When you set total timing to say 36*@3500rpm, what is your initial set to when you drop back down to idle?

 

10-11* initial.

 

I'm not a fan of "total timing". It matters, of course, but the rate at which it arrives there, the timing curve, is crucial. So, what's the timing at, say, these speeds and vacuum levels?

 

Mine idles great and starts quickly at 14* initial with the holley EFI. I'm not sure what the vacuum levels were but here are the timing increments I recorded.

10 idle
10 1500
21 at 2000
25-26 at 2500
31-32 at 3000
35 at 3500
35-36 at 4000

 

Agree with 22GT, your timing curve is crucial and something you can plot yourself by moving up 500 rpms at a time and seeing where your timing is at that point.

10-11* initial is not bad.

 

Many things can effect initial timing. Spec for the 289HP is 12°BTDC. Mine runs real nice at 14°BTDC.

 

Hmmm… I haven't used that particular distributor, but compared to the chart I posted, it's too much and too late. Were those numbers recorded with the vacuum advance disconnected?

 

Yes, disconnected. I may have misspoke, the manufacturer of my engine recommends 32-34* total and 10-16* initial.

I can swap to lighter springs if you all think that would be better, but my real question is the limiters and how to get my initial and total where it should be.

 

The chart I posted was for the BOSS 302, which was all-in by 2000.

 

that's distributor RPM. most people talk about engine RPM. So the boss 302 was all in at 4000 engine rpm.

 

If you were to set the Total at say 34*, what does your initial drop down to?

 

Man I really apologize for not getting up there to look at that thing yet. This job change is killing me.

 

No problem at all! I actually switched to EFI and messed with the TFI distributor for a long time then finally switched back to my Pertronix so I could rule out this SOUND I am hearing.

Yeah, was paying more attention to my barbecued burger and not reading. Have you tried using the 20* limiters, but orienting them more toward the spring anchors, which is the advance weight's pivot point, instead of at 90*?

This is how I positioned them. I even tried bending the 90* arm out some.

Why aren't you using the TFI? EFI without timing control is like chicken parmigiano without the chicken lol.

I'm chasing down that F'n sound so this is process of elimination. Once I figure that out, I will likely go back to TFI.

 

Try using the 20* limiters, 12* initial, one light and one medium spring.

 

Without installing the add on limiters, initial would be around 8-9* to reach 34 total. If I add the 20* advance limiters then initial would have to be set at about 18*. Remember, the 20* limiters actually limit advance to 16* for some reason.

 

Yeah, was paying more attention to my barbecued burger and not reading. Have you tried using the 20* limiters, but orienting them more toward the spring anchors, which is the advance weight's pivot point, instead of at 90*?

 

Why aren't you using the TFI? EFI without timing control is like chicken parmigiano without the chicken lol.

 

Interesting limiters. I've never seen that before. I have a set of donuts of differing lengths that get screwed under the timing levers and springs on my MSD. I have been running 18-38 but decided to try the 25 degree pill so 13-38 to see if that would help my hot engine cranking issues. It didn't help anything but I then picked up just a very small touch of stumble when I nail it hard. Mine is all in by around 3000. I could just about get by running a start retard and total timing though because my engine doesn't wake up good until it hits around 3500.

 

Those limiters just float on the pin, you could slot the hole a small amount if you need the extra advance, have you tried running it at 18 initial? As long as it will start when it's fully warm it shouldn't be a problem. As a rule of thumb, I always set my initial timing as high as I can intel the hot start makes the starter labor then I back it off two degrees at a time intel it will hot start without the starter laboring then I set up the distributor to achieve the total advance I need to run.

 

Correct, those limiters just slide over the pins and under the springs and float. So the key is notching the hole a bit more, not trying to bend the elbow out? If I were to notch the holes, would I want to notch the side towards the elbow (left arrow in pic) or the other side (right arrow in pic)? That's probably a dumb question....would have to be toward the right arrow.....

[URL=http://s1125.photobucket.com/user/66FSTBCK/media/Holley%20Terminator%20EFI/AB9A0B9F-FB08-46DB-8102-4E9772902730_zpsktboxthk.jpg.html][/URL]

I had hot start issues with the tfi at a higher initial timing. I haven't had it above 16* initial with the pertronix setup.

I can also try and medium and soft spring combo like bartl said so the total timing can come in a little quicker.

 

I'm certainly not at my best on this thread.

I have to keep translating in my head, because I never adjust distributors on the engine, because it's a complete pain for the centrifugal, and near impossible for the vacuum. I always use a distributor machine. Results are excellent if you do it that way.

However, even given you are correct with your analysis, he still has too much advance.

 

Ok, got that the limiters simply slide over the pins.... have to ask one question, though....does it look to anybody else, in the picture above, with everything connected, that the weights aren't totally flush with the sides of the center spindle? I wonder if removing about 1/8" from the small ends of the weights so they could close up a tad more would provide the necessary additional 4* of travel.

 

This subject always interests me. For the record: most of you are way better at engines than me, I acknowledge that. But with that said. ...

I always go with total timing first. All my high performance builds are dyno'd, on an engine stand. Normally costs me 400-600, but well worth it. (tuning and having documentation backing up my numbers)

I set total timing for peak performance. (normally ends up 30-36, usually around 3000ish, without vacuum, not that it would do much at that power setting)

...then I look at curve

...then I just see where it falls at idle. adjust mechanical & vacuum #'s to give it as much efficiency as possible. vacuum, idle, whatever. this is where I see the most difference, from my jet boats/v-drives to my cars. whether they are mild, strokers or big block torque monsters.

...but I always start at the top and work backwards. was taught that on my first dyno and have yet to have one of the guys correct me or question my process. but many of you do this for a living, ...I get it... my way is just fast/simple and so far, max power for my engines.

 

Maybe it's just me but IMO the centrifugal advance mechanisms on that Petronix distributor seem a bit hokey. I'm surprised you prefer tinkering with this as opposed to the TFI where the curve is infinitely more programmable. I am also quite certain you haven't tuned ALL the areas you need to in order to have a more perfectly tuned setup.

 

Maybe it's just me but IMO the centrifugal advance mechanisms on that Petronix distributor seem a bit hokey.

Yes they are, I did buy one once and sent it back for a return for that very reason, summit racing traded it in for a Mallory , much better. The limmiters don't seem accurate to advertised because the weights are off the resting stop at idle , so they are already starting the advance.