Cam is installed advanced 2 degrees

[Paul_G]

Just finished the install of the cam in the 505. I installed the cam to 108 intake centerline like I was instructed to do. Had to advance it 2 degrees to get 108 IC. Spent some time learning how to degree a cam. Not hard at all once you get it figured out.

On the cam card it states cam to be installed on 108 intake center line. First I installed the cam straight up and checked IC. It was at 111. Curious why it didnt come ground on a 108 IC?

 

[Paul Secoy]

Timing chain and gears can vary quite a bit, as can the cams themselves. I can't remember which mag tested a bunch of them, and found one that I recall being like 16 degrees off.. They said it wasn't a cheap one either. I spoke to a well regarded engine builder, and he told me its very hard to spot 2 degrees even on a dyno.

 

[BSB67]

Just finished the install of the cam in the 505. Cam was set to 108 intake centerline like I was instructed to do. Had to advance it 2 degrees to get 108 IC. Spent some time learning how to degree a cam. Not hard at all once you get it figured out.

On the cam card it states cam to be installed on 108 intake center line. Installed the cam straight up and check IC. It was at 111. Curious why it didnt come on a 108 IC?

I don't know.

Back before there were multi key adjustability in the timing sets (i.e. only one key and no adjustability) there timing always seemed to be close on initial install. Since all of the new fangled timing sets, they always seem to be off by 4° or so. It almost seems like the manufacturers are not to concerned about getting the "0" right because you can adjust it to what ever you want it to be. Just speculation.

 

[Lefty71]

Since all of the new fangled timing sets, they always seem to be off by 4° or so.

Suspect this to be the "China factor"

 

[451Mopar]

What are the cam specs? Most split pattern cams with longer exhaust duration are installed advanced for split overlap.

 

[Hemirunner]

It’s tolerance stack up. A degree here a degree there, it all adds up. There’s the crank slot location, the crank gear, the cam, the cam gear, chain tension and crank to cam centerline also plays a part. Very few individuals had the knowledge or equipment to even check cam location in the 80’s so there was very little need for the multiple keyway sets. As that changed, the need grew. If anything, the tolerances have gotten tighter in manufacturing. In the 80’s, your cam might’ve been 6 or 8 degrees off but you just didn’t know it. The other thing to consider is that some manufacturers grind varying amounts of “advance” into the camshafts. The intent was that the cam is in the right place when installed with your one location timing set.

 

[451Mopar]

I have had good results with the 440 Source 9-way timing set. Used that timing set with a few comp cams and Lunati cam and the cams checked out within 2 degrees. Worst I have seen was on an Olds stroker engine. Not sure if the stroker crank had the keyway machined offset, or the unknown brand timing set or the cam, but when installed straight up the cam was 15 degrees retarded.

I think the crank keyway is aligned with the first crank throw, so when #1 cylinder is at TDC, the keyway is at 45 degrees or in-ling with the #1 Cylinder.

 

[dvw]

Let me add this. After degreeing many cams you can check timing at many spots. Open, close, C/L, .050", .020", etc. Most times not all of the checking points will match the card. So which spot do you use? I use intake closing at .050". I feel its the most important. Actually in a race engine it's just a starting point. Moving the cam is just something else to test.
Doug

 

[Paul_G]

What are the cam specs? Most split pattern cams with longer exhaust duration are installed advanced for split overlap.

Its a 76 motor home 440 block. 440 Source stroker kit, Comp Cam, Summit Racing timing set.

 

[Paul_G]

Biggest PITA I had was with the cam button. Looking for .005" to .010" cam end play. The ARP cam bolt heads and the Comp Cam roller cam button were touching the timing cover, and the cam button was flush with the heads of the ARP cam bolts. I decided to make a "bump out" in the timing cover, then shim out the cam button. Now the cam button is out about .010 further than the bolt heads so they can not rub on the timing cover, and I have .006 cam end play.

 

[BSB67]

It’s tolerance stack up. A degree here a degree there, it all adds up. There’s the crank slot location, the crank gear, the cam, the cam gear, chain tension and crank to cam centerline also plays a part. Very few individuals had the knowledge or equipment to even check cam location in the 80’s so there was very little need for the multiple keyway sets. As that changed, the need grew. If anything, the tolerances have gotten tighter in manufacturing. In the 80’s, your cam might’ve been 6 or 8 degrees off but you just didn’t know it. The other thing to consider is that some manufacturers grind varying amounts of “advance” into the camshafts. The intent was that the cam is in the right place when installed with your one location timing set.

Interesting. I'm a back yard mechanic and I've been degreeing cams since the 1970s in my dad's garage. It's not a new concept. Bushing were, and still might be available. I actually think it was easier and faster back then, Cloyes Hex-a-Just aside. Yes, its stack up, but the acceptable tolerance by the manufacturers is what causes the magnitude of the potential stack up. What was more likely the case back then was either they were very close, or they were way off. Today, they just seem sloppily in the middle.

