Advancing camshaft

What are the limits to advancing a camshaft and what is the most some of the experienced builders have advanced a cam? If you have the P/V clearance, is it out of the ordinary to advance a cam 10 degrees from what it is cut at? Pros/cons of it I understand, just looking at what the limits are and what guys have seen or used.

*Not an expert opinion. Advancing a cam opens the valves earlier. I think it adds more low RPM torque while trading off some higher RPM horsepower. Getting my popcorn while waiting for a real expert to come online.

I would say ten degrees would be out of the ordinary.

Four is quite common but unusual to see much more than that.

My guess is that if the cam needed that much advance it really needs a different cam.

^^^This
If the cam is better/faster @ +10°:
1. the cam is too big
2. not enough static CR

That is why I am asking! stand by for the experts....It does seem excessive, but would there be a situation where the engine would benefit from it without getting another cam?

Four is common, I agree, but why would they make timing chains with up to 8 degrees built in if it is uncommon to do? Thanks for the replies and help with this

It often takes more or less than a four degree adjustment for the cam actually to be installed at four degrees advanced. .

I have advanced one cam 10* but if you do need to know that when you do advance it you will lower
the rpm.. I gained torque but lost rpm which I needed... that cam I moved it like 6 times advancing it
each time then moved it back based on rpm needed

exactly! if you have to advance a cam that much then it's just the wrong cam. for me, if the cam needs more advance than what is ground into it i look for something else.

I can’t really think of a situation where I would “choose” to run a cam 10* advanced from the “straight up”(int & ex c/l equal to lsa) position.
In other words, a 110lsa cam installed at 100......108lsa in at 98, etc.

I have had to move the cam more than 10* before to put it where I wanted it, but the installed position still wasn’t 10* + or - from the lsa.

I’m not saying it “couldn’t” work, I just can’t think of a normal Mopar v8 build where that would end up being optimum.

Advancing the cam will close the intake earlier, creating more cylinder pressure. In theory we would all advance cams earlier and earlier to gain pressure/power. But the overlap events critical to head flow get outa whack. I have personally run cams as early as 96* intake lobe center. Better check intake valve to piston if attempting this. Never really affected the et by more than a tenth or two.

A tenth of two....... better or worse?

A tenth of two can represent a fairly significant change in power.

Before the NHRA allowed porting in SS, I knew some guys that had engine combos with pretty weak heads that ran cams installed in the mid/upper-90’s int c/l.
But....... they weren’t installed all that far advanced.
They had cams that were 102-104lsa.

One of the Ford circle track racers we worked with was playing with some pretty tight lsa’s...... like around 100*....... installed at 95-96.
Those things made fantastic mid-range tq........ but they didn’t hang on all that well.

All kinds of cams, engines. The one I remember it helping was a cam with a lobe sep angle of 112.

I’ve never done it....... and don’t think I would....... but it would be interesting to know the whole combo on something where that worked.

the only reason I can think of to advance a cam something like 10 degrees is if it has retard ground into it. there are some factory smog cams that have retard ground into them. the stage 2 wedge cam is recommended to be advanced 8 degrees but for some reason, and I could be wrong, I think they may have a couple of degrees retard ground into them. I've noticed that some older profiles (and it seems like lobes with longer closing ramps) may have 5 degrees ground into them. I have advanced cams with 108lsa a couple of degrees but that still ended up being 4 degrees total and I wouldn't go any further.

This motor has iron heads (same motor with intake/heads not fitting issue we fixed by grinding it on four corners) and the guy putting it together called comp cams with the spec sheet while he was degreeing it in. They said good to go. He has a ton of circle track experience with building motors, mostly bowties, and has done it in the past. Cam is a xs290s solid with 110* lsa. He put it in at 99* and me not knowing [censored] thought that was a lot too...

I guess we will find out how it runs when the virus starts to slow down.

as i am not an expert, doesn't a lot of this confusion stem from the cam manufacturers advertising "x degrees advance ground in" ?
i also remember a magazine article from 25+ years ago, state to advance and retard the cam x degrees, plus try straight up, and whichever position produces the most cylinder pressure, that is where that cam will work the best.
you obviously need to check valve to piston clearance before and after TDC.

