The Ford Barn

itstom · 11-14-2011, 07:11 AM

Back when I was playing with muscle cars (30 years ago) a perennial bench racing topic was cam timing. A lot of aftermarket items like offset drive bushings and adjustable gears were available to let you dial in your cam timing where you wanted it.

With all of the threads on here and the HAMB you'd think there would be a thread a week on the topic but I'm not seeing any.

So the questions; Is there something inherent in the flathead design that makes changes to cam timing unwanted or simply ineffective? Would any changes be noticable on a mild street engine?

The engine has Fenton headers, two 97's an an Edmonds intake, Navarro heads stamped 8.25, (old heads aren't off yet so not 100% sure on the bore), I'm going to go with the L100 cam. The car is a '41 coupe.

Thanks, Tom

Walt Dupont--Me. · 11-14-2011, 08:21 AM

Somewhere I have seen flathead cam gear with more than 4 holes to change cam timing. Someone might remember. Walt

flatjack9 · 11-14-2011, 09:53 AM

Yes, cam gears with multiple holes are available. Don't know what increments in timing they will allow..

JWL · 11-14-2011, 10:29 AM

If you read my book you will see how to change cam timimg, the theory of how and why cam timing alters engine performance and, you will get to see an actual test result. As I stated in my book, there is no magic. However, adjusting the cam can help overcome some of the unfavorable characteristics of a poor cam choice.

Karl Wolf · 11-14-2011, 11:35 AM

Seems to me that Reds used to carry them... I agree with JWL, that in an engine with well selected components, it's not worth messing with... You can move the power band up by retarding the cam, and move the power band down by advancing it... Seems odd doesn't it??
Karl

itstom · 11-14-2011, 12:37 PM

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Thanks for the replies. Sounds like it is possible, but I'm sure not getting a list of reasons to do it. I think I'll just leave well enough alone for now.

Tom

flatjack9 · 11-14-2011, 01:34 PM

I think JWL answered your question. The only reason to change would be a poor cam choice in the first place.

Vergil · 11-14-2011, 04:09 PM

I changed mine to give it a little more dynamic compression but after 1,000 miles I change it back to straight up. JWL's book does explain it well.

Vergil

Ol' Ron · 11-14-2011, 04:26 PM

We tried it in the stockcar several times, but didn't noticed the difference.Air pressure in the right front did more.

Cartravel · 11-21-2011, 04:42 PM

I believe someone makes a gear that allows for 6 degrees of advance. That is quite a large change. If that much change is an improvement then the cam was wrong to start with. Flathead cams are harder to advance than most engines due to the odd spacing of the holes. Why doesn't someone make a gear like this one which is for a Model T

Lawrie · 11-21-2011, 04:47 PM

They do,try Flatattack in Australia.
Lawrie

Ralph Moore · 11-21-2011, 10:25 PM

I have a flathead cam gear that has eight holes in it for adjusting the timing. But I have built many engines, most stock or mild street, and have never adjusted the cam timing on any of them. Is that right? I don't know, but they all ran OK.

11-14-2011, 07:11 AM	#1
itstom Member Join Date: Jun 2010 Posts: 65	Cam Timing Back when I was playing with muscle cars (30 years ago) a perennial bench racing topic was cam timing. A lot of aftermarket items like offset drive bushings and adjustable gears were available to let you dial in your cam timing where you wanted it. With all of the threads on here and the HAMB you'd think there would be a thread a week on the topic but I'm not seeing any. So the questions; Is there something inherent in the flathead design that makes changes to cam timing unwanted or simply ineffective? Would any changes be noticable on a mild street engine? The engine has Fenton headers, two 97's an an Edmonds intake, Navarro heads stamped 8.25, (old heads aren't off yet so not 100% sure on the bore), I'm going to go with the L100 cam. The car is a '41 coupe. Thanks, Tom

11-14-2011, 08:21 AM	#2
Walt Dupont--Me. Senior Member Join Date: May 2010 Location: Gardiner Me. Posts: 4,200	Re: Cam Timing Somewhere I have seen flathead cam gear with more than 4 holes to change cam timing. Someone might remember. Walt

11-14-2011, 09:53 AM	#3
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,527	Re: Cam Timing Yes, cam gears with multiple holes are available. Don't know what increments in timing they will allow..

11-14-2011, 10:29 AM	#4
JWL Member Emeritus Join Date: May 2010 Location: Fitzgerald, Georgia Posts: 2,204	Re: Cam Timing If you read my book you will see how to change cam timimg, the theory of how and why cam timing alters engine performance and, you will get to see an actual test result. As I stated in my book, there is no magic. However, adjusting the cam can help overcome some of the unfavorable characteristics of a poor cam choice.

11-14-2011, 11:35 AM	#5
Karl Wolf Senior Member Join Date: May 2010 Location: Mill Valley,Ca. Posts: 1,509	Re: Cam Timing Seems to me that Reds used to carry them... I agree with JWL, that in an engine with well selected components, it's not worth messing with... You can move the power band up by retarding the cam, and move the power band down by advancing it... Seems odd doesn't it?? Karl

11-14-2011, 12:37 PM	#6
itstom Member Join Date: Jun 2010 Posts: 65	Re: Cam Timing Sponsored Links (Register now to hide all advertisements) Thanks for the replies. Sounds like it is possible, but I'm sure not getting a list of reasons to do it. I think I'll just leave well enough alone for now. Tom

11-14-2011, 01:34 PM	#7
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,527	Re: Cam Timing I think JWL answered your question. The only reason to change would be a poor cam choice in the first place.

11-14-2011, 04:09 PM	#8
Vergil Senior Member Join Date: May 2010 Location: Tehachapi, CA Posts: 361	Re: Cam Timing I changed mine to give it a little more dynamic compression but after 1,000 miles I change it back to straight up. JWL's book does explain it well. Vergil __________________ Bigger fonts to aid in reading

11-14-2011, 04:26 PM	#9
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,860	Re: Cam Timing We tried it in the stockcar several times, but didn't noticed the difference.Air pressure in the right front did more.

11-21-2011, 04:47 PM	#11
Lawrie Senior Member Join Date: May 2010 Location: Qld, Australia Posts: 4,218	Re: Cam Timing They do,try Flatattack in Australia. Lawrie

11-21-2011, 10:25 PM	#12
Ralph Moore Senior Member Join Date: Oct 2010 Location: North Pole, Alaska Posts: 1,470	Re: Cam Timing I have a flathead cam gear that has eight holes in it for adjusting the timing. But I have built many engines, most stock or mild street, and have never adjusted the cam timing on any of them. Is that right? I don't know, but they all ran OK.