NEED HELP DEGREEING CAMSHAFT

[ozconv]

On Tue Feb 09, 2010 11:47 pm falcon1963 wrote:

You have run so many numbers by us its a cluster to even try to figure out.
With a 112 L/C cam advanced 3-4 degrees.
264 intake @.050 will be close to 36 abdc & open 2 atdc.
274 exhaust @ .050 will open 48 bbdc & close at 4 btdc.
These numbers if close would be a 112 L/C camshaft advanced 3-4 degrees.
I am getting:

264 intake @.050 closes 30 abdc & opens 2 btdc.
274 exhaust @ .050 opens 46 bbdc & closes at 3.5 btdc.

Comparing to your numbers, my exhaust lobe is pretty close (1/2 degree too advanced for closing, 2 degrees too advanced for opening). My intake, however, is way off, 4 degrees too advanced for opening, 6 degrees too advanced for closing. Looks like there is 4 degrees more between my intake and exhaust lobes than there should be for a 112 L/C camshaft so I suspect that I currently have a 108 L/C cam advanced 3-4 degrees. Would you agree??

 

[ozconv]

Actually, I just realized my exhaust is 1/2 degree too retarded for closing and 2 degrees too retarded for opening instead of advanced. Either way, the exhaust looks pretty close and the intake is still about 4 degrees too advanced.

 

[falcon1963]

Install it as is if you have 9.1 compression, if you have 9.5 compression retard the camshaft 2 degrees.

That cam checks out close enough. Falcon Man

 

[ozconv]

When I CC'd my combustion chambers they varied a little (less than 1cc) with the smallest at 51.5. After taking the head back off I measured the gasket (Felpro) and it was 0.048". I am not sure wether my dished pistons are 6.5 or 7cc but assuming they are 6.5 and my block is truly 0 decked (the smallest feeler gage I have is 0.006" and it wouldn't fit between the piston at TDC and a straight edge) I calculate a maximum possible static CR of 9.269:1. If the variables are at the other end it could be as low as 9.16:1. SInce I should be closer to 9.1 than 9.5 I will leave it as is and finish the assembly (next is putting checking springs on #1 intake and exhaust to check Piston to valve clearance). Thanks for all your help.

 

[CNC-Dude]

When checking P to V, you might already know this, and some may not, but when the piston is at TDC in overlap, this is NOT when either the intake or exhaust valve is closest to the piston. Many people mistakenly assume this is where you check it when checking their P to V, and make a serious error in doing so, especially if the engine has an interference type of valvetrain.

 

[falcon1963]

Don't worry about clearance piston to valve clearance especially with that mild camshaft.
I would get the victor head gasket available at a carquest store. That gasket is .044" compressed.
That will get you close to 9.5 compression. Being said i would retard the camshaft -2 on the crank pulley & then check your events.Falcon Man

 

[ozconv]

From what I have read, I was planning to check the intake from 15btdc to 5 atdc and the exhaust from 5 btdc to 15 atdc. With the checker springs, my 1.6 roller tipped rockers, and a pushrod with the solid lifter from the cam degree kit installed with a dial indicator at the retainer, I was planning to measure every 2 degrees or so by manually pushing the rocker arm further until the valve touches the piston and measure the delta. I've messed around with this already with the piston at TDC and could open the intake about 0.3" (no rocker arms installed). Since the total lift seems to be about 0.47" with these rockers, I don't expect a problem since I won't be anywhere near full lift between 15btdc and 5atdc but I plan to go through the exercise just for the experience. If my timing chain ever fails I guess I will be in a world of hurt but I think the rod bolts can interfere with the cam in that case anyway so I guess it would be a bad day no matter what. I have the double roller timing set so it should be reliable but when I temporarily installed the oil pan with the timing cover off it looked like the chain and pan would be really close (maybe 0.050" to 0.075"). I know I am supposed to leave the oil slinger off (there wasn't one on tear down) but do you know of anyone ever having interference issues with the double roller chain and the front cover/pan?? Thanks for the advice on the head gasket. I'll check into that, change to the +2 key way on the crank sprocket, and recheck. BTW, I pulled the cam part way out yesterday and read the numbers on the back and it is indeed specified as an H264/274 112. Thanks again.

 

[falcon1963]

interference issues with the double roller chain and the front cover/pan??

Yes, possible interference with the repo oil pan sold by NPW when using the double roller chain.
Might have to dimple the pan just below the sealing lip. Falcon Man

 

[CNC-Dude]

From what I have read, I was planning to check the intake from 15btdc to 5 atdc and the exhaust from 5 btdc to 15 atdc.

Thats actually backwards, the intake is closest to the piston between 12- 18 degrees after TDC, and the exhaust is closest to the piston 12-18 degrees before TDC.

 

[ozconv]

Thanks. I will make sure to check at those locations.