The 300 i recently swapped into my truck, seems to have low compression. While turning the motor over by hand it seems almost effortless to turn, Even with the sparkplugs in. Is this normal? Or is there something i'm missing?

Also, the engine rotates Clockwise correct? If not...this might be my problem....

 

Yes, the engine rotates clockwise.

Define "effortless to turn"; almost spins freely, tight grip on the crank can turn it, ????????
Under normal circumstances, you should be able to turn the motor by hand fairly easily. Too easily, however, may indicate a problem.

 

Its just fairly easy, as best as i can describe it. Maybe its because i'm using such a long pull-handle to turn the engine with. There may be absolutely nothing wrong with it.

I'll post more later.

 

I've been able to turn some motors by hand, grabbing the crank pulley with both hands, maybe using thr belt for more leverage. Hit compression and it'll get about impossible. With a wrench on it, it's eaiser. With a long breaker bar, oughta be a snap to rotate. Maybe you should just do a compression check to put a number on it? Worry more precisely, as I like to say!

-Ed

 

Well i tried it this morning without the breaker bar, and its a bear to turn on compression stroke, and only slightly easier on the rest of the cycle. It "feels" alright to me. I guess once i get the trans behind it, and get it all setup..i'll do a real compression test and see where i stand. Thanks ya'll.

 

I wondered about mine and today a friend gave me a compression tester so I checked it. 100 to 115 pounds. I admit to being surprised to see it that high. I should have tried the hand-test! Tomorrow, if I get a chance.
-Ed

 

I think the engine is in worse shape that previously imagined. I'm too tired to exactly put into words whats going on...but it refuses to run. All it will do is "spit" back out the carb like its out of time, but i've played with the timing in every which direction...and this is all i get.

Hopefully after a compression test tomorrow...i'll know more

 

I did mine, 140-150 on all @110K as of yesturday

i'm suprised

It might be 180 out on the distributer.

DT

 

The symptoms of no or very little compression, won’t start, and spitting back through the carb could mean that your timing gear is broken. A quick check is to remove the distributor cap. Does the rotor turn as you crank the engine?

 

Are your valves adjusted correctly?

 

Distributor button rotates as the motor turns. Honestly i've tried everything i can to check the timing...rotating the plugs around on the dizzy forewards and backwards to see if its out of time...and it still just backfires through the carb.

As for the valves, i didn't think the hydraulic systems needed to be adjusted. I've never touched the motor since i got it...aside from trying to fire it off these last few days.

 

Turning an engine by hand to check compression is very misleading. The compressed air will find many places to leak by when you turn by hand. Piston rings not only seal against the wall of the cylinder but are sealed to the bottom of the ring grove by the compression (compressed air)of a moving piston, at the same time that is happening the ring is also sealed to the cyl wall by the compressed air entering from on top of the ring and getting behind the ring and forcing the ring in contact with the cyl wall. It is something like blowing into a collapsed plastic bottle. Low compression isn't going to make the engine backfire thought the carb. You could have a burned valve. Take a compression test with a gauge and all plugs out.Run the starter. If a cyl comes up low squirt some oil in it and see if it comes up. If it does you have a worn cyl or rings, if it doesn't you could well have a burned valve, if you have two next to each other you could have a blown head gasket.
You could have a slipped damper ring giving you false timing settings. What mark are you using for timing? Later fords have two marks on the damper, a notch and a scribed line--the line is the correct one.pull your valve cover and set the engine to TDC of the firing stroke and see where the timing mark is and where the rotor points. It doesn't mater where you set the number one cyl on the dist cap as long as the wires in the cap follow the firing order. And the dist was set to TDC of the firing stroke and the rotor points to your #1. The ford books show #1 a being in 3 different places usually at the 5 O'Clock or the 7 O'Clock position the 6 O'Clock position is where the cap clip is. Don't take all this as the final truth LOOK IT UP FOR YOURSELF.

stractor

 

i know this sounds basic... but make sure that you have the spark plug wires in the right order. had a buddy with about the same problem and we did everything - he had the wires one off on the distributor. runs much better now.

 

I read my car manuals like a kid with the latest Harry Potter book! Well, almost, except for the starry-eyed-mug-for-the-camera look!
-Smoky

 

Well i finally figured out at least what part of my problem is with the truck. Aside from it only having 50psi of compression on #1 cyl and 65 on #2, the rest of the engine had 0 psi. 4 dead holes.

I removed the valvecover, to find to my expectant surprise 4 stuck intake valves. I'm not so much worried about these, because they can be unstuck, or the head can be worked to free them up.

My main concern now, is why do i have 2 cylinders with such low compression.. since those valves appeared to operate correctly while i was watching the engine crank over.

Hopefully, theres nothing more wrong than what meets the eye....

I also read the book to my truck like a kid with a new HP book too, i'm just a mechanical/technical freak...