[1978 T/A]

I degreed the cam and lining up dot to zero I came up with a 109 ICL. Advanced it 2 degrees to end up with 107 ICL. Using a JP timing set. The cam card recommended a 108 ICL but I couldn't hit that by simply turning the crank sprocket. Am I missing something?

Do any of you guys have similar experience and what did your installed ICL end up at?

Karl

[old66tiger]

It is a crap shoot where the timing will come in at with these timing sets. There are 1 degree offset keys available to get you spot on.

[Bill Eveland]

A one degree offset camshaft key will move the crank 2 degrees. If you can find a 1 degree long crankshaft key is needed. I went thru this on my 455 with my cam. I bought a 9 keyway set thinking I would be good. I still had to buy an offset 1 degree cam key and move the sprockets around till I hit my number.

[jonmachota78]

Dave told me 106 - 108 with a new timing set.
When I went through this I scoured the earth looking for a 1 deg offset cam key couldn't find one anywhere..... I ended up taking a 4 degree key weld and filed it down to get the offset I needed...

If you got 107 I'd run it!

[PunchT37]

I ended up at 107.5, 4 times, with Road Paver. Good enough for me. It came in at 111 straight up. Rollmaster chain. It`ll stretch out to 108 soon enough.

[Skip Fix]

I doubt you can fell the difference of 1 degree, probably even 2 degrees in most motors.

We made a 1 degree key once using a thicker one and a file on each side.

[Cliff R]

What size engine, what heads, and what compression ratio?

The ICL is more important than you think, and we NEVER advance them simply to account for timing chain stretch at some point.

Here's a case in point. We prepared a set of KRE heads for a customer, and supplied a custom HR camshaft for him. The CR of his 455 was right at 10.5 to 1, and his cam came in right at 109ICL. I told him to leave it there.

He drove the car and raced it for over 2 years. It ran high 11's up near 4000 lbs race weight, and managed pump fuel fine on the street. He thought the engine was just a tad "lazy" right off idle for "normal" driving, and used a bit more fuel than he liked, so he decided to advance the cam 2 degrees.

He said that this move made a very slight improvement right off idle, and in idle quality, but really didn't help anything else. He also mentioned that he could hear some audible detonation in the mid-range at heavy/full throttle........In less than a week he busted the ring lands out of two pistons!

What he did was take a very well optimized set-up with proven parts and try to push the limits a bit with it. These engines are pretty sensitive to the intake closing point, especially if you are running optimum compression for making good power on pump fuel. it is ALWAYS best to have the cam retarded slightly vs advancing it.

When I'm degreeing those cams here, many come in around 108.5 to 109.5 ICL, I leave them alone....FWIW......Cliff

[tpssonic]

Cliff,

Was that block 0-decked?

[Cliff R]

Yes, EXACTLY zero decked, and ran flawlessly for several years. The customer was trying to super-fine tune it as it was his "daily driver" at that time. So he bought into the BS that advancing the cam makes the engine more responsive at lower rpms, and improves efficiency, more torque, etc. (He'd have been better off to fine tune the vacuum advance and APT instead, but that didn't happen.)

That's a great theory, but my own testing with moving cams all over the place doesn't follow that logic. The 455 is a HUGE engine, with too much stroke and relatively long rods in it. Piston speed is super-fast, and they are very sensitive to the intake closing point, LSA, and actual seat timing. With tiny heads supporting them (by modern standards) they quickly pinch off a LOT of upper mid-range and top end charge advancing the cams in them. They also very quickly become octane sensitive trying to improve cylinder filling at low rpms.

My own engine has SD"s Old Faithful cam I it, idles nearly smooth at 750rpms, tach barely moves when placed in gear, and ICL is 109.5 degrees. SCR is also 11 to 1, and it EASILY manages 87 octane fuel on a daily basis. I put better fuel in it on my way to the track, but it actually slows the car down about .04-.05, but I do sleep better at night.....Cliff

Here's a clip from Norwalk, with initial timing at 6 degrees (26 total timing), and shifting at 5000rpm's to stay roll bar legal. Notice that it still idles smooth in and out of gear at 750rpm's, and I'm NOT using MVA to run the timing clear off the scale, ported vacuum to the advance instead.....

http://www.youtube.com/watch?v=6zVdoLR-VzM

[Skip Fix]

I think some motors are much more sensitive to cam degree settings. I still doubt a 1-2 degree setting will stay that exactly as the timning chain stretches with time, yet most motors do not drop off much with time due to that.

Bet if you degree most motors with a fair amount of runs they are different by a few degrees from initial build.

My RAIV 400 I retarded the UD 304/312 HFT to get safer recommended V-P by 8 degrees from what UD recommended(they always liked them advanced a lot). Decided to get bold and chance the V-P and advanced it the 8 degrees from where it was-ran to the .01 sec the same time and same mph.

Jim Hand did many runs changing IC to find the best , but most did not make a dramatic change at once.

[Tim Corcoran]

Cliff, your total timing is 26 degrees? Is that a typo?

[grandville455]

I only run 28 total in my setup, going to try 31 this week even tho its going to be 92!

[ta man]

I'm at 31 with mine haven't touched the total in two years at a slightly lower compression than Cliff and Grandville..I may play with it a bit next time..the combo just keeps getting faster...goal is to run 120 in the fall..but will need tire slip to stay above 11.50..
What is your cranking compression Cliff and Darby?

[Cliff R]

"Cliff, your total timing is 26 degrees? Is that a typo?"

No, that's how I tune it for 1/4 mile racing.

With the timing set at 30 degrees and shifting at 5500-5600rpm's the car runs 11.30's in hot/humid conditions.

To keep folks happy at Norwalk I retard the timing, add some weight, and shift at 5000rpms......Cliff

[grandville455]

Originally Posted by ta man

I'm at 31 with mine haven't touched the total in two years at a slightly lower compression than Cliff and Grandville..I may play with it a bit next time..the combo just keeps getting faster...goal is to run 120 in the fall..but will need tire slip to stay above 11.50..
What is your cranking compression Cliff and Darby?

Last time i checked it was right after i put this motor in this car with the hyd
lifters and it was 175-180.Havent checked with the solid roller's..Thats with the road paver.

[Cliff R]

Cranking compression on my engine last time I checked it was 198-200psi for all cylinders.

Static compression is 10.99 to 1, and using the Old Faithful HR camshaft, ICL is 109.5 degrees.......Cliff

[1978 T/A]

4.165 bore, 4.21 stroke, zero deck. Heads are KRE's from SD and say 72cc on the invoice but flow sheet it says 70-71? Puts my SCR arouns 10.7.

I am using the old chain off the engine that previously detonated. So the chain has about 3k on it.

Where can I go about in finding an offset key?

[72LuxuryLeMansLa.]

Originally Posted by 1978 T/A

4.165 bore, 4.21 stroke, zero deck. Heads are KRE's from SD and say 72cc on the invoice but flow sheet it says 70-71? Puts my SCR arouns 10.7.

I am using the old chain off the engine that previously detonated. So the chain has about 3k on it.

Where can I go about in finding an offset key?

http://www.moparperformanceonline.co...haft-keys.aspx

Karl

[1978 T/A]

Seeing is how the chain has some miles on it and has probably already stretched some am I better backing it off to 109 or get offset keys to hit 108?

[72LuxuryLeMansLa.]

Originally Posted by 1978 T/A

Seeing is how the chain has some miles on it and has probably already stretched some am I better backing it off to 109 or get offset keys to hit 108?

I am no expert but if Dave said 108, install it at 108. I doubt the chain will stretch more and would replace it if it did.

Karl