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#1 |
Registered User
Join Date: Nov 2005
Location: Newton
Posts: 174
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72 gmc 350
Valve lifter making pecking for quite sometime. Plug fouling out at bad lifter location.What is the best way to tell if cam lobe is bad or collapsed lifter, Tried to adjust lifter but could not tighten enough.thanks terry
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#2 |
Sierra Grande Club
Join Date: Jan 2007
Location: New Mexico USA
Posts: 2,433
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Re: 72 gmc 350
I’m think you can tell with a dial indicator by checking how much it raises, & compares it to the others.
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. ![]() |
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#3 |
Registered User
Join Date: Nov 2005
Location: Newton
Posts: 174
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Re: 72 gmc 350
I dont think it moves much at all. Did a head job couple years ago on it. Plug totally fouls out one cylinder only where exhaust valve not working . I am not sure if cam lobe bad or one collapsed lifter. terry
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#4 |
Sierra Grande Club
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Location: New Mexico USA
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Re: 72 gmc 350
Are the valve covers off now?
s/t
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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. ![]() |
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#5 |
Registered User
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Location: Newton
Posts: 174
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Re: 72 gmc 350
No.
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#6 |
Sierra Grande Club
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Location: New Mexico USA
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Re: 72 gmc 350
I’m thinking the only way to tell for sure is to remove the cover and start it up and watch what is going on. If it’s not moving at all you’ll be able to see that. I’m thinking if the cam lobe is wiped, it won’t be moving as much as it should, and this is where you’ll need to measure the lift. Do you have a dial indicator?
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. ![]() |
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#7 |
Registered User
Join Date: Nov 2005
Location: Newton
Posts: 174
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Re: 72 gmc 350
No I do not have one .Any other way besides the obivous out removing.terry
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#8 |
Sierra Grande Club
Join Date: Jan 2007
Location: New Mexico USA
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Re: 72 gmc 350
not sure, (I'm thinking)
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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. ![]() |
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#9 |
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Location: Mt Airy, MD
Posts: 85,858
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Re: 72 gmc 350
If it`s not moving the rocker at all,it`s probably the lifter.A bad lobe wouldn`t be that bad.It sounds like a visual inspection will determine that the rise of the pushrod is less.
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"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
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#10 |
Sierra Grande Club
Join Date: Jan 2007
Location: New Mexico USA
Posts: 2,433
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Re: 72 gmc 350
If, it’s not opening at all, then a leak down tester could possible tell. (will hold pressure in the exhaust stroke) but I have doubts that it is not opening at all, just not opening as much would be my guess.
Did you make sure the plug wires are good allowing good spark to the plug? Just wondering why you suspect it to be the cam. 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. ![]() |
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#11 |
Registered User
Join Date: Nov 2005
Location: Newton
Posts: 174
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Re: 72 gmc 350
When valve job was done the lifter in suspect could not be adjusted down.This is the same valve where plug fouls out. Pecking noise at start up then stops when hot. terry
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#12 |
Registered User
Join Date: Nov 2005
Location: Newton
Posts: 174
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Re: 72 gmc 350
Plug wire fine got plenty of fire to plug.terry
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#13 | |
Sierra Grande Club
Join Date: Jan 2007
Location: New Mexico USA
Posts: 2,433
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Re: 72 gmc 350
Quote:
Anyone else?? 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. ![]() |
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#14 |
Registered User
Join Date: Nov 2005
Location: Newton
Posts: 174
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Re: 72 gmc 350
I think I will remove the intake and remove lifter . If the lifter is just seized is there any other remedy to try first . terry
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#15 |
Registered User
Join Date: Nov 2005
Location: Newton
Posts: 174
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Re: 72 gmc 350
Thanks sport-truck and special-k.
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#16 |
Sierra Grande Club
Join Date: Jan 2007
Location: New Mexico USA
Posts: 2,433
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Re: 72 gmc 350
I think you can free it up using ATF. Not sure how to go about this with the lifter out though. I would check before I pulled the intake off. Because if it just a sticky lifter, you may be able to run some type of cleaner (I think ATF works) and fix the problem.
I would hate for you to do allot of unnecessary work for no reason. Try Google with sticking lifter and see what you find. 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. ![]() |
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#17 |
Sierra Grande Club
Join Date: Jan 2007
Location: New Mexico USA
Posts: 2,433
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Re: 72 gmc 350
IMO this could go either way, but I’m thinking if it was the cam lobe, it wont go away when it’s warm.
Anyone else?? 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. ![]() |
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#18 |
Registered User
Join Date: Nov 2005
Location: Newton
Posts: 174
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Re: 72 gmc 350
Thanks I will try that.
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#19 |
Registered User
Join Date: Nov 2005
Location: Newton
Posts: 174
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Re: 72 gmc 350
Seized lifter or bad lobe either woul cause plug to foul constantly wouldn t it?
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#20 | |
Sierra Grande Club
Join Date: Jan 2007
Location: New Mexico USA
Posts: 2,433
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Re: 72 gmc 350
Quote:
What did you find with Google? 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. ![]() |
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