Valve adjustment question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

lukecp · 06-15-2003, 01:59 PM

I just got done adjusting the valves after putting new heads on my 350. I adjusted the valves as instructed by my Haynes manual. I put the #1 piston at TDC on the compression stroke, then tightned each rocker nut until i felt a drag on the pushrod while turning, and i could no longer move the pushrod up and down. I then tightned each nut another 1/2 turn. I adjusted all of the valves by turning the crankshaft 90 degrees, and in the order of the firing order. After i adjusted them, i went back over them to double-check everything. It seems that about half of the rockers have a bit of play in them. That means i can grab the rocker by my hand, and it will move a little bit. Is this normal? I thought they were supposed to be movement free?

All i need to do is put my carb, headers, valve covers, and vaccum hoses on and start the truck up, but i want to make sure i didn't screw up the valve adjustment.

lukecp · 06-15-2003, 03:43 PM

ttt

bpmcgee · 06-15-2003, 04:34 PM

Yellow,

I've found that when I tried that my valves were way overtight. My best luck has been to tighten them until you can JUST START feel the drag on them. Then stop.

Brian

jef5150 · 06-15-2003, 04:56 PM

#1 position do, exhaust 1,3,4,8...intake 1,2,5,7 till play is gone then 1 full turn.... rotate till#6cyl firing pos,,{"0"}on dampner,,then exhaust 2,5,6,7.intake, 3,4,6,8 till play is gone ,then 1 turn////////SOME ONE AGREE OR DISAGREE,,,,,,I DONT WANT HIM TO RUIN HIS MOTOR

Longhorn Man · 06-15-2003, 05:16 PM

One turn past zero lash is what GM does say, however, your engine will rev a bit better and (in thorey) you'll get more power and better MPG with just 1/2 past zero. (old hot rodder's trick)
however, at only 1/2 past zero, you do run the risk of the clip holding the plunger in the lifter poping out.
With these facts in mind, i normally do mine 3/4 (or so) past zero lash.
The movement you feel in your rockers is most likely fine. You can fine tune them after initial start up.

jef5150 · 06-15-2003, 05:36 PM

the reason for the 1 full turn is to center the push rod into the lifter plunger cap,,,,,

lukecp · 06-15-2003, 05:39 PM

Sounds good then. I think i will go ahead and tightnen them 3/4 turns to split the difference, lol. If i start it up and the rockers are a bit off, will it hurt anything? I just spent quite a bit of money on the heads, and my 20k rebuilt shortblock appears to be in excellent shape, so i don't want to mess anything up.

Thanks alot for the help.

jef5150 · 06-15-2003, 06:21 PM

you know you have to adjust CERTAIN VALVES at #1 firing position,then rotate motor to #6 firing and adjust the others,,,,,

lukecp · 06-15-2003, 07:38 PM

I adjusted both valves on #1, turned the crank 90 degrees, than adjusted #8, and i did that for the rest of the firing order. That was so each cylinder would be at TDC on the compression stroke when i adjusted the valves.

I got the truck put back togheter after tightening down the valves to 3/4 turns, and i tried to start it. It cranks pretty smooth ( a bit slower due to the higher compression, lol), but it wouldn't start. It backfired twice. I know it has fuel. Maybe i put the #1 plug wire on the #8 spot on the distributor and got the wires all out of wack. It is getting kinda dark and i am tired of working on it, so i will just mess with it more tomorrow.

Longhorn Man · 06-15-2003, 09:29 PM

Sounds liek the dreaded 180degrees off thing.
Why do we always do that?

Blue_71 · 06-15-2003, 09:47 PM

i actually got lucky and didnt do mine 180 off when i put the points dist in, now with the new hei it wont start for anything!!!! no fire at all, just turns.......

try retarding the timing before you take the dist out again

Longhorn Man · 06-15-2003, 10:06 PM

I got way luckey when i put the caddy engine back together. The bottom pully said it was at TDC (which as most of us know can be right, or 180 off), so i just tossed the dist in there, wired it up, and got it on the 3rd or 4th time. I did end up having to retard it by moving the wires back one and relocating all of them one over...but I never had to pull the sucker back out though.

