Timing help needed

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roccodart440

roccodart440

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I have a 440 in my dart with a billet MSD distributor. It has a 950 proform carb on it (4150) It has a set of fully ported 2.20 valved RPM heads on it and a roller cam in the ballpark of 255/[email protected], 112 LSA and .650

I know my old convertor is too tight but this thing isn't 100% happy at idle. Timing is currently 18/36 in at 3,000.

MSD's biggest bushing is 20 degrees (black) I found Don Gould makes CNC bushings at 10 degrees and at 14 degrees and ordered a set last night.

Do you guys think 4 more degrees of advance at idle will help? (22/36) and also, is 2500 ok to have full advance or should I try to keep it around 3000?

One of the issues is youhave to create you own spring graph becasue DOn doens't tell you what springs to run. He just says full advance 500RPM under your flash stall.

@IQ52
 
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Run the timing up at idle slowly until it stops picking up rpm. That’ll tell you where it wants idle timing. With 255/260 @ 050 and depending on your compression, fuel, and overlap I’m gonna say it might want more than 18. We had to make our own bushings to get more initial on the race truck as the black MSD wasn’t enough. MSD has good graphs for their springs. I usually start with one light spring and one medium spring and that brings it in pretty quick.
 
TT5.9mag said:
Run the timing up at idle slowly until it stops picking up rpm. That’ll tell you where it wants idle timing. With 255/260 @ 050 and depending on your compression, fuel, and overlap I’m gonna say it might want more than 18. We had to make our own bushings to get more initial on the race truck as the black MSD wasn’t enough. MSD has good graphs for their springs. I usually start with one light spring and one medium spring and that brings it in pretty quick.
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Compression is 10 or 10.5:1, I forget. I only know the duration, LSA and lift on the solid roller. I run 91-94 premium fuel.

The new custom bushing allows for 14 degrees advance which puts me at 22 initial, 36 total vs. 18/36
 
I run 31* intial 34* total on my SB 340. I use the MP distributor with the Mallory guts (every .010 in advance gap = 1*). All mechanical in at 1800 which is what I launch at with a 3200 flash tight converter. I'm also running a V can on manifold port which starts moving at 12" of vacuum and adds 14*. This is 10.3:1, [email protected] on pump gas.
Bump your timing up at idle and set where it runs the best, don't be surprised if it likes a lot. Adjust curve after figuring out best timing at idle.
 
mderoy340 said:
I run 31* intial 34* total on my SB 340. I use the MP distributor with the Mallory guts (every .010 in advance gap = 1*). All mechanical in at 1800 which is what I launch at with a 3200 flash tight converter. I'm also running a V can on manifold port which starts moving at 12" of vacuum and adds 14*. This is 10.3:1, [email protected] on pump gas.
Bump your timing up at idle and set where it runs the best, don't be surprised if it likes a lot. Adjust curve after figuring out best timing at idle.
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The spped of the curve is easy to set. The bushings are very limited. I have 18/36, 22/36 or 26/36
 
Somebody on here was selling an 8 or 10 made bushing I've forgotten. Might have been Crackedback, but I'm not sure
 
I'll add one more thought on AFR. If you are setting the AFR to meet a number I have found it does not always end up being the best idle setting. I run a tight converter and I can't run anything leaner than 12.8 in neutral, engine fully warmed and maintain smooth off idle transition. In drive at idle AFR goes to 13.4 and the plugs stay clean. I use the AFR as a tool only. With a loose converter this probably would not apply. Every combo is different so give it what makes it run the best for you.
 
I don't normally tune big blocks.
And the biggest cam I have tuned, in a 340/360, is the MP292/292/108, which IIRC is [email protected]..
That said;

I have found, that lots of Idle-Timing, by and large, covers a less than ideal Idle-AFR.
In my own combo, (Eddie-headed, 11/1Scr, 367/A833) I too started at 18* because it wouldn't run right otherwise. And the Idle-speed was up around 850 with an ancient Holley 750DP.
Eventually, after I learned a few things by trial an error,and I got the AFR right. After that, I applied what I had learned, and got that combo to idle down to 600/550 in first gear @5* advance.No I didn't run it there full time.
The rest of that summer and the next two even, I spent quite a few hours getting other guys ugly-combos running right.

The point being;
IMO,
if you get the AFR dialed in closer, you won't need a lot of timing.
Then;
Being as how your combo is an automatic, you can run more idle-timing than us Manual-trans guys, without incurring jumpiness, cuz most of that gets lost in the TC. And more initial timing also helps to get the cruise-timing, that your engine will crave. Also since your DCR is so low, you may not even experience jumpiness.
Then;
there is no good reason to run less than 16/18 idle-timing, unless it screws up your Idle-AFR,beyond what the cam is already doing, that is to say; destroys your Transfer slot sync.

To tune your idle, you have six tools in your tool-belt; namely;
1) temperature; of the Coolant, and Inlet Air Temp
2) the wet and running, fuel level,
3) the low-speed circuit; which consists of; the transfer slots, the emulsion tubes, the IABs, plus the mixture screws,
4) transfer slot synchronization,
5) idle-air bypass, and
6) Base-timing.

Your job as a tuner is to balance those cowboys on the AFR seesaw, to make the engine happy; not just at idle, but also as the throttle slowly tips in; to prevent sags,hesitations, or stumbles.

