Finding top dead center - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69see20 · 11-08-2002, 03:41 PM

I just rebuilt the top end of my 307. I have the heads intake and timing chain cover all back on. I am ready to set the valve lash and set in the distributor, but am curious how to set top dead center with the dizzy out. does anyone tell me how to find top dead center like this? I know to look for the timing mark on the balancer, but do not know if it is on the compression stroke or exhaust stroke.

lux hauler · 11-08-2002, 03:50 PM

with the #1 spark plug removed, put your finger over the spark plug hole and turn the motor over. when air starts pushing out of the hole, the piston is coming up on the compression stroke. bring the piston to the top.

72K10 · 11-08-2002, 08:59 PM

Another way that has worked well for me is to wet a 1/4 chunk of paper towel and stick it in the # 1 cylinder hole ( plug pulled). Bump the engine until you hear the paper towel blow out - sort of a "pshhhhhht" sound. If you have your harmonic balancer installed, turn over by hand until line on balancer aligns with tab. Then your at / very close to TDC.
Chris

Capitol68 · 11-09-2002, 12:16 AM

Yea what 72 said is the easiest if u are by ur self. or use a shop rag

crazy longhorn · 11-09-2002, 12:47 AM

If you still have the valve covers off, you can set the timing mark to zero.......if both valves on #1 are shut, you are in the right spot. If not, turn the eng 1 revolution back to zero.....

**COBALT** · 11-09-2002, 01:59 AM

I once did the "blow out the hole" trick, but found that it was easier to rotate the engine with all the plugs out and stick my pinky in the spark plug hole until I could feel the top of the piston. For some reason I had a hard time getting TDC with just bumping the starter...

11-08-2002, 03:50 PM	#2
lux hauler Psycho-billy Member Join Date: Jul 2001 Location: about 40 miles west of Cleveland, Ohio Posts: 2,591	with the #1 spark plug removed, put your finger over the spark plug hole and turn the motor over. when air starts pushing out of the hole, the piston is coming up on the compression stroke. bring the piston to the top. __________________ '72 C-10 350 w/Lunati Voodoo cam (207/213, .437/.454), Performer intake, 625 Road Demon Jr. and Hooker headers. Support your community, support yourself. Buy local, buy American (or Canadian).

11-08-2002, 08:59 PM	#3
72K10 Registered User Join Date: Dec 1999 Location: New York Posts: 288	Another way that has worked well for me is to wet a 1/4 chunk of paper towel and stick it in the # 1 cylinder hole ( plug pulled). Bump the engine until you hear the paper towel blow out - sort of a "pshhhhhht" sound. If you have your harmonic balancer installed, turn over by hand until line on balancer aligns with tab. Then your at / very close to TDC. Chris __________________ RLTW 70C10 72K10 72K10 Cheyenne 72C10 Cheyenne Super

11-09-2002, 12:16 AM	#4
Capitol68 Registered User Join Date: Sep 2002 Location: Austin,Tx Posts: 327	Yea what 72 said is the easiest if u are by ur self. or use a shop rag __________________ '68 Fleet LWB orig 307 .030 over GM Hei/w Accel Super coil orig. stock TH 400. _______________________ “What we do for ourselves dies with us. What we do for others and the world remains and is immortal.” Albert Pine English author d.1851

11-09-2002, 12:47 AM	#5
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	If you still have the valve covers off, you can set the timing mark to zero.......if both valves on #1 are shut, you are in the right spot. If not, turn the eng 1 revolution back to zero..... __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

11-09-2002, 01:59 AM	#6
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	I once did the "blow out the hole" trick, but found that it was easier to rotate the engine with all the plugs out and stick my pinky in the spark plug hole until I could feel the top of the piston. For some reason I had a hard time getting TDC with just bumping the starter... __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

11-08-2002, 03:41 PM	#1
69see20 Registered User Join Date: Aug 2001 Location: spring lake NC Posts: 50	Finding top dead center I just rebuilt the top end of my 307. I have the heads intake and timing chain cover all back on. I am ready to set the valve lash and set in the distributor, but am curious how to set top dead center with the dizzy out. does anyone tell me how to find top dead center like this? I know to look for the timing mark on the balancer, but do not know if it is on the compression stroke or exhaust stroke.

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