How to time my engine, with a cam degreed at 1.25 degrees advanced??

[OldBlueDually]

Gent's, after searching this site, then searching the innerweb I am still not coming up with an answer of what to do here. This truck & engine build has been a lot of "new things" I have never done before.

So, I want to know: How do I properly time my engine, with my cam degreed at 1.25 degrees advanced? (When I degreed the cam, the closest I could get is 1.25 advanced).

I have the stock harmonic balancer on the engine, and the stock stamped metal plate with the "0" on it and tic marks to either side of it. Do I try to put it at 0, or....???

The closer to 0 I got with the timing light, the worse the engine ran, so timed it by ear for now.

Thanks for the advice & input guys!

Here is the camshaft information;

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[Craig Nedrow]

Lots of questions. Is this a recent cam change? If it is, when you changed the cam, did you find TDC (top dead center)? The cam would need to be installed @TDC to line up the timing gear marks. If you were 1.25 degrees off, (it would still run) then it is not off a tooth, but sounds like your pointer is not lining up with the zero on it with the line on the Harmonic balancer. If, for example, this is a 9to1 compression engine running 87 octane you could probably run a total advance of 30-40 degrees. So if it is advanced 1.25 degrees, just retard it 1.5 degrees from say 35 degrees where you thin it should be, so 33.75. Having run lots of SB and BB, whatever gas you choose to run will dictate total timing advance, which includes the Dist advance, so not at idle. Start the engine, warm and increase the rpm using a timing light and watch the mark on the harmonic balancer (HB) move forward until an increase in rpm does not advance the HB mark. The mark will be way off of the tab on the timing cover, so if you have an adj timing, turn the advance nob until the HB lines up with 0, if it is 35 deg, that means you are running 35 degrees TOTAL advance, (static advance where you set the dist, + the dist advance. My 454 runs 38 deg total advance on 87 just dandy as the compression is right at 8 to 1. For me, I use a degree wheel to install a cam, @ TDC. Rule of thumb, retarding gives more torque for towing, advancing more power in the upper rpm range. To much advance and it will damage the pistons through detonation. Good luck!

 

[OldBlueDually]

@Craig Nedrow sorry, I should have added more details. I am using a 1969 Olds 455, so bigger compression (9:1 to 10:1) engine with C heads. I installed a new Comp Cams Thumpr series camshaft. I also installed a new Cloyes brand timing gear set with 9 keyways in the lower gear to get it degreed properly.

Prior to degreeing the cam, I made a dead-stop for cylinder #1 (by using a 1x1 piece of steel bolted to deck, and a round head carriage bolt about 3/4" into the cylinder to bump the piston against). I then attached my degree wheel, rotated engine forward, and backward to get "true" TDC. I then used the degree wheel, and a dial indicator to get the cam close to the 102 degree intake centerline (seen on above image of cam specs). I was told to "get it degreed within 2 degrees advance/retarded of 102 centerline" by Comp Cams.

I was able to get it degreed to 1.25 degrees advanced of their 102 centerline. I left it at that. (had I retarded it I would go beyond the 2 degrees of 102 centerline they recommended).

So what you are saying is use one of those dial type timing lights, set it to around 30-40 degrees and check the timing? So I should search around and find out what total timing should be with this 455, then using that dial timing light try to get it set is what you are saying? I think I get it...I think. I was not doing a search for total timing on a 455.....guess what I am going to do now that you have said the above!

This is ALL new to me! Previous engines I would "throw the cam & gears in, time to 0, and go"....

 

[Craig Nedrow]

Either that, or buy a tape for the HB with the timing marks on it. Use clear paine to keep it on.

 

[Blue Ox]

I think my 455 was base timed to 4° BTDC with the vacuum advance disconnected. Zero sounds a tad on the low side. Never did total advance since it was just stock and set to factory spec.

 

[OldBlueDually]

@Blue Ox and @Craig Nedrow thank you again for the help on this!!!! Now, had I known even just a little bit of what was posted above here, I would have known a bit more of what to search for to find some answers. As I stated, I am used to stuff just being stock....

Looks like these BB Olds engines like to have a total advance of 34 to 36 degrees around 2,800 RPM (16 initial, 20 in distributor), but they said to check total first, then see what initial is at. I did see on an Oldsmobile forum people mentioning using the timing tape like you posted a picture of, or use a dial back timing light.