I don't know about big blocks,
but with STREET SBMs it is easy to get carried away with too much idle timing; especially with a, high-compression, manual-trans equipped, combo.
It's not that the timing is too much, rather it's a bad ratio of transfer slot, to mixture screw, to bypass air,etc., that calls for the extra timing, to make the engine happy.

You probably know all or most of this, but sometimes it just helps to see the options ... in print.

BTW; I don't have an AFR gauge, so I have to pay more attention to what the engine is telling me.
 
AJ/FormS said:
The point being;
IMO,
if you get the AFR dialed in closer, you won't need a lot of timing.
<snip>
I don't know about big blocks,
<snip>
BTW; I don't have an AFR gauge, so I have to pay more attention to what the engine is telling me.
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Bigger cam, more idle timing. If it's big enough you will have start problems unless you crutch it with a retard, or separate ignition and starter switches to get it spinning.

Or a mechanical jury-rig like mine (10.3:1 451, [email protected]): One superlight spring, one heavy spring with loop, 22 crank degree rotor plate. This allows cranking at 16, goes to 27 as soon as it starts (idle at 1200), then a long slow curve up to 38 (less the box retard with rpm). I also run vacuum advance for street driving, otherwise I'd have it go straight to 36 or so. I may need a spring with a slightly longer loop so it'll idle at 28-30. Currently it may not be optimal but it doesn't ping on the "premium" swill of today.

AJ, I would pay for your trip down here just to see you try to get my combo to idle at 5 degrees :poke:
 
Make sure your ignition box isn’t retarding. I just caught a box retarding at about 2800 which is the lowest I’ve ever seen. I caught that with a timing light. I did his distributor but not his box.

It will definitely affect everything.
 
roccodart440 said:
Compression is 10 or 10.5:1, I forget. I only know the duration, LSA and lift on the solid roller. I run 91-94 premium fuel.

The new custom bushing allows for 14 degrees advance which puts me at 22 initial, 36 total vs. 18/36
Click to expand...

FOOD FOR THOT , I`M RUNNING 24 INITIAL , AND 34 ALL IN AT 3000 (93 octane ) , W/ A LOOSE 3500 CONVERTOR , OUT ON THE ROAD CRUISING HAVE IT SET AT 52 FOR A LIMIT .
I think Andy F. said he was running 25 initial , ------------------
 
yellow rose said:
Make sure your ignition box isn’t retarding. I just caught a box retarding at about 2800 which is the lowest I’ve ever seen. I caught that with a timing light. I did his distributor but not his box.

It will definitely affect everything.
Click to expand...

Mine is all in at 3,000. I've revved it past that just to check and it shows ok.

My issues are just at idle. I'm not happy with the idle. Off idle and beyond it runs 100%.
 
DrCharles said:
AJ, I would pay for your trip down here just to see you try to get my combo to idle at 5 degrees
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There are lots of smarter guys than me , living a lot closer to you; and like I said I got no experience with BBs, never mind strokers, nor cams as large as yours.
Waitaminute!
I just remembered something from 20 or so years ago; I know three fellas in nearby towns, that had ugly-idling engines; two Hemi's and a 440, that I managed to get the stink out of.
The Hemi's were MP crates, and I hesitate to say this but they were no trouble.
But that 440 had a wicked solid-lifter cam in it, and she was a challenge.
If you lived next door I'd be giving it my best shot.
 
A little update, I'm still waiting for my custom 14 degree bushing to arrive from Don Gould.

In the meantime I wanted to go to a show this weekend so I put the dizzy back in.

For ***** and giggles I replaced the rusty black bushing with a new msd black.

I also went to a lighter spring setup. (light blue and light silver) All in by 2,000. It seemed to like that all around and believe it or not, it helped at idle and with re-starts. I think it was retarding in gear as yellow rose suggested.
 
HAd the dizzy put on a suntach machine (or similar) and come to find out the 18 degree MSD bushing is actually 14 degrees and the advance they say is supposed to be all ion at 2,000 is actually all in at 2,500

Those of you with MSD distributers, i'd have them put in a tach machine and see what they are really doing. DOn't rely on their charts.
 
rocco;
you can use your engine to be a distributor machine, you don't 100% need to put your D on the machine. And if there is a discrepancy between the engine and machine, and your light and tach are know to be good, then I would believe my tools.
 
I bought an MSD timing light (worth every penny) and an MSD tape to put on my FLuid dampner.

It's at 22 initial, 36 total.

Still a bit rich and not as happy as i'd like at idle.

Next up, the proper converter, an AFR port and more carb tuning.
 
roccodart440 said:
I bought an MSD timing light (worth every penny) and an MSD tape to put on my FLuid dampner.

It's at 22 initial, 36 total.

Still a bit rich and not as happy as i'd like at idle.

Next up, the proper converter, an AFR port and more carb tuning.
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I’m surprised your FD wasn’t degreed all the way around.
 
yellow rose said:
I’m surprised your FD wasn’t degreed all the way around.
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It is but the powder coat or clear coat makes it hard to see. The tape is much better. I also made marks at initial and total. with sharpies to help.
 
Hire the right powder coater and you'll never have to worry about seeing the marks.
7779633_orig.jpg
 
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