Timing marks - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Sport/Truck · 05-05-2007, 10:24 AM

There’s a thread started in the engine/drivetrain (please read) and since some of you don’t go there very often I wanted to ask for this favor here. If you have a new motor sitting around, can you look at something for me? I need a picture of the timing chain markings with the #1 TDC.
Thanks,
s/t

**truckdude239** · 05-05-2007, 10:39 AM

crank mark up and cam mark down facing the other one on small block v-8

Sport/Truck · 05-05-2007, 11:03 AM

Quote:

Originally Posted by truckdude239

crank mark up and cam mark down facing the other one on small block v-8

Dave, that what it is now, but that’s technically not correct, but seems to be the norm. I’m just wondering if I should leave it as it is.

RustyParts · 05-05-2007, 11:17 AM

When the marks are facing each other that is #6 cylinder TDC #1 is when the marks are crank at top and cam at top.

**truckdude239** · 05-05-2007, 05:59 PM

umm i just put my 305 together this way and it was the way the manual said to do it my number 1 is top dead center it said to top the number one piston out the mark on the crankshaft should be pointing up then the cam should be on the bottom lined up with the one on the crankshaft mark

**john** · 05-05-2007, 06:46 PM

Quote:

Originally Posted by RustyParts

When the marks are facing each other that is #6 cylinder TDC #1 is when the marks are crank at top and cam at top.

I have to agree with Rusty Parts. You install the cam with marks facing each other, then you have to turn eng. 360 to install dist on number one cyl.

Sport/Truck · 05-05-2007, 08:26 PM

Thanks RustyParts & John, I really need to drop the lifters in to see what they have. Hopefully all I need to do is turn it 180 to make it correct. Is it impossible to install the cam wrong? I’m going to look at it tomorrow AM and see what they did.
s/t

wibilly · 05-05-2007, 11:15 PM

i just spent hours going through this with a engine on a stand. lined the timing marks up togather, cranked it over watching the valves and said no way in hell is this right.i know that the intake valve must open and close then the fuel must be compressed then it will fire.well guess what, that ain't what was happening. checked the chiltens manual it showed them lined up to gather done it over and over same ****, i knew better, checked second chiltens same **** finily checked a third and just what common sense told me i don't know who in the hell writes these books or marks the gears but the should get togather i just came in to vent when i spotted this post. both marks up for #1 burn the books and do it the way you know it should be

eedgell · 05-05-2007, 11:29 PM

It doent matter which way you put the gears together, marks facing each other, then rotate 180 deg for distributor install, or both marks up and no rotation for distributor install. Either way the same result. Do what is most comfortable.

**truckdude239** · 05-06-2007, 05:50 PM

okay i am confused now i got my timeing marks facing each on my 305 with number1 at tdc so i am going to have to rotate it 180 to get the distbator in?

**john** · 05-06-2007, 06:52 PM

Quote:

Originally Posted by truckdude239

okay i am confused now i got my timeing marks facing each on my 305 with number1 at tdc so i am going to have to rotate it 180 to get the distbator in?

I misspoke, you turn the crank 360 and that will turn the cam 180.

eedgell · 05-06-2007, 07:51 PM

line up the marks, this times the engine. Rotate the engine to tdc, intake and exhaust lifters down, piston at the top . install distributor pointing at #1.

Sport/Truck · 05-06-2007, 08:26 PM

Basically you use the two marks to install the timing set, has nothing to do with the firing order.

eedgell · 05-09-2007, 11:23 PM

Thats correct sport/truck. Why they index the motor this way for install I dont Know. Install marks facing each other, then install lifters, distributor is ready for install on #1 when both #1 lifters are down, or closed. Remember that the crank rotates 360 deg. while the cam only rotates 180 deg. The crank goes top dead center for #1 comp. or fire. It also goes #1 tdc for #1 exhaust, both are tdc on the crank but both serve different function with the cam. The crank is tdc every full revolution while the cam only turns 180deg or half as much providing closed valve for fire then 180deg and provides exhaust. Both fuctions happen at tdc on the crank. The cam must be timed with the crank, hence the timing marks, the cam must "know" where the crank is, or the piston, in relationship to tdc so that the valves are "timed" with tdc. IT is confusing at first but when you think about it its not bad. A full ten page report could be written on this question. Hope this helps.

