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stock 170 timing issue
https://www.slantsix.org/forum/viewtopic.php?t=29267		 Page 1 of 1
Author:  zooter86 [ Sun Jun 01, 2008 7:17 pm ]
Post subject:  stock 170 timing issue
freshly rebuilt 170 installed, starts easily (and what motor wouldn't on a 70 degree day) idles smoothly revs up and down nice but the timing is not even close to where it should be. I can't even get the timing mark to be on the little metal tab, I tried pulling the distributor and bumping a tooth, but it's either off on one side or the other.

I have a cheap timing light with the advance knob from harbor freight and with the distributor where the engine runs happiest I dialed in 35 degrees to get the mark 0 at idle.

motor seems to run fine I adjusted the valves and the carb before touching the timing. suggestions welcome, please help
Author:  DusterIdiot [ Sun Jun 01, 2008 7:46 pm ]
Post subject:  So who?
Who rebuilt the 170?

Is the damper new or used? Is the damper matched to the timing cover? (there are some differences over the years)....

Hopefully it's not 'slipped', or someone decided a 1976 225 damper was fine for a 1963 170 timing cover....

-D.Idiot
Author:  zooter86 [ Sun Jun 01, 2008 7:54 pm ]
Post subject: 
my friend with my overseeing. we both took engines class at college so I got the engine rebuilt with free machining work which was a HUGE cost savings for this engine. the damper came off this car but the car came off a shady used car lot so who knows.

I was thinking maybe the timing chain was off one tooth or something like that but it runs so smoothly I wanted to be sure before tearing the front of the engine apart
Author:  DusterIdiot [ Sun Jun 01, 2008 7:59 pm ]
Post subject:  Hmmmm....
If it runs fine, the timing chain and cam to crank is probbly correct, but the damper may need to be 'remarked' (hopefully it's not 'slipped')... run it up to TDC and mark with the 0 on the tab and see where things lie...

-D.Idiot
Author:  zooter86 [ Sun Jun 01, 2008 8:14 pm ]
Post subject: 
this may be a duh but what's the best way to determine what is exact tdc on cylinder 1?

and if the damper indeed is off what should I do? do they make new ones or do nI need to take mine off and have it rebuilt?
Author:  tlrol [ Sun Jun 01, 2008 8:19 pm ]
Post subject:  put a finger in it!
Well, there may be better ways to find TDC but I learned that the easiest way is to do the following:

1. Remove the coil to distributor plug wire/cable
2. Remove the #1 spark plug
3. Get a remote starter--either the living kind or the switch
4. Stick your finger over the #1 plug hole
5. Bump the starter until your finger is "blown" off the hole
6. Stop cranking when that happens
7. You should be pretty close to TDC...plus or minus a few degrees.
Author:  DusterIdiot [ Sun Jun 01, 2008 8:43 pm ]
Post subject:  and...
#8 ) use a peice of coat hangar to check and see if there's more piston rise, while rolling the engine over more by hand either using the newly added crank bolt, or the fan belt/fan

#9 ) You may also be able to determine TDC by pulling the oil cover cap and checking to see if the rocker arms are in proper alignment, but this would assume that your cam and crank are in good alignment. timing chain stretch/skipped a gear tooth won't help there...


-D.Idiot
Author:  zooter86 [ Sun Jun 01, 2008 8:47 pm ]
Post subject: 
I'll try tommorow. timing chain stretch I really doubt as the timing set is brand new and this engine has a total of 1 hour run time since the rebuild and has been driven as far as around the block. I was thinking one tooth off but it just runs so damn sweet I am hesitant to condemn that
Author:  Doc [ Mon Jun 02, 2008 12:18 pm ]
Post subject:  Positive Piston Stop for finding True TDC
DISCONNECT THE BATTERY! Do not use the starter to perform any of these steps if you decide to use a positive piston stop method to determine true TDC.

To find Top Dead Center use a piston stop, to stop the piston in the same position on either side of TDC and take readings from a degree wheel. You will then split the difference in these readings and move the pointer this amount, making it the true TDC point. At this point. you can accuratly re-mark your vibration dampener and check cam positioning.

