Bog/rough running at 70mph

[HO455]

Asto the OP's question. To check the timing advance hook up a timing light and while looking at the timing mark on the balancer rev the engine up. The mark should move about an inch. This the very basic test to see if the mechanical advance is working. For more detailed information there are dozens of videos and other articles on the interweb that detail how to set the timing properly.

On the fuel side a quick and easy check would be to remove the gas cap and do a test run. That would tell you if your tank isn't vented properly.

You didnt mention what year or how modified your truck is. That information may help us troubleshoot.

Also any rubber hose between the fuel pump and the tank should be checked to see if it has collapsed. If it looks flat it may be collapsing and restricting flow to the fuel pump.

Good luck and keep us posted on what you discover.

[Awann99]

Originally Posted by HO455

Asto the OP's question. To check the timing advance hook up a timing light and while looking at the timing mark on the balancer rev the engine up. The mark should move about an inch. This the very basic test to see if the mechanical advance is working. For more detailed information there are dozens of videos and other articles on the interweb that detail how to set the timing properly.

On the fuel side a quick and easy check would be to remove the gas cap and do a test run. That would tell you if your tank isn't vented properly.

You didnt mention what year or how modified your truck is. That information may help us troubleshoot.

Also any rubber hose between the fuel pump and the tank should be checked to see if it has collapsed. If it looks flat it may be collapsing and restricting flow to the fuel pump.

Good luck and keep us posted on what you discover.

I'll put in an order for a new sock along with the fuel filter. I didn't even think about that. It's still running it's original tank so it probably could use a good cleaning too.
The truck is a 69 1500 lwd 2wd. Goodwrench 215 hp V8 sitting in the i6 position. I'm running an ancient edelbrock sp2p intake. The truck is as stock as I can keep it. I'm running a 1969 original air cleaner housing as well. The fuel lines have not been swapped over to the v8 size.

Thank you for the advice on the timing. It's good to hear this is probably just an issue with fuel starvation and not timing.
I will keep y'all updated when the parts arrive.
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