The Ford Barn

fredski53 · 04-10-2020, 03:54 AM

Does anyone know the correct length of an original cam spring? The replacement spring I got from Snyders I think is too short.

Joe K · 04-10-2020, 07:34 AM

I have just examined two I could access from engines "apart."

One of these measures 1-3/16. This one I don't give a lot of credence to since it came from a timing cover where the plunger was "stuck" in place flush with the boss which contains it. The cam was obviously free to move forward and back and had worn the plunger boss. The spring itself seems somehow "thin" and weak.

The other measures 1-1/2. This one I put to "more original" of the two. Fully functional albeit worn engine when removed. No evidence of modification and the spring seems somehow more "stout." This one I would re-use after wire-brushing.

Hope this helps. I see at least one new spring in my Model A future.

Joe K

redmodelt · 04-10-2020, 09:35 AM

Even if the spring is shorter, under compression it could still have the same force of the original if the diameter of the wire used to make it was larger.

If the spring for example needed to be compressed to say 1 inch, a spring with larger diameter wire would need to be compressed less to get the same working force as a spring that was made of smaller diameter wire.

Example; If spring A with larger diameter wire is 1-1/4 inches long and when compress to working length of 1" has a force of 15 LBS (numbers are examples for illustration only, not real) and spring B with smaller diameter wire is 1-1/2 inches long and when compressed to 1" has the same LBS force.

Both springs would work in the case of the plunger springs because the working length changes very little. As springs are compressed the force increases, that is why valve springs have two working numbers, closed and open given in most cases given in pounds force.

burner31 · 04-16-2020, 11:15 PM

My computer is messing up so I can't post pictures, so, let me say...
Just changed out on original spring and plunger, plungers looks the same so no issue there, but the springs are way different, original is thinner wire but much longer, new one is thicker wire and much shorter but more stout.
After fitting the old against the new on the engine I noticed that the compression felt more or less the same until the cover started tightening against the engine, the new short one felt much stronger and better to do the job.
I went with the new short spring.

Joe K · 04-17-2020, 07:02 AM

Sponsored Links (Register now to hide all advertisements)

This is one for "Doc" Kalinka - who wrote for the Model A Magazines with (dare I say) original research on the Model A. Doc's articles inspired me to collect the whole set of "Technically Speaking" of which his articles played center stage.

Doc would take on a component inspired (usually) by some anomaly found at a Flea Market - and usually ending up for an afternoon at the Benson Archives and would tell you everything you needed to know.

But alas, Doc passed in 2016. Certainly missed.

https://www.wietingfuneralhome.com/o...kalinka-dvm/s/

Joe K

04-10-2020, 03:54 AM	#1
fredski53 Senior Member Join Date: Jul 2013 Location: La Porte, IN Posts: 143	Cam spring Does anyone know the correct length of an original cam spring? The replacement spring I got from Snyders I think is too short.

04-10-2020, 07:34 AM	#2
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: Cam spring I have just examined two I could access from engines "apart." One of these measures 1-3/16. This one I don't give a lot of credence to since it came from a timing cover where the plunger was "stuck" in place flush with the boss which contains it. The cam was obviously free to move forward and back and had worn the plunger boss. The spring itself seems somehow "thin" and weak. The other measures 1-1/2. This one I put to "more original" of the two. Fully functional albeit worn engine when removed. No evidence of modification and the spring seems somehow more "stout." This one I would re-use after wire-brushing. Hope this helps. I see at least one new spring in my Model A future. Joe K __________________ Shudda kept the horse. Last edited by Joe K; 04-10-2020 at 07:54 AM.

04-10-2020, 09:35 AM	#3
redmodelt Senior Member Join Date: May 2010 Location: Portland OR Posts: 6,340	Re: Cam spring Even if the spring is shorter, under compression it could still have the same force of the original if the diameter of the wire used to make it was larger. If the spring for example needed to be compressed to say 1 inch, a spring with larger diameter wire would need to be compressed less to get the same working force as a spring that was made of smaller diameter wire. Example; If spring A with larger diameter wire is 1-1/4 inches long and when compress to working length of 1" has a force of 15 LBS (numbers are examples for illustration only, not real) and spring B with smaller diameter wire is 1-1/2 inches long and when compressed to 1" has the same LBS force. Both springs would work in the case of the plunger springs because the working length changes very little. As springs are compressed the force increases, that is why valve springs have two working numbers, closed and open given in most cases given in pounds force. __________________ I know the voices aren't real but damn they have some good ideas!

04-16-2020, 11:15 PM	#4
burner31 Senior Member Join Date: Dec 2014 Location: Shawnee, Ok Posts: 3,471	Re: Cam spring My computer is messing up so I can't post pictures, so, let me say... Just changed out on original spring and plunger, plungers looks the same so no issue there, but the springs are way different, original is thinner wire but much longer, new one is thicker wire and much shorter but more stout. After fitting the old against the new on the engine I noticed that the compression felt more or less the same until the cover started tightening against the engine, the new short one felt much stronger and better to do the job. I went with the new short spring. __________________ Keith Shawnee OK '31 SW 160-B

04-17-2020, 07:02 AM	#5
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: Cam spring Sponsored Links (Register now to hide all advertisements) This is one for "Doc" Kalinka - who wrote for the Model A Magazines with (dare I say) original research on the Model A. Doc's articles inspired me to collect the whole set of "Technically Speaking" of which his articles played center stage. Doc would take on a component inspired (usually) by some anomaly found at a Flea Market - and usually ending up for an afternoon at the Benson Archives and would tell you everything you needed to know. But alas, Doc passed in 2016. Certainly missed. https://www.wietingfuneralhome.com/o...kalinka-dvm/s/ Joe K __________________ Shudda kept the horse.