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Timing and Vacuum question
https://www.slantsix.org/forum/viewtopic.php?t=29316		 Page 1 of 1
Author:  MichaelS [ Wed Jun 04, 2008 3:20 pm ]
Post subject:  Timing and Vacuum question
I have a '74 225 with 1945 Carb. OSC disconected, EGR disconected.
At idle the timing is at 6 degrees before TDC, were should it be?

When I disconected the vacuum line to the distributer it has no suction, all the other lines hiss when removed, is this normal or is my distributer not getting the vacuum it needs? The line is not clogged and I can blow thru it to the carb with no restriction.

Last question, my PCV valve rattles at idle, is this normal? When I pull it off it has lots of suction, it just likes to rattle.
Author:  SlantSixDan [ Wed Jun 04, 2008 3:27 pm ]
Post subject: 
6° BTDC is a reasonable timing setting as a starting point for a '74 like yours with a stock distributor and EGR disconnected, but keep a careful ear open for pinging.

The vacuum advance hose should not have vacuum at idle — only at higher-than-idle engine speeds. Rev the engine and you'll probably find the vacuum you thought was missing.

The rattling PCV valve is more an annoyance than anything. If it bothers you, install a replacement valve.
Author:  MichaelS [ Wed Jun 04, 2008 3:33 pm ]
Post subject: 
Thanks Dan, I was hoping it was OK.
I do get slight pinging under throttle up a hill, any sugestions? Reduce timing a little?
Author:  SlantSixDan [ Wed Jun 04, 2008 3:46 pm ]
Post subject: 
How to fix this depends on how much time, effort, and money you want to put into it. Quick 'n' easy would be to try a setting of 4° BTDC and see if that takes the pinging away. What spark plugs are you running?
Author:  MichaelS [ Fri Jun 06, 2008 6:47 am ]
Post subject: 
Dan, I have NGK GR4 plugs in it. What is the sugested gap setting, the ignition is stock except for the wires ( magnacore 8mm)?
Author:  SlantSixDan [ Fri Jun 06, 2008 8:27 am ]
Post subject: 
Try a set of ZFR5N plugs, which are one heat range cooler, and see if that doesn't take the ping away altogether. Remember to remove the metal ring washer from each plug before installing it. Gap to 0.040" if you pay reasonable attention to your plugs and will make your NAPA counterman give you a real, actual, tan plastic Echlin #MO-3000 rotor (and not a misboxed white plastic MO-13...he may have to get his W.D. to order directly from Standard-Echlin's factory stock). Otherwise gap to 0.035".
Author:  LUCKY13 [ Fri Jun 06, 2008 10:10 am ]
Post subject: 
On the EGR thing I take and cut the valves off/out of the mounting plate until there is nothing but the base/mounting plate left. THen you have a blockoff plate just by turning it 180* and bolting it back on.


Jess
Author:  Aggressive Ted [ Fri Jun 06, 2008 11:57 am ]
Post subject: 
MichaelS,

Sent you a PM on another fix for reducing pinging. Dial back the vacuum can so it doesn't come on so soon. Mine used to ping all the time and I never understood why or how badly the factory set the 74's up. Mine called for zero degrees timing. One thing offsets another and when you take off some of the pollution control it will change the tune. The distributor recurve is another fix that helped mine significantly.

I am now running 16 degrees initial, with 16 degrees mechanical by 2500 rpm and 22 degrees from the VC-208 vacuum can with no pinging! Now that Juan has shown me how to tune the 1920 Holley, it will keep the tires lit with the posi-traction and not fall on its face. Feels like an entirely different engine. :D
The VC-208 can is dialed back 4 turns so it won't kick in right away.
Author:  MichaelS [ Mon Jun 09, 2008 1:00 pm ]
Post subject: 
Ted, don't know what vacuum can mine is (stock '74 variety) but I dialed it back 3 turns today to see what it would do. Just came back from the mail run and couldn't make it ping at all. It's still at 6 degree timing, I may try a little more advance and see how far I can go. thanks for the tips.

Also, could Chrysler have put the Distributer in a harder to get to location?
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