super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
Would the Power Valve opening at idle affect the vacuum reading?
Transfer slots look like small "squares" when viewed from the bottom of the carb. I think this is right.
Just let the car idle for a while and check the plugs? I guess I always assumed that the idle circuit ran a bit rich and plugs would always look black after just idle. Is this incorrect? I can check this tomorrow. As you can tell, I'm not an expert at reading plugs - but I know the difference between black, tan and grey. From my old snowmobiling days, gray is the color you get when "she's running faster then she ever has" right before you melt it down 
Any other opinions on the vacuum level for a 509 cam?
To answer some of your questions, "Yes", if a PV is opening at idle, it will affect the manifold vacuum, because its dumping excess fuel when its not needed, your spark gets week, the manifold vacuum suffers as a result.
If your plugs ARE black, then they need to be changed with a fresh set, in some instences, you may need to go through 3-4 sets of plugs getting things dialed in if your haveing an overly rich condition. You can't properly tune any engine with foiled plugs, the reason it is breaking up at higher RPMs is the fact that the plugs heat range is being interupted & there for causeing them to not fire properly, its simple really, a plug has a specific heat range, this drasticly changes as an engine is under any "load", when they are foiled in any way but not gas/oil soaked, they will fire under the lightest conditions (idles or free reving), its the plugs ability to transfer that heat.
.509s manifold vacuum, on adverage, they will useally be around 10 inches out of gear, the thing about them is there overlap & dur. @ 50, its alot considereing the lower lift, these cams do not have any advance ground into them when built like comp cams do, so when you line up the dots like alot of us do (even though we don't admit it), this can cause issues, i will be the 1st. to admit i just line up the dots, but i'm ready for what may unfold with the tuneing, & for the most part, i get them tuned nicely & they kick ass, they really like to be advanced when installed, you can set them at 106*, but 103-104* would be better, i just put alot of int. timing in them, alot of stall & gears.
I would start with getting more int. timing in it 1st., say 22*, then drop in a fresh set of plugs, install a 4.5/5.5 PV, you also could "barely" crack open the sec. butterflies to let in alittle more air, but don't get carried away doing this, it can & will cause a dead spot, if mainold vacuum still doesn't increase once all this is done, you'll need to advance the cam.
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