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Factory Timing, why?

Nate S

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I was looking at some factory distributor and timing specs and just can’t figure out why these were done this way. Some are pre-emissions so I don’t buy that as a reason. Anyway, most of us would agree that a B or RB wedge does best at 38*, some might argue less and that’s fine. So we look at some factory numbers and I just wonder WTF? *Note, figures here are in proper crankshaft degrees.

‘64 361 init 10*, w/ all mech 33*, w/ vac 59*
So this seems reasonable, a bit short of our 38 but ok.

‘64 426w init 10*, w/ all mech 26, w/v 44
This seems pretty short on advance

‘64 413 390hp 300k, init 12.5, w/m 23.5*. W/v 41.5*
This seems really short.

‘70 383-4 init 0, w/m 22, w/v 44
Still seems wimpy

‘70 440-6 init 5*, w/m 31, w/v 51
Seems more reasonable

‘70 426-8 init 0, w/m 30, w/v 46
Hemis like less, this seems the most believable of the bunch.

So have any of you actually used a stock distributor before actually timed to stock specs? Do the cars do ANYTHING? The most promising of this bunch is the old 361. Some with 22* all-in mechanically? Does that even work? Not looking for “I put in a single ball point pen spring so it’s all in at 400rpm etc. I know that, I do it too, curious if these actually could have performed as spec’d from the factory.
 
High octane leaded gas. Less timing advance needed then keep the engine “happy”. Plus the factory compression ratios were higher than most of the engines that get rebuilt run nowadays. Higher compression requires less advance as well.
 
Throw your timing light back in the toolbox, numbers mean very little. Use your ears make very small adjustments test drive with a load like up a hill listen to the motor and you will know when you find that sweet spot. Every motor is different, you can build 2 identical motors and I would put money on them running best at each having different degrees of timing.
 
I was looking at some factory distributor and timing specs and just can’t figure out why these were done this way.

‘70 426-8 init 0, w/m 30, w/v 46
Hemis like less, this seems the most believable of the bunch.
I don’t subscribe to that theory either given the large 170cc chamber and the relatively low compression. Besides if you listen to Garlits talk about early times when the first 426 arrived on the scene, he said once the figured out the 426 loves ignition lead, they really picked up.
 
I don’t subscribe to that theory either given the large 170cc chamber and the relatively low compression. Besides if you listen to Garlits talk about early times when the first 426 arrived on the scene, he said once the figured out the 426 loves ignition lead, they really picked up.
Ok, I won’t argue that. Still fits with the original question. There’s a Looong way between these different factory figures and all seem low. Kinda guessing it was a place where they would run well enough with minimal BS. Just seems like a lot to be left on the table and I’m curious how these behaved if actually set up to the specs. I know how to make them run well, that’s not the question.
 
Ok, I won’t argue that. Still fits with the original question. There’s a Looong way between these different factory figures and all seem low. Kinda guessing it was a place where they would run well enough with minimal BS. Just seems like a lot to be left on the table and I’m curious how these behaved if actually set up to the specs. I know how to make them run well, that’s not the question.
You’re absolutely correct and I agree as well. Given the fuel available then, these things should have been able to take more timing. What’s frustrating is reading all the people who still recommend these timing settings for aftermarket builds with more cubes, better heads, much larger cams that have very little in common with the original engines. The only thing 10 degrees initial timing is good for is easy starting.
 
Some people also don't buy that the earth is round...
Prove it. Besides the hills and mountains, if you go to the central plains, you'll clearly see the earth is flat. People are flat, just look at your flat TV, and you'll see that's true. What happens when you let the air out of a round basketball ? It gets FLAT. Just like a round tire without air, goes flat. The sky at night is flat. The sun & the moon ? Look at them... flat. ( And, everything I just posted is flat-out nonsense :D )
 
Quoting your original premise,
"Some are pre-emissions so I don’t buy that as a reason. Anyway, most of us would agree that a B or RB wedge does best at 38*, some might argue less and that’s fine"
With the dawn of the emission control requirements, manufacturers were forced to modify existing engine design and operating parameters to achieve the Federally mandated required compliance standards. One purpose of the early modifications to the ignition system's initial and total was to increase combustion chamber temperature to achieve a more complete conversion of HC (Hydro Carbons)and CO (Carbon Monoxide). Lazy spark advance characteristics, along with leaner fuel mixtures, helped to achieving the goal, increasing combination chamber temperature. Gasoline refiners were begining to introduce low lead fuels, in advance of no lead fuels required by catalytic converters. Engine designers were changing combustion chamber designs and lower compression ratios to be more tolerant of the available fuels. These were the underlying reasons for the ever changing emission regulations. Just my opinion of course.
BOB RENTON
 
Bob, I agree. But in 64? I guess they has a PCV by then but harly anything else. And even at that, the huge difference between a 361 and a 413 in a 300K? There was clearly a reason, I’m not grasping why though.
 
