Pro Flo 4 Timing

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I have initial timing at 20* on my 340. No starting issues. The only problem is the backfire around 30*.

Plenty of talk on here and on the Edelbrock site about faulty TPS sensors.

My guess is when they went to the ProFlo4 the price was reduced about $1K for the kit. Some of the savings must have come from cheaper sensors.
 
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Mopar73340 said:
I have initial timing at 20* on my 340. No starting issues. The only problem is the backfire around 30*.

Plenty of talk on here and on the Edelbrock site about faulty TPS sensors.

My guess is when they went to the ProFlo4 the price was reduced about $1K for the kit. Some of the savings must have come from cheaper sensors.
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Everyone loves to save money. Its when they tell you over the phone you need to buy another is when I freak out.
 
JD Erisman said:
I checked the phasing, seems to be in line with Edelbrock’s instructions, though they spend more time explaining how to install an intake manifold than anything else.
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I bet you it isn't. Set the crank at 20 degrees and look how far away the rotor is from the #1 post on the cap.
 
I messaged @BergmanAutoCraft earlier and he told me that the adjustable rotor he tried was too big to fit in his distributor. I think I may have an alternative, I'll know in a day or so. Here's the info I have currently.

This is, the best I can tell, the rotor used in the pro flo 4 distributors. It matches up with the one in my car, exception being the color.

Edelbrock Replacement Rotor #22733 For Max-Fire Distributors, Chevy V8

This is the rotor from an MSD that appears to be an almost identical copy.

MSD 8467 Racing Rotor MSD Billet Distributors

MSD makes an adjustable version of the one above, model 84211

MSD 84211 Rotor Phasing Kit for MSD Distributors

I was able to order the non-adjustable version p/n 8467 for pickup tomorrow at NAPA. It was only $11, so no great loss if it doesn't fit. If it does work in place of the edelbrock one, I plan to order the adjustable version and try it as well.

Pictures of the rotor out of my car below for comparision.

IMG_20210414_180255.jpg
IMG_20210414_180307.jpg
 
TurboGLH said:
I messaged @BergmanAutoCraft earlier and he told me that the adjustable rotor he tried was too big to fit in his distributor. I think I may have an alternative, I'll know in a day or so. Here's the info I have currently.

This is, the best I can tell, the rotor used in the pro flo 4 distributors. It matches up with the one in my car, exception being the color.

Edelbrock Replacement Rotor #22733 For Max-Fire Distributors, Chevy V8

This is the rotor from an MSD that appears to be an almost identical copy.

MSD 8467 Racing Rotor MSD Billet Distributors

MSD makes an adjustable version of the one above, model 84211

MSD 84211 Rotor Phasing Kit for MSD Distributors

I was able to order the non-adjustable version p/n 8467 for pickup tomorrow at NAPA. It was only $11, so no great loss if it doesn't fit. If it does work in place of the edelbrock one, I plan to order the adjustable version and try it as well.

Pictures of the rotor out of my car below for comparision.

View attachment 1715723516 View attachment 1715723517
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I could be wrong but I thought that Edelbrock list the 22734 rotor for SB Chrysler?
Replacement Rotor #22734 For Pro-Flo 4 Distributor, Press On Type

upload_2021-4-15_20-33-25.jpeg
 
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TurboGLH said:
I've seen the same info, but it's not accurate, at least not on the distributor in my kit.

Best I can tell the units are their max fire distributor with some modifications.
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Thanks, I’ll have to have a look at my (yet to install) distributor! I’ll let you know, hopefully we can run an adjustable rotor.
 
Remember guys, the distributor is too tall for A bodies. I shortened mine 3/4" by taking a section out of the billet lower housing and cutting/rebroaching the shaft to create clearance.
 
BergmanAutoCraft said:
Remember guys, the distributor is too tall for A bodies. I shortened mine 3/4" by taking a section out of the billet lower housing and cutting/rebroaching the shaft to create clearance.
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Thanks, I’m lucky for once with a RHD car as there is plenty of distributor to wiper motor clearance!
 
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BergmanAutoCraft said:
Remember guys, the distributor is too tall for A bodies. I shortened mine 3/4" by taking a section out of the billet lower housing and cutting/rebroaching the shaft to create clearance.
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What year/model do you have yours installed in? I had clearance on my 72 duster, it was close, but it fit.

