Goofy TDC question - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old Aug 3rd, 09, 01:16 PM Thread Starter
Senior Tech
 
Join Date: Apr 2009
Location: NJ
Posts: 434
Goofy TDC question

Ok, this is a goofy question but maybe somebody can help me out. While the motor, 454 Mark IV based, was apart I lined it up at TDC for ease of installing the distributor etc. However, my friend "tested" the new mini torque starter and now I have no idea where the motor is. The aluminum timing cover has no timing pointer, I have to make one for it. The timing cover is on and the motor is in the sub frame. Taking it apart is the last resort. I put the motor on the compression stroke, both valves closed, piston coming up. So, is there a way to accurately determine TDC? Can you determine anything from the crank keyway? Can you measure rotations between a certain valve open and closed and divde by a magic number, anything?!?!?
AintQik is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old Aug 3rd, 09, 01:36 PM
Senior Tech
Tom
 
Join Date: Jun 2001
Location: Rochester Mn
Posts: 7,749
Smile Re: Goofy TDC question

Make a piston stop tool out of an old spark plug. Then you can use it to find your TDC.

69 Camaro -originally a LM1 car. 327, Edelbrock E-streets, hooker, DUI performance distributors, ultradyne cam, stewart, TRW etc. Vintage Air, AGR steering, Corbeau GTSII seats, 700R4 transmission, 12-bolt w/Eaton 4.11:1
TJS69 is offline  
post #3 of 12 (permalink) Old Aug 3rd, 09, 01:44 PM Thread Starter
Senior Tech
 
Join Date: Apr 2009
Location: NJ
Posts: 434
Re: Goofy TDC question

But since the piston "floats" at TDC for a few degrees how do I get an accurate measurement?
AintQik is offline  
 
post #4 of 12 (permalink) Old Aug 3rd, 09, 02:12 PM
DjD
Retired
Dennis
 
DjD's Avatar
 
Join Date: Apr 1999
Location: Fortuna, CA
Posts: 26,486
Garage
Re: Goofy TDC question

How did you line up TDC when putting the engine together to begin with?

...Dennis

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


"Don't take life so serious, you won't get out alive..."
DjD is offline  
post #5 of 12 (permalink) Old Aug 3rd, 09, 02:18 PM
Senior Tech
Alan
 
Join Date: Oct 2007
Location: SoCal
Posts: 3,903
Re: Goofy TDC question

Couldn't he ball park it and then put a dial gauge on the #1 intake valve, slowly rotate it, get his figures and split the difference via the dial indicator and harmonic balacer? He would have to know his cam specs. But then how do you attach the timing scale to the cam cover? One must be 1. very sure where the drill is drilling 2. be extremely brave when drilling a hole into a timing chain cover.

alan
alanrw is offline  
post #6 of 12 (permalink) Old Aug 3rd, 09, 02:38 PM Thread Starter
Senior Tech
 
Join Date: Apr 2009
Location: NJ
Posts: 434
Re: Goofy TDC question

I've just made an old big block timing tab "fit" by cutting and drilling a new hole. It's about where a stock tab would be but I'm unable to verify. It looks like stock and mounts using the cover bolts. I just plan on knowing where TDC is and if its not "0" on the tab just make a note of how much I need to compensate.

I don't know the cam specs. It's not stock by any stretch of the imagination. I hate messing with junk that was not built by me. This motor came in the car and was pretty stout so I left it alone. I didn't take the engine apart, I just cleaned it up and put on a new timing chain cover and oil pan as the old ones were pretty beat up. The inside of the motor was very fresh so I decided to run it till it gave up. It looks like its a 80ish 454 block, there are no numbers, so its been decked or it was a crate block. It has 66 396/427 closed chamber heads and that's just about all I know.

I've got it pretty close as I said by looking at the motor and valve train. But what I need is some math to determine true TDC if some exsists. If not I'll wing it but that's always asking for trouble.
AintQik is offline  
post #7 of 12 (permalink) Old Aug 3rd, 09, 02:52 PM
Senior Tech
Eric
 
Join Date: Oct 2005
Location: Ohio
Posts: 437
Re: Goofy TDC question

I have used a piston stop that I got from Jegs, I extend it down a bit, then rotate untill it stops, mark the balancer, then pull it, get the piston past, re install the piston stop to the exact same depth (I used blue locktight on mine), back the piston to the stop, Mark the balancer, then Top dead center is exactly between the two marks.

