Doing cam timing

Bottom end 100%, just installed block and head. Before installing camshafts I found TDC with degree wheel and piston stop. It came out about 4 degrees off from the OEM timing mark. Is that normal?

I prefer to use a dial indicator to a piston stop.
The 4 degrees could be from a stack up of tolerances.
Material remove from the block or head on an over head cam engine will retard cam timing.


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You need the rubber chain guide in valve cover temporary mounted to do
the cam timing right!!!

Nebr_Rex wrote: I prefer to use a dial indicator to a piston stop.
The 4 degrees could be from a stack up of tolerances.
Material remove from the block or head on an over head cam engine will retard cam timing.


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Possible. I took about .006" of both the block and head. Wondering if I should apply the difference when setting ignition timing. Like have the degree wheel at TDC when I remove it, and scribe the ignition mark accordingly.

Scirocco wrote: You need the rubber chain guide in valve cover temporary mounted to do
the cam timing right!!!

Yeah. I cut a cover in half. You can see it on the bench behind the engine with all the junk. That's tomorrows project. Just installed the cams today. Pain in the ass getting the marks and cam position safe for install.

I had the sprockets counter-bored to center the chain in the guides, and had to reverse them , and they sent me 2 intake sprockets. Long story, but every aftermarket cam sold for a J engine is actually a KZ cam, and they don't fit perfect. Blew me away when I saw how off-center the sprockets were. And if you look closely several lobes are off-center with the buckets. And if you have a tach cable, it won't work. The drive gear on the exhaust cam isn't even close to lining up with the J engine driven gear.

VTEC wrote: Bottom end 100%, just installed block and head. Before installing camshafts I found TDC with degree wheel and piston stop. It came out about 4 degrees off from the OEM timing mark. Is that normal?

I have found the TDC mark on the ign case to be very accurate and have never had to alter it for ignition purposes .
If done correctly you will get the cam timing correct in relation to the crank using the disc and the TDC mark on the case is good enough for ignition settings.
Even using the best strobe you will never get the ignition timing accurate to the exact degree and my Orient express turbo drag bike runs perfect using the factory mark.
I presume you used the stop on the piston closest to the degree wheel ( number 4 ).

zed1015 wrote:

VTEC wrote: Bottom end 100%, just installed block and head. Before installing camshafts I found TDC with degree wheel and piston stop. It came out about 4 degrees off from the OEM timing mark. Is that normal?

I have found the TDC mark on the ign case to be very accurate and have never had to alter it for ignition purposes .
If done correctly you will get the cam timing correct in relation to the crank using the disc and the TDC mark on the case is good enough for ignition settings.
Even using the best strobe you will never get the ignition timing accurate to the exact degree and my Orient express turbo drag bike runs perfect using the factory mark.
I presume you used the stop on the piston closest to the degree wheel ( number 4 ).

Hey Zed, So have you seen the OEM TDC marks be that far off compared to piston stop/degree wheel when doing cam timing. Actually I have a Dyna ignition so the rotating mark isn't OEM.

Nebr_Rex suggested metal off the block and head decks may be the reason. But now that I think about it that would affect cam timing, but not TDC.

VTEC wrote: Hey Zed, So have you seen the OEM TDC marks be that far off compared to piston stop/degree wheel when doing cam timing. Actually I have a Dyna ignition so the rotating mark isn't OEM.
Nebr_Rex suggested metal off the block and head decks may be the reason. But now that I think about it that would affect cam timing, but not TDC.

I've found the oem mark to be very consistent with the result from the degree wheel and as already stated even if it is off a fraction it's not what you are degreeing off and is good enough for ignition.
Even with the Dyna S fitted it still uses the original advancer mark.
The only thing that would affect the TDC mark would be an out of true crank.
Material removed from the head or block etc won't change the crank orientation.
I would get on and degree the cams then once done go back and double check the accuracy of true TDC against the case marks.
If it is still found to be off and it bothers you, you could then scribe new tdc and advance marks on the rotor for doing the dynamic timing but i'd bet it's so close you couldn't get the ign timing any better than it has been previously.

zed1015 wrote:

VTEC wrote: Hey Zed, So have you seen the OEM TDC marks be that far off compared to piston stop/degree wheel when doing cam timing. Actually I have a Dyna ignition so the rotating mark isn't OEM.
Nebr_Rex suggested metal off the block and head decks may be the reason. But now that I think about it that would affect cam timing, but not TDC.

