440 - Initial timing and advance clarification please?

[Nickrc3]

...O.K., making some progress. I took the day off from work to devote into the tuning of the 440.
First thing this morning I completely disassembled the AVS carburetor in preparation for a rebuild. I was unsure on the condition, so figured a rebuilt wouldn't hurt in my diagnosis.
Initially noticed the float levels were way off:
.
Readjusted to 7/32" level and 23/32" drop. Nothing unusual other than some miscellaneous crud. The one thing that kept me confused was why the accelerator pump doesn't squirt throughout the mechanical range of motion with the primary throttle plates. The plunger movement is 7/16" w/ throttle plates about a 1/4 open. I didn't fret, as I understand the accelerator pump circuit is likely for initial throttle response. I reassembled as it was taken apart, and everything appeared fine.
Completed carburetor was installed onto stock intake manifold.

After some squeeze-bottle priming, she started and idled nicely, however, still had the 'bog' upon hard throttle application.

Taking Ron's advice, I moved the timing north while observing the vacuum gauge for max reading. I twisted the distributor to 24* with no adverse issues, though I now could not lower the RPM's from 1100. The idle screw was backed out, but still the idle wouldn't drop down to 700-800.
I finally decided on 21* w/16" of vacuum. Vacuum advance disconnected and plugged.

Idle-mixture screws tweaked to max vacuum and RPM.
Took the car out and everything appeared fine with 'normal' acceleration. Engine response appeared improved. When I reached my secluded tuning area, I immediately punched it and yes, it did 'bog' and hesitate, then stabilized and off she went. In fact, the vehicle pushed me back into the seat and continued to pull hard through 5500 RPM's, burning tires and swinging sideways through 1 & 2. Once Drive was reached, she straightened out.
A young man was loading a delivery truck and observed this crazy older guy performing these gyrations in this odd car. Upon returning to the scene to view the rubber patches left behind, he commented how angry the engine sounded. I mentioned these burn-out activities are my testosterone release. He chuckled.
Seriously, I think Ron and Cooter hit the nail on the head - the cam is just too much for a relatively stock engine. The tuning is crazy, so I'll probably have to tolerate with the 'bog'.
Maybe I'll get bored and installed the Lunati 'Voodoo' series cam in a few months.

Ron and Cooter - couple questions if I may. At 24* initial, the idle RPM's would not drop below 1000, as the idle speed screw was backed out. Why is this? What would cause a significant drop in RPM's upon shifting out of Park into Drive? A vacuum leak? I've got to maintain a relatively high idle @ 800 RPM's, so upon shifting into Drive, it won't die.
I probably won't reinstall the vacuum advance. If I did,the total advance would shoot up into the 40* range. Would a problem exist if I'm NOT experiencing detonation or increased engine temperatures?
Ron, should I leave the vacuum advance line off and play with the mechanical advance within the FireCore distibutor? She's coming in around 2500 RPM's.

Thanks Guys!

[firefighter3931]

In fact, the vehicle pushed me back into the seat and continued to pull hard through 5500 RPM's, burning tires and swinging sideways through 1 & 2. Once Drive was reached, she straightened out.

Nice work Nick 

A young man was loading a delivery truck and observed this crazy older guy performing these gyrations in this odd car. Upon returning to the scene to view the rubber patches left behind, he commented how angry the engine sounded. I mentioned these burn-out activities are my testosterone release. He chuckled.

Crazy old guy huh....that made me    Sounds like you woke the beast up ! 

Ron and Cooter - couple questions if I may. At 24* initial, the idle RPM's would not drop below 1000, as the idle speed screw was backed out. Why is this? What would cause a significant drop in RPM's upon shifting out of Park into Drive? A vacuum leak? I've got to maintain a relatively high idle @ 800 RPM's, so upon shifting into Drive, it won't die.
I probably won't reinstall the vacuum advance. If I did,the total advance would shoot up into the 40* range. Would a problem exist if I'm NOT experiencing detonation or increased engine temperatures?
Ron, should I leave the vacuum advance line off and play with the mechanical advance within the FireCore distibutor? She's coming in around 2500 RPM's.

Thanks Guys!

You don't have a vacuum leak but the cam needs/wants lots of base timing so the idle speed will be higher. To lower the idle speed would require retarding the initial timing and that just kills "off idle" power and throttle response. It's a catch 22.....you can't have both at the same time with the current setup. 

The problem is ; cam is too big for the current torque converter. When you drop it into gear the engine is fighting the "too tight" torque converter. This often happens when cam swaps are done and the stock torque converter is still in place. If you have the right converter for the application the rpm's should only drop 200-300 when you put it in gear. 

