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Discussion Starter #1
I need advice. Lots of it. I bought a truck with a newly rebuilt engine. It's a 1968 350 block. I've had some problems with it since I bought it. Only have a couple hours on it. The last thing that happened was a rocker bolt broke, sheared like it was made of glass. Didn't strip... just broke. This left a rocker sitting on the head with the nut and washer. The next rocker had been pushed cockeyed on the lifter spring and had bent the pushrod. When I took it off only half the pushrod was there. I found the rest of it mangle in the oil pan. Fished it out with a magnet. Here is the deal. I'm learning my way around an engine. More of a body and paint guy but learning. Thinking this is a good opportunity to pull the motor out and check to make sure the push rod didn't do any damage inside. Hate to start it back up and loose the engine. Give me the chance to clean the firewall up and paint the doghouse. My question.... is there anything I can do while I have this motor apart to make it better. I mean within reason. It has aluminum heads, aluminum intake and a 750 Holley. Ran great before the rocker thing. Needs rear gears but ran really strong. The only problem I had with it before it fell apart was when I set the timing to take pedal it was hard to start hot. When I set the timing back down it hesitated taking fuel. Other than that it ran great.
This board has been great and I figured before I tore into this thing I would get some opinion on what you all would do to this motor while I had it out. I don't know much about the motor part so I'm learning from everything I do and all the info I get. I'll use the truck to play with around home. Not planning to drive it on any long trips and not planning on any racing. Just fun and reliable.

Thanks ahead of time for any input.
Dave
 

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Some Punk Kid
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Buy a "How to rebuild a small block chevy" book and go to it. Thats what I did and it was alot easier than I tohught it would be. I didnt have to use the book while I built it I just read through it one day and was good to go. I only had to refer back for torque specs. And in your case I would open that engine up to find out if anything bad happened in the bottom end being that you found half a pushrod in the oil pan.
 

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I put up the tools against$300
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I would highly suggest the HPbooks. I have learned a lot from them and are indispensible when it comes to reference material. you can get them at just about any bookstore
 

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Discussion Starter #5
poncho62 said:
Book or no book...I would find out why that rocker stud broke.
What could have made the rocker stud break? I've heard of them stripping out, but no one I've talked to has heard of one breaking. It is broke below the upper threads as clean as a whistle. Too loose? Too tight?
What should I be looking for?
Thanks,
Dave
 

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Sloe Lurner
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Bad stud

With aluminum heads it's strange that the stud broke and didnt pull out. who adjusted the valves at rebuild? And what springs are you running and what ratio rockers are you using? Ive only put together about 10 motors so I'm no expert by anymeans but Ive never heard of that happeneing before
 

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Discussion Starter #7
DV8 said:
With aluminum heads it's strange that the stud broke and didnt pull out. who adjusted the valves at rebuild? And what springs are you running and what ratio rockers are you using? Ive only put together about 10 motors so I'm no expert by anymeans but Ive never heard of that happeneing before
I can't give you an answer to any of that. I don't know. I know that the speed shop that built the engine adjusted the valves. I'm in a situation that I don't want to deal with the guys that built it and I'm going to somewhat start from the basics with it. I'm pulling it out to check everything on it before I put all of it back together. I'd hate to put it back together to have a problem that ends up having to break it down anyway. I already have it partially apart and winter setting it so I figured I start from the beginning. Well, I'm not planning on taking out the pistons, crank or cam unless something is damaged.
Dave
 

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Obviously, something in the valve train got out of line and pulled on the stud crooked.....or, a defective stud.
 

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I would replace all of the studs, replace the pushrods, check for coil bind, and replace the rockers with roller units. That should take care of your problem- while its out I would also find out what cam you're running.
 

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I would suspect a valve either stuck or it hit a piston.
 

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rods

well if was it I, I would pull the heads and check the valves to c if it hit the piston, do u have a lock down? and check when u take them off could have been up side down(not like it did that!!! well ok so i did what about it lol cost me about 1500 for that 1 lol ) and i would also check the OIL PUMP! mine went thought it and broke some gears in it. I had my studs break but mine was from my rockers not on right, no bent rods just a lot of metal, change my oil alot lol, good luck with hope all goes well
 

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Discussion Starter #12
Seems that the brass guide that fits into the head that the valve spring sits on was just a tad too long which caused a bind. Everytime the valve opened it was put in a bind and it finally broke the stud. I'm having the shop that built the motor before I bought it go back through it. Seems they had a similiar problem with another set of heads from their supplier. I've never heard of it happening before but it seems plausible.
Dave
 

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Discussion Starter #14
It was a bind issue. The extra length of the brass guide was keeping the rocker from fully making it's stroke and was bottoming out. When it got into the high RPMs something had to give and it was the stud.
 

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simple fix. this is a common problem when running an aftermarket cam with factory iron heads. but if I remember correctly you said that the motor had aluminum heads. have a machine shop cut the valve guides down. .100" should be enough. the head munufacturer should be able to advise.
 
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