The Ford Barn

topfuel724 · 10-28-2015, 05:27 AM

Have a Harmon Collins cam for early flathead. Numbers on front of cam are 7RA 3/4. Cam lift measures 320. Anyone have the opening and closing timing specs for this?

scooder · 10-28-2015, 08:18 AM

Are these numbers around the outside of the timing gear flange?
I ask as the h&c cams I've seen are marked around there, they had "Harmon & Collins" then a number like 6352, then 3/4, I just made that 6352 number up for an example.
I'm not with my notes right now, I can have a look after work, see if I got the specs.
Martin.

topfuel724 · 10-28-2015, 08:49 AM

Yes they are on the flange. Harmon Collins logo and then the 7RA 3/4.

flatjack9 · 10-28-2015, 12:28 PM

7RA would indicate it is for a 49 - 53 engine. Specs I have are: IO-19, IC-59, EO-59, EC-19 for 248 deg duration and .320 lift. Overlap is 33. Clearance is .011 intake and .013 exhaust.

scooder · 10-28-2015, 01:50 PM

Great stuff flatjack, I looked, haven't got those specs.
The 3/4 h&c spec I have is 19-59 54-14 .320" lift. But have a full race h&c spec of 19-59 59-19 .320" lift?
Martin.

topfuel724 · 10-28-2015, 03:04 PM

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Thanks for the information. The cam has 8BA cast into it near the oil pump gear however the front of the cam for the timing gear is for an early flathead. Maybe H&C were low on cam cores and used a 8BA shaft and modified the front of it.

Pete · 10-28-2015, 03:46 PM

H&C had at least 5 grinds they marked 3/4.
The one Flatjack9 noted is one of them.

scicala · 10-28-2015, 05:39 PM

"Specs I have are: IO-19, IC-59, EO-59, EC-19 for 248 deg duration and .320 lift. Overlap is 33. Clearance is .011 intake and .013 exhaust."

Shouldn't that figure out to 258 degrees of duration and not 248 ?

Sal

Bored&Stroked · 10-28-2015, 06:22 PM

Quote:

Originally Posted by scicala

"Specs I have are: IO-19, IC-59, EO-59, EC-19 for 248 deg duration and .320 lift. Overlap is 33. Clearance is .011 intake and .013 exhaust."

Shouldn't that figure out to 258 degrees of duration and not 248 ?

Sal

Yep . . . but I've seen so many different claims over the years on different cam specs, who knows. I tend to put them in engines and degree them - then I really know.

flatjack9 · 10-28-2015, 06:56 PM

That's the way to do it. I have a block set up on my bench specifically for checking cams.

Bored&Stroked · 10-28-2015, 07:44 PM

Quote:

Originally Posted by flatjack9

That's the way to do it. I have a block set up on my bench specifically for checking cams.

I have a big-ass degree wheel - mounted to a V8 crank pulley - makes things quite easy and accurate:

2015-05-11 22.32.30 copy.jpg

flatjack9 · 10-28-2015, 10:11 PM

Yep, looks like mine.

10-28-2015, 05:27 AM	#1
topfuel724 Member Join Date: Oct 2011 Location: Fort Worth, Texas Posts: 70	Harmon Collins Cam Have a Harmon Collins cam for early flathead. Numbers on front of cam are 7RA 3/4. Cam lift measures 320. Anyone have the opening and closing timing specs for this?

10-28-2015, 08:18 AM	#2
scooder Senior Member Join Date: Jul 2010 Posts: 2,593	Re: Harmon Collins Cam Are these numbers around the outside of the timing gear flange? I ask as the h&c cams I've seen are marked around there, they had "Harmon & Collins" then a number like 6352, then 3/4, I just made that 6352 number up for an example. I'm not with my notes right now, I can have a look after work, see if I got the specs. Martin.

10-28-2015, 08:49 AM	#3
topfuel724 Member Join Date: Oct 2011 Location: Fort Worth, Texas Posts: 70	Re: Harmon Collins Cam Yes they are on the flange. Harmon Collins logo and then the 7RA 3/4.

10-28-2015, 12:28 PM	#4
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: Harmon Collins Cam 7RA would indicate it is for a 49 - 53 engine. Specs I have are: IO-19, IC-59, EO-59, EC-19 for 248 deg duration and .320 lift. Overlap is 33. Clearance is .011 intake and .013 exhaust.

10-28-2015, 01:50 PM	#5
scooder Senior Member Join Date: Jul 2010 Posts: 2,593	Re: Harmon Collins Cam Great stuff flatjack, I looked, haven't got those specs. The 3/4 h&c spec I have is 19-59 54-14 .320" lift. But have a full race h&c spec of 19-59 59-19 .320" lift? Martin.

10-28-2015, 03:04 PM	#6
topfuel724 Member Join Date: Oct 2011 Location: Fort Worth, Texas Posts: 70	Re: Harmon Collins Cam Sponsored Links (Register now to hide all advertisements) Thanks for the information. The cam has 8BA cast into it near the oil pump gear however the front of the cam for the timing gear is for an early flathead. Maybe H&C were low on cam cores and used a 8BA shaft and modified the front of it.

10-28-2015, 03:46 PM	#7
Pete Senior Member Join Date: May 2010 Location: Wa. Posts: 5,407	Re: Harmon Collins Cam H&C had at least 5 grinds they marked 3/4. The one Flatjack9 noted is one of them.

10-28-2015, 05:39 PM	#8
scicala Senior Member Join Date: Jun 2010 Location: Detroit suburb, MI Posts: 3,698	Re: Harmon Collins Cam "Specs I have are: IO-19, IC-59, EO-59, EC-19 for 248 deg duration and .320 lift. Overlap is 33. Clearance is .011 intake and .013 exhaust." Shouldn't that figure out to 258 degrees of duration and not 248 ? Sal

10-28-2015, 06:56 PM	#10
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: Harmon Collins Cam That's the way to do it. I have a block set up on my bench specifically for checking cams.

10-28-2015, 10:11 PM	#12
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: Harmon Collins Cam Yep, looks like mine.