If you are a motor trend on demand member they just posted an episode last week about this very thing, on a 440 Mopar even. It wasn't a race motor by any means, it was a cleaned up stock 440 motorhome engine with a cam and 7.5"1 compression.

Imo, the motor is still out of the car and tracks aren’t opening for a little while yet....... so there is no rush.
Move the cam now while it's still easy.

Anecdotal story.......

I sold a cam to a customer with a 505 for a hot street build.
He was looking for something pretty hot, that wouldn’t be too miserable on the street with closed exhaust.
I sold him a cam that was 262/266-112. They installed it at around 108.
Dynoed motor with way too big headers(2-1/4”), power was down from expectations.
He comes on a forum and everyone is harping on the 112lsa and the 108 c/l is the big problem.
He gets convinced to put the cam in at around 100-102 iirc.

Made less power......... pretty much everywhere as I recall.

Advancing the cam changes all the events...... not just the ivc point.
And two of the other events often aren’t very helpful when advanced.

I'm not an experienced builder...I'm much more of an abnormal hobbyist.

That said...the most I ever tried was +6, and it helped that application quite a bit where I needed it.

It wasn't a race type of application though, it was actually on a stock cam 1972 400 daily driver.
I was really happy with the change and decided to try it around 75,000 miles when replacing the plastic timing gears.

Not V8 but when Shelby did the 2.2's for 1983 he found the stock cams were too retarded after he milled the blocks 0.030". So he had Chrysler make a Shelby spec cam sprocket to advance the cam 9 degrees to re-centerline it due to the belt pulling the cam into retard with the deck mill. When I threw the degree wheel on it it was 5 degrees advanced. I did use the Cam advance keys to set it at 8 degrees total and it ran stellar.
Years later working on a fairly stock 2.5 in a Shadow ES 5 speed. I removed Balance shafts. I had a measured 10:1 comperssion, and a 240/252 0.460" lift DC cam. I played with Cam keys but ended using the stock key and slipping the timing belt 1 tooth advanced, that was 9 degrees per tooth. Before I advanced the cam and 'Granny' shifted at 3500 RPM it got 32 MPG. Advancing the cam 9 degrees, that car had gained so much bottom and mid range power but nothing up above 5,000 RPM. Again, Granny shifting it then got 41 MPG. This was a daily driver for commuting 82 miles a day.

But back in the 1980's playing with a dead stock 318 with a Performer manifold and 600CFM Holley we ran a 360 2bb cam. It was strong and with a 74 Dart Swinger and 2.76 gears gave 20 MPG. Then we put a 4 degree advanced chain and it boosted the BUTT DYNO a lot and when babing it, it got the best of 25 MPG but avareged 23 MPG.

talked about 10* for one of my wagons i had just to get it moving

little chevy 355 cubes brodix track 1's as I recall long time ago, Nova 5.13's at say 2800...lots of fiberglass ect. transbrake with chip removed.I want to say we even moved the rockers 1.7's to the exhaust to make it work.

now I try to put everything in at 106, or as close as possible, where the valve to piston clearance works out.

You really need to know if people talking about advancing the cams are talking about crankshaft degrees or camshaft degrees, correct
I always use crankshaft degrees when talking about advancing camshafts but people some don't
The first camshaft I had to degree to get the motor to run halfway decently was a 392 hemi in a V drive flat bottom ski boat, I didn't know about cam timing and degree checking off of the lifters instead of the valves at that time or about lobe separation angles. I do now
The cam was a Sig Erson solid roller cam for ski boat racing and it was ground 8 crankshaft degrees retarded from 110 LSA on the intake lobes, they recommended running the intake lobe center at 108 and when I finally got to checking it properly it was installed at 118 ILC They insisted it was anything but their cam being ground wrong, they wouldn't replace it with one ground correctly
I ended up using the LSA method to get it where they wanted it by using offset keys on both the cam and crankshaft The only good thing that I learned form that is how to use LSA for cam timing verification and cam installing off of the intake lobes BTW, I always verify the exhaust lobes to make sure the cam is ground on the LSA the cam card says it is If it is a 108 LSA grind and installed at 104 after top dead center on the intake lobes on the crankshaft the exhaust lobes should be in it at 112 before top dead center to be ground correctly I have seen more than one cam ground wrong on the LSA from several different cam companies
I never bought another Sig Erson cam after that one though
Never, NEVER install any cam by aligning the dots and ASSUMIMNG it is installed straight up, always verify
OP, I've installed and ran and raced a bunch of motors and check all the cam timing and tested a bunch of cams in different motors advanced, straight up and retarded, none of the Mopar V8 motors like straight up or retarded, they all like the cams advanced at least four crankshaft degrees None of them liked or ran faster or made more power advanced more than six crankshaft degrees
IHTHs

