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I bought one a Howard's camshafts for my 261 inline six cylinder through Patrick's and I did not receive a cam spec card with it and I would like to get the cam specs, so that I can degree the cam. The Patrick's model # and description from their catalog are M4F, 3/4 MILD, INTAKE 12/46, EXHAUST 46/12, LIFT 0.420. I do not understand what the INTAKE and EXHAUST numbers mean, can you explain it to me? I plan on using the Intake centerline method to degree this cam and I need the #1 intake lobe degree value at 0.050" to use this method. Does anyone have this information?

Cujo,
I've got this same cam in a 235, here's what the cam card sais in answer to your question. Degrees of duration @ .050" 206 for intake and exhaust. If you have a fax # I could copy the cam card and send to you. The engine builder who degreed my cam "advanced the cam 4 degrees". By doing so the cam will come in sooner. Regular chevy v8 advance 2 degree keys work. Then from there you can play with different settings to match your rear gear. Higher gears like 332's or 273's to l like a little tighter valve clearances like .011 & .014 vs the .014 and .016 cam card suggestion. Mine has a little lope at idle with the .011 & .014 settings. Hope this helps.

52pu

The numbers you have are for valve opening and closing for intake and exhaust. They are worthless unless you know if they are at .050" or actual seat timing ( when the valve actually touches the head ). A lot of makers don't give out this information to hide there speed secrets. Its just like advertised cam spec's. ie... 308/320 ???? when or where are they measuring from? Who knows, its just a marketing scam to make there cam sound good.

You must have actual spec's to do what you want. Joe

Well I have a new problem, the first step in degreeing a cam is to determine the exact TDC. To do this I usually use my trusty Piston-Stop inserted into the #1 spark plug hole. The problem is the angle of the spark plug hole does not allow the piston-stop to come anywhere near the piston! Does anyone know another method to accurately determine TDC on this type of engine (261). The best I was able to come up with was to turn the engine upside down on the engine stand and move the crank by hand until I thought the #1 connecting rod was straight up & down and then set the degree wheel to 0. I hope someone has a more accurate way than this.

Try just sticking a long screwdriver down the sparkplug hole. Turn the engine very slow till you hit the screwdriver and mark the balancer. Then, reverse the direction till you hit it again, and mark the balancer. Next, measure the distance between marks and cut it in half. That is TDC. Joe

52pu, Are you saying if I use chevy V8 advanced 2 degree keys on my inline six, that it will advance the timing 4 degrees.
Also, I've heard that many bolter's install these cams 4 degrees advanced to improve the low end performance, but this added low end performance comes at the price of less high end performance. How noticable are these low end performance gains when you advance the cam by 4 degrees compared to installing the same cam straight up?

Advancing the cam 4 degrees moves the powerband down several hundred rpm, at least in theory, retarding the cam does the opposite.Playing with cam timing isn't for big power gains ,it's a tuning aid. .My experience with a modified 261 has the power signing off at 4200 rpm and the engine pulls down low like the stock 261 in our 51.I advanced the cam 4 degrees when I did the engine, sounds good to me.

Thanks 52pu for the cam specs and also to Joe H. for the screwdriver method of locating TDC. I just finished degreeing my cam and I came up with 205 degrees of duration @ 0.050" which is within 1 degree of the spec 52pu gave me. The 1 degree difference may be within the error of my measurement technique. I would like to advance the timing by 4 degrees using an offset key on the camshaft keyway. In which direction should the offset key be pointing? When looking at the front end of camshaft should the offset be to the right or the left? From 52pu's post I am not sure if I need a 2 or 4 degree offset key.
While I was measuring things on the engine I decided to check the cam gear run-out and I found it to be 0.015" which is 0.011" outside of the spec. From looking at the cam-gear/cam-shaft mating surface I could see it was not pressed on straight. Hopefully when I get the offset key put on I will be able to press this gear on straight this time.

