Author Topic: Timing for a stock 383  (Read 694 times)

Offline missioncritical

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Timing for a stock 383
« on: November 18, 2013 - 05:33:33 PM »
I've searched and maybe my case is unique or I don't know what to search for, but...

I have a 70 Cuda with a factory unmolested 383 (about 80K miles though).  The ignition was upgraded by previous owner to electronic.  I've replaced the cap, rotor, wires, and plugs, and the ignition box, currently running the 'orange box'.   A local mechanic 'fixed' the timing while it was in his shop to fix a transmission leak.  Seemed to run worse afterwards, and then a buddy and me messed with the timing again and now it runs OK, but was wondering:

- The fender tag says 2.5 degrees BTC.  Is that really where it should be set at with the vacuum plugged off ?

- I 'think' we have it about 10 degrees now, but am not 100% sure where zero is.  I can't read my timing tab due to too much paint.  Is the small hole zero degrees ?  I have an advanced timing light, but do not know for sure what the marks mean since I can't read 'em.

There has not been any performance changes to anything except a slighter larger exhaust and a new stock-style carb, but the car does not seem to have any get up and go.  Previous owner had it sit around a lot, so there might be internal issues.  I'm also running 91-93 octane gas to eliminate that as a problem.

Also, what is a good vacuum reading at idle ?




Offline cudabob496

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Re: Timing for a stock 383
« Reply #1 on: November 18, 2013 - 05:50:28 PM »
initial of 10 degrees BTDC should be a great starting point.
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline missioncritical

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Re: Timing for a stock 383
« Reply #2 on: November 18, 2013 - 07:12:03 PM »
Thanks; is the hole in the timing tab 0 degrees ?

Offline Chryco Psycho

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Re: Timing for a stock 383
« Reply #3 on: November 18, 2013 - 08:08:05 PM »
It should be , without vacuum you should have around a 20 * curve so idle at 16 or so & total at 36-38* should be perfect , idle vacuum can vary a lot depending on cam intake , idle speed tuning etc you coul dbe anywhere between 6-18"

Challenger - You`ll wish You Hadn`t

Offline cudabob496

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Re: Timing for a stock 383
« Reply #4 on: November 19, 2013 - 02:00:23 AM »
also idle vacuum will vary a lot depending if car idling in gear or not.
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline footin70rt

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Re: Timing for a stock 383
« Reply #5 on: November 20, 2013 - 12:02:59 AM »
I have a stock "reman" 383 in my Challenger right now while I build my stroker. Don't know the specs on the cam but it's running the stock cast iron intake, headers and idles smooth at 750rpm @ 20inhg. Total advance is set at 35* and I don't run any vacuum advance. At 38* on a hot day it will start pinging going down the track, so I backed it off to 35 with no issues. I am running 92 octane non ethanol fuel. Don't know if this will be usefull to you but hope it helps.
Thomas
Driving the same 70 R/T since October 1985
Native of Bozeman, MT