Tdc - The 1947 - Present Chevrolet & GMC Truck Message Board Network

2bits · 10-06-2007, 01:41 AM

OK, I just dropped in a freshly rebuilt 250 with a 292 head and I am trying to find TDC, to stab the dizzy, but I drop a cloth in the #1 cylinder and every time I bump the starter the thing flies out so that's not guiding me like it has in the past. I am wondering if I just watch the cylinder through the hole (I can see clearly) and when the piston is at the top and the timing marker hits at the timing mark, I should be right on or 180 off right? Anyone had this problem? Any other suggestions? The last time I did this it would wait until it was on the right stroke and then pop out, but now it pops right out every bump! Maybe my starter turns too fast?

72armyswbtruck · 10-06-2007, 02:59 AM

Can you get someone to put their thumb over the #1 hole? If not the just bump the ignition until you get close and then turn manually, sometimes you can cheat by taking the valve cover off and looking at the push rods and rockers.

PanelDeland · 10-06-2007, 06:17 AM

Time to buy a remote start switch or make one.You can have the thumb over the hole and bump your own starter.Or pull the valve cover and bump it until both valves are closed and solid on their seats.There is a write up on this in the classic trucks mag i got yester day/I think,I don't always get the mail on the day it comes my wife sometimes has to be asked"Haven't I got any car mags lately?"

Gray Ghost · 10-06-2007, 11:55 AM

Good idea...never thought of that one. He's got a remote starter, but we were both wondering how you turn a 250 manually when there's no center crank bolt?

Sinister · 10-06-2007, 12:03 PM

Quote:

Originally Posted by Buffalo Elk

Good idea...never thought of that one. He's got a remote starter, but we were both wondering how you turn a 250 manually when there's no center crank bolt?

You need one of those flywheel/flexplate turner tool things. X2 on the remote starter switch, makes this job much easier...

prg machine · 10-06-2007, 12:06 PM

Put your thumb over the spark plug hole and turn it over slowly. When you feel it suck it is on the intake down stroke and will come back up, you feel the pressure......then look for your timing mark on the damper............it will be coming up. Simple.

cdowns · 10-06-2007, 12:06 PM

if you wrap a strap around the balancer then cinch it tight with large vise grips its easy to turn the motor over by hand to get an accurate TDC position
also putting bolts in pulley holes and using a lever bar to turn engine over is another easy way to turn over by hand

either way its easier with all sparkplugs removed

68gmsee · 10-06-2007, 12:19 PM

I always remove all of the sparkplugs to make it easier to turn.

Several ways I've done it by myself. First, a remote starter helps tremendously to get it almost "there."

Then on a manual trans and if you're able to, I've put it in gear an slightly pushed on the truck to get the piston where I want it.

I've also tightened the fan belt by pushing or pulling on it and turned the engine over that way. It's not the easiest way but it will work for small increments.

The last method I've done is the way cdowns mentioned with a rubber strap.

Now, I've had the crankshaft drilled and tapped for ease of installation on the next overhaul.

Gray Ghost · 10-06-2007, 11:19 PM

Cool solutions...I like the crank drilled idea. We didn't wind up messing with that today at all did we Thomas?

10-06-2007, 02:59 AM	#2
72armyswbtruck Registered User Join Date: Feb 2004 Location: Idaho Posts: 4,034	Re: Tdc Can you get someone to put their thumb over the #1 hole? If not the just bump the ignition until you get close and then turn manually, sometimes you can cheat by taking the valve cover off and looking at the push rods and rockers. __________________ "Remember, They can Kill You, but they can't eat You, That's against the law!!!!!!!!!"

10-06-2007, 06:17 AM	#3
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: Tdc Time to buy a remote start switch or make one.You can have the thumb over the hole and bump your own starter.Or pull the valve cover and bump it until both valves are closed and solid on their seats.There is a write up on this in the classic trucks mag i got yester day/I think,I don't always get the mail on the day it comes my wife sometimes has to be asked"Haven't I got any car mags lately?" __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

10-06-2007, 11:55 AM	#4
Gray Ghost Senior Member Join Date: Sep 2004 Location: Terrell, TX Posts: 1,967	Re: Tdc Good idea...never thought of that one. He's got a remote starter, but we were both wondering how you turn a 250 manually when there's no center crank bolt? __________________ Kelly '05 GMC Sierra SLE Z71 Bone stock except for new bed rail caps.

10-06-2007, 12:06 PM	#6
prg machine Registered User Join Date: Jun 2007 Location: oregon Posts: 1,069	Re: Tdc Put your thumb over the spark plug hole and turn it over slowly. When you feel it suck it is on the intake down stroke and will come back up, you feel the pressure......then look for your timing mark on the damper............it will be coming up. Simple.

10-06-2007, 12:06 PM	#7
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Tdc if you wrap a strap around the balancer then cinch it tight with large vise grips its easy to turn the motor over by hand to get an accurate TDC position also putting bolts in pulley holes and using a lever bar to turn engine over is another easy way to turn over by hand either way its easier with all sparkplugs removed __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY Last edited by cdowns; 10-06-2007 at 12:10 PM.

10-06-2007, 01:41 AM	#1
2bits Registered User Join Date: Jan 2006 Location: Dallas Posts: 504	Tdc OK, I just dropped in a freshly rebuilt 250 with a 292 head and I am trying to find TDC, to stab the dizzy, but I drop a cloth in the #1 cylinder and every time I bump the starter the thing flies out so that's not guiding me like it has in the past. I am wondering if I just watch the cylinder through the hole (I can see clearly) and when the piston is at the top and the timing marker hits at the timing mark, I should be right on or 180 off right? Anyone had this problem? Any other suggestions? The last time I did this it would wait until it was on the right stroke and then pop out, but now it pops right out every bump! Maybe my starter turns too fast? __________________ _______________ Thomas '78 Silverado '74 Monte Carlo '47 Teardrop Trailer East Texas Classics Local Club

10-06-2007, 12:19 PM	#8
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Tdc I always remove all of the sparkplugs to make it easier to turn. Several ways I've done it by myself. First, a remote starter helps tremendously to get it almost "there." Then on a manual trans and if you're able to, I've put it in gear an slightly pushed on the truck to get the piston where I want it. I've also tightened the fan belt by pushing or pulling on it and turned the engine over that way. It's not the easiest way but it will work for small increments. The last method I've done is the way cdowns mentioned with a rubber strap. Now, I've had the crankshaft drilled and tapped for ease of installation on the next overhaul.

10-06-2007, 11:19 PM	#9
Gray Ghost Senior Member Join Date: Sep 2004 Location: Terrell, TX Posts: 1,967	Re: Tdc Cool solutions...I like the crank drilled idea. We didn't wind up messing with that today at all did we Thomas? __________________ Kelly '05 GMC Sierra SLE Z71 Bone stock except for new bed rail caps.



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