Running Sluggish

[kevin65124]

Hi,
Well recently my 68 has been running a little sluggish in the mornings or sometimes if I havnt driven it all day. It will somtimes backfire through the exhaust. I took it in to get the brakes checked and get a tune up. I was getting the tune up cause I thought that was the problem, well it didnt need a tune up. I was wondering since my exhaust just exits through Hedmen headers and then 2 1/4" pipe then flowmaster 40 series that exit right past the cab. Could the reason the engine is running sluggish be that I am not getting enough back preassure?? Should I run a full lengh exhaust system? Cuase I really need to get the thing running better.

[Piston]

sluggish performance.... backfires out the exhaust... only on startup? Sounds like choke pull-off is bad. Does it clear up after a few minutes of driving?

Before startup, pull the air cleaner off. Set the choke and start the engine, look at the choke plate. Does the plate appear to be open aprox 1/4"? If its completly closed or barely open at all, this is a problem... Shut the engine off, see if the choke pull-off valve will hold vacuum (more than likely it wont).

This is all assuming your engine/carb is stock.

[kevin65124]

The engine is a GM Goodwrench stock 350 replacement motor. The Carb is a 600cfm Holley with electric choke.
it doesnt backfire on start up, its if its running reallly sluggish and I hit the gas to hard while its running like this, it will backfire out the exhaust. But when it warms up for a bit it runs fine.