So, you have three options ;

(1) live with it
(2) install new cam
(3) install new tq converter

Quick explanation ; The stock converter is rated at 1500-1800 stall speed. Your cam doesn't hit the sweet spot until 2500 so the engine is lugging briefly until that sweet spot is reached when you mash the pedal. This is what is creating the hesitation. Sometimes you can cover it by increasing the pump shot but it will never be optimal. 

If it's running good i'd leave it alone and not bother with the vac advance. I never use it and it can cause surging issues at cruise speed on the hwy under constant load. Especially true with a lumpy aftermarket cam.

The 268* Lunati cam would be a good choice for this combination. 



Ron

[Nickrc3]

Ron, thanks so much for all your time in identifying my engine issues and providing a thorough explanation on resolving them.
Swapping out the torque converter is an intriguing thought. Can you further explain converter stall speeds and how they affect a street-driven vehicle? Will transmission shift patterns be altered? Basic driveability be adversely effected, including MPG?

As you mentioned, I may just live well-enough alone, as I'm spending more time and effort into my 68', which is an original big-block, 4-speed vehicle. It certainly needs it!


Lastly, other than the FireCore folks, do you provide distribution services w/ pricing for other manufacturer's?
PM me on details if you wish.
Thanks again.

[firefighter3931]

Hi Nick, you're more than welcome....allways glad to help those who are willing to learn. 

The Tq converter is a key player in the overall success & drivability of any car. As you've seen with your own car....a mismatched component will affect drivability. In your case a high quality tq converter that flashes up higher would only enhance your driving experience. When the converter works right it behaves just like a stocker under normal driving conditions but when you drop the hammer it flashes up to the rated stall speed and then all hell breaks loose....lotsa fun ! 

This is one area where it pays to spend the extra $$ because you definately get what you pay for when it comes to aftermarket Tq converters  If you're haappy with the street manners of the engine combination other than the soft launch then a better converter is certainly a good way to go. If you'd like to tame the engine down a bit then a cam swap that is compatible with the current converter will also work. 

With a quality converter there should be very little drop off in fuel economy if at all. Converters are now built with efficiency in mind and most quality street converters have very little slip. Most are as good or better than the factory converter. I ran a 4400 stall Dynamic with my old 446 combo and it was a really nice converter....felt like a stocker pulling away from the light at low to moderate engine speeds....yet flashed up perfectly when full throttle was applied. My current build is a 572 stroker making 720hp/725tq and i have a custom built 5000 stall unit and it drives just like a stocker. You wouldn't even know it's in there until the pedal hits the metal....then it's tire frying time. 

Hope this helps explain the converter concept and how important it is in the overall success of the car's performance. 

As for Firecore ; i really like the products and the build quality is top shelf. Excellent value for the dollar and great people to work for. Rick is a Mopar guy through and through and has spent a lot of time designing this product line and incorporating the superior features that make the product so user friendly. I was asked to become a representative and am certainly proud to be part of the FireCore team. This is the only product line that i'm directly involved with.


Ron

[Nickrc3]

This is one area where it pays to spend the extra $$ because you definately get what you pay for when it comes to aftermarket Tq converters  yesnod If you're happy with the street manners of the engine combination other than the soft launch then a better converter is certainly a good way to go

Ron, any particular brand/type you recommend, like the PTC 11" street hemi or T/A unit with a stall speed @ 2500? Again, an update to the converter will not affect my highway cruising speed?

[GPULLER]

Like Ron said, I'm running the same cam and my combo liked 25 deg initial.  I didn't have a vac gauge when I set the timing, just advanced until I got the highest idle and engine would still start without kicking back. Also I run a Holley carb, so can't help you with adjusting your Carter.  I have drilled small holes in the throttle plates and adjusted up the secondarys a little to get idle quality.  All those adjustments where done before the Firecore dist, and it was all a band-aid.  Getting the timing right was the biggest improvement, it all starts there.
I've never got idle down below 1000 RPM, likes about 1100.  I'm running a slightly looser converter.  I don't have any hesitation or bog.  I think you might want to try bumping up the initial timing and see what happens.  I locked the total timing at 35 deg, and do not run the vac advance.

Reed

[firefighter3931]

Either the PTC 11in or T/A street hemi converter would be a good choice. 


Ron

[Dino]

I run that same old purple shaft in a similar block with a thermoquad and 2.96 gears.  Yep the cam is all wrong and it'll be the reason why some day this engine will get pulled.  Still I got mine to run without any bog and it's a solid cruiser but it so desperately wants that new cam.  I'll miss the lumpy idle though...