'68 Coupe 383 Small Block
4 speed Muncie (M 21)
12 bolt rear end (4.10)
Old school slappers
Old School L-60 Mickey Thompson's


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
EC's 327 is offline  
post #8 of 12 (permalink) Old Aug 3rd, 09, 06:05 PM
Senior Tech
 
Join Date: Jul 2005
Location: California
Posts: 2,353
Re: Goofy TDC question

Quote:
Originally Posted by EC's 327 View Post
I have used a piston stop that I got from Jegs, I extend it down a bit, then rotate untill it stops, mark the balancer, then pull it, get the piston past, re install the piston stop to the exact same depth (I used blue locktight on mine), back the piston to the stop, Mark the balancer, then Top dead center is exactly between the two marks.
Wouldn't it be easier to rotate the engine til the stop hits, mark the balance, and turn the engine around the other way until it stops again. Mark and measure to the middle. That's tdc

This way you do not have to try and get the stop in the same exact depth two times...

Anyways, search the forum or summit racing for piston stops.
400bird is offline  
post #9 of 12 (permalink) Old Aug 3rd, 09, 07:06 PM
Senior Tech
Eric
 
Join Date: Oct 2005
Location: Ohio
Posts: 437
Re: Goofy TDC question

Quote:
Originally Posted by 400bird View Post
Wouldn't it be easier to rotate the engine til the stop hits, mark the balance, and turn the engine around the other way until it stops again. Mark and measure to the middle. That's tdc

This way you do not have to try and get the stop in the same exact depth two times...

Anyways, search the forum or summit racing for piston stops.
If its a flat tapet cam, and its already in, I dont like to spin it backwards. Not sure if it would hurt it or not, just always had in the back of my head "dont spin it backwards"

'68 Coupe 383 Small Block
4 speed Muncie (M 21)
12 bolt rear end (4.10)
Old school slappers
Old School L-60 Mickey Thompson's


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by EC's 327; Aug 3rd, 09 at 07:06 PM. Reason: I cant type
EC's 327 is offline  
post #10 of 12 (permalink) Old Aug 4th, 09, 06:50 PM
Senior Tech
 
Join Date: Jul 2005
Location: California
Posts: 2,353
Re: Goofy TDC question

Quote:
Originally Posted by EC's 327 View Post
If its a flat tapet cam, and its already in, I dont like to spin it backwards. Not sure if it would hurt it or not, just always had in the back of my head "dont spin it backwards"
Ya, I have no idea if its bad, but I have done it and besides its only 1 revolution. Actually less than one.

I suppose you could start with the engine just past tdc, thread the stop in and back it up a little til it hits and go forwards from there.
Im just a little to lazy to do that myself
400bird is offline  
post #11 of 12 (permalink) Old Aug 5th, 09, 06:28 PM
Senior Tech
george
 
Join Date: Sep 2006
Location: detroit
Posts: 2,291
Re: Goofy TDC question

Quote:
Originally Posted by EC's 327 View Post
If its a flat tapet cam, and its already in, I dont like to spin it backwards. Not sure if it would hurt it or not, just always had in the back of my head "dont spin it backwards"
Rotating the engine by hand in either direction will have no effect on the cam lobe/lifter wear pattern.

George
68 Camaro
8-71 blown 461 Rat on E-85
fatblock is offline  
post #12 of 12 (permalink) Old Aug 5th, 09, 06:36 PM
Senior Tech
Sean
 
Join Date: Feb 2002
Location: N.W. Washington
Posts: 7,964
Re: Goofy TDC question

Quote:
Originally Posted by fatblock View Post
Rotating the engine by hand in either direction will have no effect on the cam lobe/lifter wear pattern.
X2.
And the piston stop method mentioned above- rotate forwarde until it stops, mark the balancer/ rotate backward until it stops, mark the balancer then find the exact middle of those two points is the correct way to do it. Thats how you baseline TDC when you degree a cam but usually with a degree wheel, You don't need one though.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
68rs406 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome