Sf Gt cam flanges & key stuck

E

Evan

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Location
Texas
Flanges & key are stuck. Left them alone for the meantime. Ok the Key I was thinking about using a fold of cardboard & prying it off w/ visegrips & a little heat. I can cut a length of PVC pipe & hit the cam ends center to break off the flanges? Or should I try something else?
Some time ago someone wrote that the tapping I was getting when engine was running was from the flanges. Flanges are tight in. I know the bearings are bad. But what about the flanges? I don't need new flanges? Do I?
 

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As per the other thread did you check end float on the rocker arms? Flanges got to come off to replace the bearings, I would use heat and a press
 
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Flanges are a press fit, on and off. If not, they're loose.
A tapping noise from the top end can be a broken key, which can occur if flanges are loose.

Paul
 
Glad I did not try the hammer. Will look for a press...Anyway flanges & key are tight in. Don't see how they could have made the tapping noise.
 
Evan said:
Glad I did not try the hammer. Will look for a press...Anyway flanges & key are tight in. Don't see how they could have made the tapping noise.
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It's the broken key that leads to the tapping. Flanges stay tight but the two cam halves move one to another.

Paul
 
This is probably a dumb question because I have no experience with 750 engines, but I thought the flanges bolted up tight to either side of the sprocket. How would a busted key allow the two flanges to move relative to each other?
 
The key doesn't even go through the sprocket on our 90deg motors. Yes Cam it is the pressure on the faces that holds it together. With my 360 motors I have the slot in the sprocket widened for adjusting cam timing (with slotted stud-holes) as I want. With the 90deg motors I do each side separately as I have allen screws into threaded holes in the sprocket.
 
Paul Marx said:
It's the broken key that leads to the tapping. Flanges stay tight but the two cam halves move one to another.

Paul
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Not possible Paul (as outlined above). You could probably even assemble the whole thing without the key at all and I doubt it would allow any play to develop if those flanges are tight.

Evan, did you investigate your rockers for side play? Or valve tips for concaving and tappet surfaces for pitting/flatting?
 
I can remember reading where someone replaced their camshaft bearings in one of these engines and it stopped the tapping, despite no play felt in the old bearings. Mine taps when accelerating but I think it's always done that. Worse when the engine is cold.
 
It was even recommended to me by a highly respected forum member,
with decades of experience, to cut the key in halves to make the
assembly easier.
The flanges have to be a tight fit and are held together by the 3 bolts,
as mentioned above.
It's like the starter freewheel. The key is only there to find the position,
but doesn't hold it. That's done by the tight fit on the cone.
 
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It might be hard to believe that the screws and clamping forces are that effective, Paul, but it is fact. I don't run a key between my cam flanges and the central sprocket. Tippie has raced 12+ seasons with same. Having said that I DO fit the key between cam and flange.
 
Paul Marx said:
I doubt that the screws alone, however tight, can stop the half cams from moving slightly one in relation to t'other.
Click to expand...

Clamping force is more than adequate to stop the flanges slipping. I slotted the holes in my triple's camshaft flanges so I could adjust the cam timing. Once the bolts are tightened up, it stays put. I dialled the cams in about 13 years ago. Last time I checked (about a year ago) the timing was still exactly where I'd set it in 2009, and there's only 2 x M6 bolts on the triple's cam sprockets.
 
No Paul I did not investigate rockers for side play as the valve springs held them tight while they were on. Was unaware to look @ the time I was getting the spindles off. Valves are still on. Do you mean looking for concave ing on valves combustion side? then one of the tappits is pitted.
I don't have a shop w/ decades of experience. I believe I may have to take this to the machine shop that did 17580s bore & hone to the Ross pistons. they have done Laverdas before. Will point out to them the side play issue if I go there. I have no experience w/ heads. Don't want to ruin it! Grn bk & manual make it look easy.... Key has to come out 1st. Right? Does it come out w/ flange on a press? Or will it come out w/ vise grips? & to change the subject what size O ring goes on the tach cable shaft under the head cover?
 

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Those rockers are in excellent nick and would indicate a cam similarly tidy - nice. Checking sideplay is easy but you hav to have the valve closed and no pressure on the valve from cam-rocker. Just jiggle it side-to-side and you will hear tapping if there is play. Pitting occurs where the tappet contacts the tip of the valve stem. Can't quite tell how your tappet screws look but could all be fine. It's worth getting the valves out and having the engine place check for seating and clean and recut seats if nec and reface valves also - simple stuff for any workshop.

The key just stays in while the flange and bearing are pressed off - no need to remove it beforehand - it'll be in only one cam side anyway and will come out when the flange is pressed off that side.
 
Make absolutely certain that C3 bearings are fitted to the cams. As said, get the valves out to check for wear on faces, seats and guides. It is very easy to get valves out by putting a hunk of rag under the combustion chamber (to hold the valve onto its seat) with the head on the bench, and with a socket and extension onto the valve retainer a quick whack with a hammer the collets will pop out. Keep the valves so that they go back into same place. You can then check seats and guides etc yourself. Getting it back together requires a spring compressor.
 
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