow to the engine. If you use a screw in gauge make sure you use the correct diameter and length plug adapter. Pull all the plugs before you start. You will be able to hear the compression strokes on the cylinder you are testing. I use 8 compressions strokes per cylinder. If you battery is marginal be sure to hook up a charger.

Tom

 

Any ideas or a website that might have what each cylinder should be at?

 

Here is the procedure:
Plugs all out.
Choke and throttle wide open.
Coil disabled (some guys just pull the coil wire, I have been guilty of
doing that in the past, but then the coil can still spark) Disconnect
either the + or - wire from the coil to disable it.
There are no specs in any book for PSI readings, compression, cams,
cam timing can vary the readings. What you should be looking for are
vairations from cylinder to cylinder. As i recall for stock Mom and pop
engines this can be 10%. I will only allow 5% on a performance engine.
If you have a low cylinder that is way out of spec bring that cylinder to TDC firing, not overlap then apply compressed air through the spark plug hole. Snap on had air hoses that screwed in to spark plug hole to do this. You need 120 PSI of air. You also have to have the piston EXACTLY TDC, otherwise it will just rotate the crank and open the valves. Now assuming you are at TDC with air the diagnosis is easy, listen through the intake, the exaust pipe (pipes) and the valve covers.

Any air you hear leaking through the intake/carb is an intake valve. any air you hear leaking out of the exhaust is an exhaust valve. Any air you hear leaking out of the valve covers are rings.

Now don't get get me wrong, you just can't hear it by standing, you need to put your ear right over the carb, the exhaust outlet or the valve cover oil fill.

This was just a very quick and accurate way to tell my customers wether they needed a valve job or a rebuid...

 

As othe have said open choke and throttle.
Also remove the distributor side of the coil wire and ground it to the engine.
According to two vintage repair manuals the compression should range from 150-160 with no more than 10% difference. Crank the engine approximately the same amount of revolutions per cylinder.
Joe

 

A battery charger hooked up is the only way to get accurate results.

- Mark

 

Is there something wrong with mine? It gets 230-240.

 

I get 200-220 in my 62, 340 horse car.

 

You must have a short camshaft and or higher compression and or a cam with a LS of 112 or more.

 

yeah...youre' a horsepower freak!........

 

True.
But.......
............the 2 babes posing IFO the car in yer aviator could make me forget about horsepower for awhile.

 

LSA is 110, durations are in the 250 degree @ 0.050" vicinity, and static compression is 11.65:1.

 

The 097 has a very early closing intake valve. It was properly matched to the 283 but was given too much static compression for a 327. There were always more detonation complaints from owners of cars equipped with 097 cammed 327's from the factory. The addition of a second shim steel head gasket helped alleviate some complaints, but the motor still had too much SCR for that cam.