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King Trashmouth
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21,891 Posts
Discussion Starter #1
If you've been keeping up with my project thread, cams are the next big step so I can start to get things buttoned up. Naturally I had a few questions.

1.) Can anyone point me to a good book or writeup on how to degree DOHC cams? Maybe even a good shop in southern Indiana that would help guide me? I know how to do SOHC/OHV, but DOHC is a totally different ballgame. I'd like to go beyond the simple "line up the dots" which is both against my principle of doing things right no matter the effort on this build, as well as impractical with the cams I'm using.

2.) Can anyone reccommend a good 4.6L DOHC cam degreeing kit?

3.) What would you say is the best LSA for a S/C (positive displacement) 4.6L DOHC motor? I've seen anywhere from 112-118 claimed.

4.) What bolts are torque to yield? I'm assuming the bolts on the cam gear and crank are at the very least. I want to make sure I don't reuse any.

Reps to whoever helps.

...and if all goes well, I should have a nice set of FR500 cams and springs soon. A video showed an 03 Cobra with nothing but a pulley and FR500 cams run 11's on 275 street tires. Bonus: FR500's have a slight lope at idle. :cool:
 

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a.k.a. Racecougar
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4,775 Posts

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a.k.a. Racecougar
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4,775 Posts
No, I haven't touched the cams on my GT. I was referring to the 5.0L stroker DOHC in my XR7. I stuck a set of Ford GT cams in it when I built the engine back in '07.

 

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a.k.a. Racecougar
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4,775 Posts
Yep, it's running a KB, meth injection, etc.

I lined up the dots to get everything in the ballpark, then went from there. It wasn't my first rodeo, so I had a pretty good grasp on what I was doing. My biggest piece of advice is just to take your time and double check your numbers.
 

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King Trashmouth
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21,891 Posts
Discussion Starter #7
I've only done OHV in the past, so my guess is DOHC goes something like this:

1.)Degree intake cam just like OHV to its LCA spec.
2.)Lots of cursing and math to calculate how to achieve desired LSA.
3.)Degree exhaust cam using a seperate LCA spec based on the desired LSA.
4.)Repeat 1-3 for other bank.
5.)???
6.)Profit.
 

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a.k.a. Racecougar
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4,775 Posts
That's sort of correct, but you'll start with the exhaust cam, not the intake cam.

Here are Sean Hyland's instructions that I'm just copy/pasting from over at Corral. This should lay it all out for you.





Degreeing 4-Valve Camshafts

Required Tools:

Ford service tool number T93P-9589-AH (camshaft lock tool)
Ford service tool number T93P-6256-A (camshaft positioning tool)
Dial indicator with 4-inch extension
Screw-in post for dial indicator
Positive-stop tool
Solid valve adjuster
Timing wheel
Pointer

1. Install the camshafts in the cylinder heads. Torque the camshaft caps using Ford pattern and torque values.

2. With the number-1 piston at top dead center, attach secondary camshaft gears and short chains, matching copper coated links to marks on gears. Use secondary camshaft gear part number F3LY-6256-A on late engines with integral key. Do not install camshaft keys. Ensure camshaft keyways are pointed down.

3. If stock or reground camshafts are being installed, positioning tool T93P-6256-A may be used to locate camshafts by inserting tool into slots in rear of camshafts. New billet camshafts will not have a slot that can be utilized.

4. Install the primary gears and chains, matching the copper coated links to the crankshaft and camshaft gears per the diagram.

5. Lock the camshafts with camshaft lock tool and torque the camshaft bolts to 95 ft-lbs.

6. Check the valve-adjuster preload. Using a collapsed valve adjuster, check the preload by installing the valve adjuster and rocker arm. With the rocker arm touching the camshaft base circle, mount the dial indicator so extension rests on the adjuster end of the rocker arm. Zero the dial indicator, and using the rocker-arm installation tool, cycle the valvespring up and down. Without the rocker arm losing contact with the camshaft, measure range of valve adjuster preload. The correct range of preload is .040 to .080 inch. In the case of camshafts that are reground on stock cores, it may be necessary to shim the valve adjuster to achieve the correct preload.

7. Install the timing wheel and pointer, set to top dead center.

8. Rotate crankshaft clockwise 90 degrees and install positive-stop tool in the number-1 spark plug hole.

9. Rotate the crankshaft clockwise until you reach the stop, and record the number displayed on the wheel.

10. Rotate the crankshaft counter-clockwise until you again reach the positive stop, and then record the number.

11. Split the difference and move the timing wheel to the center of the range of movement. For example: if the first reading was 42 degrees before TDC and the second was 44 degrees after TDC. In this case, the wheel should be moved so each end of the range of movement reads 43 degrees. The wheel is now centered. Check the readings in both directions one more time and remove the TDC tool.

12. Install the solid adjuster and rocker arm on the number-6 cylinder exhaust lobe.

13. Set the dial indicator extension on the valve retainer, and then zero indicator.

14. Rotate engine clockwise until .050 inches of valve opening is measured. Record the valve opening number observed on the degree wheel.

15. Continue rotating the crankshaft, measuring the total valve lift, and stop the rotation of the crankshaft when the valve is within .050 inches of the seat again. Record the valve closing number.

16. Using the camshaft lock tool, lock the camshaft and loosen the cam bolt.

17. With the camshaft still locked in place, rotate crankshaft to the desired closing point. There is a range of 3-4 degrees available with the slop in the camshaft gear key and the camshaft. If you need to move the camshaft more than the amount available, grind the integral key on the primary exhaust gear to allow a greater range of adjustment.

18. Torque the camshaft bolt to 95 ft-lbs and remove the lock.

19. Check open and close points as before and adjust as necessary.

20. Once the exhaust camshaft is degreed in, you can move to the intake camshaft, since the exhaust camshaft drives the intake camshaft. Any change in timing on the exhaust camshaft will require adjusting the intake camshaft.

21. With cylinder number 6 timed, move over to the passenger-side cylinder head, setting up on cylinder number 1. The intake camshaft on the passenger-side cylinder head will lag behind as the tensioner is compressed. It is necessary to hold the tensioner in the extended position, simulating the engine in a running condition, in order to properly time the passenger intake camshaft. Complete the checking and adjusting process, as previously done on the left head, and then you are finished.
 

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1,276 Posts
Use the centerline method as oultined in the Comp instructions (not the SHM instructions); the process will go much quicker and there will be less cussing. Also, when doing this, put some counterclockwise pressure on the cams. This will take a second set of hands but it will be worth it.

Let me know if you wanna borrow my stuff.
 
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