Quoting your original premise,
"Some are pre-emissions so I don’t buy that as a reason. Anyway, most of us would agree that a B or RB wedge does best at 38*, some might argue less and that’s fine"
With the dawn of the emission control requirements, manufacturers were forced to modify existing engine design and operating parameters to achieve the Federally mandated required compliance standards. One purpose of the early modifications to the ignition system's initial and total was to increase combustion chamber temperature to achieve a more complete conversion of HC (Hydro Carbons)and CO (Carbon Monoxide). Lazy spark advance characteristics, along with leaner fuel mixtures, helped to achieving the goal, increasing combination chamber temperature. Gasoline refiners were begining to introduce low lead fuels, in advance of no lead fuels required by catalytic converters. Engine designers were changing combustion chamber designs and lower compression ratios to be more tolerant of the available fuels. These were the underlying reasons for the ever changing emission regulations. Just my opinion of course.
BOB RENTON
It's hard to find any reference to lowering lead content before 1970. Leaner mixtures slow down flame travel so reducing timing seems backwards, just as backing off the timing reduces cylinder head temperature but raises exhaust temperature. Just about every manufacturer kept compression levels until 1970 when NOx started to be an issue. Prior to that, raising compression and advancing timing was a good way to reduce hydrocarbon emissions. So there must be another reason for those 1964 timing figures. In an ideal situation for power, maximum cylinder pressure occurs at 17 degrees after TDC, so timing should be adjusted to reach that goal.
 
Most of it was probably due to the use of the engine - it may have been designed to run low octane fuel perhaps?
The other thing I can think of is combustion chamber design - the earlier wedge style and open chamber designs were detonation prone.
The manufacturer did not really care about performance if the car detonated like **** and blew up before it got out of warranty.
 
If you look at the 383-2bbl specs in the later 1960s and then compare those distributor and timing specs to the similar 383-4bbl high-compression engines, the 2bbls usually had 38 degrees total (+/- 2 degrees). But the 4bbls (even with the same 256/260 cam) with 10.0CR were in the 32 degrees total range, even the 4bbl 440s.

THINK about who ONE of the major purchasers of the 4bbl V-8s were, back into the 1960s. Law Enforcement entities. This does not really matter until you realize that most of them did not desire to spring for the full-tilt 100 Research Octane gasoline just for the police cars. As they had tanks full of 94-5 Research Octane regular gas for all of their other vehicles. So, with Chrysler catering to that particular market, the 4bbls were calibrated to operate decently well on the lower octane fuels at WOT. Saved the taxpayers a lot of money, I suspect, too.

NOW, in an old SAE paper I found where Chrysler presented the paper/transaction to SAE in about 1957 as the new '58s were just out, they claimed the engines were designed to operate on the premium fuels of the time, which were 97 Research Octane.

To get to the current PUMP Octane numbers, subtract about 4 numbers from the Research Octane to get to the current Pump Octane rating.

As for "less is more", Nick (Nick's Garage) usually gets higher power numbers on the dyno with about 34 degrees BTDC total, but I know from my own experiences, that 38-40 degrees total makes for a nicer driving engine.

FWIW,
CBODY67
 
These are interesting insights. Warranty and law enforcement certainly aren’t things that were initially coming to my mind but doubtless they played a part here.
 
Low compression, 906 heads and 38 will probably be in the ballpark. Good aftermarket heads and decent compression and it’ll make max power at 32-35.
 
I think you will find that (conservative timing) is pretty typical of all manufacturers in the 60s and early 70s at least. I’ve seen it with Ford and Chevrolet too. FWIW - my stock 68 440 in my 67 running on 93 ethanol pings bad under full throttle until I back the total timing down to about 33 degrees. Might be some carbon in there though.
 
If you watch enough of those engine builders and tuners out there that work with basically close
to stock Mopar engines, you'll actually notice their dyno sessions typically show 35-36 degrees BTDC
to be the "sweet spot" for the typical zero-decked 440 - as proven by the dyno itself, as they experiment
and tune to get best results...

That's on today's gas, of course - but I gotta say, my own "butt dyno" on Fred's 440 (which is very stock,
short of the 484 purpleshaft cam, headers and what not) bears that out here, too.
Basically, I didn't take timing any further than "what is the stock electronic distributor giving me at idle
when I hold 35-36 degrees "all in" " (wound up in this case being like 13-14BTDC @ 850RPM idle).
 
Another data point... When all that "on road" and longevity stuff didn't matter.
'64 Max Wedge
initial: 10°
All-in mechanical: 32-36 at 2060 rpm(crank)
no vac
 
Had to be set up for alot of different driving conditions. Beach to mountains, -10 to 100+ all with the bank manager and his family, not a bunch of car enthusiast. Better to give up a little than to have grumpy/griping customers that would not no the difference.
 
Back in "the day"...

(note "my" "day" was the dawning of the unleaded era when 89 octane "regular" was still around)

The first thing anyone did with an older car from the 60's was see how much advance it would take.
...and stretch the advance springs in the distributor to get it there faster.

However, the book spec on my 73 318 at idle is "0".

...and it does not like even one degree more.
 
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