Timing set alignment?

[S10xGN]

I was on the phone with Tim Cole yesterday about the problems I'm having with the odd-fire nosed cam. He said "you do realize the cam is 180° out when the dots are lined up?" I got a chill when he said that because it seems I do remember hearing that once, but I've just spent 30 minutes looking through all my on-line sources (along with the factory manual) and cannot find any reference to it. Everything I can find indicates that with the dots lined up, the motor is on #1 cyl TDC firing stroke.

After furthur consideration, I don't think it would make any difference at all. The only variable here is the setting of the cam sensor, and I ALWAYS verify #1 cyl. is on TDC of the firing stroke. So, what exactly is CORRECT?

 

[TurboJim]

Use a degree wheel and see how it lines up.

But you're right, a 180 out cam just means the cam sensor would be in backwards.

 

[Iceman]

Originally posted by TurboJim
Use a degree wheel and see how it lines up.

But you're right, a 180 out cam just means the cam sensor would be in backwards.

I would check the cam out with a degree wheel.I have found cams to be out as much as 20°.
When I checked mine is was out 6°.I have installed it 2°advanced.

 

[Iceman]

Do you have a Update!

 

[S10xGN]

No update, I'll be reassembling the motor this weekend. I could find absolutely nothing wrong with my setup. Don't really know what Tim was trying to tell me, but I've e-mailed our resident "roller guru" (Lonnie Dyers) and am awaiting his reply...

I did degree my cam initially, 2° advanced was what it ended up at.

Later,

 

[quickt]

When you are lined up dot to dot with the timing chain you should be on overlap which would be 180 out if I remember correctly. This is still the correct way to install the cam (dot to dot).

 

[Steve Wood]

When he turns the crank and #1 comes up on compression stoke, the timing mark on the damper should be pointing at the pointer, should not it? Roller cam or not?

Not arguing, just trying to put what Tim Cole told him into perspective.

 

[S10xGN]

Dot to dot is the #1 cyl firing stroke, at least on my Comp roller with the Dynagear double roller set. I spent 4 hours degreeing the dang thing in last Saturday. But it still won't run, so my mechanical abilities are for cr@p - what do I know...

There are too many things pointing to this: when the dots are lined up, both #1 cyl valves are on the base circle, as observed by looking with the intake manifold off; doing the "finger in plug hole" compression test gives the same results.

Since NOTHING else has worked, I may try putting the cam sensor 180° out to see what happens.

 

[Steve Wood]

Drain the tank...put a few gallons of fresh fuel in it and blow a bit thru the rail.

 

[TurboJim]

Make a checklist

air, fuel, compression, fire (at the right time)

pull #1 plug, put it in the wire and lay down on the header with the spark plug being grounded

crank the motor, listen for the compression hiss, have a helper crank while you watch the plug for spark, make sure that spark coincides with the compression hiss coming out of the hole. ( more or less, you can use a timing light for this too, fire it at the balancer to check timing too) Check for fuel by smell or a noid light

The car IS missing one of those.. now you need to see which

 

[Kid with a toy]

Hey bro,
If Scott isn't around to help, you know who is.

 

[QKRNYRS]

If the Cam sensor is 180° out what will the symptoms be? Such as track times and feedback from the ecm (i.e. O2 volts etc...)

 

[S10xGN]

I swapped out the gas, flushed the tank with xylene and refilled with 10 gallons of 92, still no start. Tried putting the cam sensor in 180° out (just in case), still no start. Next, I'll do what Jim says: pull #1 plug and see if all the events are happening at the proper time. I do have injector pulse and spark, but *maybe* not at the proper time.

Later!

 

[Chuck Leeper]

Cam timing

The real meal deal.. Strait from the General's shop manual.
page 6A5-10.
1. Turn the crank so that the #1 piston is at TDC.
2. Turn the cam so that, with the sprocket temporarily installed, timing mark is straight DOWN.
3. Assemble timing chain on the sprockets with timing marks in their closest together position. Figure 12 shows this layout.
4. Torque the bolts to 31 ft/lb. [LOC TITE!!]