 

[BSB67]

Let me add this. After degreeing many cams you can check timing at many spots. Open, close, C/L, .050", .020", etc. Most times not all of the checking points will match the card. So which spot do you use? I use intake closing at .050". I feel its the most important. Actually in a race engine it's just a starting point. Moving the cam is just something else to test.
Doug

I do take some enjoyment on the great lengths we'll discuss where exactly to measure asymmetrical lobes to "get it right", when in reality "right" is application specific and can only be determined by testing in probably 3 cam position locations a very controlled environment.

 

[BSB67]

Biggest PITA I had was with the cam button. Looking for .005" to .010" cam end play. The ARP cam bolt heads and the Comp Cam roller cam button were touching the timing cover, and the cam button was flush with the heads of the ARP cam bolts. I decided to make a "bump out" in the timing cover, then shim out the cam button. Now the cam button is out about .010 further than the bolt heads so they can not rub on the timing cover, and I have .006 cam end play.

That's similar to what I do. I support the timing cover bump out with the water pump housing.

 

[Paul_G]

When I push the cam against the timing cover there is some deflection of the timing cover. I was thinking of making a strap to weld across the bump out. Have the strap long enough to weld it close to ends of the timing cover.

I wonder how much force can the cam can actually put against the timing cover? I have read that the natural direction of the cam in a running engine is to push toward the back of the engine.

 

[BSB67]

When I push the cam against the timing cover there is some deflection of the timing cover. I was thinking of making a strap to weld across the bump out. Have the strap long enough to weld it close to ends of the timing cover.

I wonder how much force can the cam can actually put against the timing cover? I have read that the natural direction of the cam in a running engine is to push toward the back of the engine.

I weld a piece to the back of the housing that touches the cover. Then the housing actually dictates clearance.

 

[66Satellite47]

My 1st cam, General Kinetics 585/308 solid was 1 1/2* retarded intake C/L. Used the offset bushing to correct. Checked several times & with 2 new Cloyes Tru roller setups. With later cams had a couple right on & a couple 2* off. But starting at manufacturers number & the doing the testing at the track (advanced & retarded) to see what the motor combo likes is what my race motors got.

 

[Paul_G]

Some helpful info.
https://www.hotrod.com/articles/cam-install-from-the-start/

"After the initial baseline cranking-compression check, advance the camshaft 2 degrees. Be sure to check piston-to-valve clearance before cranking the engine over, or damage could occur. Remeasure No. 1 cylinder’s cranking compression. Now retard the cam the same amount and check the cranking compression again.


If advancing or retarding the cam raised the cranking compression, continue to alter the cam position by 2-degree increments in the same direction cranking compression improved until the cylinder pressure drops, then back off to the highest observed number.

Maximizing cylinder pressure using this technique offers a fairly reliable method of determining optimum camshaft position for a given engine combo, compensating not only for valve timing, but also for the given engine’s rod/stroke (R/S) ratio. Circle track engine builders have had good success with this technique if they aren’t able to sort out the cam on an actual engine dyno."

 

[beanhead]

Luck of the draw these days(maybe it's always been?!) l My last one (a custom-ground comp) called for 106° and came in at 106.5° with no adjustments.
This is a great discussion, just goes to show the importance of cam degreeing..
and like PaulG mentioned, it's no big deal once you do one and you'll wonder why so many people skip it!

 

[IQ52]

Timing chain and gears can vary quite a bit, as can the cams themselves. I can't remember which mag tested a bunch of them, and found one that I recall being like 16 degrees off.. They said it wasn't a cheap one either. I spoke to a well regarded engine builder, and he told me its very hard to spot 2 degrees even on a dyno.

If they found it 16 degrees off they most likely had the cam gear 1 TOOTH off.

Interesting. I'm a back yard mechanic and I've been degreeing cams since the 1970s in my dad's garage. It's not a new concept. Bushing were, and still might be available. I actually think it was easier and faster back then, Cloyes Hex-a-Just aside. Yes, its stack up, but the acceptable tolerance by the manufacturers is what causes the magnitude of the potential stack up. What was more likely the case back then was either they were very close, or they were way off. Today, they just seem sloppily in the middle.

I was only a kid but I remember my dad degreeing cams in 1959.

 

[IQ52]

Biggest PITA I had was with the cam button. Looking for .005" to .010" cam end play. The ARP cam bolt heads and the Comp Cam roller cam button were touching the timing cover, and the cam button was flush with the heads of the ARP cam bolts. I decided to make a "bump out" in the timing cover, then shim out the cam button. Now the cam button is out about .010 further than the bolt heads so they can not rub on the timing cover, and I have .006 cam end play.

Spend the money and do it right.....................
http://arengineering.com/products/timing-chain-cover/