Hello All,

I posted a question regarding my carb problem yesterday and got no responses.Today I did some more work on this carb.I removed the spacer thinking the misalignment might be the problem.No better.Than I put a vacuum gauge on and set the timing using it.Advanced dist. to get the highest steady reading(21) and back off till it drops about 1 inch of reading.Now the timing marks are advanced about 25 degrees from proper mark on damper.Motor starts fine hot.This has improved the driveability.Now at least I can take it for a run.There is still "delay" of about 2-3 seconds before more fuel kicks in when the pedal is depressed further.This is happening at all speeds.It will cruise at a set speed but is sluggish if more pedal is applied.I checked the plugs and they look OK maybe a little lighter than normal.This is with the limited driving done to test it.I believe the carb is running lean.The build sheet I got with carb says 512 primary and 54 secondary.I have never heard of 512 jets.Disconnecting PCV makes no difference either.Anyone have experience with these 390 Holleys.If I want to change the jet size what should I go with?Any other suggestions on my problem?Thanks Mark

  

512 is a "finer tuned" jet than a 51.  Its basically a 51+ that is less than a 52.  You cant buy a 512 jet, only avail from factory.

On my 292, I wound up with a 56 primary and a 58 or 62 secondary - I bought the kit to convert from metering block secondary to allow jetting.  My block was stamped "59" but I couldnt find consistent cross reference - put in a 62 (IIRC) and it worked fine.

I had similar symptoms, but wouldnt pull high vaccuum (i have a lopier cam).  Turned out that my base plate was not tightened enough to the main body = vaccuum leak.  Tightened up the base screws (from bottom of carb; 6 screws) and it worked MUCH better.

Here is a link to the thread with my problems:

http://www.y-blocksforever.com/forums/Topic16720-3-1.aspx

Ron Grove

Wauconda, IL

The 51 primary jets are most likely two small. Move up too a #54 and you should be ok. If it still seems alittle sluggish then move the primary jets up a #56 and see how it performes. And while the carb is off check and make sure the base plate screws are tight.

-Gary Burnette-