trying to figure out how vacuum is important to my car to track down why it's so hard to start. thinking the cam may possibly not be making enough vacuum but if that's the case then how come it runs fine after it is up and running for a minute?

 

Vacuum is what drives the MAP sensor, which (in a speed-density system) has a large degree of control over how much fuel goes into the engine. If your vac is low the MAP sensor thinks the engine is under a load and richens the mix to compensate.

Vacuum is also an indicator of the engine's ability to breathe. Low cranking vacuum will usually indicate bad valve timing or a stopped up cat, or sometimes a lack of compression. Exactly how big IS this cam anyway? And was it just stuck in the block or actually degree'd?

 

duration at .050 is 230 intake 236 exhaust. twice the size of what my old cam in my old 383 was.

so how can i check and try to fix the issue if that is in fact whats going on since the symptoms are leaning that way?

 

I'm running a 235/235 at .050 and don't have any vacuum problems. That is on a carbed car though....SD systems are fairly picky about vacuum levels, although yours shouldn't be as bad as a stock-runner TPI setup. Get a vacuum gauge on the car (use the fuel pressure regulator port) and see exactly what it is when cranking and running. If you have 15"hg or more running and at least 8-9 cranking, you don't have vacuum issues. If your running vacuum is good but cranking is low, you may need to go to a gear-drive starter to turn the engine faster during startup. If both are low, check for a clogged converter and run a compression check just to be sure.

 

thanks..i'll try that right away!