Timing Mark WAY off?

[Dean]

Has anyone here ever come across a condition where the dampener timing marks were way off, as in ~27* (39mm/1.55") BTDC?

I'm putting the finishing touches on a new engine and decided to verify the timing marks, just to be methodical so when I set the cam sensor it is as correct as can be. I did not use a degree wheel because I didn't want to take that much apart, but here's what I did:

• remove the DS rocker shaft, loosened all the plugs, removed #1 plug
• brought #1 up to near TDC, then backed it down the hole a bit, screwed in a piston stop until it touched and then backed the stop out a thread or so.
• rotate the crank to bring the piston up to the stop, back and forthing a couple times to ensure the stopping, and marked the damper
• rotate the opposite direction and repeat
• measure the distance between the two marks, divided by 2, and marked the dampener from one of the marks (actually, I remeasured from both marks to ensure I didn't screw up)

I did this twice with the same result. I have not contacted the builder/assembler to see if this is something they checked during assembly, but I could understand the mark not being referenced as they used a degree wheel during assembly and cam installation, long before the dampener would be installed.

I guess it doesn't really matter because mechanical TDC is what it is, but I was/am surprised at such a difference. I wouldn't have been overly surprised at a degree or even two, but 27?! I looked at the dampener still on my original engine and they appear to be identical, so I believe it to be a correct damper on the engine.

Thoughts?

 

[bison]

I ignore the marks and just scribe my own relative to the timing tab after finding true tdc

 

[Dean]

That's what I'm thinking, it is what it is. I was just a bit shocked to see it was so far off!

 

[bison]

That's what I'm thinking, it is what it is. I was just a bit shocked to see it was so far off!

Maybe it was used with a completely different setup and a custom timing indicator before you got it.

 

[Dean]

Nope, it is just an old stock dampener, like I mentioned, identical to the one on my old engine. I'm going to ponder if I did something wrong, but dang, it seems such a simple thing to check. Do you see anything wrong with the process?

I think I'll take my old engine for a spin with the piston stop as well... now I'm real curious.

 

[pacecarta]

is the woodruff key in the keyway in the crank?

and it does matter because the crank position is determined by the reluctor wheel on the balancer and is important to the spark timing and the injector timing

 

[bison]

Use a degree wheel to find tdc. I've never seen a stock one wrong. I have seen the reluctor off though

 

[Dean]

Excellent point on the reluctor, pacecarta! Now I need to figure out what the heck I'm doing wrong or is going on.

 

[Nick Micale]

............I guess it doesn't really matter because mechanical TDC is what it is,.................................Thoughts?

It DOES matter when setting TDC, and that statement is not accurate because the piston is at the top of the cylinder on the compression stroke, as well as the exhaust stroke.

When you set TDC, was it on the compression stroke where it should be?

Many times I have found cam sensors 180 degrees out as the person did not understand how to determine TDC properly.

 

[Dean]

BTW, Pacecarta, woodruff is in place.

Nick, what I was thinking and meant at the time of the post was, it doesn't really matter what the timing marks are, mechanical TDC is reality, and one has to work from there. Now, did I screw something up during the check? That is entirely possibly, but I can not figure out what. The TDC was definitely on compression stroke (verified by watching the valve train, and with the ol' "wet thumb" method), but even if it wasn't on compressions stroke, the piston would still hit the piston stop at the same degree points.

I have done nothing since. I have a collapsed rear porch to rebuild, hopefully finishing in the next couple/few days, and then I'll get back to this. Just doesn't make sense how I could have f'ed this up, but that is a viable reason.

Thanks, folks...

 

[novaderrik]

It DOES matter when setting TDC, and that statement is not accurate because the piston is at the top of the cylinder on the compression stroke, as well as the exhaust stroke.

When you set TDC, was it on the compression stroke where it should be?

Many times I have found cam sensors 180 degrees out as the person did not understand how to determine TDC properly.

in this case, TDC is TDC regardless of which stroke it's on.. this is just about where the mark on the balancer is when the piston is at the top of it's travel.

i'd look at the balancer and see if the outer ring has slipped- find out where the TDC mark is supposed to be relative to the keyway and go from there.

 

[RmvBfrFlght]

When the #1 piston is at true TDC, is the crankshaft key directly in line with the center of the #1 cylinder? It should be, otherwise it is not cut in the proper location.

RemoveBeforeFlight

 

[Dean]

The "issue" was resolved. The problem was 50% process, 50% parts.

The fault with the process was my not putting the mechanical mark to the arbitrary reference point I was using when I did the "to and fro" spinning of the engine and THEN looking at where the factory timing mark aligned with the timing indicator. That reference point was the bottom/DS edge of the timing indicator, BTW. I stated the timing mark was off ~27 degrees because that was the difference between the arbitrary mark and the factory timing mark. That was stupid, on my part, however that only made up for 15 degrees. of the 27 degree discrepancy. The factory timing mark was still off by 12 degrees according to the timing indicator.

The other 50% of the issue is the timing indicator itself. I sprung for one of TA Performance's TA_1533B front cover/oil pump assemblies. I'm trying to make this engine complete, without having to rob much of anything from my original engine (the only exception is the upper manifolds and attached bits). With that in mind, I contacted TA Performance again, since they had one, their TA_1341 Timing Cover Indicator. The indicator is described as being a "Timing Indicator for ...TA 1530 Timing Covers". I asked is that meant it would work with my 1533B, and I was told yes, and that in fact it had to be used with their front cover. That actually irritated me a bit because if that indicator had to be used with that front cover, why the frick doesn't is come with it?? So anyhow, I ordered it. Well, turns out is DOES NOT work with their 1533B front cover, except that it bolts up, as it is off by 12 degrees. What a pisser. With that 12 degrees, plus my dumbazz 15 degree procedural error, the 27 degrees has been mitigated.

 

[John Wilde]

I am glad you got to the bottom of it buddy,
When may I have a ride in this beast?

 

[Dean]

Beast? What beast? Your heads and cam are 'bout the same as mine.

 

[Dean]

BTW, why "Applied Pumping Technologies" in your sig line. Put a call name for the shout out, man!

 

[Chuck Leeper]

Maybe, get hold of Nick Micale.[ Arizona GN]. He can straighten them out at TA, and see that they send you the correct part.

 

[Dean]

Chuck, I sent them an email. I don't see any other timing indicator on they site, so I don't have much hope. I suppose I could also cut a new timing mark into the damper. I have having multiple marks, though. I'll take a look at rigging something up with parts from Summit.

 

[Dean]

Sherri already got back to me. I need a TA_V1341.