IMG_20200926_144220.jpg

IMG_20200928_175602.jpg
 
Once the wires were on, mine was jammed up against the wiper motor. However, I'm using a 72 and earlier k with sandwich mounts. There are several other scenarious that could affect the height; ie, solid mounts, 73 and up K, /6 k and conversion mounts.

F85A949F-24C2-4EDB-81BE-4608846A48DF.jpeg
 
MSD 8467 is 100% the same rotor. I ordered the adjustable version P/N 84211 today. Fastest I can get one is next tuesday, but I'll post some pics when it comes in.

IMG_20210415_170841.jpg
IMG_20210415_170901.jpg
IMG_20210415_171032.jpg
 
BergmanAutoCraft said:
Awesome. Super good news.
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I'll post back how far out mine was later this week, I've only checked fit so far.

Thanks for bringing this up, I've been dealing with some driveability issues that might be explained by it being so far out of position.

Edelbrock says the ECU is the same regardless of application, wish they'd be a little more open. I'd love to run an LS tone ring and COP.
 
TurboGLH said:
I'll post back how far out mine was later this week, I've only checked fit so far.

Thanks for bringing this up, I've been dealing with some driveability issues that might be explained by it being so far out of position.

Edelbrock says the ECU is the same regardless of application, wish they'd be a little more open. I'd love to run an LS tone ring and COP.
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That would be ideal. At some point I’d probably spend so time on that. In the meantime, my setup runs so perfectly that I’m super happy with it. The driveability is perfect.
 
I'm going to throw out what I found on my setup, and hopefully other people can confirm/deny what I've found. I don't want to drill/cut a hole in the cap to use a timing light, so I checked by eyeball and used the marks on my balancer. Zero was confirmed as TDC when I degreed my cam.

I started by marking the positions of the posts for cylinder 1 and 2 on the outside of the distributor body.

It looks like I might have mistimed the distributor when I stuck it. The Edelbrock addendum wants to see 12deg of advance "built in" by having the motor at 12° and then sticking the distributor in with the rotor at 0 and the hall effect right on the t short tooth.

When at TDC rotor was right at #1, so already not ideal. Every degree of advance moves it further back away from the post.

There's a 45 deg arc between any two posts on the cap (360/8=45). Rolling the motor to 15° btdc the rotor is approx 7.5° away from the #1 post. Rolling it to 35° btdc it's approx 15° away from the #1 post.

So, all in all, on my setup, it's not ideal, but it's unlikely that there would an accidental firing of cyl #2 instead of #1. I'm going to try advancing the rotor to place it as close to #1 when when running 25° of advance, or as much as the rotor adjustment will allow.

I'd like to see what others have on their setups, to confirm if they're seeing something similar.
 
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TurboGLH said:
I'm going to throw out what I found on my setup, and hopefully other people can confirm/deny what I've found. I don't want to drill/cut a hole in the cap to use a timing light, so I checked by eyeball and used the marks on my balancer. Zero was confirmed as TDC when I degreed my cam.

I started by marking the positions of the posts for cylinder 1 and 2 on the outside of the distributor body.

It looks like I might have mistimed the distributor when I stuck it. The Edelbrock addendum wants to see 12deg of advance "built in" by having the motor at 12° and then sticking the distributor in with the rotor at 0 and the hall effect right on the t short tooth.

When at TDC rotor was right at #1, so already not ideal. Every degree of advance moves it further back away from the post.

There's a 45 deg arc between any two posts on the cap (360/8=45). Rolling the motor to 15° btdc the rotor is approx 7.5° away from the #1 post. Rolling it to 35° btdc it's approx 15° away from the #1 post.

So, all in all, on my setup, it's not ideal, but it's unlikely that there would an accidental firing of cyl #2 instead of #1. I'm going to try advancing the rotor to place it as close to #1 when when running 25° of advance, or as much as the rotor adjustment will allow.

I'd like to see what others have on their setups, to confirm if they're seeing something similar.
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Not sure if it’s been referenced previously but I found this video interesting and enlightening regarding the topic of vacuum advance & total timing!!
 
