I am building a 408 stroker and am having trouble making sense of the numbers that I got when degreeing the cam. I am using a Hughes timing chain with adjustable sprocket. the cam is a Racer Brown SSH-25 238/238 @.050. I have read every article I can find and watched you tube videos, I am pretty sure I understand the basics, but cant seem to reconcile the results of my measurements with the degree wheel. All of these measurements were checked and rechecked several times to validate that they are correct.

The lobe separation is 110 and it is manufactured ADVANCED 4 degrees
I came up with the following for intake centerline as well as opening @ .050

Centerlines Measured @ .050 from max lift at lobe
Cam Card says Intake Lobe Centerline = 106 / Measured 103.5
Cam Card says Exhaust Lobe Centerline = 114 / Measured 115.5

Valve Opening @ .050 Measured @ .050 from the lobe base zero lift
Cam Card says Intake Open 13.0 BTC / Measured 13.5 BTC
Cam card says Intake Close 45.0 ABC / Measured 40.5 ABC

Cam Card says Exhaust Open 53.0 BBC / Measured 53.5 BBC
Cam Card says Exhaust Close 5.0 ATC / Measured 1.0 ATC

I would think that if the cam centerline was off and needed to be adjusted by using an offset key or the adjustable crank gear all of the figures would be off by the same amount. I am also not sure if I need to add or subtract or do noting with the 4 Degree advance hat is already built in.

Any help in clarifying this would be appreciated.
Thank you
Scott

What your checking is how good the cam grinder is. You might think that once the lobe is cut it's exactly like the master...but what your seeing is that it's not.
To really make a cam perfect, it takes additional grinding time and may or may not happen depending on the grinder.

Even if the cam was cut with 4° advance, doesn't mean once installed in the engine it is where it needs to be.
That's why we degree it in.
So right now the cam is in with 6° advance and the true lca is 109.5. So if you want only 4° advance you need to back it up 2°.
Lifter bores that are not true can also cause this...I would try a different cylinder and see if your results repeat...if not, it may be the bores...and it may not be!!
Aint engines lovely....?

As mentioned, it looks a bit advanced.
I record the degree wheel reading at various tappet lifts. Usually 0.002", 0.004", 0.006", 0.008",0.010", 0.015", 0.020", 0.030", 0.040", 0.050", 0.075", 0.100", 0.200", 0.250", 0.300", and 0.050" increments till peak lobe lift. I also record the measured peak lobe lift, but not the duration. This helps show the average installed centerline and if the lobes/ramps are the same.
Make sure to keep track of if the numbers are BTDC, ATDC, BBDC, and ABDC, because most degree wheels are 0-90-0 reading type.
I put my readings into a computer spread sheet because it's easier and faster to do multiple calculations. You can also plot out a graph of the lobe profile, but it won't look too great unless you have more data points.
For the mild RV cam in my 360, I took all those readings and they came out pretty consistent from 0.030" to 0.300" (max lift was only 0.313" on the intake lobe.) So my eight readings from 0.030 to 0.300" ranged from 103.0 to 104.3 with most around 103.5.
My Average (or mean) was 103.69, with a standard deviation of 0.10. Having multiple readings will increase your confidence in the true centerline.

Thanks,
I like the idea of taking several measurements but I still need to understand if I needto factor the 4 degrees advance into the calculations, and if so how?
Scott

I am still at it. Now that I know that I do not have to factor in the 4 degree advance built into the cam I verified that the cam needed to be advanced.
I have a Hughes double row timing chain with a crank gear adjustable in 2 degree increments. Learned the hard way that RETARDING at the crank gear ADVANCES the cam......$4!@ so after pulling the timing set twice got the crank gear in the correct slot. Checked it again averaging various points of the lobe and came up with:

Intake Centerline is at 105 vs spec of 106
Exhaust Centerline is at spec at 114

So not I have to figure out if I am better of dialing in the Intake at 106 and having the Exhaust move toward 113 or leaving it all as it is? What effect will this have on power, if any?

Thanks
Scott

Think of it this way your cam is ground on a 110 LSA so it would be 110 ATDC intake max lift (intake lobe centerline) and the exhaust would be 110 BTDC max lift (exhaust lift centerline)
so 110 + 110 = 220 /2 = 110 LSA
Now you cam man installs the dowel pin to in theory to have the intake max lift (intake lobe centerline) advanced 4 deg or in at 106 ATDC since the lobes stay the same in relation to each other this would put the exhaust lobe max lift (exhaust lobe centerline) in at 114 BTDC so
114 + 106 = 220/2 = 110 LSA.

Now on your numbers on the base circle you may see the indictor move up and down a bit at 0 lift so this can throw you off a tad on some cams. You may have to watch and 0 just before ramp.
I like to do .050 before and after max lift and .100 before and after max lift but rollers and some other cams have a slower down ramp on the lobe than the up lift so it may be off a bit.
the larger the degree wheel the less margin of error.

what are all the cam specs.

one degree you will hardly notice I would leave it at 105 I like cams advanced a bit more then the cam manufacturers.