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Author Topic:   Question about timing and pinion angle?
70coupe
Gearhead

Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000

posted 09-29-2002 02:39 PM     Click Here to See the Profile for 70coupe     Edit/Delete Message   Reply w/Quote
I went to the track yesterday finished 2nd in "mod ET" and 3rd in "mod street". Track was very greasy in the eve and fish tailed,then had to let off so I lost that race. Anyways, back to my question, I haven't checked my timing in a bit so decided to check it. It read 15 initial and 45 total!!! The car was running great over the last few months but I still decided I better bump it down. Now the car doesn't 60' well. My best was a 1.66 compared to my best of 1.610 and an average of 1.63. I want to make sure I checked my timing right before I check to see if the balancer ring has slipped. I set the light to 0 then idled the car at 850 and bumped the digital reading until the balancer line moved to TDC, the reading was 15. Then I moved the rpm up to 3000 bumped the digital reading up from 15 to 42 (thats where the balancer TDC lined up at 0 on the pointer. I then moved the rpm up to see where it would stop it went to 45 at 4000. Am I doing something wrong or should I check the balancer and distributor gear?
The pinion part of the question is I put a 1/4 inch spacer between my traction bar mounting plate and the leaf spring. Will this change the pinion angle? My snubbers used to be just resting on the spring eyes but I decided to try 1" on the right and 3/4" on the left for traction.

It was the best air day of the year and my best time is 11.95 with a corrected air density of 1500', yesterdays air was corrected to 850', I should have ran high 11.8's
------------------
351c 4v clsd heads
60'1.619
1/8 [email protected]
1/4 [email protected]

[This message has been edited by 70coupe (edited 09-29-2002).]

[This message has been edited by 70coupe (edited 09-29-2002).]

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70coupe
Gearhead

Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000

posted 09-29-2002 03:35 PM     Click Here to See the Profile for 70coupe     Edit/Delete Message   Reply w/Quote
I was just outside heres what I found. I pulled the #1 plug out,placed a feeler in the cylinder and found out where on the balancer the #1 piston came up. It showed on the balancer 10 degrees before TDC to 4 degrees before TDC that the piston was at the top. So the balancer must have slipped. If the piston is at the top for roughly 6 degrees then TDC should be between 3 before and 3 after TDC. Therfore 10-7 would put me in the 3 before to 3 after range. Does that make sense. So the balancer is 7 degrees out which would put me at 38 total.
I need a new balancer or atleast mark a line over both halves to see if it moves again.

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kid vishus
Gearhead

Posts: 6590
From: middle of NC
Registered: Oct 2000

posted 09-29-2002 05:07 PM     Click Here to See the Profile for kid vishus   Click Here to Email kid vishus     Edit/Delete Message   Reply w/Quote
I dont know if your balancer did slip or not. All that stuff was over my head.

However, I have alays had the best luck with my clevelands, both with open heads and closed heads, with over 40* of timing. Even when the car was on gas, using closed chamber heads, it ran best with 42* in it. It might have liked more since it kept going faster to that point, but at that time I was to "skeert" to try more.

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70coupe
Gearhead

Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000

posted 09-29-2002 06:13 PM     Click Here to See the Profile for 70coupe     Edit/Delete Message   Reply w/Quote
I figured it might be hard to follow. I'll try again.
What I did was take a long thin piece of metal and put it in the #1 cylinder and turned the motor over by hand.I watched until the piston was at top dead center on the compression stroke. The piston is a TDC for about 6 degrees I figure. The balancer read 10BTDC then I turned the crank until the piece of metal started to go back down, this was 4BTDC. So I know my balancer is off. If the piston is at TDC for 6 degrees then actual TDC would be half of the 6 which would be 3 degrees. Still with me? So to find actual TDC from the balancer numbers,if I subtract 7 from 10BTDC=3BTDC and subtract 7 from 4BTDC=3ATDC. So the difference is 7 degrees off. Theoretically this should be right but I'm just a back yard mech like most of the rest. Can anyone confirm this is right????

Help!!

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Rustang
Gearhead

Posts: 821
From: Clarion PA
Registered: Nov 2000

posted 09-29-2002 09:29 PM     Click Here to See the Profile for Rustang   Click Here to Email Rustang     Edit/Delete Message   Reply w/Quote
One time I was running my clevor (boss 302 heads) I had bumped the distributor ahead and failed to recheck the timing. After I made my first pass I checked my timing and it was around 48degrees! I bumped it back to somewhere around 38 and the car slowed down the rest of the day! I've since been told by a couple of people that the cleveland heads like LOTS of timing especially on a hot humid day.

------------------
'68 mustang 351 clevor- [email protected]
'67 Stang, 351W [email protected]
'69 351C [email protected]
'78 Pickup [email protected]
'79 Pickup 460 ET=??

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clevelandstyle
Gearhead

Posts: 1309
From: central Indiana
Registered: Jul 2001

posted 09-29-2002 11:32 PM     Click Here to See the Profile for clevelandstyle     Edit/Delete Message   Reply w/Quote
Hey Coupe, at your level I would think about locking out your timing. Then you won't have to worry about it. You still need to fix that balancer though.

