Fired up the 440 with open hedders

[Highbanked Hauler]

   I don't know if I have a vacuum problem or not. I had to have the manifold cut down so it could bolt in and I put the thin gaskets in to  to take up any space.   Compression is supposed to be 12 to 1 and the starter had to grunt to turn it over with and a bunch of stuff done to the heads. I put a Carter 750 CFM carb on it and lit it off. No neighbors complained this time anyway. Even after it warmed up some I couldn't keep it running below 2000 rpm and that was with the choke closed also which brings me to believe there is a sizable  vacuum leak and the manifold is first in line. I had the carburetor on my other car and it ran fine so I am sure that isn't it.  I know the cam is over 500 lift with 1-6 rockers.  ideas?

[justcruisin]

Could be a vacuum leak for sure, could be lots of stuff. I had a problem similar, swapped carb checked lifter preload checked for vacuum leaks and badly seated intake valves by lifting rocker gear and blocking carb flange and pumping some air into the manifold while listening for a leak, checked valve seating again with air pressure in cylinder, checked for a tight guide, all OK. Swapped out the new hydraulic lifters that I had fitted - bingo  - problem gone.

[Chryco Psycho]

could be a lot of things going on , vacuum leak is a possibility but so it valves adjusted too tight & staying open
,timing settings , start checking everything over .
even at 12;1 compression it should crank over easily

[terrible one]

If the starter is having a hard time you are likely too far advanced. Not the only problem I'm thinking but a good place to start.

[Highbanked Hauler]

could be a lot of things going on , vacuum leak is a possibility but so it valves adjusted too tight & staying open
,timing settings , start checking everything over .
even at 12;1 compression it should crank over easily

   Timing is by sound and feel but I am sure it needs to be fine tuned.  This thing has adjustable push rods and when sitting there is no pressure on any valves. I keep going back to having the choke closed to keep it running ?

[bobs66440]

could be a lot of things going on , vacuum leak is a possibility but so it valves adjusted too tight & staying open
,timing settings , start checking everything over .
even at 12;1 compression it should crank over easily

   Timing is by sound and feel but I am sure it needs to be fine tuned.  This thing has adjustable push rods and when sitting there is no pressure on any valves. I keep going back to having the choke closed to keep it running ?

Are all the bearing clearances correct? It's not too tight is it?

[Highbanked Hauler]

could be a lot of things going on , vacuum leak is a possibility but so it valves adjusted too tight & staying open
,timing settings , start checking everything over .
even at 12;1 compression it should crank over easily

   Timing is by sound and feel but I am sure it needs to be fine tuned.  This thing has adjustable push rods and when sitting there is no pressure on any valves. I keep going back to having the choke closed to keep it running ?

Are all the bearing clearances correct? It's not too tight is it?

  No,you can roll it over with a short bar  on the crank.

[Highbanked Hauler]

  Are there "thick" intake manifold gaskets for it ?

[justcruisin]

Manifold gaskets are available in .015 and .030 or you can get some paper of the size you want and cut some. But generally any variation can be taken up with a little RTV.