Timing unrealistically out of range

[Surfdude]

Hi all,
Been lurking here and searching as I go along.
To the problem which I have found similar threads but no 'solutions'.

The truck:
1978 C10 Stepside with a 350/350 combo.
The engine was replaced at some point with a crate Goodwrench engine.
Because it is California, SMOG is required and no fudging.

It passed last year with no troubles.
No changes to the engine, no adjustments
Driven daily.
When last setup, for smog by the way:
The timing was set @ 8 degrees BTDC with vacuum removed from distributor and vacuum line plugged.

I go in for check and the tailpipe numbers are great:
HC (PPM) Max 324 Measured 128
CO (%)   Max 3.80 Measured 0.05
NO (PPM) Max 2125 Measured 833

However, I failed due to timing being 63 degrees BTDC.
They grabbed a couple different lights trying to figure that out as the truck starts right up with a touch of the key.
I checked the balancer and it was correct.
I changed it anyway just because I was out of ideas.

The plugs are a nice tan color and with the vacuum advance plugged the engine sits about 20" of vacuum.
When I hook up the vacuum advance advance the gauge drops to around 12".
I realize that is a bit low but the timing is set with the vacuum advance disabled and plugged.
In any case, the engine shouldn't run at 63 BDTC, certainly not as well as it does.

I am going to try to setup a different timing mark and see if I can get them to buy that off, but I am doubtful.
I checked that the distributor mechanical advance is not stuck, it is fine.

Ideas?

Thanks in advance.

[SILV]

Maybe your balancers outer ring has spun. That's really the only thing I can think of. Mine has spun and it's about 50 degrees off. If I try to time it correctly where it's at it won't run at all. Maybe a backfire or two through the carb.

Edit: I missed where you said you replaced the balancer. I don't understand if the emissions test passed and it's running properly, why check timing.

[Irish_Alley]

i would start by verifying tdc
http://forum.73-87chevytrucks.com/smforum/index.php?topic=32085.0

[Surfdude]

Thank you for the replies.
I changed the harmonic balancer mostly because I couldn't think of anything else.
I bumped the engine around with #1 spark plug out until my thumb was pushed off.
TDC appeared close.  If it is really so far out that 63 degrees BDTC is needed I would think it would appear obvious.
The link you posted was one of the ones I have read looking for clues, but thank you for the replies.

I don't want to get started down a rabbit hole so I am making sure I am thinking this through correctly.
The distributor timing is the relation between the crankshaft and the distributor gearing so if I jumped a cam chain there would be different problems.
And again, things were set at 8 degrees last year and I have changed nothing.
I am kicking myself for not pulling the cam cover when I had the balancer off, but I was being single-minded about things and really thinking that if I jumped a tooth that I would have been having problems such as back-firing, pinging, etc. 

63 degrees, one complete piston off is 45 so that would make ~1 1/2 off in the firing order?  I can't for the life of me even figure how it is running.
I cannot even see the timing mark at the moment when trying to setup the timing and advancing it until the distributor is at the stop yields about 16 degrees BTDC and really crappy running.

BTW, the title is what the smog shop wrote as a failure reason. 

Thanks again.

[rich weyand]

No, the crank goes around twice every time around the firing order, so one piston is 90*.

Vacuum advance should be on the order of 15*, so you should read 23* at idle when set for 8* BTDC base timing.

What vacuum advance can is on it?  (Numbers are stamped on the metal tang visible between the vac can and the distributor cap.)

[VileZambonie]

Did you verify they had the inductive clamp on #1 cylinder? How were they checking the timing? At idle with vacuum advance plugged?

[Surfdude]

Rich,
I am not sure I am looking at the spot I understood you were asking about.  There is no number stamped on the vacuum tab for the distributor.  Picture enclosed.

Yes, timing checked with distributor vacuum off and plugged.

Looking at how all this is lined up, it looks like I need to move the distributor since #1 is closer to the 5 o'clock position but...how did all of this move?

TIA

[rich weyand]

Well, if pix 2 and 3 were taken at the same crank position, then #1 is forward, which is right.  And the vac can comes off at the right angle, so that's right.

The vac can normally has a number on it, like this:
http://www.nastyz28.com/~copo/images/b28_va_can1.JPG

So that's not a stock vacuum advance canister.

But, you said the timing indications are off even though the vacuum was disconnected, so that's not it.

You didn't change the balancer or the timing tab?  You should know that there are three different tab locations and balancer wheels.  The crankshaft keyway at #1TDC is at 45 crankshaft degrees clockwise from straight up on all Chevy small blocks: call it 1:30 o'clock looking at the front of the engine. The three timing tab locations are 40* counterclockwise from the keyway (5* total off vertical, called 12:00), 10* counterclockwise (35* total off vertical, called 2:00, though it's more like 1:00 really), and 2* counterclockwise (about 43* off vertical, called 2:30, though it's more like 1:30 really).

If you have the wrong tab for the balancer, you could be off by 30* or 38* in your timing reading.

[Engineer]

63°? Woah!

You don't have a couple of your plug wires reversed do you? Like #s 2 & 1 switched at the cap? Just for giggles run your firing order if you haven't already. 1-8-4-3-6-5-7-2.

[roundhouse]

I'd just get the degree stickers for the crank pulley and fake it


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[gwcrim]

I'd just get the degree stickers for the crank

Nothing like a problem  solver!

[Surfdude]

Putting the degree stickers on the balancer is my last 'go to' solution, that seemed to be the way that this was solved every other time it is brought up on other boards.  My concern is the state is pretty finicky about the smog stuff.  They check that gas caps are in place and holding pressure. 

Pix #2 & #3 were taken at the same time.
I don't know any history of this engine.  Obviously at some point before it was parked for a couple decades, the engine was changed to the current Goodwrench engine.  The distributor is marked as an ACCEL "all 50 state legal" distributor.  It makes me wonder what they did to the previous engine that they couldn't even save the distributor.  The timing tab is the same one that was on it.  I saw that conversation on another board about timing tab location, where would I get a 'different' timing tab?

Engineer, I will check firing order again.  The truck runs smooth with nice acceleration.  It won't win any races except perhaps except bicycles but I don't drive it for that.  That is why I have a motorcycle.

One of the questions I hope to be able to answer is how did the timing move so much?  When the title was transferred, I had to smog the engine and while the numbers were not as good as they are now (due to sitting, I'll wager) the timing was at 8 degrees BDTC for it to pass.  The P.O. thought he could remove smog, but the car has to be pre-1975 in order to ignore smog in this state.     

I had to work out the vacuum lines and other issues that this board was invaluable in finding the information to get the ol' girl running.  After I set it all up, I haven't moved any settings.  This has just been a DD for picking up kids and teaching one of the kids to drive     Speaking of which gotta run to get them to their various sports.

I do appreciate all of the help, being able to think out loud does help such as remembering that I don't have a 2-stroke engine (thanks Rich).

[VileZambonie]

Do you have a timing light and have you verified their readings?

[Surfdude]

Do you have a timing light and have you verified their readings?

I have a basic timing light not one with regressive timing abilities.  I can say that the timing mark is not  currently visible at the tab.

I see that the distributor is at 6 o'clock position when currently at TDC. I can move the gearing so it is at the 5 position where # 1 is located to see if that helps although I don't see how it could jump teeth during normal driving.

If it fixes the immediate problem I can come back to the why, I suppose.


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[roundhouse]

Does it run OK ?

Only problem is with what the smog station thinks the timing is set at ?

If you actually had that kind of timing I don't think the engine would even run

If that's the only issue. I'd slap the sticker on and let them see what they want to see


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