would anyone know where i could purchase the timing mark pointer to go on the bottom of my 454 the top one is impossible to get to or could it be made?

You might have to get one out of a junkyard... I don't see where they sell an aftermarket one for the oil pan.

This is the style Richard is talking about - you would set the timing using cylinder #8 if your harmonic balancer only has one notch in it.

You can also use cylinder #5 if it is easier to get to (same side of engine as the marks.) That is the same plate I have. I have not found it even on the web.

I will call my old buddy who works the parts counter at a GM dealer to see if he can chase one down. I know a guy who has a junkyard with a pile of iron engines as big as a garage. Might be one out there... but I ain't going out there till the snow melts!

Makes the timing job sooo much easier!

Richard: I talked to my GM parts guy. They are indeed called "timing pointers" and the standard one is easy and cheap (GM# 3991435) but not what you want, attaches to timing chain cover.

There is another number (obsolete, naturally) GM# 354407 which might be correct. Not found in the GM system any more.

A junkyard might be your best bet, as Bill says.

quote:

Originally posted by rp's barth:
...or could it be made?

sure. Stiff wire or rod. Find TDC for 5 or 8. This is best done with a TDC tool, which is available or can be home made.

Rotate engine by hand until piston touches tool. Mark pointer line on damper.

Rotate engine in opposite direction until piston touches tool. Mark pointer line on damper.

TDC is exactly between the two marks.

Stick on a timing tape and you are good to go.

Since older dampers can slip the inner and outer parts, it is always good to verify TDC. Once it is verified, a stripe or chisel mark will show any slippage. Slippage not only affects timing, but if the outer part comes completely off, it will wreck the radiator and fan and who knows what else.

Does this information apply to the 350 cubic in as well? (for those of us with the "Baby" Barths)

Bud

quote:

Originally posted by bud@YXY:
Does this information apply to the 350 cubic in as well?
Bud

If you mean my post on finding TDC, yes, it applies to all engines.

~ I was asked a few questions about this privately and thought I would answer them so more people could benefit from the answers ~

1 - 8 - 4 - 3 - 6 - 5 - 7 - 2

This is the firing order of the GM power plants we're talking about.

Because the motor is a 4 stroke, the crank turns 2 times before the same cylinder fires again.

What this means is each timing mark has 2 cylinders that are at TDC (Top Dead Center) when the timing light is firing.

Here is the firing order again

1 - 8 - 4 - 3
one crank revolution
½ camshaft revolution

6 - 5 - 7 - 2
two crank revolutions
1 camshaft revolution
1 distributor revolution

So, any timing mark can use two cylinders to set the ignition timing because the crank turns twice before the distributor and cam shaft turns once.

In the case of one timing mark you can either use cylinder 1 or 6.

If you relocate the timing mark 90°, as shown in the above photo from my earlier post, you must use either cylinder 8 or 5 to set the timing.

Likewise, if you set the timing pointer 180° off, you would need to use cylinder 4 or 7 to do the timing.

If a harmonic balancer had 4 timing notches cut into them, 90° apart from each other, you could set the timing using ANY spark plug wire.

Cylinder one is located on the drivers side at the front. All of the odd number cylinders are on the drivers side. 1-3-5-7

Cylinder two is located on the passengers side at the front. All of the even number cylinders are on the passengers side. 2-4-6-8



Now, technically you could set TDC with the harmonic balancer and pointer that is already on the engine. Or, use the procedure that Bill H described. Then scribe a mark anywhere in the balancer that would allow you to remote mount another pointer. It could be attached to any part of the motor or oil pan that would allow you to secure it. Now, you use cylinder 1 or 6 to set the timing.

Timing is set with the motor at an idle, your vacuum advance disconnected and plugged on the hose coming from the carb and the engine at its normal temperature operating range.

Four additional notes related to the distributor...
Check the distributor weights for being able to move freely. Check the ability of your vacuum advance to operate freely and make sure the plunger can hold a vacuum. If you see red dust particles inside the distributor, blow them out and clean that off. This conducts electricity and that isn't a good thing.

Is this guy good or what? Actually, he's just one of several absolutely fantastic tech guys on this site. But he's the 'grand pooh ba'

Bravo for the excellent explanation!

The lower marks on the 454 driver side allow use of cylinder 5 or 8. As the diagram shows, cylinder 8 is on the opposite side. I use the timing light on the driver side and hook to cylinder 5 (same side)

Ultimately, it boils down to having the maximum advance so there is no detonation when climbing the steepest hill on the hottest day with the maximum load with the lowest-octane gas you use. This can be done by ear or by a detonation sensor. Modern computer-controlled engines do this automatically.

My hearing is getting worse, so I use Susan as my detonation sensor.

quote:

Originally posted by Jim and Tere:
Is this guy good or what? Actually, he's just one of several absolutely fantastic tech guys on this site. But he's the 'grand pooh ba'

+1

Actually, the term for too-advanced timing is "knock"; "detonation" is the result of a too-lean mixture

very good information i am checking to see if there are any salvage yards here in North Carolina that might have one if not i will try to fab one . if i were still in Fl i would go to Bobs RV

Here is a web document for the 454 Chevrolet P30 motorhome. Your Barth has the same engine.http://www.bdub.net/manuals/P30/P30.pdf. The timing pointer appears to be the same as the one on top, just mounted on the opposite lower side. If so just google 454 chevrolet timing pointer and several sites show it is available for $5.79.