Ted, "averaging" the values worked. Installed straight up it came out to 111 LC  (on a 110 LC cam) every time I checked it. I'll try a different cam today & see what happens. Who said you cant teach an old dog new tricks. Thanks.

Dan      Kingman Az.      86409

Ted, now that makes sense. I tried both the beginning and the end of the lobe lift and like you said nothing was repeatable. I'll give it another try today. Once Im satisfied I have figured out I'm going to try out the Mummert cam.

Dan      Kingman Az.      86409

Dan.  Are you taking degree wheel readings on each side of the max lobe lift and averaging the values?   If trying to simply center up on the top of the lobe, there will be a significant amount of error involved besides not being repeatable.  It’s normal to take readings 0.050” before and after the max lobe lift and then take the average of the two numbers for a lobe centerline measurement.

Lorena, Texas (South of Waco)

Charlie, I had that illustration next to me yesterday when I was checking things. When I advanced the cam in relation to the dot on the inner part I installed the chain in relation to the outer dot. I was checking things yesterday with the cam installed straight up & came up w/104 CL, 110 CL is the spec. That might be close. I read somewhere that CompCam grinds them a bit advanced. But Im not sure if its a correct reading. Reading CompCams instructions they say highest lift is when the needle starts to fall as you rotate it. There seems to be plenty of crank movement between when the needle stops & when the needle starts to fall. Where is the correct place to stop? Then I figured if I had a 104 CL I could retard the cam 6* and end up close to a 110 CL. I couldnt get it to read above 106 CL. I figured it was operator error & gave up last nite.

Bill, Im a big fan of the Ford 4100. I was going to run one on this until I ran across a "price is right" Holley 600 CFM w/ a manual choke on it. I guess if it doesnt work out I can go to the 4100. Are you running a manual or automatic?

Dan      Kingman Az.      86409

Dan, I tried to post last night but was getting server errors, anyway, I am running G heads sheved .030 along with intake surfaces shaved the correct amount for port alignment, pistons .010 in the hole, B manifold with 108 Ford 4 brll, hd a 112 on there which performed pretty good also, not sure if i can tell the difference in power, but the 108 comes on a lot smoother.

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

In regard to the Rollmaster timing set, when you change the sprocket's position on the crank, you also have to move the chain in relation to the crank sprocket. If you only move the crank sprocket, the timing will be changed quite significantly. This is probably why you are getting such a dramatic difference.



http://www.ford-y-block.com/timinginstall.htm


Lawrenceville, GA

Tedyes I am using a Rollmaster timg set and use the inside dot to advance the cam. You caught me on checking the cam position on this. I've always struggled with that. No problem setting things up but when I go thru the crank rotation/degree wheel readings it never comes close to being right. Obviously I'm doing something wrong. Sounds like a good project for today. That said, the more info I read about the Mummert cam running 4* advanced the more intriguing it becomes. Just sounds like a better set-up.

Dan      Kingman Az.      86409

And John is absolutely right in that V/P clearance issues happen at ~8-10° before TDC for the exhausts and ~8-10° after TDC for the intakes.  Using the clay method for V/P checks disregards the exact number of degrees where the minimum clearance takes place but if using the light spring method, the engine must be slowly stepped through the ‘minimum’ intake and exhaust areas to obtain the absolute minimum clearance numbers for each valve.  But I see where you are using the clay method which is a proven method for checking the V/P clearance.

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Because you have such a disparity in V/P readings in just a 2° change in cam timing makes me think your cam is out of time in what you think is the 2° advance position.  So that leads me to wonder whether you’re verifying the actual camshaft location each time you move the lower sprocket.  The outer teeth not being marked on the lower gear makes it touchy to move the camshaft forward or backwards without double checking the ‘as installed’ intake lobe centerline angle.

If this is a Rollmaster timing set, then each key position on the lower gear may be labeled appropriately while the outer row of teeth are only marked with a single dot that matches up with the zero keyway slot.   If you’re using the single dot on the outer row of teeth for both cam timing checks, then you’re likely about two teeth off when you have the crank key in the 2° ADV position on the crank gear.  Each key way movement on the lower gear corresponds to at least a two tooth movement on the outer row.  Checking the intake lobe centerline each time the crank gear is repositioned will validate if you are indeed moving the camshaft as desired.  If you indeed are double checking the cam position either by the opening/closing specs or by the intake lobe centerline method, then never mind.

But back to the camshafts.  The Mummert 270 camshaft at 4° advance will have a higher DCR than the Comp Cam 264(Int) installed straight up (0° advance).  That essentially means the cranking compression on the Mummert cam will be higher than the Comp stick which translates to increased lowend torque with the Mummert cam.  Here are the numbers from the spread sheet I use.

                     Comp Cam Specs                                                                                      Mummert 270 cam specs

      

Lorena, Texas (South of Waco)

Ok I went back through & ckd my piston/valve clearance. Clayed the piston, installed the head gasket, head,push rods & rocker arms. Adjusted the valves to cam spec .018. Turned the engine over 2 crankshaft revolutions then removed the head, sliced the clay form to see the valve impression. I did this at 2* advanced & straight up. Pic 1 is 2* advanced. Thats a .078 drill bit next to the clay impression, just about the piston/valve clearance. Pic 2 is straight up. Thats a .219 drill bit next to the clay impression. Again just about the piston/valve clearance. If I did something wrong let me know. I couldnt get the second pic to load but you get the idea.

Dan      Kingman Az.      86409

Remember that valve to piston clearance needs to be checked through a few degrees travel near TDC, not merely at TDC.  For instance, as the intake valve is opening just after TDC, it is often opening faster than the piston is descending, and the "crash" happens a little after TDC.

John - "The Hoosier Hurricane"