------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 351C 4V

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TomP
Gearhead

Posts: 6120
From: Delta BC Canada
Registered: Dec 99

posted 09-29-2002 11:52 PM     Click Here to See the Profile for TomP   Click Here to Email TomP     Edit/Delete Message   Reply w/Quote
I wouldn't lock out the timing on that. Maybe if it were a bunch faster and not used on the street.

Make the timing pointer line up at actual TDC, or make a new mark at 7 degrees BTDC and call that TDC. Set the timing to 40 degrees total (or whatever works) and don't worry about the initial timing numbers.

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TomP
Gearhead

Posts: 6120
From: Delta BC Canada
Registered: Dec 99

posted 09-29-2002 11:55 PM     Click Here to See the Profile for TomP   Click Here to Email TomP     Edit/Delete Message   Reply w/Quote
the pinion angle thing.

If you didn't move the rear end relative to the springs or change the ride height of the car it won't affect pinion angle... but increased gap will allow the angle to change more while under acceleration.

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70coupe
Gearhead

Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000

posted 09-30-2002 09:52 AM     Click Here to See the Profile for 70coupe     Edit/Delete Message   Reply w/Quote
Thanks guys, I think I'll mark the balancer at 7BTDC or replace it. 40 degrees seemed to work the best for me as well. What I did was put a spacer between the traction bar and the bottom of the leaf so like you said it wont change the pinion angle other than when I'm launching there will be more travel in the rear end.
Brian

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kid vishus
Gearhead

Posts: 6590
From: middle of NC
Registered: Oct 2000

posted 09-30-2002 09:59 AM     Click Here to See the Profile for kid vishus   Click Here to Email kid vishus     Edit/Delete Message   Reply w/Quote
If the car ran best with that amount of timing in it, and wasnt getting hot, detonating or anything like that, I wouldnt worry about it. I would probably replace the balancer though.

What style of balancer was it? Stock, or aftermarket?

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70coupe
Gearhead

Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000

posted 09-30-2002 10:13 AM     Click Here to See the Profile for 70coupe     Edit/Delete Message   Reply w/Quote
stock balancer with that rubber seal that always slips.
Brian

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Just Strokin
Gearhead

Posts: 754
From: Tuscaloosa, Alabama
Registered: Dec 2001

posted 09-30-2002 11:43 AM     Click Here to See the Profile for Just Strokin   Click Here to Email Just Strokin     Edit/Delete Message   Reply w/Quote
You can not accurately find the TDC by watching the piston nor by placing something into the cylinder that isn't securely fastened. Because you can't be sure you get it back into the same place each time when you rotate the crank in the other direction.

As with the old 292/312 Y blocks, the best way to set the timing on them was by ear and how well the car would run. You had to foget a timing light most all the time.

TomP, changing the ride height doesn't always change the pinion angle. For sure, you can raise or lower the front end and the pinion angle phasing will stay the same as it was inrelation to the output shaft of the transmission. Adding or removing lowering blocks between the leaf springs and the axle housing won't change the pinion angle unless you add an extreme number of blocks.

Now, changing shackles to adjustable ones could and probably will affect the pinion angle/driveshaft u-joint phasing.

[This message has been edited by Just Strokin (edited 09-30-2002).]

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70coupe
Gearhead

Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000

posted 10-17-2002 07:19 PM     Click Here to See the Profile for 70coupe     Edit/Delete Message   Reply w/Quote
Put a new stock balancer on the motor today and it was out by 7 or 8 degrees. Obviously the rubber seal let go. I marked both pieces this time to see if they move.

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Just Strokin
Gearhead

Posts: 754
From: Tuscaloosa, Alabama
Registered: Dec 2001

posted 10-18-2002 08:36 AM     Click Here to See the Profile for Just Strokin   Click Here to Email Just Strokin     Edit/Delete Message   Reply w/Quote
70 Coupe,

beofre you say the balancer is out of spec, have one of your buddies make you a a piston stop out of an old spark plug if you don't have a welder handy.

Break out the insulator, weld in a bolt or rod with the end that goes in the cylinger rounded and smooth. Instert into the spark plug hole, tighten it securely and then turn the engine over BY HAND WITH A RATCHET!!!. Turn the engine in both directions (best to remove the plugs from all cylinders) and mark the spot where it stops in both directions. Then you split the difference between the two marks and that will be TDC.

Any other method of trying to use a feeler gauge or measuring will not give an accurate reading of TDC.

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70coupe
Gearhead

Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000

posted 10-18-2002 10:24 AM     Click Here to See the Profile for 70coupe     Edit/Delete Message   Reply w/Quote
Thats a great idea. But just to let you know I removed the old balancer and lined up the dowel keys on the two of them and noticed how much out of wack the old one was. The timing marks were out about 7-8 degrees with the dowel keys lined up.
Brian

ps. now its time to go out and check my valve train and lash.

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kid vishus
Gearhead

Posts: 6590
From: middle of NC
Registered: Oct 2000

posted 10-18-2002 10:43 AM     Click Here to See the Profile for kid vishus   Click Here to Email kid vishus     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by 70coupe:

ps. now its time to go out and check my valve train and lash.


Might also be time to consider buying a good aftermarket SFI approved balancer.

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