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06-15-2014, 02:11 AM
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#1 |
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Registered User
Join Date: Jul 2011
Location: Whitney Point, NY
Posts: 90
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Tapping in cam area
I have a pretty loud tapping in the cam area, front. I have adjusted the lifters loosening them till they rattle then tighten till rattle goes away, then another 1/4 turn. Then tried the way GM has in their manual to take them 1/4 turn every 10 seconds till they are 1 full turn past, the engine doesn't like that. Will shut it down just doing one valve that way. Anyhow, I'm starting to think that the noise may be from the fuel pump pushrod. A friend of mine had that same issue crop up on him once. I'm hoping it's not a warn cam, can't really afford that right now lol.
Is there any actual specs to what length the pushrod is supposed to be so I can measure it ? This is the factory 307, 86k miles on it. |
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06-15-2014, 06:11 AM
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#2 |
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Registered User
Join Date: Apr 2013
Location: South Westerlo, New York
Posts: 1,325
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Re: Tapping in cam area
5.750 inches...
__________________
Thanks, Joe.. 1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB. |
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06-15-2014, 06:43 AM
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#3 |
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laying low
 
Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,118
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Re: Tapping in cam area
I had a hard peck on an 85 one time. It turned out it was the fuel pump. My guess was the internal spring had weakened or broke allowing it to lose contact with the pushrod. I always buy AC replacement parts when available. No more problem.
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Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
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06-15-2014, 08:00 AM
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#4 |
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Senior Member
Join Date: May 2003
Location: Sandown, NH
Posts: 2,806
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Re: Tapping in cam area
I had the same thing yrs ago, it was my fuel pump, the spring in the pump broke. I use a stethoscope to zero in on were thr sound was coming from.
Gary
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Gary 72 SWB 4x4 My 72 SWB Build http://67-72chevytrucks.com/vboard/s...d.php?t=259859 |
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06-15-2014, 12:31 PM
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#5 |
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Registered User
Join Date: Jul 2011
Location: Whitney Point, NY
Posts: 90
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Re: Tapping in cam area
Thanks guys, I never had one fail that way but can see why it would cause the tapping. I'll look into the fuel pump first then measure the pushrod if that didn't solve it
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07-30-2014, 09:13 PM
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#6 |
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Registered User
Join Date: Jul 2011
Location: Whitney Point, NY
Posts: 90
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Re: Tapping in cam area
Just a little update on the tapping noise. Before I looked into the fuel pump and pushrod I decided to recheck my valve adjustment a little closer and found two valves on the passenger side not opening only but half way. I never payed attention to that when I checked everything last time. I haven't checked the driver side but I suspect there are probably a couple there also not opening all the way. There's no slop in the adjustment so the cam has got to be bad.
So with that in consideration I'm thinking there's no sense in just replacing the cam with the chance that there's blockage in the oil journals and starving the cam. Might just as well overhaul the whole engine seems it's gotta come down that far. Or replace it with something bigger, plenty of other small blocks listed on CL and even some big blocks (366, a wicked 427, and 454's....even a low mileage 6.2 diesel) Decisions, decisions, decisions........ Last edited by FrankenCub; 07-30-2014 at 09:30 PM. |
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