Luke Cochran

1980 trans am SBC 350 + cam. Just bought this and ran well for about a month. Was really hard to start one night and died on the way to church next morning. after sitting for about 10min I got it to start again. But it died right as I got home. It's weird because it will appear to be fine and then suddenly start running rough. When it's running rough, the rpm will be everywhere on acceleration. (will idle somewhat less than desirable but really doesn't like gas). After it dies it needs to sit at least 10min before i can get it to start again. Please check out the video fuel maybe? timing?

Gumby22

I’m not able to get the video to play - maybe try hosting on TikTok/YouTube/other and provide a link?

Have you done any work to it since you bought it? Was it sitting for an extended time beforehand?

Your description of the issue indicates loss of spark or fuel.

Have you done any testing when it dies and what were the results?

Luke Cochran

Here's a link to the video on reddit... I've done pretty much no work to it yet and it hadn't been driven much consistently before i bought it. Also might be important to note it's a mechanical fuel pump with a regular old edelbrock carb. thanks for the insight!

https://www.reddit.com/r/Smallblockchevy/s/a4A997dOm3

Gumby22

Being a mechanical pump and carb doesn’t mean it’s not starving for fuel. Especially if it’s sitting more than being driven - that’s when varnish and deposits build up in the carb.

That said, from what I could hear on the video, fuel supply isn’t the first thing I’d be looking at.

To verify mechanical timing, crank the engine without starting it. It’s best to jump power to the starter solenoid control wire, but if that’s not possible, disable spark.

An engine with good timing will crank evenly throughout each revolution - if the timing is off, there will be a distinctly uneven cranking speed.

Keep in mind a weak battery can be misleading during cranking, so I recommend using an auxiliary power source or jumper cables from another vehicle to maintain power.

This is also dependent on not having a high performance camshaft - those cams are not designed to idle, so I’d recommend verifying the camshaft it has and what the base timing is set at.

Otherwise, try checking for spark the next time it stalls and won’t restart.

Luke Cochran

Thanks for the feedback. It has a pretty mild cam not sure on the exact numbers but nothing crazy. would the crank test still work?

Gumby22

Find out what the base timing is - high performance cams tend to be based at 15-20 whereas stock cams are (generally speaking) between 0-10.

If it’s less than 15, the cranking test should be accurate enough.