Cant thank all of you guys enough for posting your knowledge to help me out. As always, much appreciated. I wish I did this much research when I was in school lol. Learn a lot here

I'm still learning via the on the job training, DANG Murphy any ways
AKA aside that cam was a real painful lesson in motor building and theory

If you use a typical 9 way timing set, you can get within 1deg of where you want the cam installed........ no matter how far off it is.

Those sets can go +/- 8*, which is 1* past the 1/2 way point to the next tooth over.

So, if you’re more than 8* off...... move the the timing set over a tooth, and come at the c/l from the other side.

Some of the car companies (Ford specifically) moved their cams around by changing the crank and cam gears and not the cam. 1970 429 Ford cam gears when used on 75 or up 460's turn trucks that won't spin the tires on wet grass into trucks that will smoke the tires on any kind of pavement. That kind of retarded camshaft also effects gas mileage in the worst kind of ways. Sold many many earlier style timing sets to Ford car and truck owners after explaining the difference to them and never had a complaint from any of them.

I had a friend who owned and love Fords tell me that years ago, he had seen a 460 in a 1971 Lincoln Mark 4 loose a lot of power when they change the timing set in it to avoid it skip timing when it had around 80,000 miles on it, they bought the timing set from the local Ford dealership and they sold him one off the shelf they had in stock for a 1986 ford truck 460 motor, they went through a bunch of pain and work to figure out what had happened and fix it

if the builder is used to small block chevy engines then he may have been buying cams with LSA's anywhere from 106-102. put some advance in those cams, specifically short track, and you'll end up with around 100 or less installed centerline. I don't think what the OP's doing and what the builder does is apples to apples. i'd change it.

This may help understanding cam advance and intake centerline.

When the rod and the crank throw are perpendicular, this is the point of maximum piston acceleration.

Some would argue this is also the point of maximum draw/pull on the intake mixture, although this point
is not quite an exact mathematical relationshp, but it's probably not too far off.

For most engines, the crank throw and the rod are perpendicular at approx 70 degrees ATDC to around 76 degrees ATDC,
depending on rod length and total stroke of course. 70 degrees in a "short rod" motor, 76 degrees in a "long rod" motor.

This is A LOT earlier than 100 degrees ATDC, which is considered pretty advanced for intake valve centerline.
The hidden question is: Should the intake valve be at max lift at the point of max piston acceleration for max breathing ?

Because of this, it should not be surprising that advancing the cam, i.e., the intake centerline, generally shows
up as higher torque output of the engine (in a given RPM range). It also shows how much of a compromise cam design
really is, they are not AT ALL ideal, but, it's the best we've got.

*********************************

Edit: Replace the phrase "piston acceleration" with "piston velocity". The degree numbers are correct, everything else
is correct. I can't believe I made that mistake.

Another argument: a short rod has significantly faster piston acceleration ATDC, and initiates vacuum at the intake valve curtain earlier (for which Vizard has made a good case as not merely useful but indispensable).
It also has slower motion ABDC, and captures a greater percentage of the stroke at the same point of cam & crank rotation than a long rod. Will show higher CCP and stop reversion at lower RPM.

the highest depression is at the overlap event...at least from my understanding.

I have to think that the overlap events have more influance on power when a cam is moved than closer to max valve lift. Getting that. Intake charge moving through the intake valve at low lift is pretty important. To me it reminds me of the importance of 60ft and 330 ft times. They are the base of a great ET. Bad 60 or 330 numbers can't be compensated for.
Look at a 440 with unported iron heads. It responds to a lot of advance AND overlap because of the poor heads.