Played around with the timing Saturday, trying to time by ear following many of the links on YouTube and suggestions here (TY to all). Timing appeared to be at 10 degrees BTC with no vacuum. Ported vacuum at 2500 RPM is 50 in Hg. Test drive showed pinging under mild acceleration with vacuum reconnected to ported. Backed it off some and it seemed OK. Cold start was fast the next day. Drove to a show and on a small hill, it started pinging again. Pulled over and retarded it a bit more. Drove the rest of the way and it seemed OK. Hot and cold start seemed the same as before adjusting. I cannot get an allen wrench in the vacuum canister on the distributor due to the coil being in the way so that will have to wait until I have more time. I also need to verify the timing mark but I assumed that this was done by the machine shop when they broke in the cam.
Pertronix timing question
- Thread starter B5blueGC
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Challenger RTA
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Just some thought that might not make any sense. Engines condition. Good vacuum, Cam's specs and condition, correct distributor advance, vacuum leaks. Pretty much what is the state of the engine to diagnose it?
New rebuilt engine. Specs in an earlier post.
Challenger RTA
Well-Known Member
Broke in. But did everything seat in as it should. Rings, valves and cam. Do vacuum gauge check, compression and leak down test. Read plugs. Did a gasket go somewhere and leaking vacuum. Eliminate the varibles.
MoparCarGuy
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As mentioned earlier in this thread, initial timing and total timing is crucial. Increasing the initial to 16°-18° is needed for today's fuel.
Once you do that, you will need to measure the total timing (initial + centrifugal + vacuum advance) at around 2,500 RPM. A timing tape on the harmonic balancer will make this easy. You must limit the centrifugal advance to approximately 18° when running 16° initial for 34° total.
34° total is a good starting point. Vacuum advance is not added under acceleration (near 0 vacuum). Vacuum advance is added for part-throttle cruising.
The rate of advance is important here as well but that controversial subject would take a lot more details to work out for your specific combination.
The FBO limiter plate: How to limit mechanical advance in a mopar distributor, tuning for street, strip or all out racing, cure that rich stinky idle, win races
Read through the entire website for FBO (4secondsflat.com). A lot of good info under the Articles tab and the description of products.
Consider buying the Tuning to Win Guide as well. It is an excellent document starting Ignition, then Fueling to make your engine run with today's fuel blends (ethanol 10%), etc.
Once you do that, you will need to measure the total timing (initial + centrifugal + vacuum advance) at around 2,500 RPM. A timing tape on the harmonic balancer will make this easy. You must limit the centrifugal advance to approximately 18° when running 16° initial for 34° total.
34° total is a good starting point. Vacuum advance is not added under acceleration (near 0 vacuum). Vacuum advance is added for part-throttle cruising.
The rate of advance is important here as well but that controversial subject would take a lot more details to work out for your specific combination.
The FBO limiter plate: How to limit mechanical advance in a mopar distributor, tuning for street, strip or all out racing, cure that rich stinky idle, win races
Read through the entire website for FBO (4secondsflat.com). A lot of good info under the Articles tab and the description of products.
Consider buying the Tuning to Win Guide as well. It is an excellent document starting Ignition, then Fueling to make your engine run with today's fuel blends (ethanol 10%), etc.
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