Intake centerline advance/retard

How much does it take to make a difference?
I'm coming up with 111 on the wheel vs. 113 on my cam card.
Will this much advancing the cam only 2 degrees make a difference or would I need more to increase bottom end torque on a heavy car?
Thanks Mike

IMO

I would use offset keys to bring it to the cams recommended setting.

Not me. I haven’t put a cam straight up in years. If it was mine it would be in around 109 but I’m strictly a drag racer and if you can get it to 60 foot that sucker will run a good number. Heavy cars need all the help they can get.

I thought all the new cams were ground with that accounted for in the grind.

Make sure and verify exactly where the intake lobes are installed, always Once you have the ILC where you want it take the time to verify where the exhaust lobes are exactly at, if the cam is ground on a 113 LSA then when you advance the intake lobes the exhaust lobes you be advance exactly the same amount, if your intake lobe center is installed at 110 ATDC then the exhaust should be in at 116 degrees before TDC
Good luck, let us know your results

Do you know what ASSUME(ASS U ME) means
Never assume any mass made after market automotive parts, especially race parts, are ever made dead nuts accurate
The timing set can be mismarked, I've seen that a lot with Cloyes timing sets for both BB and early Hemi and L.A. motors
The first custom ground solid roller cam I bought(Chrysler 392 hemi boat motors) was ground 8 degrees retarded
I installed it and use a degree wheel to check the cam timing at .020, it was off around 3 degrees so I assumed that was good enough, which of course wasn't
That bad cam did end up teaching me how to check the LSA the quick way and that helped me under stand a lot more about how camshafts work with hands on experiences

I've purchased a custom roller from Herbert that was ground 8 degrees retarded, and I had a Mopar Performance timing gear with the timing dot on the wrong side.

What is the LSA?

Lobe separation angle (in degree's)

He stated that it was 113 on the cam card and he is getting 111 when checking it with a degree wheel, hopefully he is checking it on the intake lobe and not the exhaust lobe

Actually he just said the cam card says to install the cam at 113 which I am guessing is the cam manufactors recommended installed centerine and not the LSA. On my flat tappet cam the LSA is 110 but the recommended installed centerline is 106. Ron

As the timing chain starts to wear/stretch, it will retard the cam a bit anyway.

Yes I am using the #1 INTAKE lobe to check. Intake center line recommendation is 113. Lobe separation is 115.
Last year when I installed this NEW cam I had to install it straight up to get 113. That was with a used timing chain from my previous cam.
I now have a NEW Roll master timing chain and installing it straight up I am now getting 111. I am thinking this may actually work a little better advancing it since my car is heavy(3550). Cam is a Comp 800 intake 766 exhaust roller in a 572 Indy motor.
Mike

It may or may not make any difference. Very application specific.

I don't think there is anything wrong with trying it 4 degrees advanced and seeing how it compares to the 2 degree advanced that you have been running. Are you sure you have enough valve to piston clearance to move the centerline? That is the only thing I'd worry about. If you have enough clearance to play with the centerline then go ahead and try it at a few different spots and see how the engine responds.

This^^^. If you advance it too much the intake valve will crash.

LOL "This^^^. If you advance it too much the intake valve will crash."

Have already verified plenty of clearance at max valve lift.

Not expecting much just leaving it at 2 advanced. Will not know for awhile though. Snowing here right now in Penna.
This is a good example of always checking cam timing though.
Mike

The intake valve is usually closest to the piston at around 10ATDC during the intake opening.

With the intake valve at full lift, the crank is at around 113ATDC(in your case ...... which has the piston about 3" away).

On a different train of thought...... What are the lobe numbers for that cam?

I'm trying to think of a combo like yours where I'd feel a 115lsa would be the preferred choice.......

Only thing I can think of is that they spread the lobes out because the cam has so much duration. 115 seems like a lot of spread but it is a 572 so if the 050 duration is in the 290 or 300 range that could explain it.

Gross valve lift intake 800 exhaust 766
duration@ 050 283 294
lobe separation 115.0
lobe lift .4710 intake .4510 exhaust
Mike

Mike, it's a comp cam right?

What are the lobe numbers?(the grind number)

Edit: probably 1817/1964.

What heads are you running?

Koffels like cam ground on 111 to 115 LSA, depending on which heads, C.I. and so on
My thinking is the wider the LSA on a all out drag race motor the higher the peak HP RPM will be, am I correct or not on this or not

Dwayne it is a Comp Cam. Grind # "BMBB 5R" ,part # 23-000-9.
Running 572-13 CNC heads.
Mike

If you look at the intake opening and closing points, and the exhaust closing point, they will be the same as a cam with
283 int 283 ex, and an lsa of 112.25. A cam with more exhaust duration needs a wider lsa to keep the same number of overlap degrees. With 11 degrees more exhaust duration, you have to widen the lsa by one fourth the difference in intake and exhaust duration to keep the same overlap degrees.
So i look at cams as being straight up if i do that math and set them with the new number. I am not sure where i would run the cam in your motor, but i have a 285 / 296 /114 lsa cam and i run it at 110 installed.
That would be 1.25 degrees advanced IMHO.
The exhaust opening point is earlier on a cam with more exhaust duration because high compression motors can tolerate it. Much more of the power production is already done sooner when you have 15 to 1 compression.

Well.......”IMO”(which is all it is without testing the theory).......there is likely some power/performance left of the table with that cam, in that combo......especially in a heavy car........and even more so if it’s a footbrake combo.

How much power? Who knows.
Maybe not even enough to justify a change.......but I’m pretty confident there’s a cam that would be better in that motor and car combo.

I just freshened up a set of 572-13’s that came off a 588 from a well known mopar engine builder that had already made pretty big numbers on the dyno. However the owner wasn’t thrilled with a few aspects of the way the car performed, so I made a few changes to the heads and he had a different cam done for the motor........and we’ll have to see how those changes pan out.

Dwayne, care to share your thoughts on what you think the changes, both heads and cam, should be ?

I have no idea how the OP's heads are prepped, or what they flow.......so I can't really speak to what I would or wouldn't do with his particular heads.

What I can say is that "generally" the 572-13's are a bit weak on intake flow(compared to something like a B1) til they get to about .450-.500 lift.
The ex side of the head is usually pretty good.

So, "I" would probably run a more aggressive intake lobe than what I think his cam uses, run less split, and a tighter lsa.

But, both the previous cam and current cam have been speced by builders who have more experience with that type of build than I do.

I feel like it's pretty hard to really evaluate two different cams without a trip to the dyno.
Sure, ultimately it's how the car runs that really matters...... But there are also way more potential things in the car that aren't working as they should, that could hold back the performance and not allow a better piece to shine.

As I said previously....... I doubt whatever I might have come up with would be much different in terms of power.
It's not like the current cam is out to lunch...... Any change would be more like a tweak.

If you look at the cam tests Andy has done with the 470's, you can see its pretty difficult to make a big change in power by changing the cam, if the current one is close.

Here's how the cnc 385 572-13's I had here compared to a couple other heads through .600 lift.
All tested on a 4.500 bore:
Intake port only-

A- cnc 385 2.350 valve
B- cnc 345 2.250 valve
C- original b1, mild port, 2.300 valve

Lift------A----B----C
.100---58.9/ 74.8/ 73.7
.200--121.2/157.6/148:8
.300--188.4/218.4/219.6
.400--253.1/277.5/284.2
.500--312.2/329.8/338.4
.600--370.0/360.5/375.6