Puzzling cam swap issue....

Blownflatheaddeuce

Blownflatheaddeuce

Senior Member
All,

Im in the process of swapping my old worn 37 21 stud cam out for a new one ground up for me by Dave at Cam techniques before he shut down.

The old cam has a bolt on gear driving a helmet dist, the new one is a press on gear deal which will drive the same dist.

The new gear was installed onto the cam with the scribed mark on the gear aligned along the centre of the dist drive slot.

The issue Im having is that the new cam will only mesh with the oil pump gear in one spot yet with the old cam refitted, it will mesh anywhere?? :rolleyes:

The pressed on gears on the end of the cams look identical; is there any difference in the gears that Im not visually picking up?

Also, as can be seen in the pic - the best I can get it to is with the piston at TDC (compression stroke), the new gear/cam is off one tooth from the two dots aligning properly. On either side of this I cannot get the pump drive gear on the cam to mesh with the pump.

What gives, I may have screwed up but any thoughts on this one as Im kinda stumped?

Thanks !!

BFD
 

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The pump drive gear shouldn't stop the cam from being timed properly. Try pulling the cam out just enough to clear, turn the crank one tooth to the right and slide the cam back in. you can then turn the cam and crank one tooth to the left and they should be perfectly lined up.

Mart.
 
Ross F-1 said:
If you pull the oil pump out, set the crank/cam, then push the oil pump back in, what happens?
Click to expand...

Ross good qun but the engines pan is still on - I havent removed it for a cam swap.

Cant remove the pump with the pan on :D

We should'nt have to pull the oil pump to swap out the cam. :rolleyes:

BFD
 
You are loosing meshing the oil pump cam drive gear and idler after pulling cam forward. When trying to push the cam back you should have some mesh on the timing gear just unable to get cam all the way back.In this position put pressure on the cam timing gear and rotate the engine by hand and the mesh on the oil pump drive should line up and let you push the cam back at the same time.

R
 
Try to re-index (turn to a new position) the oil pump gear with the old cam. Then give it a go with the new cam.
 
Sorry to be the one to give you this bad news, but you have your timing gear located incorrectly on the cam hub. The mark on the timing gear DOES NOT align with the distributor tang slot. There is a small mark/line on the hub that must be aligned with the mark on timing gear. I can see this mark on the hub of your cam when I enlarge your posted picture. This is another reason why you are having problems with TDC. You will also need to line up the other mark on the timing gear with the "o" mark on the crank gear when you put this all back together.
Another thing that I noticed in your picture is the fiber timing gear seems to be chewed up around the teeth and the steel insert ring where it presses onto the cam hub. What's up with that? Also, you may have been better off using an aluminum timing gear if that fiber gear is a recent repro. The ones being offered today, that are coming from off shore, do not last that long. The last one I used stripped between 1000 to 2000 miles. After that I switched to aluminum and that now has over 20,000 miles with no problems
 

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God, JM you're right.

Thinking about it, at TDC the cam slot is at roughly 45 degrees. In that setup it would be vertical.

I don't think you could even put a new mark 5 or 6 teeth to the left to correct the situation. To my eye the mark on the OP's cam seems to be aligning with a tooth rather than a gap.

Can those gears be removed without trashing them?

How would it run half a tooth advanced or retarded? Could this be used to advantage?

Mart.
 
Good catch hawk eye.Indeed there is a faint mark on the cam to the left of the installed position.

R
 
JM 35 Sedan said:
Sorry to be the one to give you this bad news, but you have your timing gear located incorrectly on the cam hub. The mark on the timing gear DOES NOT align with the distributor tang slot. There is a small mark/line on the hub that must be aligned with the mark on timing gear. I can see this mark on the hub of your cam when I enlarge your posted picture. This is another reason why you are having problems with TDC. You will also need to line up the other mark on the timing gear with the "o" mark on the crank gear when you put this all back together.
Another thing that I noticed in your picture is the fiber timing gear seems to be chewed up around the teeth and the steel insert ring where it presses onto the cam hub. What's up with that? Also, you may have been better off using an aluminum timing gear if that fiber gear is a recent repro. The ones being offered today, that are coming from off shore, do not last that long. The last one I used stripped between 1000 to 2000 miles. After that I switched to aluminum and that now has over 20,000 miles with no problems
Click to expand...


Hi JM - thanks for the explanation - I found a super faint mark on the cam face.

My understanding in fitting the gear was that the timing groove in the fibre gear must be aligned with the dist tang slot in the front of the cam. Wrong huh ? I just took another look at the cams hub face - there IS a faint mark on the hum that is not visible unless you turn it in the light or hit it with a strong fluoro light. Its there so this is where it my be pressed on to the cam hub and match correct?

Re the gear the pic may be a bit deceiving but the gear is in mint condition and is a brand new, unused NOS piece that came in the original box. I purposely avoided using a repro gear for the reason you mentioned.

Im booking in an appointment with the Optometrist as we speak.... (y)

Thanx !
 
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Look 45 degrees around from the current position. It's quite faint. It's between the 7 and 8 o'clock position in your pic.
 
I found it Mart - using a strong fluoro lamp it is visible - just.

Im guessing the flash in the camera has done the same.

Oh well - its press off, press on again ;)

Thanx fellas live and learn !

BFD
 
I posted a picture of the cam hub and a timing gear pressed on a cam hub. I marked the location of the timing mark in red in both pictures so you could see them in relation to the distributor tang slot. The mark on your cam hub is in the same identical location. I downloaded your picture and enlarged it enough to clearly see this mark on your cam. The face of your timing gear looks chewed up in your pictures. This could have happened if it rubbed the inside face of the timing gear cover or maybe it was like that when you got it. You need to get all of these things corrected, including whatever is going wrong with the small gear on the back of the cam that meshes with the idler gear that drives the oil pump. Until all of this is straightened out, nothing is going to work properly.
 
It might be worth inserting the cam before you put the gear on so you can check it meshes with and turns the idler and pump gears ok.

Here's a theory: When Ford fitted these gears, they were assembled on a fixture that held the cam and gear in the correct alignment and pressed the gear on. After it was on, an operative (bloke) put a chisel in the groove on the gear and tapped it to make a mark on the cam in the right position.

In my mind there is no way that faint mark on the cam would have been used at the factory for alignment.

Pure supposition, but how else could you explain the mark on the cam being so faint?

Mart.
 
Mart, the faint mark, it looks to me that the cam has had a skim across the front face. That may explain the faint mark, it's only the bottom of the original mark.
What do you reckon?
Martin.
 
I have no idea why it so faint Mart, but it IS an old cam core and no doubt has done its share of work/been thru hands; Scooder you may be right !

Anyway, I pressed the gear off, realigned it with the faint mark on the cam and pressed it back on.

And in she went ;)

Perfect, now to get to the lifters/adjustment /heads etc...

Thanks for the input fellas, much appreciated I would have been scratching my head a while on this one not realising that cam mark was there.

Cheers !
 
scooder said:
Mart, the faint mark, it looks to me that the cam has had a skim across the front face. That may explain the faint mark, it's only the bottom of the original mark.
What do you reckon?
Martin.
Click to expand...

I agree with your observation. Saw the same thing last night when I enlarged that picture but didn't comment on that. The face of the hub on that cam looks nothing like any of the original press on timing gear cams that I have. Even the slot for the distributor tang looks shallow compared to the camshafts I have. If this face has been machined and the camshaft hub is pressed flush to the timing gear front surface, this could be the reason for improper gear mesh at back of cam. Sometimes these seemingly simple modifications get us into big problems.
 
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