Stock 200 cam lobe seperatio?

[aribert]

I searched but did not find an answer - does anyone know the stock cam lobe separation on the small 6? I am looking into possibly buying a different cam and I am trying to figure out where a stock motor is in this regard. Since I have run both of these motors, I am most interested in info on either a mid 60s or a late 70s smog motor - but any info is appreciated.

 

[CoupeBoy]

I'm no authority, but this place claims to be selling stock replacement cams..
http://www.ebay.com/itm/1973-1983-Ford- ... 37&vxp=mtr


Valve Lift (Intake / Exhaust): .366 / .366
.050" Duration (Intake / Exhaust): 185 / 185
Lobe Separation Angle:112 / 103

For early cars/engines he does not specify LSA..
http://www.ebay.com/itm/1965-1972-Ford- ... ab&vxp=mtr


Valve Lift (Intake / Exhaust): .349 / .349
.050" Duration (Intake / Exhaust): 180 / 180

 

[THE FRENCHTOWN FLYER]

Valve Lift (Intake / Exhaust): .366 / .366
.050" Duration (Intake / Exhaust): 185 / 185
Lobe Separation Angle:112 / 103

I think those angles are with respect to TDC, so the LSA with respect to each other lobe would be 107.5
([112+103]/2=107.5)with a 4.5 degree cam retard.

 

[aribert]

Frenchtown - stock cam would have been run retarded instead of advanced?

 

[xctasy]

Frenchtown - stock cam would have been run retarded instead of advanced?

On the later engines, yes. In the early engines before the 1970 Clean Air act, probably not. There was a cam profile change around about the 1970 on wards Cleveland era to 256 degree cams, but Ford did a lot of fiddling.

1.The same measuring base must be used to get Lobe separation angle, Intake lobe separation and total cam advance or retard and . I always think Seat to seat times (advertised duration) should be used. Calculating .050" durations and the valve event timings will also give the LSA/LCA, but not the advertised overlap. Most cam cards miss this out these days.

There were three cam types in Ford small I6's, 240 deg, 252 deg and 256 deg. The Big six ran a comparitively radical 268 cam, and so did the Aussie EFI 250's after October 1985. The little 144 and 170 ran the 240 cam, probably some 200's ran 240 cams, but most progressed to 252, and then the 256. Ford had some pretty tricky cam profiles for its V8's, like the dual pattern Super Cobra Jet cams, and the have always been leaders in getting big cams to work in there engines, so it's lots of fun to grab internet time, and plunder the K code 289 profiles and 5.0 roller E303 profiles and do some research.

2. LCA (lobe separation angle or LSA) is the difference in crankshaft degrees between the Inlet Lobe Center (ILC or ICL) and the Exhast Lobe Center (ELC or ECL).

3.At the end of the exhaust stroke and the beginning of the intake stroke both the intake and exhaust valves are open at the same time. This period of time (in degrees) is know as the Overlap Period (overlap hereon).

4. The NHRA has an acceptable factory cam advertised duration timing and casting numbers set for each major US engine. The calculation of "112 deg" for intake and "103 deg" for exhast is done by taking the intake degrees duration and exhast degrees duration and then running one of two types of calcultation a or b. It doesn't matter if you use 006", .050", or the given mechanical lash or even .020" figures, but you have to use the right ones to calculate LSA/LCA verses ILC/ICL. That allows you to set the cam up correctly to the cam grinders guidelines.

Just be aware that major cam suppliers chose not to provide a full list of at lash advertised duration figures, and that, rightly or wrongly, .050" figures have become the common method, so that lifter bleed down or valve lash is removed from the equation. The cam cards often include extra valve sping and keeper detail, so if you have a problem, you have to establish that the basic detail was as per the cam designers brief.

4a. The details required are for the Stirrat cam found in the first 1962 221 Windsor in the Fairlane, and in the 1963.5 200 cube four bearing engines:

Adv dur: int 252º, exh 252º
107.5 LCA, 105 ILC (1.5º advance)
Valve timing @ .006" (hydraulic cam at lash)
intake opens @ 21º BTDC
Intake closes @ 51º ABDC
Exhaust opens @ 56º BBDC
Exhaust closes @ 16º ATDC

In this example the overlap is 37º (21º+16º)

To calculate ILC and ELC

ILC = (252/2)-21
ILC = 105
ELC =(252/2)-16
ELC = 110
LSA = (105+110)/2
LSA = 107.5

If the cam is advanced, the ELC is greater than the ILC
If the cam is retarded, the ELC is less than the ILC
The degree of advance/retard is half the difference between the ELC and ILC
In this case, the cam is advanced 2.5 degrees, as the ILC vs ELC is 5 degrees different with the ILC the lessor.
Put another way, LSA - ICL: 107.5 - 112 = -4.5 deg, so 4.5 deg retarded

Summary: To arrive at the duration when the overlap and LCA are known, we take the overlap (in our example 37), divide by 2, add it to the LCA (107.5 + 18.5), then double it (126 x 2 = 252).



4b. If the seat to seat opening and closing times are not known, the overlap can be calculated using the advertised duration and the LCA (Lobe Separation Angle or LSA). This formula works for both single and dual pattern cams.

Add the intake and exhaust adv durations
Divide the results by 4
Subtract the LCA
Multiply the results by 2

Using the example cam above:
252+252=504
504/4=126
126-107.5=18.5
18.5*2=37
The overlap is 37º

If the cam is advanced/retarded, the ELC is greater then/less than the ILC
The degree of advance/retard is half the difference between the ELC and ILC

If the cam is retarded 4.5 degrees, the ILC is greater than the ELC.