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Hi, I experienced something similar in my setup. We noticed first at the dyno session and noticed some bumps in the graph and inside the car it felt like hesitations, we did not hear misfires or backfires at that time. played with the timing starting from 34 down to 30 or so, ended up in the middle ground of 32 and left the full advance until 4k RPM.

Originally the can ran kind of lean (13-13.5) with the 426 matching map, later I moved to a much larger engine map and now AFR is right where the target wants it to be (12-12.5) so it improved considerably, this allowed me to also set the full advance to 2.6k RPM, which is a lot more responsive, in parallel I pulled back final timing to 30 degrees.

When driven hard I noticed some times that hesitation at RPMs above 4k and sometimes heard misfires very seldom. Given the fact that the car has a 426 stroker and 2.73 gears I don't rev it up past 4kRPM that frequently (360HP @ 400lb-ft at the wheels at 4500 feet above sea level, using pump gas).

But your post brought this small issue immediately. When setup we set it to the 12 degrees fixed, then when outside we timed it with the light gun and it matched the edelbrock computer readings, but I don't remember how high we went in measuring it still matched. Would a good test be to check the light gun vs the Edelbrock ECU readings with the engine running up to 6k RPM?
 
Cal Tonsley said:
Not sure if it’s been referenced previously but I found this video interesting and enlightening regarding the topic of vacuum advance & total timing!!
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Definitely something that seems to indicate that the issue is common. I'm going to restick the distributor with 12deg like it says in the addendum, and then use the adjustment in the rotor to center it the rest of the way.

Ivan Baez said:
Hi, I experienced something similar in my setup. We noticed first at the dyno session and noticed some bumps in the graph and inside the car it felt like hesitations, we did not hear misfires or backfires at that time. played with the timing starting from 34 down to 30 or so, ended up in the middle ground of 32 and left the full advance until 4k RPM.

Originally the can ran kind of lean (13-13.5) with the 426 matching map, later I moved to a much larger engine map and now AFR is right where the target wants it to be (12-12.5) so it improved considerably, this allowed me to also set the full advance to 2.6k RPM, which is a lot more responsive, in parallel I pulled back final timing to 30 degrees.

When driven hard I noticed some times that hesitation at RPMs above 4k and sometimes heard misfires very seldom. Given the fact that the car has a 426 stroker and 2.73 gears I don't rev it up past 4kRPM that frequently (360HP @ 400lb-ft at the wheels at 4500 feet above sea level, using pump gas).

But your post brought this small issue immediately. When setup we set it to the 12 degrees fixed, then when outside we timed it with the light gun and it matched the edelbrock computer readings, but I don't remember how high we went in measuring it still matched. Would a good test be to check the light gun vs the Edelbrock ECU readings with the engine running up to 6k RPM?
Click to expand...

I don't think the ecu is timing things wrong, but instead it's what @BergmanAutoCraft noticed and the rotor is far enough out of position that it's causing driveability issues.
 
TurboGLH said:
Definitely something that seems to indicate that the issue is common. I'm going to restick the distributor with 12deg like it says in the addendum, and then use the adjustment in the rotor to center it the rest of the
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Sounds good, please keep us updated!
 
that is great tip, I guess thats why mine liked it when I lowered the top advance. Will check out what I have at vacuum. As a matter of fact I did notice the vacuum reading was very good for my cam specs (around 17 inch vacuum at idle), but atributed it to the fact that I put an "serious street/mild race" cam for a 360LA into a 426 stroker. I had to load a much larger map and a high acceleration pump value (over 90% for a few seconds) to get the fueling part right and avoid it from leaning out. but at the end it ran nice, check out the video below:







I will check the reading at full throttle to see if its adding the vacuum advance to the theorical acceleration advance curve to see if its doing the same as the black car.
 
I set the distributor at the #1 plug wire on the cap which I had marked on the body of the distributor with the damper set at 12*. Even if the damper had been at 0* the rotor would have been very close. Trying to move the gear on the cam one tooth either way would have been noticeably off. I have two engines, one with ProFlo4 and one with ProFlo3 and both act identical when it comes to this issue.

I don’t think all of us have mis installed the distributor.
 
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