GREASEMONKEY72 · 05-10-2007, 04:17 AM

eedgell-

after reading and trying to understand that

RustyParts · 05-10-2007, 08:32 AM

Install with the timing marks facing each other and if the engine has not been rotated you install the distributor with the rotor pointed at #6 plug wire and your ready to go.

eedgell · 05-10-2007, 11:33 PM

eedgell- after reading and trying to understand that

Rookie!

**truckdude239** · 05-11-2007, 12:06 AM

okay was told by my teacher that my distobor would point at number 1 whit timing marks lined up and number top dead center after this tread i am so confused

RustyParts · 05-11-2007, 09:34 AM

When you install your cam, install with marks facing each other and forget about it.

This will ensure your cam and crank are in time with each other. This keeps all of the rotating pieces from hitting each other as the engine rotates, that's all they do.

The reason most manuals tell you to do it this way is because there's less chance of misaligning the marks when they are facing each other than trying to align them across from each other.

Once you've rebuilt a couple of engines it will become second nature.

Good luck.

05-05-2007, 10:39 AM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,233	Re: Timing marks crank mark up and cam mark down facing the other one on small block v-8 __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

05-05-2007, 11:17 AM	#4
RustyParts Registered User Join Date: May 2006 Location: Wyman, Kentucky Posts: 403	Re: Timing marks When the marks are facing each other that is #6 cylinder TDC #1 is when the marks are crank at top and cam at top. __________________ 1972 GMC Jimmy, 4WD, 454 CI, 350 Turbo, 4" lift, 35" tires The math teacher said my son "Bubba" could be a mathmatical genius. cause he's got 13 fingers!

05-05-2007, 05:59 PM	#5
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,233	Re: Timing marks umm i just put my 305 together this way and it was the way the manual said to do it my number 1 is top dead center it said to top the number one piston out the mark on the crankshaft should be pointing up then the cam should be on the bottom lined up with the one on the crankshaft mark __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

05-05-2007, 08:26 PM	#7
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Re: Timing marks Thanks RustyParts & John, I really need to drop the lifters in to see what they have. Hopefully all I need to do is turn it 180 to make it correct. Is it impossible to install the cam wrong? I’m going to look at it tomorrow AM and see what they did. s/t __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe.

05-05-2007, 11:15 PM	#8
wibilly Senior Member Join Date: Nov 2005 Location: northwestern wi Posts: 2,111	Re: Timing marks i just spent hours going through this with a engine on a stand. lined the timing marks up togather, cranked it over watching the valves and said no way in hell is this right.i know that the intake valve must open and close then the fuel must be compressed then it will fire.well guess what, that ain't what was happening. checked the chiltens manual it showed them lined up to gather done it over and over same **, i knew better, checked second chiltens same ** finily checked a third and just what common sense told me i don't know who in the hell writes these books or marks the gears but the should get togather i just came in to vent when i spotted this post. both marks up for #1 burn the books and do it the way you know it should be __________________ common sense isn't so common anymore

05-05-2007, 10:24 AM	#1
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Timing marks There’s a thread started in the engine/drivetrain (please read) and since some of you don’t go there very often I wanted to ask for this favor here. If you have a new motor sitting around, can you look at something for me? I need a picture of the timing chain markings with the #1 TDC. Thanks, s/t __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe.

