Low idle vac.

[dodge freak 2]

Cams with 108 lobe centers are not the best for great low speed manners. They make more power but cams with 110 or 112 lobe centers will have a much smoother idle.

Are you positive the intake is sealed well / what about the carb, Holley carbs can leak between the flat surfaces where the metering block seals. No fuel will leak but the motor will idle rough.

Big cams like lots of timing advance at low speeds. This is were an aftermarket dist. is helpful to limit the amount of advance but be able to have like 20 degrees of advance at 1,000 rpms and still like 35 degrees total advance. 

[erat340]

20 years ago I rebuilt the motor with an Eddy cam, very close to stock lift/dur, I think, 114 lsa, always great, could hear each exhaust pulse at idle and cruise. this cam is 110 lsa. I really did expect it to idle better, #60403 voodoo. Tried two carbs, check vac leaks timing adjusted everywhere. Maybe Lunati mis-stamped a radical cam???

[dodge freak 2]

Well that cam is 3 sizes up, there is a 042 an 041 and even a 400.

The 401 might have been what you were looking for.

The air gap intake isn't helping by being so cold. If you check your spark plugs bet you that a few are pretty black-might still be firing but with some misses that aren't noticeable at higher rpms.

Did you try a Edelbrock carb, they do give a better idle...expect they don't like very low vacuum at idle..you need a very light metering rod springs in them cost only a few bucks and very easy to change. I would not buy a new Edel carb, just if ifs free to try, why not see.

If you live in a cool weather state-not Texas ha ha--I would try a heated intake with even the exhaust heat open and a spacer under the carb. Like a Edelbrock RPM or even the stock intake--a stock 340 intake non egr is what I would try. Unless you are looking for a much better idle, then its cam swap time-heck the old 340 stock cam would give the sound and idle you are looking for maybe. Its on a 114 centerline, a nice little cam but today its not as powerful as the new stuff but then it idle great.

 

[erat340]

DF2..you"re thinking what Im thinking...401. Plugs are lookin light tan, OK there. heated manifold?  No way.. here in the Sacramento valley, all my various carbs would hot soak and boil over till the bowls were empty....loooong crank times till I got fuel to start!   Umm, what to do... anyone here want to buy a slightly used voodoo?  LOL

[dodge freak 2]

Yeah no need for a heated intake...it be snowing a month from now where I live and high temps in the mid 40's today--I like my intake heated--the carbs and even valve covers were cool to the touch after a long drive today.

I Ebay the cam and lifters...it sell, I would never use a used cam in a different motor but seems like many will. Just be sure to mark were each lifter goes.....you get...oh between $50 to $85 for them..Ebay is a bit dead on the bidding it seems lately..think people are broke.

[dodge freak 2]

Too bad nobody to my knowledge makes break in rockers with like 1.3 ratio..for Chevy's they make them. I great way to tame a hot cam.

[dodge freak 2]

I've been thinking---those hot cams need the carbs to have air bleed holes drilled in the primary throttle plates, like a .080 hole in each plate. This allows the throttle plates to close more so the idle screws have more effect. I would try to tune it first before the cam swap. 

[erat340]

Update!...out with the 60403, in with the 60401 ...whatta difference! And still pulls as hard...ALL RPMS!..smooth idle too. Did upjet the streetavenger 3 sizes. I would recommend this cam to anyone who wants great low AND high RPM performance. Still dont know why 403 idled like CRAP!

[Chryco Psycho]

Glad you got the engine where you enjoy it 
 the old saying is true , most people buy a bigger cam than they need , possibly youe 403 cam was a poorly ground cam for some reason 

[thesado]

messy,

I'm curious, what's your idle vacuum reading now?

[shadango]

 

[erat340]

Right after the 60401 install. I had 14/15" vac. Been doing alot of advance tuning since then. Ill have to recheck idle vac tonite.

[Chryco Psycho]

there is a lot of tuning thast could have been done with the 403 cam
changing idle bleeds , drilling holes in the throttle plates , adding a lot more advance at idle , If I was there I am sure we could have sorted it out for you , but at least you have what you wanted now