I've found the oem mark to be very consistent with the result from the degree wheel and as already stated even if it is off a fraction it's not what you are degreeing off and is good enough for ignition.
Even with the Dyna S fitted it still uses the original advancer mark.
The only thing that would affect the TDC mark would be an out of true crank.
Material removed from the head or block etc won't change the crank orientation.
I would get on and degree the cams then once done go back and double check the accuracy of true TDC against the case marks.
If it is still found to be off and it bothers you, you could then scribe new tdc and advance marks on the rotor for doing the dynamic timing but i'd bet it's so close you couldn't get the ign timing any better than it has been previously.

Wondering if the accuracy of the big wheel if making the difference stand out. I'd like to go back and double check TDC. I did use the stop on #1, but I guess it's best at #4 because that's the cylinder I'll be timing.

I know it's dangerous using the stop with the cams installed. But I think it will be safe if I go like 60 degrees ATDC, install stop, raise piston to the stop (about 47 degrees), remove stop, and repeat on the other side. I don't think there will be any valve interference with the stop going that route.

Some dial gauges are very helpful in your situation to set / confirm TDC on all
cylinder to check for a twisted crankshaft.
A must have for a accurate cam degreeing .

VTEC wrote:
Wondering if the accuracy of the big wheel if making the difference stand out. I'd like to go back and double check TDC. I did use the stop on #1, but I guess it's best at #4 because that's the cylinder I'll be timing.

I know it's dangerous using the stop with the cams installed. But I think it will be safe if I go like 60 degrees ATDC, install stop, raise piston to the stop (about 47 degrees), remove stop, and repeat on the other side. I don't think there will be any valve interference with the stop going that route.

You will never get a consistent result by removing and re-installing the stop.
4 degrees is nothing on piston travel when approaching BDC or TDC and a fraction of a turn difference when tightening the stop will easily throw off your readings by several degrees .
You need a stop with a thin enough nose to clear the valves, it only needs to stop the piston just short of TDC.
Fit the stop on number 4 as this eliminates any possible stack up of minute tolerances across the crank in the rod bearings etc.
Rotate the crank both ways without moving the stop to establish TDC for your degree pointer and leave it at that.
Forget the discrepancy with the case mark .

zed1015 wrote:

VTEC wrote:
Wondering if the accuracy of the big wheel if making the difference stand out. I'd like to go back and double check TDC. I did use the stop on #1, but I guess it's best at #4 because that's the cylinder I'll be timing.

I know it's dangerous using the stop with the cams installed. But I think it will be safe if I go like 60 degrees ATDC, install stop, raise piston to the stop (about 47 degrees), remove stop, and repeat on the other side. I don't think there will be any valve interference with the stop going that route.

You will never get a consistent result by removing and re-installing the stop.
4 degrees is nothing on piston travel when approaching BDC or TDC and a fraction of a turn difference when tightening the stop will easily throw off your readings by several degrees .
You need a stop with a thin enough nose to clear the valves, it only needs to stop the piston just short of TDC.
Fit the stop on number 4 as this eliminates any possible stack up of minute tolerances across the crank in the rod bearings etc.
Rotate the crank both ways without moving the stop to establish TDC for your degree pointer and leave it at that.
Forget the discrepancy with the case mark .

I went ahead and did the method I mentioned on #4 and it was still TDC like #1. 47 ATDC/47BTDC. I'm confident the crank is true, Stan Gardner did it for me. And I think using the same stop, same hole, same torque gave me an accurate reading even though I removed it. When tightening the stop by hand it comes to an abrupt stop when it makes contact with the head. Like no variance at all between installs. Super scared about hitting a valve. I know at full lift they extend into the lane of the spark plug hole.

Came out with a cool method for degreeing. Setup a web cam at the degree wheel so I can watch up close on my lap top while turning the crank from the other side.

Next is setting up the dial indicator. I think I'm gonna borrow the one from work with the flexible locking arm, as opposed to making a plate to seat my magnetic gauge. The one at work has a longer pin too.