The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Truck running poorly under load, need help.

rich weyand · 08-26-2016, 01:57 AM

Then you're way retarded. With the vacuum connected, you ought to read about 30* BTDC. That's where your power went.

People tell you to block the port in the carb when you disconnect the vacuum advance, but you don't need to as long as it runs. It's purely a mechanical measurement.

Just pull the hose off and measure what you have. You're probably around 6* AFTER top dead center without the vacuum advance.

It could have dragged that way if the disti wasn't clamped tight.

You probably want to start with a setting between 12 and 16. Sorta depends on what vacuum advance you have. Set it at 12 for now, and let's see what you get.

08-26-2016, 01:57 AM	#20
rich weyand Registered User Join Date: Apr 2014 Location: Bloomington Indiana Posts: 1,041	Re: Truck running poorly under load, need help. Then you're way retarded. With the vacuum connected, you ought to read about 30* BTDC. That's where your power went. People tell you to block the port in the carb when you disconnect the vacuum advance, but you don't need to as long as it runs. It's purely a mechanical measurement. Just pull the hose off and measure what you have. You're probably around 6* AFTER top dead center without the vacuum advance. It could have dragged that way if the disti wasn't clamped tight. You probably want to start with a setting between 12 and 16. Sorta depends on what vacuum advance you have. Set it at 12 for now, and let's see what you get. __________________ Rich Weyand 1978 K10 RCSB DD.