Hey collective geniuses,

Car details: '68 442 with 400 and new cam, stock carb, TH400. Automatic, power steering, AC (non-operational), power trunk latch. All of the vacuum lines appear to be correctly installed from ported carb to TVS in "D-C-M" configuration. The manifold vacuum ports to the brake booster and air cleaner switch all connected and operable. Both vacuum booster cans on firewall are connected.

Background behaviors:
1. I have a not so smooth idle lower than 800rpm (possible artifact of new cam), but smooth power on acceleration
2. the car exhibits very high torque/low-end power but seems sluggish/to not follow same acceleration rate toward higher RPMs approaching 1:2 shift point
3. engine temperature swings from 180-200, and in any kind of stop and go traffic or after getting on the throttle exceeds 190* and may approach 200* (even in cool weather)
4. when engine is hot, or in the condition of some heat-soak, and applying mild-strong throttle I am getting engine ping (note: ping not audible when running cool ~ 160-180)

I measured out my manifold vacuum at idle (with port to vacuum canister plugged): 12" hg at 800rpm
With no vacuum to distributor, idle timing is 14* at 800rpm and 36* at 3000rpm


I am trying to learn what the results of different vacuum and timing configurations may be in changing any of the stated behaviors above.

I am thinking of first trying to connect the manifold vacuum to the distrubutor and then adjust timing from there. But I am not sure which port to tap into. Is it safe to put a "T" inline to the transmission modulator? or is there a better source? Will this even matter?

Should I be looking at a different vacuum canister configuration, e.g. VC1765 or other?

Thanks in advance!

--Jim

Cam Spec if you care:
Lunatic Hydraulic Flat Tappet. Good cam for moderate street applications with good vacuum and broad torque curve. Works with all power accessories. Good idle. ; Advertised Duration (Int/Exh): 272/276; Duration @ .050 (Int/Exh): 217/221; Gross Valve Lift (Int/Exh): .485/.485; LSA/ICL: 110/104; Valve Lash (Int/Exh): Hyd/Hyd; RPM Range: Idle-5500

 

Are you still running the stock distributor?

 

It is the stock distributor but the points/condenser replaced with pertronix ignitor and matching pertronix coil.

 

By bumping your initial timing up you maybe getting too much advance from your vacuum cannister. I would disconnect it and see if the pinging goes away. If it does I suggest a limiter. You can also back your initial timing down 2* and run it at 34 total. Your temps are normal and not something to worry about. Joe P has posted in other threads that you can simply disconnect the plug on top of your TCS valve to disable the transmission controlled spark while still maintaining the temperature controlled portion of the valve. The muddled idle quality may be a product of poor carburetor tune.