I am building a 200 engine and having no success in getting my numbers to match up with the cam card. I have a 278/278 110 cam and when I go thru the degreeing process I come up with 222 degrees at .050 duration and not the 228 degrees as showing on the cam card. Four days on this and untold tear downs - reassemble and the same results. Any help and or leads are appreciated.
Cam Degreeing
- Thread starter stanyon
- Start date
WSA111, yes it is the Clay Smith 278/278 -110, The bottom end of my engine has been balanced, decked .020, Silvolite 1100 pistons. The head has been ported as mush as possible, 144 intake valves used for exhaust valves, intake valves are 1.75, head shaved .060, log has been machined to accept a Weber 32/36, Valve springs are Ford 4.0 springs and retainers set at 75#, solid lifters, and dual headers will be used. Yes I reaching as far as cam selection goes, but I hope all my calculations come out.
CNC-Dude":vl1mvr8u said:
Not always. Ford must have kinda messed up a bit by over engineering the first 144 and 170 engines, because they ran the same material, a very good steel.
A set of a set of 144 1.467 intake valves with a .015 oversize stem might set you back 20 bucks if you know where to look.
This from CZLN6 in May 2013
Since this is a solid lifter camshaft, because of the valve clearance your actual duration @ .050"could be 8-10 degrees less than the 228 degrees listed for this camshaft.
What you have is 222 because of valve lash as part of the equation.
What you have is 222 because of valve lash as part of the equation.
Thanks to all for the replies, I have basically given up. The cam card does not give a degree reference for when the lift should be at .050, and this would have been a great help to me. I have been thru the process so many times, and still nothing to verify the right timing. I did find in my many searches that Crane cams do come with the degree reference I mentioned above. Anyway I will start final assembly today and hope it is all as it should be.
Degree the cam is using the lobe centerline procedure advance it 2-4 degrees as required for you engine, gearing & C4 trans or stick shift.
Set the valve lash .002" wider cold, breakin the camshaft, reset valve lash & let her roll.
Set the valve lash .002" wider cold, breakin the camshaft, reset valve lash & let her roll.
Don't advance it. Not before following Mikes processes, then check cam to rod clearance.
Some cast iron rods differ in size, and some cam sets place the cam in a different position.
viewtopic.php?t=65908
JackFish":34b295iu said:Nope. Pretty weird.
That pic is the 2° advance. #4 cylinder.
Some cast iron rods differ in size, and some cam sets place the cam in a different position.
viewtopic.php?t=65908
See as well viewtopic.php?f=1&t=71122&p=545742#p545742
Different cam but same process. Use his calculations, and you'll have all the info.
Everyone should know that this info is in fact provided by Mike W at Classic Inlines under Details
,
Its 228 degrees at 50 thou for sure, but the lash spec is 18 thou, not zero lash
and then go to
http://www.classicinlines.com/proddetai ... 278-SSP-10
and http://www.classicinlines.com/CamDegree.asp
A few notes.
1. If you have cast iron rods. Ford specifically changes the 200 and 250 rods for the 1978 to 1979 model year, reverting to an inferior quality cast iron rod. Since castings are not as dimensionally stable as dropped forged con-rods used from 1960 to 1983 for the small six, this means that the 4 degrees advance is a risk with any straight up Clay Smith cam and cast iron rods.
2. The rocker ratio changes. The blanket 1.5 or 1.65 ratio for common rocker arms you might use could in practice be 1.48 or 1.6, as the wiped tip ratio is actually not 1.5 or 1.6 as advertised. So if your seeing only 222 degrees, I'd check the rocker ratio from the rubbed tip of the valve at full lift, to the lever arm from the trunion to the pushrod. I doubt you have a 1.5:1 rocker ratio. This is often discussed when people go to higher rocker ratios.
http://mobile.pistonheads.com/gassing/t ... 9515&mid=0
3. The stated lash alters the peak duration, but how is any bodies guess....the cam designers use a lot of variables. See the last two posts here.
http://www.speedtalk.com/forum/viewtopic.php?p=9277
Different cam but same process. Use his calculations, and you'll have all the info.
CNC-Dude":hjwf925z said:
Everyone should know that this info is in fact provided by Mike W at Classic Inlines under Details
Its 228 degrees at 50 thou for sure, but the lash spec is 18 thou, not zero lash
and then go to
http://www.classicinlines.com/proddetai ... 278-SSP-10
and http://www.classicinlines.com/CamDegree.asp
A few notes.
1. If you have cast iron rods. Ford specifically changes the 200 and 250 rods for the 1978 to 1979 model year, reverting to an inferior quality cast iron rod. Since castings are not as dimensionally stable as dropped forged con-rods used from 1960 to 1983 for the small six, this means that the 4 degrees advance is a risk with any straight up Clay Smith cam and cast iron rods.
2. The rocker ratio changes. The blanket 1.5 or 1.65 ratio for common rocker arms you might use could in practice be 1.48 or 1.6, as the wiped tip ratio is actually not 1.5 or 1.6 as advertised. So if your seeing only 222 degrees, I'd check the rocker ratio from the rubbed tip of the valve at full lift, to the lever arm from the trunion to the pushrod. I doubt you have a 1.5:1 rocker ratio. This is often discussed when people go to higher rocker ratios.
http://mobile.pistonheads.com/gassing/t ... 9515&mid=0
3. The stated lash alters the peak duration, but how is any bodies guess....the cam designers use a lot of variables. See the last two posts here.
http://www.speedtalk.com/forum/viewtopic.php?p=9277
