Timing - 40 degrees

[twoseater]

Hi Steve - motor has definitely been played with at some point in time, however, the car is in great shape and has been well cared for. Haven't seen any shortcuts or signs that "Bubba" had worked on it.

However, what you say could very well be true - if it was would the car lack power? It idles fine when warmed up and is overall a good drivable car. What would the symptoms be?

 

[JohnZ]

Correct me if I'm wrong but doesn't an 8 fire every 90 deg? Gerry

Yes - that's correct.

 

[Hib Halverson]

Correct me if I'm wrong but doesn't an 8 fire every 90 deg?

"Chevyman for life" is correct.

8 cylinders.
Two rotations per firing impulse
Four firing impulses for crankshaft rotation
One cylinder fires every 90° deg.

 

[minifridge1138]

You are correct.
I was thinking camshaft rotation, not crankshaft rotation.

I hope I didn't confuse anyone too much.

Sorry.

 

[bradfordsvettes]

car would idle ok at the far advance pickup may be sluggish.If the timing were set to spec it may not run and would have no power .I did not check the other threads what if the balancer spun on the rubber cushion I have seen that before also Steve

 

[twoseater]

Update: I set it to TDC on the compression stroke and pulled the dist cap. It looked like it was on #8 but then turned the dist to retard it (What I'll call the "normal" position) and it was on #1.

There was discussion on Before or After. To clarify its 40 degrees Before (Edited: I had typed it as AFTER TDC). (Line on the balancer is ABOVE the 0 mark.)

I beleive the dist is correctly installed, wiring is in order. I will do a compression test on the cylinder to see what I'm getting there.

I am inclined to go with Steve's suggestion that its due to the aggresive CAM. However, thus far I have no negative effects - power is all there, acceleration is not a problem. I can chirp the tires in 3rd. I imagine there must be negative consequences though and the long term it can't be good.

I think I'll move on and time it at where it runs best and enjoy the rest of the summer driving it rather than working on it

 

[minifridge1138]

There was discussion on Before or After. To clarify its 40 degrees AFTER TDC. (Line on the balancer is ABOVE the 0 mark.)

Correct me if I'm wrong, but doesn't the crank spin clockwise?
If so, then if the line on the balancer is above the 0 mark, that is BEFORE top dead center.

40 degrees advance with the vacuum advance connected is a lot.

Do you have vacuum and centrifugal advance?

 

[geekinavette]

Correct me if I'm wrong, but doesn't the crank spin clockwise?
If so, then if the line on the balancer is above the 0 mark, that is BEFORE top dead center.

40 degrees advance with the vacuum advance connected is a lot.

Do you have vacuum and centrifugal advance?

If viewing from the driver's side (and what setup doesn't?)...yep that's BTDC.

When you found TDC did you make sure the balancer mark lines up with zero on the tab?

 

[twoseater]

Yeah, I had located TDC to make sure that wasn't why it was off. I used a TDC tool screwed into #1 and the timing mark was dead on zero.

It is vacuum advance (timed with the vacuum cable plugged).

I just lost all credibility it is BTDC. I read the A on the timing mark as After - now I looked and saw its A & R (Advanced/Retard). Duh...

 

[selracer]

timing 40deg

I have a 327 that I use in my oval track car that I set at 44 degrees. I know that sounds crazy but, I could not find any problems with cam, balancer or distributor everything lines up correctly! That being said after 8 races this season the I just broke a valve. I cannot figure out what happened. Everything looks good not pre-ignition problems…anyone have any ideas why I would need 44 degrees? I attempted to run 38 and I overheated bad…go figure.

 

[JohnZ]

I have a 327 that I use in my oval track car that I set at 44 degrees. I know that sounds crazy but, I could not find any problems with cam, balancer or distributor everything lines up correctly! That being said after 8 races this season the I just broke a valve. I cannot figure out what happened. Everything looks good not pre-ignition problems…anyone have any ideas why I would need 44 degrees? I attempted to run 38 and I overheated bad…go figure.

If you had initial base timing at 44 degrees, it wouldn't even start, much less run. Sounds like you have the timing light on the #8 wire instead of the #1 wire, and are actually set at 1* AFTER top dead center on #1; if you then backed off the "indicated" 44* to 38*, you're actually at 7* AFTER top dead center, which would definitely cause it to overheat.

 

[Kid_Again]

OK, time for an anecdote and confession.

First the confession. I screwed up even the basics about TDC and installed the distributor off by one tooth.

But the full story is that I put a new (old) tripower manifold on my '66 zz440, new carbs, the whole nine yards. Absolutely had #1 at TDC. Put the distributor in and went to fire it up. Took a lot of fiddling with the distributor location but I finally got it started. It seemd awfully advanced to me when I fired it up but I figured what the heck, it's running OK. I never got back to it because I had other things to do.

So, one day I decided to put the light on the balancer because I knew it ran fine but was incorrectly set up. I was certain that I was on wire #1 and hit the light button. WTF is the line? Can't even see it. Note this is a factory timing tab and balancer on a new GM crate motor.

Since the light was a dial back, I started walking back (advancing) the numbers. I turned and turned and turned and finally got the line to "Zero" at 52* advance. Yup, 52* at base.

Whether that was accurate or not, I pulled the distributor cap and when #1 was at TDC (Boy, did I get good at doing that), the rotor cap was actually pointing half way between two posts. So if it wasn't 52*, it wasn't far off. Nobody believes the engine would have started.

She's really much happier now at 12* BTDC.

Eh, one tooth here, one tooth there, whatever. :W

 

[henny496]

The rubber on the balancer can let go and the timing marks may not be in the right spot anymore(ring slipped) It can be dangerous on a car that you are buzzing up a bit as the ring can let go and go through your hood
I had a engine that had the wrong timing tag on it(different spot) and you could not set it up by the marks

 

[magicv8]

Did you remove/replace the distributor drive gear while the cam was being changed?

You may have it backward on the shaft........