Cold Starts after a tight Tuck Header install and 2.5 inch Exhaust system

[MakoJoe]

Hi all,

Been Struggling with this for a few weeks and will give as much info as I can.

I have a 1977 Corvette that I had tuned in with the stock manifolds running CATs and 2 inch Exhaust system.   This is a Low Altitude Carburetor I live and run the car between 5000 and 9000 feet above sea level.  I was able to do cold starts without much problems before I installed the new exhaust system. 

With the engine hot I put a Vacuum Gauge on the engine and was able to achieve 14 PSI on a Vacuum Gauge on the PCV valve intake into the base of the carburetor without really changing the Idle Mixture screws much.   

I am 3.5 turns out on my Idle Mixture Screws.

After installing the Tight Tuck Headers, 2.5 Inch Exhaust to Magna Flow Mufflers this thing runs like crap and been struggling to get it back in tune.   Once the engine heats up it runs ok but stumbles when I kick in the Secondaries at Higher RPMs

I think is that like between 2500 and 3000 RPMs

Cold Starts and Hot Starts are now my problem.   Takes forever to start the engine up and 50 % will start on idle when hot without priming the engine again.

I have a clear filter and can see it drain down back towards the tank.

need some help

thanks

Joe

[Cliff Ruggles]

If it's running poorly after the install but better when warmed up things are too lean.

Poor starting is most likely unrelated to the header installation, as free flowing exhaust changes nothing for idle quality and cold or hot restarts.

What is the carb number and what has been done to it?.....Cliff

[nikothenomad]

Thought I would jump in on this one and see what comes of it.

I've had this hot weather starting difficulty since we bought the van in 2010.  We bought it during the cooler season and it started and ran wonderfully.  No problems.  As temps warmed up we noticed that it was harder to start.  Once started though it runs wonderfully.

The problem continues to this date and I haven't figured out a fix. 

We are in super warm FL right now and if we try to start the van in the afternoon it gives us trouble.  If we instead go out in the morning hours when it is still cooler she fires right up after closing the choke and giving her a shot of fuel (one pump).

The numbers I've found stamped on the side of my carb are 17087175 under it are 1468 and 419.

Thanks.