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Discussion Starter · #1 ·
ok i am looking at buying a 78 z28, but there is something wrong with the engine. the guy told me that it makes a popping sound. he thought it was the timing chain so he replaced it, but that didn't fix the problem. i haven't had a chance to go look at the car yet. but does anyone have any idea what it could be. i was thinking something was wrong with the carb. also what kind of 4 speeds did this year car come with (saginaw or muncie) and if it is the saginaw how much power will it handle?
thanks
 

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Could be a flat lobe ot two on the cam... Pull the valve covers, disconnect the coil and turn the motor over and look for lack of movement in the rockers (some not opening and closing the valves as much as others). If it is the cam, don't let anyone talk you into just replacing it and the lifters. The metal from the flat lobes had to go somewhere and the lower end is the primary target. I learned the hard way. Even if it's just a tear down and inspection it better than the alternative!

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The trans should be a super T10. Check the size of the yoke, if it is the same size as a TH400 that is what is in the car. A Saginaw will have a small yoke, TH350 size, and will have all three shift levers protruding through the side cover.

Steve R.
 

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Discussion Starter · #5 ·
first question is, is this car worth buying fir $1000. it has a few spots that have surface rust or than that the body is straight(no bondo, checked with magnet) the interior is in decent shape and it has t-tops. second question, how strong is the T10. will it hold up to 350Hp and close to same torque if not more.
 

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Hey Tom,

DJD is right in where to look but it could be as simple as broken rocker,or bent push rod which can be checked the same way DJD said to check lobe.

If none of this is wrong check for broken valve spring. Make sure the rocker you are checking is up (valve closed)and check each spring to see if the opening pressure feels close to the same,if one is much weaker you found it.(use large screw driver)

Ask the guy if the popping noise sounds something like a pop corn popper when you nail the gas if he says yes you defenately have valve train problems.

By the way if you do find a broken valve spring,get a hose out of a compression checker,remove the valve core from the threaded end and use air pressure to hold the valves closed to change the spring.Most any parts store will have the special tool to change the spring.

Good Luck
Larry
 

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I had the same problem many years ago. It was not consistant but I found a broken valve spring. Sometimes it would misfire and other times was just fine but under load was when I would hear it the most. Good Luck.
 

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same problem a while back.....one mech. advance weight was "caught" under the rotor.....

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"Laissez Le Bon Temp Rouler' Cha!"

"Jungle" Jim
Team Chevelle
70SS396 & 70 Malibu
"I don't drive FAST, I just FLY low!"
 
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