In THE FRENCHTOWN FLYER's example, the cam is retarded because the ILC is greater than the ELC
Put another way, LSA - ICL: 107.5 - 105 = +2.5 deg, so 2.5 deg advanced

Read more:
http://www.popularhotrodding.com/tech/0 ... z2InWWsrsL
http://members.uia.net/pkelley2/Overlap.html
See Page 100 in How to Build, Modify & Power Tune Cylinder Heads
By Peter Burgess, David Gollan

http://books.google.co.nz/books?id=283b ... SA&f=false

Bootleg examples of Brand C#@%& cam cards from a common supplier below, showing the bare minimum of detail you should expect.

 

[THE FRENCHTOWN FLYER]

Here is a picture of a stock cam for a big six. For years I waged a one-man-war in Ford to stop using the polar charts as shown above, which are great if you are a camshaft manufacturer but far inferior to the "time line" layout I present here in terms of understanding what is happening at the valve wrt time. This graph will show the lift events as time progresses.

 

[xctasy]

Here is a picture of a stock cam for a big six. For years I waged a one-man-war in Ford to stop using the polar charts as shown above, which are great if you are a camshaft manufacturer but far inferior to the "time line" layout I present here in terms of understanding what is happening at the valve wrt time. This graph will show the lift events as time progresses.

Yep, totally aggree. Maybee its because to the uninitiated, the time based cam card looks like mamory glands...

The free market can create a situation where there is no level playing field.

airbert, you got a Clifford cam card with the right details

When I can't get overlap or seat to seat duration, I feel dumbed down by the supplier. This is not a tirade against the best suppliers in the world, as the US cam indusrty is heads and shoulders above other countries for cam supply. The expertise is miles deep. All cam grinders tend to get really antsy when they have gone to the trouble of making the cutting edge grinds available to the public, and tend to protect the investment by only supplying details that have to be form the suppliers perspective.

The solution is to upskill the public. Everyone in the industry is worried when someone copies a grind developed by time, money and talent. The grind is important for dyno performance, but true excellence is in the blank preperation and sales back up, and so one cam supplier should never feel that suupling extra info is lost Intellectual Property when declaring the 12 things below that allow a full time line cam plot to be made. The info safegaurds a multi millon dollar industry.

This time based info is important, because we are now learning from the experience with trained ex FoMoCo and other people that its nothing to have an aftermarket cam
1. ground from the wrong blank,
2. with the wrong advance clocked in,
3. or even to have a cam which was ground by the maker some time ago which now has a twist in it that results in different timming from the front cylinders to the back, especially if the cam is high lift and has a reduced base circle diameter as all high lift flat tappet cams have to. An I6 Ford cam can be twisted within an inch of its life in a performance application, and they can and do suffer some maladies when cranked.
4. We are also aware that the any 200 and US 250 timing gear has differences, and that degreeing a cam takes a little more time and consultation to get right depending on the application.

5. The customers safe gaurd is buying a cam which is backed up by the supplier. The most excellent, smart and quality focused suppliers are human, and can make mistakes, so have the decency as a customer to do the home work first. It's to our suppliers credit here that we have the freedom to discuss these issues in this forum, and keep a level head while learning about our big and little in-line sixes.

Back a few years ago, we had to understand a few issues with the small six

I've got some major pointers.

1. If full "time line" cam details in the above layout doesn't exist, ASK FOR IT.

See http://store.schnitzracing.com/product_ ... enters.jpg

See http://store.schnitzracing.com/cam-lobe ... explained/

Then have the decency to check all the set up instructions to the letter. If the cam supplier doesn't supply the details so you can make a full list, then shop elseware. At the very least, these figures below must be able to be horse traded and compared

1 or a.Adv dur: int 252º,
2 or b.exh 252º
3 or c.107.5 LCA,
4 or d 105 ILC (1.5º advance)
5 or e.Valve timing @ .006" (hydraulic cam at lash)
6 or f.intake opens @ 21º BTDC
7 or g.Intake closes @ 51º ABDC
8 or h.Exhaust opens @ 56º BBDC
9 or i. Exhaust closes @ 16º ATDC

This allows advance to be calculated by c-d
And Overlap by f+i

If you don't have these nine (9) pieces of info, your likely to be wasting your time if the cam gets worn, incorrectly ground or has an interferance problem. Base circle diameter is a 10th figure (j), and 11th (k) and 12th (l), the respective lift at the lobe for intake and exhast.

I know why cam makes supply 50 thou figures, but they should be in addition to the above, not a replacement for them.

2. Be VERY carefull with advancing all cams on Ford small sixes. Ford small 200 and 250 I6's can become interferance engines. When the cam is able to freewheel in relation to the crank, the rods WILL HIT THE CAMSHAFT on 200 and 250 sixes. A totally stripped timing chain is unlikely, but if it did happen, the cam is very close to the crank centerlines in short deck US 200 and all 250 engines. The US 144, 170, (and Aussie/Argie 187/188 and 221, and the US HSC 2300 and 2500 I4's) are free from this problem. I've got a 1985 250 turbocharged cross flow 268 degree EFI cam in my basement, and it has hit the rod under extream duty, and its possible that conrod failure is an interferance issue with cam, not just a plasticine rod bolt issue.

3. See viewtopic.php?t=65908 for what happens when a 4 deg advanced cam blank doesn't quite have the stock clearance required for all the 200 I6 con rods. This is something to check always with our Ford 200 and 250's

4. All off the shelf Competition Cams have 4 degrees of advance ground into them.

5. All stock Ford cams seam to have four degrees advance ground into them

6. Clay Smith cams are not advanced, they are ground straight up