F-303 cam and timing chain questionz

[saleenx029]

I have a ford motorsports F-303 camshaft and I was wondering if I must degree it in. I have never done this and I am told that alphabet cams you line up dot to dot with the timing marks, is this correct? Also, if I do degree it, am I just measuring the camspecs or do you measure just if you plan on advancing or retarding the cam (I want to run straight up)? I see no adjustablity in the cam or timing chain itself, so if I degree it and a measurement is off, how do I know the nubers are off and what do I do to fix it. In general I don't understand what you are "degreeing" actually, exept to make sure the motor is at tdc and the timing chain marks are aligned, which is obvious (heads are off) Why would I need a degree wheel to measure the cam, it seems to only go together one way, there seems to be no adjustablility in the set-up even if my valve events are found to be "off".

Also I have an aftermarket timing chain that seems to be indestructible compared to any other chain I have seen, but it seems to be loose fitting, lots of play/slop, but doesn't seem to be able to jump a tooth. Is this play ok? Is it streched? How can I test it? What can you do to the motor to make it stretch a hardcore timing chain? I'm not sure the brand, but I know it is pretty new(less than 15,000 miles) Any one that canm help me I would be very appreciative, thanks

 

[Michael Yount]

Degreeing is the process of installing the cam with an adjustable timing set so that you can alter the timing if measurements indicate that "dot to dot" isn't installing the cam the way it's called for on the cam card. Usually there is data on the cam card that shows the valve timing. It will call (just making up an example here) for the intake valve to be at 2 degrees BTDC at .050" lift when it's opening. If all were perfect, when you installed it dot to dot, and then measured with a degree wheel and dial indicator you'd see that when the lobe is at .050" of lift, the degree wheel would be reading 2 degrees BTDC. The problem is that for that to happen - the cam has to be manufactured perfectly, the pin placement must be perfect, the pin hole in the cam and slot in the crank gear has to be perfect, the dots must be imprinted perfectly, the slot for the key in the crank must be perfect, etc. As you might imagine, rarely are all those things manufactured perfectly. Occasionally, all the errors add the same way, and you find that a dot to dot install is 4-6 degrees off. My buddy's custom cam install ended up 4.5 degrees off from where it should have been based on a dot to dot install. The cam card called for the intake to open .050" at 5 degrees BTDC. When we measured on the dot to dot install he was actually at 9.5 degrees BTDC. We had to retard the install by 4 degrees to get it close to where the cam card called for it to be.

Installing dot to dot is little more than a guess that the cam timing is correct. I recommend you pick up a degree wheel, dial indicator and indexed timing set and learn how to degree the cam. Get someone who's done it before to help you through the first one. You'll learn tons about how your engine actually works. Your cam timing will be correct - rather than a guess and a hope that it's correct. And it's real easy to check piston to valve clearance with the same equipment - which you should also do if you're changing the cam. In fact, you should degree the install, and then check p to v. Good luck with it.

 

[Ranchero5.0]

Ditto that...

As a heads up, if the chain has slop it's junk, no exceptions. In fact I usually set the cam a degree or so ahead of the specs so it stays close as the chain starts to wear and the cam timing retards. Expect to pay over $60 for a good chain. FMS sells a decent setup that has a 9 position crank sprocket that allows you to adjust the cam degrees by using different keyways. Avoid setups that use a offset bushing for the cam sprocket. I've seen them spin completely around and ruin the cam timing.

Jamie

 

[saleenx029]

Thank you Michael you have answered my quesions abo degreeing a cam perfectly. I didn't realize that the cam could be made so imprecisely, it would seem to me that it would have to be made within the strictest of tolerances, hell if a cam can be made a few degrees off, then any other dimension could be way off as well. I will degree in the camshaft tomorrow, thanks.

 

[Michael Yount]

Ranchero's right - you'll be able to alter things in 2 degree increments, so if you're an odd number off, you have a choice to make. Advance it by a degree to compensate for wear.

Saleen - it's tolerance stacking that usually does it. Everything is off by just a little in the same direction - and it adds up to enough to make a difference - even if the cam is perfect. Frankly, I'm surprised they get it as close as they do.

 

[Michael Yount]

Oh - use the .050" intake open number to set it by, not the intake lobe centerline. Some cams have assymetrical centerlines which are very difficult to locate. You don't have to worry about that with the F, but degreeing by the centerline is a good habit to break. Degree it by the .050" intake opening.

 

[saleenx029]

Where can I find the cam card information on the F-303 camshaft? The cam was in the motor when I bought the car. I need the numbers for degreeing the cam. Also since it is a ford cam, wouldn't the cam be more likely to be accurate with the marks compared to the lobes than if it was a aftermarket custom grind? Does a ford alphabet cam need a different timing chain than stock? (I assume no)

On the timing chain issue I have been told that some slop is needed in a timing chain and that they don't really stretch too much, they just break. This chain I have has 5 links wide and straight across teeth and seems to be heavy, heavy duty, how can I test to make sure the chain is good? It shows no visible damage and looks brand new, just sits quite loosely on the motor with approximately a half inch deflection with the other side pulled tight. I have been told that an aftermarket chain that is heavy duty must fit looser than normal because the design of teeth and sprocket and it would set off the knock sensor if it wasn't. Is this correct?

 

[Michael Yount]

Ford manufactures very little if any of the Ford Racing stuff (the E303 was designed by Crane - it's identical to their PowerMax 2040, for example). The FRPP 1.7 roller rockers actually have the Crane logo cast into them, even though they come in the FRPP box - another example. So no, the Ford Racing stuff isn't any more accurate than anything else. Any indexed chain set for the 5.0 HO should work fine with the cam. Not sure where to tell you to go to get the cam card. I'd contact Ford Racing (see if this link gets you somewhere in their catalog http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=1771 ) and ask them about cam card info.

On your whole second paragraph, if you're gonna check the install (degree it) you have to replace the gear set anyhow, so the shape of the stock one is moot. And the shape of the new one will be, well, new. And all that stuff about tight, loose, etc. - well those are all subjective terms. The stock chain is pretty heavy duty - my experience is they all fit about the same but for the fact that new ones do seem to be more difficult to line up, slide on and off, etc. I always like to emery cloth the inside of the gears, and the outside of the shafts - especially the crank - just to be sure things can slide on and of relatively easily. Lube it all up good. You may find that a gear puller will help break the old ones free. And a long screw driver or pry bar used VERY GENTLY will help to rock them off as you're sliding on and off while doing all this. As you might imagine, they may have to come on and off several times during the process. I'd rotate it dot to dot to remove the old stuff, then install the new dot to dot to check the install. Unless of course you think the timing chain that's there is ok. If so, check your degree with the old one hooked up, and if all is good, take the new chain back.

 

[90Notch]

F303

288/288 226/226 .512/.512 (w/1.6) 114LSA installed on 109ICL

0.050" events:
IVO 4 BTDC IVC 42 ABDC 109 ICL
EVO 52 BBDC EVC -6 ATDC 119 ICL

 

[Michael Yount]

Thanks 90!!!

Saleen - the info you need is here courtesy of 90Notch:

0.050" events:
IVO 4 BTDC IVC 42 ABDC 109 ICL
EVO 52 BBDC EVC -6 ATDC 119 ICL

IVO 4 BTDC - means that at .050" lift with the intake just opening, the pointer should be showing 4 degrees before top dead center. IVO means intake valve open.

Do you have a positive stop to determine true TDC? You'll need that as well - I made on out of an old spark plug. Do you know how to use the stop to determine tdc?