To find the TDC, I ALWAYS use the degree wheel to find it. DO NOT GUESS!!
No degree wheel? Since the balancer is not rubber mounted and thus not subject to slipping, I'd install the ft cover, slip the balancer on and rotate to TDC.
There are 2 ways to check the accuracy of the marks.
1. Cover and balancer on, head off. Make a steel bar to go across the bore. Add a bolt thru the bar to stop the piston down in the bore, bolt it on the #1 cylinder.
Rotate the crank clockwise until the piston comes to rest on the stop. Mark the balancer , using the tdc mark on the cover for reference.
Rotate the engine CCW to the stop, mark the balancer again.
Split the difference... It best come out on the original TDC marks!!

You can also use a degree wheel to this. [Usually if the engine is out of the car.]
If the head is on, you can modify a spark plug w/ a bolt thru the shell to act as the stop and do the same procedure as w/ the bar.

ALSO, When the balancer is off, I always measure and mark it for 25* ATDC for setting the cam sensor. I paint the balancer flat blk and the TDC slot is white and the 25* mark is a filed slot that's painted yellow. [Model car paint kits are nice to have in the shop, along w/ a fine brush or 2.]


I'd be willing to bet that the cam sensor is the culprit here...
180* out and the fuel is dumped on closed valves... Set somewhere other than dead on or 180 out, and the backfiring, no-start, etc takes place. Close to right and the engine runs, but not good.

If it's not the cam sensor.. IS the crank sensor intrupter wheel on the balancer in the right location?? loose ??

 

[chiken]

Re: Cam timing

Originally posted by Chuck Leeper


If it's not the cam sensor.. IS the crank sensor intrupter wheel on the balancer in the right location?? loose ?? [/B]

how do you know if the intrupter wheel is in the right position?
i am having the same problems with my car.

 

[quickt]

Originally posted by S10xGN
I swapped out the gas, flushed the tank with xylene and refilled with 10 gallons of 92, still no start. Tried putting the cam sensor in 180° out (just in case), still no start. Next, I'll do what Jim says: pull #1 plug and see if all the events are happening at the proper time. I do have injector pulse and spark, but *maybe* not at the proper time.

Later!

What is the car doing? back firing anything at all?

 

[Chuck Leeper]

Crank sensor location

I have a new balancer. When checking a used balancer, I put them together w/ a piece of key stock and compare the window locations. There is a reference for the window vs the keyway, but I have not been able to find it. Anyone??
If someone will find the spec, I can make a fixture, [a cheapo piece], that can be made at home for checking.

 

[S10xGN]

Sorry for the delay in replying, my DSL has been broke for several days...

Chuck - I've got that same GM info. My cam (was) installed with the dots lined up, and degreed in on 108° intake centerline using the 2° advanced keyway. TDC was verified with a positive stop and degree wheel. I also marked my balancer for 25° ATDC with a hacksaw groove and red paint. I've tried the cam sensor (one base and 2 different caps) at both "25° ATDC" positions...

Lonnie - occasionally the car will pop through the exhaust (a VERY loud bang), but mostly it just cranks away. Seems like it's loading up with fuel and one or plugs finally blow off. I do get some vapors from the breathers while cranking, though (rings are prolly not sealed yet - only a few hours of idle time).

As for the crank sensor - I've always lined up the groove closest to the electrical connector with the interrupt slots in the balancer. I looked at trying the other groove, but there was not enough of the housing left in the bracket to "pinch" on.

Is there a surefire way to tell if this thing is NOT trying to run on the CalPak chip? I do NOT have any codes showing.

Thanks!

 

[TurboJim]

If the check engine light blinks rapidly, its running off the calpak. It still sure sounds like the cam sensor is off...or a valve is hanging up

 

[quickt]

I had the same problem last year. Found I had a bad module after I blew the mufflers off the car. Took 2 to get one that worked. I did get 2 new one in a row that were bad out of the box. I also seen it on Dave Fiscus car when the cam sensor broke the tab off that lines it up and it would move and was almost the same.