Pro Flo 4 Timing

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TurboGLH said:
Weather hasn't been great the last two days, still no test drive yet. Car starts and idles much better is all I know so far.
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hopefully you can test drive it soon. I will check what mine is doing at WOT to see if its adding vacuum timing while doing that if the sensor is reading incorrectly. Got a flat tire I have to fix tomorrow in order to drive it :S

I think that since the ECU can play with the timing electronically there may be two ways to fix this.
 
So, Pulled my distributor cap off today since the MSD adjustable rotor arrived and found the following.

7088673E-674E-42C4-A392-C6E3A789B7BE.jpeg


E1C08A54-A3BD-4AA3-878C-9AEB2F59DDF0.jpeg


BD46E406-1804-4CC7-8E3B-81E780478D9C.jpeg


4E80A312-8935-467C-85D4-BC496094C284.jpeg


First picture =0*
Second =12*
Third =30*
Fourth =35*

2B0D1C29-7408-4C75-A8CB-AF14CEDB8759.jpeg


And the last one shows the rotor with about 1K miles on it. Obviously the spark has been predominantly using the left side.
 
Ok, drive report. Huge improvement everywhere. Cold start is much better, spins twice and idles right away, no throttle req as before. Warm and hot starts are even better, barely spins before it catches.

Previously when cruising the car had a stumble with small throttle input and required extra throttle to clear up. That's all gone, drivability is vastly improved.
 
TurboGLH said:
Ok, drive report. Huge improvement everywhere. Cold start is much better, spins twice and idles right away, no throttle req as before. Warm and hot starts are even better, barely spins before it catches.

Previously when cruising the car had a stumble with small throttle input and required extra throttle to clear up. That's all gone, drivability is vastly improved.
Click to expand...
Great to hear, thanks for the update!
 
TurboGLH said:
Ok, drive report. Huge improvement everywhere. Cold start is much better, spins twice and idles right away, no throttle req as before. Warm and hot starts are even better, barely spins before it catches.

Previously when cruising the car had a stumble with small throttle input and required extra throttle to clear up. That's all gone, drivability is vastly improved.
Click to expand...

This is great to hear. I hope to try mine out tomorrow if it doesn’t rain. I also have the stumble on light throttle.
 
it sound excellent, please share the screenshots of your timing settings in the edelbrock tuner application, as well as general engine specs to see what we are talking about.
 
Ivan Baez said:
it sound excellent, please share the screenshots of your timing settings in the edelbrock tuner application, as well as general engine specs to see what we are talking about.
Click to expand...

416ci, CNC SM heads, mechanical roller 242/242 @ .050, .571 lift.

Also has 5 deg of vacuum advance.

Screenshot_20210423-191812.jpg
 
Thinking about this a little more, the SB Chev PF4 Distibutors that I’ve seen (and maybe others) do in fact use the replacement rotor that Edelbrock specify (see photo below) To me it looks like this rotor is broader than the SBM (OE Chev based) rotor, this may explain why this issue is Mopar specific.
Anyway, we’re the lucky ones if we can buy an adjustable rotor and phase it’s position accurately!
upload_2021-4-24_9-57-51.jpeg
 
TurboGLH said:
416ci, CNC SM heads, mechanical roller 242/242 @ .050, .571 lift.

Also has 5 deg of vacuum advance.

View attachment 1715727629
Click to expand...

thanks, that is good info. in my case:

426ci, 12.5:1 comp, ported Edelbrock performer heads with 2.08 intake valves, 1.6 ratio rockers, SB HYD RLR CAM 238/242 -110o LSA. run on 91 octane pump gas. 1150RPM idle. driven at 6500 ft above sea level.

Theses are the settings I have now, plus 5 degrees vacuum advance:

WhatsApp Image 2021-04-23 at 8.01.03 PM.jpeg
 
Today I finally was able to drive the car, and saw some interesting behavior, similar to the one posted by a member on a video on this thread.

The vacuum readings are off, which confirmed what I suspected in why I had to pull the timing back so much to make sure the engine stays smooth at WOT all the times and avoid thos small hesitations I felt sometimes when getting close to the RPM limit.

When the engine was not running you can see it reading -5.9 of vacuum already. (see attached pic). At WOT the reading is around -7 inches of vacuum, so if I have -5 vacuum advance that is adding 1.2 degrees to my top RPM based advance. when I had that set at 34 or so it was really going to 35-36 or so. At cruising or when releasing the pedal with no load most of the time my vacuum reading is between 15-19 inches of vacuum.

Since gas quality here is not as good sometimes here and my compresion ratio is rather high (12.5:1) I will change the parameters in a way that at WOT I will have around 32 degrees total and plus 10 degrees more at -30 inches of vacuum.

For what I read in the edelbrock forums the vacuum advance is linear from 0-30 inches, so whatever max value you put in there will be applied linearly additively all the time the engine is running as long as you dont have 0 inches of vacuum, so be mindful of that when setting your parameters.

I hope the info helps.

WhatsApp Image 2021-04-27 at 9.51.42 AM.jpeg
 
TurboGLH said:
416ci, CNC SM heads, mechanical roller 242/242 @ .050, .571 lift.