Cujo,
I faxed you the cam card this morning. Yes 4 degrees advanced keys worked for me in the 235. Can't remember exactly without looking but I think we put it in so the cam gear rotated more left than straight up with the advance keys inserted. Try my recommended settings. Let us know how it goes. Its always a thrill to hear it crank for the first time.

I had the machine shop install the 4 degree advance key on my cam shaft and they fixed the gear runout issue today. I also came up with a better piston-stop tool, which worked better than the screwdriver method I had used earlier. I used a brake spring removal tool, which after inserting in the #1 sparkplug hole, was held tight in place with the rocker stand using a large zip-tie. After determining TDC and adjusting my degree wheel I went on to check camshaft timing. I am using the Intake Centerline method, which was outlined in my CompCam Degree kit. This method measures the total duration in degrees between the 0.050" position on either side of the cam lobe and then divides this value by 2. 52pu gave my the cam spec of 206, which is the total duration (Not divided by 2). With the straight cam key I originally came up with 205 degrees, which is pretty much on spec. Now with my 4 degree offset key installed I came up with a total duration of 192 degrees. CompCam uses the total duration divided by two to figure how far a cam is advanced or retarded. Therefore 206/2=103 & 192/2=96, and the difference 103-96 = 7 degrees advanced. If my original measurement of 205 was accurate, that would still make my cam 6.5 degrees advanced. My questions are 1) why if I installed a 4-degree offset key, am I getting almost twice that amount? 2) How will this 6.5-7.0 degree advanced cam timing effect my engine performance?

Cujo, Sorry to be the bearer of bad news, but the offset key should be installed on the crankshaft gear, not the cam gear. You double the advance/retard by installing on the cam gear. This will kill any top end from your motor.

Removing the key from the cam gear can be touchy, it's easy to break the thrust plate.

I'm dubious about advancing cam timing. I've used the offset keys only to correct cams that are off-spec. If you buy the right cam in the first place, you shouldn't need to play with the timing.

Jack
www.inliners.org

OOOOh, yes on the crank gear, ouch
Jack,the timing card that came with my Howard M4F 6 years ago suggested advancing the cam 4 degrees from the figures shown on the cam card.

The problem I have with the idea that the offset key goes on the crank gear is this, When you get one of the timing sets in which the crank gear has three key ways in it, so that you can either install it 4 degrees retarded, straight up, or 4 degrees advanced,are all 120 degrees apart on these crank gears. How is this offset key, which is only offset <1/8", going to achieve the same result? I am sure glad I am not in a hurry to get this engine finished.

I agree with Tony. The 4 degree advance key works for the Howard M4F solid lifter cam.

52pu

I sent this post over to my dad to see if he could figure it out.

This is what he said,

On the cam, the 206 number has to be at .050". And that would make the quoted open and close numbers be at the advertised duration. The open/close numbers at .050" are considerably different. But the fact is that both are at 107 lobe center.
The cam runs at half speed of the crank - all duration and open/close numbers are referenced to the crank. So a one degree change at the cam changes the numbers at the crank by two degrees. Thus, the owner put in an inaccurate 4 degree key, and that advanced the timing by 7-8 degrees. If he wanted 4 degrees advance, he should have used a two degree key.

Also, its very hard to find a off set key big enough for the crankshaft. To get corrected, you need to change the cam key. You got the gear off once, it should come off again. Joe

I think Joe H's Dad has the correct answer to this problem, since I installed a 4 degree offset key and ended up with about twice the advance that I was after. Therefore if I replace the 4 degree key with a 2 degree key I will now have the the cam timing advanced by 4 degrees.

Today I switched the 4 degree offset key with a 2 degree offset key on camshaft keyway. The cam timing is now 4 degrees advanced, which was what I was after all along . Patience is indeed a vitue! A little persistence doesn't hurt either. Now I can finally move forward with this engine rebuild with that issue behind me now. Here is a link to some pictures, which show the engine rebuild so far and the new piston-stop I made out of a standard brake spring tool.
http://community.webshots.com/scripts/editPhotos.fcgi?action=viewall&albumID=109150147