06-15-2003, 03:43 PM	#2
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	ttt __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

06-15-2003, 05:39 PM	#7
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Sounds good then. I think i will go ahead and tightnen them 3/4 turns to split the difference, lol. If i start it up and the rockers are a bit off, will it hurt anything? I just spent quite a bit of money on the heads, and my 20k rebuilt shortblock appears to be in excellent shape, so i don't want to mess anything up. Thanks alot for the help. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

06-15-2003, 07:38 PM	#9
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	I adjusted both valves on #1, turned the crank 90 degrees, than adjusted #8, and i did that for the rest of the firing order. That was so each cylinder would be at TDC on the compression stroke when i adjusted the valves. I got the truck put back togheter after tightening down the valves to 3/4 turns, and i tried to start it. It cranks pretty smooth ( a bit slower due to the higher compression, lol), but it wouldn't start. It backfired twice. I know it has fuel. Maybe i put the #1 plug wire on the #8 spot on the distributor and got the wires all out of wack. It is getting kinda dark and i am tired of working on it, so i will just mess with it more tomorrow. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

06-15-2003, 01:59 PM	#1
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Valve adjustment question I just got done adjusting the valves after putting new heads on my 350. I adjusted the valves as instructed by my Haynes manual. I put the #1 piston at TDC on the compression stroke, then tightned each rocker nut until i felt a drag on the pushrod while turning, and i could no longer move the pushrod up and down. I then tightned each nut another 1/2 turn. I adjusted all of the valves by turning the crankshaft 90 degrees, and in the order of the firing order. After i adjusted them, i went back over them to double-check everything. It seems that about half of the rockers have a bit of play in them. That means i can grab the rocker by my hand, and it will move a little bit. Is this normal? I thought they were supposed to be movement free? All i need to do is put my carb, headers, valve covers, and vaccum hoses on and start the truck up, but i want to make sure i didn't screw up the valve adjustment. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

06-15-2003, 04:34 PM	#3
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	Yellow, I've found that when I tried that my valves were way overtight. My best luck has been to tighten them until you can JUST START feel the drag on them. Then stop. Brian

06-15-2003, 04:56 PM	#4
jef5150 Inline 69 Join Date: Apr 2003 Location: valleysprings,california Posts: 1,018	#1 position do, exhaust 1,3,4,8...intake 1,2,5,7 till play is gone then 1 full turn.... rotate till#6cyl firing pos,,{"0"}on dampner,,then exhaust 2,5,6,7.intake, 3,4,6,8 till play is gone ,then 1 turn////////SOME ONE AGREE OR DISAGREE,,,,,,I DONT WANT HIM TO RUIN HIS MOTOR

06-15-2003, 05:16 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	One turn past zero lash is what GM does say, however, your engine will rev a bit better and (in thorey) you'll get more power and better MPG with just 1/2 past zero. (old hot rodder's trick) however, at only 1/2 past zero, you do run the risk of the clip holding the plunger in the lifter poping out. With these facts in mind, i normally do mine 3/4 (or so) past zero lash. The movement you feel in your rockers is most likely fine. You can fine tune them after initial start up.

06-15-2003, 05:36 PM	#6
jef5150 Inline 69 Join Date: Apr 2003 Location: valleysprings,california Posts: 1,018	the reason for the 1 full turn is to center the push rod into the lifter plunger cap,,,,,

06-15-2003, 06:21 PM	#8
jef5150 Inline 69 Join Date: Apr 2003 Location: valleysprings,california Posts: 1,018	you know you have to adjust CERTAIN VALVES at #1 firing position,then rotate motor to #6 firing and adjust the others,,,,,

06-15-2003, 09:29 PM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Sounds liek the dreaded 180degrees off thing. Why do we always do that?

06-15-2003, 10:06 PM	#12
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I got way luckey when i put the caddy engine back together. The bottom pully said it was at TDC (which as most of us know can be right, or 180 off), so i just tossed the dist in there, wired it up, and got it on the 3rd or 4th time. I did end up having to retard it by moving the wires back one and relocating all of them one over...but I never had to pull the sucker back out though.



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