Timing pointer off TDC with light

[FirstMach1]

Ok so without giving you all the backstory of how I screwed things up or why….here it is.

While this is not my Mustang engine, it is a universal engine question that should apply anywhere. It happens to be a '78 Chevy 350.

1. I have verified that the timing pointer on the balancer is indicating TDC when the #1 cylinder is at TDC on compression. I think I need to reverify this but 90% sure I'm good on this.

2. The dizzy is pointing to the #1 wire at the same time.

3. The car is running very good again (finally) but the problem that got me all crossed up is still there.

4. The problem is that when I use the timing light with the #1 wire, the pointer on the balancer is 15 to 20 degrees AFTER the actual TDC tab. Even though when stopped it all lines up. Because of this I am unable to correctly time the engine with a brand new digital light.

I have the light set at 0 for now.

What would be the proper method to get the tab and pointer lined up with the timing light so I can correctly adjust timing?

I am new to timing also so please offer the most obvious possibilities that I could easily have overlooked. This makes no sense at all to me.

Bad plug wires?

Timing chain out of whack?

Thanks for any thoughts on this.

 

[sicndhed]

SBCs had a change in the balancer/pointer relationship. The miss-matched parts will all bolt up an look fine but you will not get a true reading. If you use a screw in piston stop you can verify the accuracy of the TDC mark pretty easily. Also it is common for old Chevy balancers to slip as the rubber ages. This will make it look like the timing is late.

One last easy thing, Chevy # 1 is front of driver's side.

 

[FirstMach1]

Wow! Thanks for the quick reply.

SBCs?

Didn't know there was rubber in there. I've never been into a timing chain or balancer area. Shouldn't be a problem for me to get in there though. What rubber and can it be replaced and fixed if that's the issue?

 

[sicndhed]

The outer balancer ring has rubber between it and the inner portion where the pulleys attach.

If it slipped you need a new balancer (some aftermarket units can be rebuild but not OEM).

 

[FirstMach1]

The outer balancer ring has rubber between it and the inner portion where the pulleys attach.

If it slipped you need a new balancer (some aftermarket units can be rebuild but not OEM).

Ok thanks. That sounds like a high probability then for this issue. Big help tonight. I appreciate the input.

 

[sicndhed]

If I can help with Chebby questions I'd be happy to send my phone # if that's easier.

 

[jbojo]

I think that you need to verify that you are really at TDC when the timing mark is at 0*. As Sicndhed mentioned get a piston stop to ensure TDC.

 

[FirstMach1]

Thanks guys. I'm definitely gonna verify TDC with the right tools tomorrow.

sicndhed, thanks for the most generous offer of your time via phone. I just might take you up on that sometime. I will put you on my buddy list for now and email you in the future if that becomes needed. Most likely it will but I hate to bother folks unless I absolutely have to do so.

TDC verification tomorrow on the Vette and then off to play with my electrical on the Mustang. Too much fun!

 

[sicndhed]

It's not a problem. Sometimes it's just so much faster to talk through issues.

I wouldn't claim the SBC is the best engine but it is the engine that I know best

 

[barnett468]

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Are you using a chevy or a ford timing lite?

 

[jbojo]

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Are you using a chevy or a ford timing lite?

I use a candle with a slotted pin wheel

 

[FirstMach1]

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Are you using a chevy or a ford timing lite?

Gee whiz Wally, I hadn't thought of that. Gosh thanks.

 

[barnett468]

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Are you using a chevy or a ford timing lite?

Gee whiz Wally, I hadn't thought of that. Gosh thanks.

oh...thats ok beav.

by the way, mom said you can determine if the chain has enough play that it should be replaced also.

remove the distributor cap

turn the engine by hand cpounter clockwise asyou face it until the timing marks are on 0.

turn it the other way until the rotor just starts to move.

measure how far the damper rotated until the rotor moved.

if it moved around 3/4" or more, it is pretty worn.

this will also tell you approximately how many degrees your lite will be off due to the loose chain.

add this number of degrees to the timing you actually want then set it to that combined number also adding or subtracting how far the mark might be off from tdc.

.

 

[sicndhed]

It's a chebbie, the chains don't wear because once the nylon teeth fall off the gear there is no tension pulling on the chain.

 

[Don C]

Did you try rotating the distributor to see how engine runs when the timing light shows that you're showing 6° advance? You didn't say whether you have points or an electronic ignition. You need to check the relationship of the cam in the distributor to the points (if that's what you have) when your timing pointer is at zero. The rotor pointing at #1 doesn't determine timing, when your points open determines timing.

 

[barnett468]

It's a chebbie, the chains don't wear because once the nylon teeth fall off the gear there is no tension pulling on the chain.

Eliminating the teeth on the cam gear substantially reduces drag thereby substantially increasing horsepower.

When a timing chain jumps a tooth, it is called variable cam timing.

 

[c9zx]

Try a non-dialback old time timing light. The dial back lights are notorious for being "off". Just an easy thing to try. Chuck