[b5blue]

My engine had an old drag race vintage build with the Mopar 509 cam and closed chamber heads when I bought it. Now with 346 heads and a Resto Roadrunner cam it drives really nice. 

[Nickrc3]

...current update - my decision to either replace the camshaft to a modern grind or replace the torque converter?
I chose the converter change for the reason to retain the RPM powerband designed for the PurpleShaft's camshaft. In addition, I really didn't want to break down the engine (again) and go through the labors of cam degreeing, break-in, possible leaks, etc.

A few weeks back, I contacted Kenny @ Performance Torque Converters (PTC). As recommended by FireFighter (Ron) and others, Kenny suggested the 11" street hemi converter. Four days later, it was delivered to my doorstep.



Careully installing the PTC unit into the transmission (after replacing the seal) and observing she's fully engaged.


So now I'm all excited, raising the transmission up into position via a motorcycle jack. A slight shove forward and she's resting on the engine dowel pins.
All five bellhousing bolts get hand started and tightened. I then look directly up into the flex plate/converter cavity and notice the flex plate does not match the convertor bolt pads  Oh S%#t! Did I feel like a complete buffoon, never bothering to confirm the bolt centering of the new converter to the existing flex plate. This screw-up ended any motivation to continue wrenching that day!
The following day I did contact PTC and they had the correct Mopar flex plate in-stock (bolt configuration of 10" OC). Again, it was delivered within three days.

So, this President's Day weekend I finally removed the transmission, replaced the flex plate and reinstalled. Oh, don't forget the starter shield!


An unrelated issue that continually annoyed me was this constant exhaust manifold leak (ticking). I observed paint discoloration of the side of the engine block adjacent to the heat riser. Apparently, exhaust was leaking from the extended shaft on the heat riser. Since the riser was already  hard-wired open, I chose to weld a bead around the area to permanently seal. Also note the purchase of Percy's aluminum gaskets.


With everything together now, I start the engine and immediately hear this nasty clanking sound from the transmission/converter area. Oh no, here we go again!
Turns out the new converter bolts (on 10" diameter) ride outside the shallowed area of the original dust shield.

-note scrape off-center, upper right.
My attempt to extend the shallowed area with a block of wood and some sharp hammer blows was unsuccessful - it still produces noise.
Anyone have an aftermarket source for these modified dust shields?

With dust shield removed and all fluid levels triple-checked, the engine is restarted.  Immediately I sense a smoother Park-to-Drive transistion -  no more violent motion. Also, I can now obtain a manageable RPM setting of 830. As Ron indicated in his earlier response, the higher stall speed solved this issue.
Timing was bumped to 24* initial, 38* total @ 3000 RPM's. Vacuum reading peaked @ 15". No detonation, no starter bump-back - everything's good.
The test drive went very well. Drove immediately to my secluded area designated for burn-outs, and dropped the hammer.  Wow - the engine immediately roared to life and quickly rev'ed to 5800 RPM's before shifting into 2nd gear! Of course, both rear tires were smoking with the rear swinging in the torque direction.
She continued winding upon the final shift of Drive, which was followed by a nice, distinctive chirp. MPH's were now getting a bit high for my comfort level - time to back-off.
That engine roar, the 'thrown back into the seat' feeling of brute torque, smell and sight of burning rubber, and my ability to countersteer the goobs of torque,  instantly transports me back to 1976 with exiting my High School parking lot each afternoon. I sure hope I never tire of this performance sensation! 
I am very satisfied with this modification. I did notice more acceleration is now required from a stop to propel the vehicle (from 0-30 MPH), and the RPM level has increased within highway cruising speeds. Obviously mileage will be affected, but this isn't my concern. The car gets driven, maybe, 25 miles a month. 
I wish to thank everyone, especially our Moderator, 'FireFighter 3931' for all responses and accurate assessments to the issues faced. You Guy's are great!
Maybe soon, I can learn how to post a You-Tube video of the performance. 

[Dino]

I will send you a plane ticket and money for the parts, come do this to my car!  You got me all excited now!   

Thanks for the write up, I do believe a video is in order.   

Wise decision on the Percy's.   

[firefighter3931]

Hey Nick....sounds like we're starting to have some fun ! 

Glad the tweaks are working in your favor. I had a feeling you'd be happy once it was all dialed in 

As for the dust shield ; you can trim a bit off the top tabs that normally tuck inside the bell housing and use a few washers to space the shield back a bit. If you can find a dust shield for a 383 it should have the scallops located in the right spot for the PTC converter. All 383's came with an 11in converter using the 10in bolt spacing that is on your new PTC Tq Converter.   

Good call on the Percy's exhaust gaskets. 


Ron

[GPULLER]

Good to hear it's coming around!