05-05-2007, 11:29 PM	#9
eedgell It's the air up here Join Date: Mar 2007 Location: Western Colorado Posts: 710	Re: Timing marks It doent matter which way you put the gears together, marks facing each other, then rotate 180 deg for distributor install, or both marks up and no rotation for distributor install. Either way the same result. Do what is most comfortable. __________________ 1971 cheyenne k10 4 speed np 205 454 BB factory a/c Never drink down stream of the herd! Eric

05-06-2007, 05:50 PM	#10
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,233	Re: Timing marks okay i am confused now i got my timeing marks facing each on my 305 with number1 at tdc so i am going to have to rotate it 180 to get the distbator in? __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

05-06-2007, 07:51 PM	#12
eedgell It's the air up here Join Date: Mar 2007 Location: Western Colorado Posts: 710	Re: Timing marks line up the marks, this times the engine. Rotate the engine to tdc, intake and exhaust lifters down, piston at the top . install distributor pointing at #1. __________________ 1971 cheyenne k10 4 speed np 205 454 BB factory a/c Never drink down stream of the herd! Eric

05-06-2007, 08:26 PM	#13
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Re: Timing marks Basically you use the two marks to install the timing set, has nothing to do with the firing order. __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe.

05-09-2007, 11:23 PM	#14
eedgell It's the air up here Join Date: Mar 2007 Location: Western Colorado Posts: 710	Re: Timing marks Thats correct sport/truck. Why they index the motor this way for install I dont Know. Install marks facing each other, then install lifters, distributor is ready for install on #1 when both #1 lifters are down, or closed. Remember that the crank rotates 360 deg. while the cam only rotates 180 deg. The crank goes top dead center for #1 comp. or fire. It also goes #1 tdc for #1 exhaust, both are tdc on the crank but both serve different function with the cam. The crank is tdc every full revolution while the cam only turns 180deg or half as much providing closed valve for fire then 180deg and provides exhaust. Both fuctions happen at tdc on the crank. The cam must be timed with the crank, hence the timing marks, the cam must "know" where the crank is, or the piston, in relationship to tdc so that the valves are "timed" with tdc. IT is confusing at first but when you think about it its not bad. A full ten page report could be written on this question. Hope this helps. __________________ 1971 cheyenne k10 4 speed np 205 454 BB factory a/c Never drink down stream of the herd! Eric

05-10-2007, 04:17 AM	#15
GREASEMONKEY72 Registered User Join Date: Aug 2006 Location: Bakersfield,CA Posts: 7,893	Re: Timing marks eedgell- after reading and trying to understand that __________________ -steven Alte Seele S.S. "Allison" '72 C/10 LWB 350SB/TH350 - DD PITBULL IS NOT A CRIME

05-10-2007, 08:32 AM	#16
RustyParts Registered User Join Date: May 2006 Location: Wyman, Kentucky Posts: 403	Re: Timing marks Install with the timing marks facing each other and if the engine has not been rotated you install the distributor with the rotor pointed at #6 plug wire and your ready to go. __________________ 1972 GMC Jimmy, 4WD, 454 CI, 350 Turbo, 4" lift, 35" tires The math teacher said my son "Bubba" could be a mathmatical genius. cause he's got 13 fingers!

05-10-2007, 11:33 PM	#17
eedgell It's the air up here Join Date: Mar 2007 Location: Western Colorado Posts: 710	Re: Timing marks eedgell- after reading and trying to understand that Rookie! __________________ 1971 cheyenne k10 4 speed np 205 454 BB factory a/c Never drink down stream of the herd! Eric

05-11-2007, 12:06 AM	#18
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,233	Re: Timing marks okay was told by my teacher that my distobor would point at number 1 whit timing marks lined up and number top dead center after this tread i am so confused __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube



Register or Log In To remove these advertisements.

05-11-2007, 09:34 AM	#19
RustyParts Registered User Join Date: May 2006 Location: Wyman, Kentucky Posts: 403	Re: Timing marks When you install your cam, install with marks facing each other and forget about it. This will ensure your cam and crank are in time with each other. This keeps all of the rotating pieces from hitting each other as the engine rotates, that's all they do. The reason most manuals tell you to do it this way is because there's less chance of misaligning the marks when they are facing each other than trying to align them across from each other. Once you've rebuilt a couple of engines it will become second nature. Good luck. __________________ 1972 GMC Jimmy, 4WD, 454 CI, 350 Turbo, 4" lift, 35" tires The math teacher said my son "Bubba" could be a mathmatical genius. cause he's got 13 fingers! Last edited by RustyParts; 05-11-2007 at 09:40 AM.

Register or Log In To remove these advertisements.