What is the best way to find TDC? - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 05-02-2007, 05:40 AM
muzzfactor's Avatar
Registered User
 
Last photo:
Join Date: Sep 2005
Location: San Antonio, TX
Age: 44
Posts: 99
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
What is the best way to find TDC?

I've got a Pontiac 400 that's been stroked to a 455 and I'm getting ready to start it for the first time and need to find TDC. What is the best way to do this? Thanks.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-02-2007, 06:20 AM
F&J F&J is offline
Registered User
 

Last journal entry: 32 Ford cabriolet conversion/windshield
Last photo:
Join Date: Mar 2007
Location: Connecticut
Age: 62
Posts: 1,571
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Bump the engine over as you watch the valves work on #1 cylinder. As the intake valve just closes, now watch for the timing mark to come up to the timing tab. When you set it to the zero mark, you should theoretically be at TDC for #1. To double check to see if you got it right, roll it over more, and then the exhaust valve will start to open next, not the intake.

(When building the engine you normally check to see if that mark is accurate when the heads are off, using a dial indicator.)


Then align the rotor for the #1 wire on the dist cap, and recheck the rest of the plug wires for correct firing order.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-02-2007, 08:59 AM
FiveFeezy's Avatar
Fishing poles in the hot rod!
 
Last photo:
Join Date: Mar 2004
Location: Richmond, CA
Posts: 109
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The way I do it is to disconnect the coil and remove the number 1 spark plug, stick your finger in the spark plug hole and rotate the engine. When the compression pops your finger out of the hole you are pretty darn close to top dead center on the compression stroke. This should be close enough to TDC to get the distributer aligned close enough to start the motor.

To get a closer reading of the true top dead center, then stick a piece of wire into the spark plug hole and touch it to the piston top. Rotate the engine by hand back and forth and watch the movement of the wire. From this you should be able to tell when the piston is at the top of its stroke. This is close enough for setting your timing mark. Thousandths of an inch aren't important here.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-02-2007, 10:33 AM
Registered User
 
Last photo:
Join Date: Nov 2006
Location: Iowa
Posts: 97
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
i usualy remove the plugs and drop a wooden dowel (or somthin gof the sort) into the #1 cylinder and turn it over by hand until it is at its furthest point out. Havent had any issues yet
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-02-2007, 10:46 AM
blown67SS's Avatar
67 chevelle SS
 
Last photo:
Join Date: Apr 2007
Location: naples,FLORIDA
Age: 28
Posts: 20
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
the best way is with a dial indicator and a degree wheel with the head off....but im guessing the engine is together so i would just disconnect the coil pull number one plug out and crank the motor over till you feel the compression come out of the hole... the timing mark on your balancer should be on zero
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 05-02-2007, 09:42 PM
Registered User
 
Join Date: Aug 2006
Location: Alexandria, VA
Posts: 1,762
Wiki Edits: 0

Thanks: 4
Thanked 66 Times in 64 Posts
Auto parts places and some of the online stores (e.g., Summit) sell a TDC tool that screws into the #1 spark plug hole. I think its basically a spark plug with the center electrode replaced by a metal rod that touches the piston. The rod moves up and down with the piston and you just look for the highest point in the travel.

Bruce
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 05-03-2007, 09:54 AM
tornado-tech's Avatar
Member
 
Last photo:
Join Date: Aug 2004
Location: Kansas
Age: 47
Posts: 320
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I agree with 75gmck25. It the tool I used on mine and turning it over by hand
I know the motor was dead on at TDC which made me get the new balancer on the crankshaft at exactly the right point to get it perfectJust make sure if you use this tool, do not use the starter at all or you will damage your motor
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 05-03-2007, 10:10 AM
301Customs's Avatar
Registered User
 
Last photo:
Join Date: Aug 2006
Location: Monrovia, MD
Posts: 60
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Which size?

Saw several on sale at Summit Racing (14mm, 12mm, and 18mm thread)

Which size should I get for a 1984 351W or am i reading the description wrong?
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 05-03-2007, 10:16 AM
pi71's Avatar
Member
 
Last photo:
Join Date: Sep 2003
Location: TX
Age: 43
Posts: 349
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
i took an old spark plug and busted out the ceramic, you can spin the motor over with the starter and it will "whoooosh" when at TDC.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 05-03-2007, 08:26 PM
Registered User
 
Join Date: Nov 2005
Location: CT
Posts: 195
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 75gmck25
Auto parts places and some of the online stores (e.g., Summit) sell a TDC tool that screws into the #1 spark plug hole. I think its basically a spark plug with the center electrode replaced by a metal rod that touches the piston. The rod moves up and down with the piston and you just look for the highest point in the travel.

Bruce
The correct way to use a TDC tool is to screw it into the #1 plug hole and turn the stop in. Rotate the crank by hand until it comes against the stop. Make a mark on the balancer where the timing pointer shows. Now rotate the engine by hand in the opposite direction until the piston again hits the stop. Mark that position from the timing pointer on the balancer. Find the mid-point of the two marks and mark you balancer as that is the exact TDC
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last 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 for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
where do you find the JEG'S InJEGster!!??!? VEGA1971 Engine 2 11-24-2006 05:10 AM
Help find comp stroke... SecGenLvr Engine 12 02-11-2006 06:35 PM
True TDC / using a piston stop driveability Engine 6 01-07-2006 12:44 AM
Where can I find.... bonuts General Rodding Tech 6 10-30-2003 10:23 PM
Sure fire way to find TDC ? 54 Chevy Engine 8 05-02-2002 04:22 PM


All times are GMT -6. The time now is 06:26 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.