Finally some Cam Degree Numbers - Now what?

Russ/40 said:
I'm back, and have no idea what I am supposed to make out of the numbers. Here they are. If you recall I have been reluctant to pull the heads, and it was suggested I degree the exhaust valve on number one.

Reconfirmed TDC and very repeatable.
The info I found on the 77B: Int and Exh durations 260* or 220* at .050"
Lobe separation 111*, lift .325* Lash .014".

I got: .050" open at 148*
Exhaust starts to open @ 120.5*
Exhaust starts to close @ 348.5*
Exhaust is closed at 9* ATDC
Exhaust Lash is .014"

Is this enough to get a feel for the cam location? What else need I do. Exhaust centerline?
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Russ, In your numbers you say the exhaust closes at 9* ATDC, the 77B is supposed to close at 19* ATDC. That's 10* early, If you closed up the lash what would it close at?
Bill
 
flatrod said:
How is the compression? Retarding it will be losing compression, advancing it will add compression. It won't be much, maybe 20 pounds but its noticeable. Advancing it more than 4 degrees will start to lose compression again. Installing at the highest compression will be the best running, but that's a lot of dicking around to find it. I would go with a intake center line spec if you have it.
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flatrod, I repeat from an earlier post, the cam ran fine in my car a number of years ago. The cam now is in another engine. The engine will not time correctly with a setup stock helmet type Ford distributor. It static times at 25 degrees advance. At rpm it will advance to 35 degrees. The centerline is supposed to be 111 degrees both intake and exhaust. As flatjack9 states, the centerline or lobe center is at 120 degrees, so, if the 77b is the same lobe center int and exh, the cam is ok, but its not timed correctly, which corresponds with my original complaint regarding where the static timing is

Compression is low, about 85lbs. Probably due to extreme advance.

bbrocksr, - since I am using a dial indicator on the valve head, in my way of thinking the lash is of no concern, as I am taking it out of the equation by measuring only valve movement.
 
I assume that your working with a bolt on cam gear and not a press on?

If so, this is how you can time the cam. turn the engine, until the valve are both open, the same amount. You can do that with 2 indicators or, you can use a straight edge, across them, if the margins are the same (indicators preferred).

Then, with the #1 piston at TDC, slide the cam gear into place, on the cam. If the holes line up, the cam will be set, at or very close to "split overlap" or the other term, is "straight up".

If it doesn't line up, you'll have to off set it, to get the correct timing.

Nothing new, I learned this from Chet Herbert (of roller cam fame), when I was very young.
 
I've never given mush thought to the 77B cam as it quite mild and doesn't offer much in performance. With todays prices I would think that spending 500$ bucks on a cam Assy, you might consider the application alittel better. The stock EB cam might work just as well, or a Max #1might give bette rpreformance. If you want a Rump- Rump cam just pull out the choke alittle bit and you have a free L-100
Gramps.
 
Ol' Ron said:
I've never given mush thought to the 77B cam as it quite mild and doesn't offer much in performance. With todays prices I would think that spending 500$ bucks on a cam Assy, you might consider the application alittel better. The stock EB cam might work just as well, or a Max #1might give bette rpreformance. If you want a Rump- Rump cam just pull out the choke alittle bit and you have a free L-100
Gramps.
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Thanks Ron. I'm trying to utilize a cam that's been sitting for a number of years. Not trying for any performance over stock, just trying to get another one running. I seem to have come upon a erroneously marked cam gear
 
Russ/40 said:
Thanks Ron. I'm trying to utilize a cam that's been sitting for a number of years. Not trying for any performance over stock, just trying to get another one running. I seem to have come upon a erroneously marked cam gear
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Where did the gear come from and how long have you owned it.


R
 
Easiest thing at this point, at least in my mind, would be to replace the timing gear or try moving it a notch over and recheck the valve timing.
 
Back in the day whenyou had to buy your way out of a problem, we slotted the cam holes and used ster washers under the hold doew locking plate, Cams never moved.. Skipping a tooth is 16 degs I think.
Gramps
 
Ol' Ron said:
??????????????????
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While one cam-gear tooth is approximately 8 degrees of cam timing, the crank turns at twice the speed, so it is 16 on the crank.

360 / 44 = 8.18 (cam gear has 44 teeth)
360 / 22 = 16.36 (crank gear has 22 teeth)

So if you move the cam one tooth in either direction, you're changing the timing events on the cam by 16 crankshaft degrees (which is where all the timing numbers come from - a degree wheel on the crank).

I kind of doubt that he needs to move it that much - he probably needs a "tweener" - something in the middle. So, I'd try a new cam gear first (to see if it was somehow indexed wrong on the bolt holes). If that doesn't work, then you either custom drill a cam gear (on a mill with the correct tooling), or you come up with a method of increasing the bolt hole size and using some "offset" cam bolt-bushing sleeves (like we used to do before we had adjustable timing chains on SBCs).

Hope this makes sense . . .

B&S
 
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Bored&Stroked said:
I kind of doubt that he needs to move it that much - he probably needs a "tweener" - something in the middle.
B&S
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From Ross's original post on this topic:

"Side distributor timing set for 1/2 increment advance, like every other flathead I've had which was correct. Net is again 25 degrees advance at idle. Vacuum brake is screwed all the way in, but will still advance to about 35 degrees with RPM."

This is off quite a bit, sounds close to one tooth of the cam gear to me, maybe two.
 
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