Manbearpig
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This trucks kinda pissing me off lately.
- Thread starter Irishman999
- Start date
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crazy4offroad
Equal Opportunity Destroyer
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With all the bent pushrod problems, what did you do to fix the valves? You could have collapsed the lifters as well. You should just gather the parts to do a rebuild and be done with it.
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- HotRod
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- 85 K20 LWB
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- 454 - Turbo 400 - 3.73
Don't you dare park it at Pick N Pull. These old Square Bodys are so easy to work on, cheap to find parts for, parts are plentiful, so no reason to junk one just cuz it has a hiccup. Only good excuse for scrapping one of these trucks is excessive rust.
I'd imagine if you put an RV cam or smaller specs, you'd have 20" of Vac at idle.
Its a good possibly of cam lobe damage if you had stuck valves, or the valves were ever adjusted to tight. Sounds like someone did a good job on the Qjet rebuild and if no vac leaks at the intake runners or carb, and its in time, keeping in mind, even with a timing light and lots of slack in your chain and gears, can make a liar out of a timing light too. Here is another suggestion to consider. Depending on the year model or the heads on the truck, I had an 81 GMC that I bought used for real cheap cuz the guy said it had a miss that he could never find and he got sick of being pissed off and frustrated with it, as it sounds you are with yours. I forget how or why now that I decided to pull the heads off, and when I did, I found the exhaust valves were recessed considerably. The good old unleaded gas damage that some claim does not happen and is just a myth. BS, I have the proof it happens. Those valves on the worst cylinders were recessed almost a 1/2 inch. Duh, no wonder it had a miss and lacked power. Put a set of rebuilt heads with hardened seats on the motor and it ran like a raped ape and smooth as glass afterwards.
I'd imagine if you put an RV cam or smaller specs, you'd have 20" of Vac at idle.
Its a good possibly of cam lobe damage if you had stuck valves, or the valves were ever adjusted to tight. Sounds like someone did a good job on the Qjet rebuild and if no vac leaks at the intake runners or carb, and its in time, keeping in mind, even with a timing light and lots of slack in your chain and gears, can make a liar out of a timing light too. Here is another suggestion to consider. Depending on the year model or the heads on the truck, I had an 81 GMC that I bought used for real cheap cuz the guy said it had a miss that he could never find and he got sick of being pissed off and frustrated with it, as it sounds you are with yours. I forget how or why now that I decided to pull the heads off, and when I did, I found the exhaust valves were recessed considerably. The good old unleaded gas damage that some claim does not happen and is just a myth. BS, I have the proof it happens. Those valves on the worst cylinders were recessed almost a 1/2 inch. Duh, no wonder it had a miss and lacked power. Put a set of rebuilt heads with hardened seats on the motor and it ran like a raped ape and smooth as glass afterwards.
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Irishman999
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There's no way its going to pic-n-pull haha. Im committed at this point since i told my uncle the next time he see's it the truck will be restored, maybe not restored but have paint and run great.
The valves were either rusted shut in the valve guide or gummed up with varnish from old fuel, im thinking they were rusted. You would not believe how i fixed it, I got PB blaster and soaked the piss out of the valve springs and let the spray seep down the valve into the guide. After hours of doing that i started tapping on the valve with a hammer until they started moving. Once they started moving they would stick open and slowly creep out. I did this for many hours until they seemed to move fine. I put the rockers back on and marked them with neon paint, Then i had my wife watch the rockers while i turned the motor by hand. The valves that still stuck i would remove the rocker and place a socket over the pushrod and crank down on the nut until the spring was compressed all the way. Once the motor turned 4 or 5 times with no stuck valves i put new pushrods in it and she ran PERFECT.
It worked to an extent, it was just a band aid for the problem until i had time and space to tear it down. The most amazing thing is the piece of pushrod that is still bouncing around in the lifter valley haha. I drove the truck well over 1000 miles pulling a trailer and it cost less than 20 bucks.
Its still plenty drivable and actually getting great mileage. I guess i will just keep an eye on craigslist for a set of heads i can get rebuilt, buy a after market cam and lifters and just dedicate a weekend to fixing it the right way.
The valves were either rusted shut in the valve guide or gummed up with varnish from old fuel, im thinking they were rusted. You would not believe how i fixed it, I got PB blaster and soaked the piss out of the valve springs and let the spray seep down the valve into the guide. After hours of doing that i started tapping on the valve with a hammer until they started moving. Once they started moving they would stick open and slowly creep out. I did this for many hours until they seemed to move fine. I put the rockers back on and marked them with neon paint, Then i had my wife watch the rockers while i turned the motor by hand. The valves that still stuck i would remove the rocker and place a socket over the pushrod and crank down on the nut until the spring was compressed all the way. Once the motor turned 4 or 5 times with no stuck valves i put new pushrods in it and she ran PERFECT.
It worked to an extent, it was just a band aid for the problem until i had time and space to tear it down. The most amazing thing is the piece of pushrod that is still bouncing around in the lifter valley haha. I drove the truck well over 1000 miles pulling a trailer and it cost less than 20 bucks.
Its still plenty drivable and actually getting great mileage. I guess i will just keep an eye on craigslist for a set of heads i can get rebuilt, buy a after market cam and lifters and just dedicate a weekend to fixing it the right way.
85k10383
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Only good excuse for scrapping one of these trucks is excessive rust.
That would be my truck, but I love her and can't quit her! LOL Mine now runs like a champ but looks like hell.
Irish I challenge you to try that "bang on valves with hammer" trick on a junked import some time! Ten bucks says it won't work LOL
