505ci Tuning Tips, Thoughts, Opinions

[MJFUR]

69 Chrysler 300, the 440ci is now a 505ci, 727 TF, 4640S Carb (reworked by Woodruff), Edelbrock Performer Manifold, 906 Heads with larger valves, Liberty Crankshaft, Icon Forged Pistons, Lunati Voodoo Cam .494/.513, 9.8 - 10.0 c/r.

I've got the Idle Mixture Screws backed out 2 turns. If I pull the PCV line off of the carb (creating a vacuum leak) engine rpm will drop down to about 500rpm, then quit.
When at normal operating temperature, idle is set at 1000rpm in Neutral. When I put the car into Drive with foot on brake, engine drops to 800rpm. If I then turn on the A/C, engine will drop to about 730-750rpm.
The engine doesn't really like to idle much below that 750rpm mark.

Any others with similar results or can I tweak some more?

Thx

 

[mikedrini]

69 Chrysler 300, the 440ci is now a 505ci, 727 TF, 4640S Carb (reworked by Woodruff), Edelbrock Performer Manifold, 906 Heads with larger valves, Liberty Crankshaft, Icon Forged Pistons, Lunati Voodoo Cam .494/.513, 9.8 - 10.0 c/r.

I've got the Idle Mixture Screws backed out 2 turns. If I pull the PCV line off of the carb (creating a vacuum leak) engine rpm will drop down to about 500rpm, then quit.
When at normal operating temperature, idle is set at 1000rpm in Neutral. When I put the car into Drive with foot on brake, engine drops to 800rpm. If I then turn on the A/C, engine will drop to about 730-750rpm.
The engine doesn't really like to idle much below that 750rpm mark.

Any others with similar results or can I tweak some more?

Thx

View attachment 533278

Yeah man, my 505/727 setup has the 440 source 505 kit, 10.5:1 CR, a .600 lift Howards Cam in it, Trickflow 240 heads with Hughes Roller Rocker Arms (which are AMAZING by the way), custom pushrods, Cometic Head Gaskets to raise the CR to around 11:1, RPM Performer Intake, shorty truck headers, 900CFM custom carb with annular boosters and mechanical secondaries, vacuum advance dizzy custom built and curved by our own Halifaxhops and a stock torque converter with modified stall around 2800. I had to install an electric vacuum pump and cannister to use power brakes (DISC/DRUM setup). My initial timing is at about 23, idle RPM's in Park about 11-1200 depending on the season. I'm no expert, so I installed an AFR gauge and bought a Innova Digital Timing Light to set my timing. I'm currently learning how to read plugs, so that will help too, but I love having that AFR gauge as a beginner.

I don't have AC, but I did have similar issues to what you're describing. I couldn't wrap my mind around bumping my timing and idle speed up that high, but after doing research, seeing what others did, and then trying it, it made sense and worked! She's running strong with no ping, fouled plugs, etc.

 

[CBODY67]

Something doesn't sound "right" to me, just reading your posts. I know the cams are larger than normal, but so is the engine they are feeding. It's mainly the cams and torque converters which are dictating how things act at idle, just like with a smaller displacement engine. But over 1000rpm, considering? That part seems a bit out of whack, to me, all things considered. Plus needing 23 degrees BTDC for base timing to act better? Which makes me wonder if you used a degree wheel and dial indicator to find real TDC and mark it?

Just some curious thoughts,
CBODY67

 

[mikedrini]

I wouldn't sweat it, it's only money, can't take it with you.

 

[66 Monaco 500 365]

Is there a chance at 1000 RPM the centrifugal advance is coming in?
When the RPM drops, the ignition retards making bigger changes in RPM than normal.
My $.02