heys guys and girls, got a little problem maybe someone can help. i have a 73 with a 350 motor. started running rough like it's missing a couple weeks ago. i replaced the distributor cap and rotor, all the plugs, and checked the timing. still runs rough. i hate
to take to the shop, all you have to say is "corvette" and the $$$$$$$$$$$$ start ringing. had a broken valve spring a few years
back, and that's kinda what it seems like again. how hard is this to diagnose, and is something i can manage myself. have plenty
of room in the garage, and many tools. any ideas???. thanks for the help...

 

It sounds like you would benefit from a compression test and/or a vacuum check. Look for low compression in one or more cylinders.
You did not replace the plug wires? Could be a bad wire......

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If you've already experienced a broken valve spring, then there's a good chance you've got another one. I broke two on mine before I went to the Chevy high performance springs. Found out that the small blocks were using regular psgr car springs. []

Try pulling one wire at a time 'til you find a cylinder that it has no effect on.

 

you could pull the valve covers off and look for a busted spring. And if very careful, you could change the spring with out removeing the head. Unless you decide to replace them all(suggested action to take)

 

As stated by "Blk and Blu" firstly, the compression and vacuumgauges will point to the problem. Obviously, "Blk and Blu" is a "hands-on" motor-head who knows the two tools that get to the point right off the bat, without guessing or jumping to conclusions.
IMO, these two gauges are two of the very best tools one could have in their box.


As much of a drag as it is, after 1971, the 'VetteWAS given the regular old "run of the mill" internal enginecomponents (as stated by '73 Shartk) as the EPA got their way and 'Vette engines (along w/ all the others) no longer needed extra strong internals as compression was lowered and in-turn horse power with the remains of the internal combustion system falling in line. (Along w/ the 55 speed limit and unleaded fuel ONLY)

 

thank you all for the suggestions, i know what i'll be doing this weekend now. what i don't
have, i can get my hands on. i'll start with the plug wires, don't know why i didn't go ahead
and replace them with the other items mentioned. i'll keep you posted as to the outcome.
again thank you all.

 

DeeVee,
SO sorry for mixing up the user names with the info given. I read the replies and didn't pay close enough attention to the names. My bad, again, very sorry.
Pulling the wires one by one works, but a resistance test w/ a multi meter on each wire along with a visual inspection works well also, and keeps you from possibly getting "ZAPPED" and saying bad words in the process. LOL. Each wire should read very close. If one shows a big difference, alot more reisitance, then replace it and see what the outcome is. Good luck.

 

No Problem! But I want some of whatever it is that you're drinking (or smoking)!

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9673, May I suggest; before you go renting or investing in a bunch of test guages, check out all your vacuum hoses. These engines will get rough with any small vac. leak. Good Luck! j