The Ford Barn

Geo.T · 04-09-2019, 04:36 PM

I am experiencing some knocking in the engine. I am going to drop the pan and check mains and rod bearing clearances etc. Can I just wiggle the rods to get a feel for wrist pin clearances with the pistons in place?
Thank you,

Synchro909 · 04-09-2019, 05:49 PM

Others may differ but I think not. There will be end play of the rods on the pins and movement as the piston "slaps" in the bore. It would be difficult to get a feel. In this regard, the Model A is one of the easiest engines to work on. You can take the pistons and rods out the top and replace them the same way with the engine in the car. If you're reasonably confidant that is where the problem is, I'd do that.

chap52 · 04-09-2019, 07:22 PM

I know that I was able to find a bad wrist pin in a old 390 Ford engine years ago. Ran fine for many years before I sold it.The quick fix worked, that time.
BUT, if you got it opened up might as well disconnect the rod caps from the crank and remove the pistons one at a time and check them all. How are your rings? Good time to change them also. And the snowball continues to roll. Enjoy the adventure, Chap

Jim Brierley · 04-09-2019, 07:38 PM

I agree with synchro!

J Franklin · 04-09-2019, 10:13 PM

Sponsored Links (Register now to hide all advertisements)

With the pan off and a trusted helper you can do a preliminary check with a socket wrench and breaker bar on the crank nut with the plugs out. Put your finger on the pin to bushing or pin to piston and have your TRUSTED helper turn the engine back and forth slightly, and feel for slop. Tell the helper that he will be fired (or worse), if he pins your arm with the crank.

04-09-2019, 04:36 PM	#1
Geo.T Member Join Date: May 2010 Posts: 36	Wrist pin check I am experiencing some knocking in the engine. I am going to drop the pan and check mains and rod bearing clearances etc. Can I just wiggle the rods to get a feel for wrist pin clearances with the pistons in place? Thank you,

04-09-2019, 05:49 PM	#2
Synchro909 Senior Member Join Date: Jun 2014 Location: Melbourne, Australia Posts: 7,488	Re: Wrist pin check Others may differ but I think not. There will be end play of the rods on the pins and movement as the piston "slaps" in the bore. It would be difficult to get a feel. In this regard, the Model A is one of the easiest engines to work on. You can take the pistons and rods out the top and replace them the same way with the engine in the car. If you're reasonably confidant that is where the problem is, I'd do that. __________________ I'm part of the only ever generation with an analogue childhood and a digital adulthood.

04-09-2019, 07:22 PM	#3
chap52 Senior Member Join Date: Jun 2013 Location: Marana Arizona Posts: 1,774	Re: Wrist pin check I know that I was able to find a bad wrist pin in a old 390 Ford engine years ago. Ran fine for many years before I sold it.The quick fix worked, that time. BUT, if you got it opened up might as well disconnect the rod caps from the crank and remove the pistons one at a time and check them all. How are your rings? Good time to change them also. And the snowball continues to roll. Enjoy the adventure, Chap

04-09-2019, 07:38 PM	#4
Jim Brierley Senior Member Join Date: Jun 2010 Location: Temecula, CA Posts: 4,081	Re: Wrist pin check I agree with synchro!

04-09-2019, 10:13 PM	#5
J Franklin Senior Member Join Date: May 2010 Location: Oregon Posts: 5,958	Re: Wrist pin check Sponsored Links (Register now to hide all advertisements) With the pan off and a trusted helper you can do a preliminary check with a socket wrench and breaker bar on the crank nut with the plugs out. Put your finger on the pin to bushing or pin to piston and have your TRUSTED helper turn the engine back and forth slightly, and feel for slop. Tell the helper that he will be fired (or worse), if he pins your arm with the crank.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode