HELP! Vacuum at idle?

[Tor-King]

Hi everyone!

I am in the process of syncing the carbs.  I am using a Morgan carbtune and it sounds like it is dialed in.  The readings across the board at 1100 RPM idle is 190 mm Hg (19 cm Hg).  I know that it is critical to ensure that all carbs are set to within 10 mm Hg (1 cm Hg) but is the absolute reading important?  I thought I had read that each cylinder should be 240 mm Hg.  If so, how do I bring it up to those readings without increasing idle speed??  Also, it hangs up ever so slightly at about 1200 or 1300 before settling down to 1100.  I cannot remember if that means the mixture screws should be turned IN slightly or OUT slightly.

PLEASE help!

Thanks,
Dean

[Pat Conlon]

Hello Dean,
Don't worry about vacuum readings on the Morgan Carbtune, just sync the carbs so the level of the 4 rods are as close as possible to each other. Make sure the Morgan is hanging close to vertical so the rods move freely.
Start with balancing 1 and 2 together then move over to 3 and 4 then with the center adjuster balance 1/2 with 3/4

Re: blip test...a hanging idle indicates a lean condition so you want to richen your idle mixture screws by turning them out. Try 1/2 turn increments.
You know it will be too rich when blipping the throttle the idle drops down (bogs) to 800-700 rpm then returns back up to 1100 so you will have to turn your screws in to lean the idle mixture.

In to lean (clockwise).....Out to richen (counterclockwise)    Hope this helps.  Pat

[Tor-King]

Hello Dean,
Don't worry about vacuum readings on the Morgan Carbtune, just sync the carbs so the level of the 4 rods are as close as possible to each other. Make sure the Morgan is hanging close to vertical so the rods move freely.
Start with balancing 1 and 2 together then move over to 3 and 4 then with the center adjuster balance 1/2 with 3/4

Re: blip test...a hanging idle indicates a lean condition so you want to richen your idle mixture screws by turning them out. Try 1/2 turn increments.
You know it will be too rich when blipping the throttle the idle drops down (bogs) to 800-700 rpm then returns back up to 1100 so you will have to turn your screws in to lean the idle mixture.

In to lean (clockwise).....Out to richen (counterclockwise)    Hope this helps.  Pat


Hi there Pat!

That was the response that I was hoping for.  I think I have it all dialed in now.  All four rods finally settled in around 20 cm Hg at 1100 rpm.  This was after playing with the mixture screws a little and the idle adjuster.  They are now turned out 2 turns from lightly seated. 
Now for the next question:
I recently rejetted the carbs back to stock (with Randy's kits).  They had 42.5 pilot jets (stock for UK and Canadian models) so I had to play with the mixture screws a little.  Because the pilot jets are larger than I had before (37.5) with the mixture screws at 3 turns out, should the mixture screws be leaned out slightly to compensate for the larger pilots?  Does that sound about right?  Hope that makes sense.   

Thanks again and have a good one,
Dean

[Pat Conlon]

Yep, that is correct. It is common when going to larger pilots to (after a blip test) turn in, or lean the idle mixture screws.