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I have a 1978 Chevy van and 3 days ago it started to a ...
Sent to Car Experts February 05 09:05 AM

I have a 1978 Chevy van and 3 days ago it started to a poping sound through the carb. I removed the valve covers and noticed 2 valves were not moving so I replaced all the lifters.The valves work now, but I still have the same problem but as the engine runs the worse the poping gets till the engine stalls. Could it be in the timming? Please help. This is the only transportation we have. Please contact me at Customer (name blocked for privacy)@comcast.net

Optional Information:
Pre-1981 Chevrolet van 350

Customer (name blocked for privacy)
Status:  Closed   Value: $10
Answer
February 5 9:13 AM (8 minutes and 5 seconds later)
         
REPLIEDCheck Mark

There are a couple of things that happened here. Look closely and see if it broke a valve spring first.

The most likely scenerio is it just wore the lobes right off the camshaft. Those older small block Chevy's were pretty notorious for doing that. With the valve cover off and the ignition disabled, try to push down on the lifter side while someone cranks the engine and see if they are lifting the same amount as the other ones.



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Hammer Time -- L1 Master Technician -- 98% Positive Feedback on 2714 Car Accepts
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February 5 7:33 PM (10 hours and 20 minutes and 3 seconds later)
         
Reply to Hammer Time's Post: The lifters seem to be working properly & the valve springs look good.The popping sound gets worse as I drive.It is backfiring through the carb.Within a mile or two it gradually looses power and dies.If I let it sit for about an hour or so I can drive it another mile or so.

Edited by Customer (name blocked for privacy) on February 5 2006 at 7:58 PM
Customer (name blocked for privacy)
Answer
February 5 7:37 PM (4 minutes and 20 seconds later)
         
ACCEPTEDCheck Mark
If it's popping through the intake, either the intake valve is open or burnt or the exhaust valve is not opening at all.

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February 5 8:06 PM (29 minutes and 6 seconds later)
         
You dont think it could have jumped time?
Customer (name blocked for privacy)
Answer
February 5 8:21 PM (14 minutes and 35 seconds later)
         
REPLIEDCheck Mark
That would not cause the valves to stop moving up and down. Just bring it up on #1 timing mark and see where the rotor is pointing to find out. You can also move the crank pulley back and forth and see how much the crank moves before the rotor moves to determine how much slack you have in it.

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Hammer Time -- L1 Master Technician -- 98% Positive Feedback on 2714 Car Accepts
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February 5 8:49 PM (27 minutes and 37 seconds later)
         
All the valves started working again after I replaced the lifters
Customer (name blocked for privacy)
Answer
February 5 9:04 PM (15 minutes and 58 seconds later)
         
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Hammer Time -- L1 Master Technician -- 98% Positive Feedback on 2714 Car Accepts
ASE Mastertech with Adv level Engine performance cert.
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February 6 8:19 AM (11 hours and 14 minutes and 31 seconds later)
         
Reply to Hammer Time's Post: Im sorry to be such a pain in the neck, I'm just aggrivated from loosing tim from work over this
Customer (name blocked for privacy)
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February 7 7:04 PM (1 day and 10 hours later)
         
Relist:
It turned out to be the timming. The chain was so loose that it was barely catching the edge of the teeth on the gears
Customer (name blocked for privacy)
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