Also has 5 deg of vacuum advance.

View attachment 1715727629
Click to expand...

were you able to check the physical timing advance with a timing light vs what the edelbrock application says after you made the adjustement in the cap?. I wonder if the EFI computer will now think it has a different timing than the physical one.
 
Ivan Baez said:
thanks, that is good info. in my case:

426ci, 12.5:1 comp, ported Edelbrock performer heads with 2.08 intake valves, 1.6 ratio rockers, SB HYD RLR CAM 238/242 -110o LSA. run on 91 octane pump gas. 1150RPM idle. driven at 6500 ft above sea level.

Theses are the settings I have now, plus 5 degrees vacuum advance:

View attachment 1715727678
Click to expand...

How is it you’re at 12.5:1 compression with 91 octane fuel?
 
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Ivan Baez said:
were you able to check the physical timing advance with a timing light vs what the edelbrock application says after you made the adjustement in the cap?. I wonder if the EFI computer will now think it has a different timing than the physical one.
Click to expand...

I didn't, but I can. I'm working on a header leak that I think is causing me to run super rich, but once I'm back together I'll check and report back.

I was able to set base timing with no issues, so I'm expecting the timing to be where it should be. The adjustable rotor doesn't move the trigger wheel inside the distributor, just where the rotor and post are in relation to each other when a plug is fired.
 
I note that ‘Bite Me’ on the Edelbrock forum is now putting it down to timing chain slackness and the need to run a tensioner. I replied by stating that if that’s the case then phasing of the rotor should be no benefit.
I still suspect that the different, narrower rotor they use on SBM’s is really the culprit, I’ve asked why they choose to use this on SBM’s.
 
Ivan Baez said:
Today I finally was able to drive the car, and saw some interesting behavior, similar to the one posted by a member on a video on this thread.

The vacuum readings are off, which confirmed what I suspected in why I had to pull the timing back so much to make sure the engine stays smooth at WOT all the times and avoid thos small hesitations I felt sometimes when getting close to the RPM limit.

When the engine was not running you can see it reading -5.9 of vacuum already. (see attached pic). At WOT the reading is around -7 inches of vacuum, so if I have -5 vacuum advance that is adding 1.2 degrees to my top RPM based advance. when I had that set at 34 or so it was really going to 35-36 or so. At cruising or when releasing the pedal with no load most of the time my vacuum reading is between 15-19 inches of vacuum.

Since gas quality here is not as good sometimes here and my compresion ratio is rather high (12.5:1) I will change the parameters in a way that at WOT I will have around 32 degrees total and plus 10 degrees more at -30 inches of vacuum.

For what I read in the edelbrock forums the vacuum advance is linear from 0-30 inches, so whatever max value you put in there will be applied linearly additively all the time the engine is running as long as you dont have 0 inches of vacuum, so be mindful of that when setting your parameters.

I hope the info helps.

View attachment 1715729486
Click to expand...
Thanks Ivan, good info!
 
TurboGLH said:
I didn't, but I can. I'm working on a header leak that I think is causing me to run super rich, but once I'm back together I'll check and report back.

I was able to set base timing with no issues, so I'm expecting the timing to be where it should be. The adjustable rotor doesn't move the trigger wheel inside the distributor, just where the rotor and post are in relation to each other when a plug is fired.
Click to expand...

If I understand you right that would mean the rotor and the post will fire when they are aligned at the middle, rather than when they are getting apart, ensuring a more direct spark path?. If this is so it sounds like a basic design issue Edelbrock should have got right since the beggining.
 
Cal Tonsley said:
I note that ‘Bite Me’ on the Edelbrock forum is now putting it down to timing chain slackness and the need to run a tensioner. I replied by stating that if that’s the case then phasing of the rotor should be no benefit.
I still suspect that the different, narrower rotor they use on SBM’s is really the culprit, I’ve asked why they choose to use this on SBM’s.
Click to expand...

I have a timing chain tensioner already, that should not be the issue.

WhatsApp Image 2021-04-27 at 5.09.13 PM (1).jpeg


WhatsApp Image 2021-04-27 at 5.09.13 PM.jpeg
 
Ivan Baez said:
If I understand you right that would mean the rotor and the post will fire when they are aligned at the middle, rather than when they are getting apart, ensuring a more direct spark path?. If this is so it sounds like a basic design issue Edelbrock should have got right since the beggining.
Click to expand...

You got it spot on. It seems to be an issue specific to mopar small blocks, based on the replies on the Edelbrock forums. But, it seems to be fixed, so I'm happy to just move on and enjoy the car. Like the TPS I had to replace, not happy, but it's fixed now.
 
BigBlockMopar said:
Why are your pistons are installed upside down...?
Click to expand...

They were just put there for the picture when the parts arrived but before engine assembly I guess, since I was following up remotely the engine build.

Here is a more recent pic of the actual assembly with the correct orientation.
 
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I have not been able to drive mine but it starts easier and I can take it up to 4-5k rpm now with no miss or backfire. Before could not get past 3k rpm.

I also disagree with the chain tensioner theory as both of my engines did this the worst being the one with the tensioner in it.
 
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