- Thread starter boler76
- Start date
ou are not likely to find that number.. From those who really should know, it is said that the cam wears very little due to small spring pressure and the fact that lobes are flame hardened. I would measure all & compare to one another & if all are about same, call it good.
TheOldHokie
Well-known Member
- Location
- Myersville, MD
Here is an interesting little graphic. FWIW a high performance Crane cam for a V8 Ford flatty is pushing .400 lift.
This source is a treasure trove of information and says a stock flatty was .307: Camshaft Design History
TOH
TheOldHokie
Well-known Member
- Location
- Myersville, MD
Careful - look at the column dividers in that table. Those numbers are only for the OHV engines - not the L-head.
TOH
learly still not looking close enough!
And if trying to check cam for wear on those OHV engines, one would need to measure at the valve, not the cam lobes, unless he knew the rocker arm ratio, since the chart gives valve lift. That would be obvious to TOH, but maybe not for the world wide population. :wink:
I have been looking for those numbers and have not found any .
I measured 6 USED front dizzy "N" cams and got .296 - .298 for a mean lift . They could all be worn .060 for all I know . I threw a quick digital caliper on them and will use a dial gauge down the lifter/valve bore this winter when I get around to building some N motors . I want to throw a degree wheel on it so I can post those numbers too .
They sell reground cams on this site but I have not talked to anyone who has purchased one .
I would bet these numbers have been measured 1000's of times over the years , but I can't find any posted .
I forgot to write it down , but the bearing journal was the same diameter as a 1937 - 21 stud flathead V8 cam I had in the shop . The V8 cam had a low lift of about .298 also .
I will measure the V8 block for an O.D. cam bearing diameter and post that someday ???
P.S.
These are front mount distributor cams , I think I have read that the side mount cams have a higher lift .
After WWII and the introduction of better fuel , the industry raised compression ratios and valve lifts . The cam was redesigned with the side dizzy so I assume the engineers pepped it up a little ????
TheOldHokie
Well-known Member
- Location
- Myersville, MD
The stock valve lift and profile for the flathead cams varied (all numbers taken from original Ford prints):
[list:26cac1052d][*:26cac1052d]1932-38 Ford V8 used a 6 arc profile with a .307 lift. Camshaft numbers 18-6250 and 78-6250[*:26cac1052d]1949-51 Ford V8 used a triple curve profile with a .307 lift. Camshaft number 8BA-6250[*:26cac1052d]1949-50 Mercury V9 used a triple curve profile with a .380 lift. Camshaft number 8CM-6250.[*:26cac1052d] The 1937-48 Ford six cylinder used a triple curve profile with .350 lift. Camshaft number 7HA[/list:u:26cac1052d] The 120 CID 4 cyl camshaft journal diameters are the same as for the V8's. Clevite camshaft bearing set SH-21S fits the V8 and has OD of 1.9275/1.9285. You would need to punch the 120 CID L-head out .131 over to use them in that motor - should be plenty of meat to accomodate that.
TOH
TheOldHokie
Well-known Member
- Location
- Myersville, MD
(quoted from post at 10:25:15 10/14/12)learly still not looking close enough!
And if trying to check cam for wear on those OHV engines, one would need to measure at the valve, not the cam lobes, unless he knew the rocker arm ratio, since the chart gives valve lift. That would be obvious to TOH, but maybe not for the world wide population. :wink:
Or one could determine the rocker ratio and simply compute the cam lift needed to get the specified valve lift :idea:
TOH
Just adding info .
Ford Flathead Cam Lobe Designs
TThe Ford Flathead engine used various cam designs. Among these were the Model T cam, Model A/B cams, and the V-8 cams. Camshaft performance was usually described in terms of a number of terminologies in relation to the timing of the valve movements. These include the Top Dead Center (TDC), Bottom Dead Center (BDC), Before Top Dead Center (BTDC), After Top Dead Center (ATDC), Before Bottom Dead Center (BBDC), and After Bottom Dead Center (ABDC).
Model T and Models A/B Cams Specifications
The Model T cam BTDC, ABDC, BBDC, and ATDC were -12, 52, 39 degrees and one degree. Its duration was 220 degrees for both the intake and exhaust. The Lift was 0.250 inches and the Lobe Separation was 115.5 degrees. Model A/B cams BTDC, ABDC, BBDC, and ATDC were 8, 56, 56, and degrees. The duration was longer than that of the Model T cam at 244 degrees. The Lift was also higher at .334 inches during intake and 0.341 inches during exhaust. Lobe Separation was 114.0 degrees.
Flathead V-8 Cams
The Flathead V-8 camshafts came in four versions from 1937 up to 1952. These were the 78-6250 cams from 1937-1948, 8Ba-6250 cams from 1949-1951, 8CM cams from 1949-1950, and the 7HA cams from 1946-1952.
The 78-6250 cams BTDC, ABDC, BBDC, and ATDC were 0, 44, 48, and 6 degrees. It was 5, 44, 48, and 3 degrees for the 8BA-6250 cam, 10, 50, 50, and 10 degrees for the 8CM cam, and 11, 41, 48, and 10 degrees for the 7HA cam. The duration was 224 degrees for the 78-6250, 229 degrees for the 8BA-6250, 240 degrees for the 8CM, and 22 degrees for the 7HA. The 78-6250 and 8BA-6250 had Lifts of 0.307 inches. The 8CM's Lift was .338 inches, while the 7HA measured 0.350 inches. The Lobe Separation for the models ranged from 107.0 degrees for the 7HA up to 111.5 degrees for the 78-6250 cam.
TheOldHokie
Well-known Member
- Location
- Myersville, MD
Yep - my source for the flathead data. Also a lot of very good camshaft engineering info there if you are in the mood for some reading.
TOH
TheOldHokie
Well-known Member
- Location
- Myersville, MD
OK - I have to ask. How slow was it? Did you have a cam laying on the bench yearning for a mic. Or did you pull one out of a running tractor????
TOH
TheOldHokie
Well-known Member
- Location
- Myersville, MD
OK - just to clarify for folks who may not be as precise and careful as you with their terminolgy :lol:
[list:ce4dc27254][*:ce4dc27254]Your .285 number is a true measured [u:ce4dc27254][b:ce4dc27254]valve[/b:ce4dc27254][/u:ce4dc27254] lift measured on the valve itself.[*:ce4dc27254]The [u:ce4dc27254][b:ce4dc27254]cam[/b:ce4dc27254][/u:ce4dc27254] lift as measured on the cam is actually .010/.012 [u:ce4dc27254][b:ce4dc27254]more[/b:ce4dc27254][/u:ce4dc27254] to account for tappet clearance.[/list:u:ce4dc27254] Which is why you said your .285 number agrees with Ken's .296/.298 camshaft measurements. Correct?
TOH
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