Stock 78 Z28 Running Poorly. Help!

78Z28350

New Member
Jul 5, 2022
23
I had a similar problem with my 80 Z28, lacked power, backfired through carb, turned out some of the cam lobes were worn down, I was able to witness this by removing both valve covers and viewing the rockers, two were hardly moving.
Just though I would chime in.
Thank you for the suggestion. If the timing adjustments make no improvement to the car's performance, I'll look at this next.
 

78Z28350

New Member
Jul 5, 2022
23
That's the part. The wires on those can fray or break and cause a misfire when the distributor advances. If the broken wire separates it can kill the engine on acceleration and then restart once the engine stops running.
That's simple to check. I'll look at it at lunch. Thanks for the tip!
 

78Z28350

New Member
Jul 5, 2022
23
what oil are you running in this engine? did this problem start after you tuned it
I'll have to ask my uncle. If if recall correctly he's always ran Valvoline 10W30.

What prompted the carb rebuild and fuel system refresh was the car stumbling then completely stalling out when driving and being hard to restart. I immediately noticed the accelerator pump was toast so that is why I went through the carb. I found evidence of rust in the fuel system when i looked at the old filter, so I pulled the tank and confirmed it.

It hadn't been tuned up in 15 years so I went ahead and did that while I was at it.

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ob355

Member
Mar 4, 2022
66
modern oils do not provide the proper PSI for flat tappet cams. you need to determine if its a mechanical or air/fuel problem.
 




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