- Mount the degree wheel on the end of the crankshaft, and rotate the engine to approximate TDC

- Mount a pointer or use the current timing mark and line it up at zero on the degree wheel.

- Rotate the engine to move the piston down into the cylinder. Install your positive piston stop device into the spark plug hole and extend the bolt.

- Turn the engine slowly by hand, rotating it until the piston comes up and stops against the piston stop bolt. (having all spark plugs removed helps to make the engine easy to turn)

-Look at the degree wheel and write down the number of degrees shown by the pointer.

-Turn the engine by hand in the opposite direction until the piston comes up and stops on the piston stop bolt again. Go back to the degree wheel and write down the degrees it now reads.

-Add these two readings together (the sum) and divide the answer by two. (divided amount) TDC is at the center of the sum. The divided amount on either side.

Now either add a chalk mark on you dampener or move your pointer by this many degrees, or carefully loosen the degree wheel (without disturbing the position of the crankshaft) and move the wheel this required amount.

Retighten everything and rotate the engine again, making sure that the readings on each side of TDC are equal degrees away from zero. If they are, the zero on the degree wheel will now be the true TDC point. You can remark (punch or saw slot) your dampener at this position.

Be Sure to remove the positive piston stop device from the spark plug hole BEFORE reconnecting the battery.

Now that you have found true TDC , you can easily check your cam's position and adjust it as needed.
DD
Author:  digger12 [ Tue Jun 03, 2008 12:31 am ]
Post subject: 
Another way to find true TDC is to use a dial indicator. You might be able to borrow one from a mate!

Image

Mount the dial indicator so the piston will half compress the stem at roughly TDC. Turning the engine by hand will cause the dial to start rotating in a forward direction, Then it will have a dwell point where the needle will no longer rotate, then as the piston starts going down the needle will go in reverse. It is at this dwell point that the engine is at TDC.

There will be a few degrees of crank rotation where the piston will be at TDC or dwell on the dial. So rock the engine back and forward until you find the center!

I am new to Valiants and Slants but have used this technique before on other engines with success. Easy and accurate.
Author:  digger12 [ Tue Jun 03, 2008 1:17 am ]
Post subject:  Re: put a finger in it!
Quote:
Well, there may be better ways to find TDC but I learned that the easiest way is to do the following:

1. Remove the coil to distributor plug wire/cable
2. Remove the #1 spark plug
3. Get a remote starter--either the living kind or the switch
4. Stick your finger over the #1 plug hole
5. Bump the starter until your finger is "blown" off the hole
6. Stop cranking when that happens
7. You should be pretty close to TDC...plus or minus a few degrees.
Firstly sorry if I'm over stepping the mark as a new board member and my apologizes to tlrol but I think this method would be highly inaccurate at best.

Firstly is everyones finger pressure the same? Probably not.
Secondly when you release the starter how much further is the engine going to continue to rotate? Maybe 1/4 turn. I dont know?

There are a few ways to go about finding TDC and all the above suggestions are great. But personally I wouldnt use this one.
Author:  DusterIdiot [ Tue Jun 03, 2008 5:30 am ]
Post subject:  Er...
Quote:
Firstly sorry if I'm over stepping the mark as a new board member and my apologizes to tlrol but I think this method would be highly inaccurate at best.

Firstly is everyones finger pressure the same? Probably not.
Secondly when you release the starter how much further is the engine going to continue to rotate? Maybe 1/4 turn. I dont know?

THis is a rough in, the member probably isn't going to pull the head for a full TDC setting via the method you used ( which works great if working up the block), the 'rough' method is fine when trying to determine if the damper has slipped, or if pulling the distributor and needing to reset the timing a bit... Doc's method using the positive stop is very easy (and actually very accurate when degreeing in the cam). If using the 'rough method to get it close, you can stick your finger in the hole, it will blow it out, I then use my damper bolt and a wrench to go the rest of the way/ make sure it doesn't 'over run'...



-D.Idiot
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