I should probably purchase my own dial back timing light anyhow, I would rather not be taking stuff apart to put tape on the harmonic balancer. Not to mention, this will not be the last engine I build, or tune in this manner anyhow (and I like cool tools anyhow!). I have a Flathead V8 build coming up at some point, and will be helping my brother degree the cam in his 56 Pontiac Chieftain engine so the dial back light would be handy.

Now I am thankful I did not hurt anything the other day when I took it down the road & stood on it, probably not the best idea without being sure timing was correct....oops.

I appreciate your help on this!!

 

[QBuff02]

Camshaft timing has nothing to do with ignition timing. One is controlling the valve train events and the other is controlling the ignition events. I find most times I set the timing by feel and ear and then verify it with a timing light afterwards. My 454 didn't even have a timing pointer on it before I rebuilt it and it fired right up no matter the temp or time of day. For your engine I would try with the timing for starters around 10-16BTDC with the advance plugged off and go from there.

 

[OldBlueDually]

@QBuff02 I left the vacuum advance disconnected this entire time, and still have it disconnected. Are you saying I should try to achieve initial timing of 10-16, then rev it up to 2,800 and check the rest? I assume you made your first statement of camshaft timing/ignition timing due to my thread topic? I actually did not know what to say for this thread title, but I thought because my cam was degreed at 1.25 it may have made a difference for regular timing of the engine.

It's unreal the amount I have now learned just in this thread alone, and now searching for the correct information! I like to hear your guy's opinion and gain some of your knowledge of this stuff. I am no stranger to stock engine stuff, but anything with modifications I need some guidance here so I am thankful you guys are chiming in!!

With the help of you guys, I should have this baby running awesome when I am done!

 

[QBuff02]

@QBuff02 I left the vacuum advance disconnected this entire time, and still have it disconnected. Are you saying I should try to achieve initial timing of 10-16, then rev it up to 2,800 and check the rest? I assume you made your first statement of camshaft timing/ignition timing due to my thread topic? I actually did not know what to say for this thread title, but I thought because my cam was degreed at 1.25 it may have made a difference for regular timing of the engine.

It's unreal the amount I have now learned just in this thread alone, and now searching for the correct information! I like to hear your guy's opinion and gain some of your knowledge of this stuff. I am no stranger to stock engine stuff, but anything with modifications I need some guidance here so I am thankful you guys are chiming in!!

With the help of you guys, I should have this baby running awesome when I am done!

Yes, set the initial timing with the vacuum advance disconnected and then hook the advance back up and check the curve to make sure your total timing is all in by your target rpm. After I redid my engine, the initial is at 18BTDC and all in by 2,600rpm. I put the lightest springs on the advance in my distributor when I dialed in the timing and that's where my engine is the most happy. Every engine will be a little different. Performance upgrades and engine modifications will cause slight changes to the timing requirements of a given engine. A factory stock engine for example might call for 8 btdc but a cam and intake and headers and higher compression might be happiest at 12-14 or even more. If it starts up good cold and then starts up good once there's a little heat soak in the engine i'd say you're really close with the timing. If for example after you've set the timing and think its good but then shut it off and let it sit for a few minutes and it's hard to start or sounds like it might be laboring to crank, your timing might be just a few degrees too much advanced. Back the distributor off a few degrees and you'll be just about spot on.

 

[Ricko1966]

Initial is irrelevant total is what you are worried about I know some body on here already told you how to do it.Set total with vacuum advance Disconnected and plugged. Your vacuum advance comes into play for cruising mpg and at idle connect vacuum advance to manifold vacuum.
Total should be around 36.To really dial it in start with total of 32 check top speed at the end of 2nd gear.Advance it 2 degrees try again,advance it 2 degrees try again when top speed in Second drops or you encounter pinging bring it back 2 degrees. The reason you are using speed instead of time and the reason you are checking in second gear that compensates for wheel spin.

 

[OldBlueDually]

Initial is irrelevant total is what you are worried about I know some body on here already told you how to do it.Set total with vacuum advance Disconnected and plugged. Your vacuum advance comes into play for cruising mpg and at idle connect vacuum advance to manifold vacuum.
Total should be around 36.To really dial it in start with total of 32 check top speed at the end of 2nd gear.Advance it 2 degrees try again,advance it 2 degrees try again when top speed in Second drops or you encounter pinging bring it back 2 degrees. The reason you are using speed instead of time and the reason you are checking in second gear that compensates for wheel spin.

Thanks for that info Ricko. I have actually not timed it yet, I took another few steps back once again on it and have the valve-train taken apart right now to put in adjustable rockers & heavier pushrods. Once I get it back together I will be re-firing it and then start to tinker with the timing on it.