6 by 8—I live on the edge, which means I’m used to being on the **** list. One might assume I enjoy being on that list….LOL.

So let’s see here; you are female with the name Mary-ann but you have a beard, you’re old as dirt, and you live in your mom’s basement. Hmm, that translates to you being an old *** transgender with mommy issues….BWAHAHAHAHAHAHA

I do have a slider rear window, so I guess she’ll have to sit in the bed directly behind me. But on second thought, since she is the one who does the cooking (I hate cooking), that means I need to not bite the hand that feeds me, which means it would be stupid of me to get her pissed off at me. That means I should avoid making her ride in the bed. She’s used to the truck being loud and has accepted that as a reason we can’t have a conversation when we’re driving down the road. So my solution to this scenario is that I shouldn’t change the status quo, which means I should never replace the door and window seals and she’ll be none the wiser. It will be our secret. SHHHHHH…..LOL.

Regarding the timing curve numbers, I’ll need to make plans to have my son come over and help me with this. He’s 19, living on his own and is working 2 jobs. So this isn’t something that will happen immediately. In the meantime, like you said, do one thing at a time. So before I go changing the idle timing, timing curve, and all that stuff, I first must focus on figuring out if I have the correct heat range of plug and determine if my a/f ratio is correct. So to start this process, I just went out and pulled the #1 plug and took a couple pictures. Then I came in the house and looked up a website that tells me how to read spark plugs. https://www.dragstuff.com/techarticl...ead-plugs.html

So the basics of reading plugs, according to this article, is this: The “Ground Strap”= Heat Range; the “Plug’s Base-Ring” = Jetting; and the “Porcelain” = signs of detonation/pre-ignition. So comparing my spark plugs, correct me if I’m wrong, but the extremely white ground strap means my heat range is way too hot…..correct? So I need to try an Autolite 24 or 23. Which one should I go with given how my plug looks?

Now onto the base ring. My base ring is black along with a buildup of some dry soot. According to this article, I’m a little too rich. The problem I have is I don’t know if the condition of my plugs is the result of running the 750 carb or the 600 carb. I’m assuming the 750 carb because I’ve only had the 600 carb on the engine a couple days and I have maybe 5-10 miles on it so far. But I think I need to go buy colder plugs and start over with just the 600 carb so I’m not guessing. Question….given the way the plugs look, should I go one or two stages colder????

As far as the porcelain is concerned…I’m not seeing any signs of detonation even though I’ve been hearing pinging. But if you look closely at the bottom side of the ground strap, I can see a few specs of something brown. I had to zoom in on my computer to see it, so I’m not sure if you can see it.

So tell me your thoughts on my plugs. What are you guys seeing?

Matthewq4b—So when you’re saying I have too much vacuum advance, are you basically saying I need to get an adjustable vacuum advance canister so I can back off the vacuum advance? My distributor doesn’t have an adjustable vacuum advance canister.

Regarding the 14* idle timing, you’re suggesting I dial it back a little; let’s say 12*. So then if I install the green bushing (23*), that puts my mechanical advance at 35*. Or I could use the blue bushing (21*) and put the advance at 33*. Then I can change springs and bring the total timing in at 3100-3200 rpm with the green bushing and right at 2900-3000 rpm with the blue bushing. Does this setup sound like a good plan?

But before I make any of these changes, I want to get the proper plug installed first. If I get the proper heat range plug and jetting, it might eliminate the pinging the way it’s set now. But I still need to bring the total advance rpm down to around 3000 or less regardless.

 

The only way the plug would causing the pinging is if they were way to hot. And you missed this in that article (VALID ONLY for full load acceleration or steady state dyno tests.)

Your plug are reading just fine for (fuel air mix) in fact are about perfect... they might be a heat range cold. Also do not get hung up on plugs. As you will not be able to get a proper read till the ignition timing is sorted.

Your base timing is a function of your total minus your mech. You do not set your base but your total. Once your total is dialed in you can check your base to make tune-ups and making checking easier.
If you want to raise your base timing then you reduce you mech timing if you want to lower your base timing then you add mech timing.

Do not concentrate on your base timing but on your total timing that is what counts. Your base timing is just a by-product of total minus mech. And if you have 23° mech advance with your total at say 34° your base will be 11°. If you want to increase your base timing you will reduce the 23° of mech timng.

And yes you will need an adjustable vacuum advance. if you are running an MSD distributor is should be adjustable.

 

I'm not saying a word to change what you wrote.

The idea of an angry Mrs 78 Ford F150 460 looking for an elderly person resembling the ZZ Top guys living in his/her Mum's basement in an igloo in Antartica makes me giggle.

You make an excellent point about the cooking. I didn't think of that.

Mind you, I wouldn't think of that coz my Mum still cooks for me. LOL

I also like the door seals comment, in fact so much so, that I've started making notes.

Could Mrs 78 Ford F150 460 help you with the timing curve instead of your son ?

If no, fair enough.

Before I forget again to say, you won't regret buying the AFR gauges. They are a great tool.

If you have space next to them, consider a vacuum gauge, which is another great tool to have.

Your timing 'range' of 14 to 32* is in the ballpark, and with no pinging, you can leave it there while you test drive with other changes. (Carb etc)

Do not change your springs yet !!

Why not ?

Well, if you do, the timing range might end at 3,000 rpms instead of 3,500rpms, but you'll get a whole load more pinging.

Why ?

Coz you've accelerated the curve, which means the timing at the ''pinging part throttle rpms level' will be higher than it is now, and you'll be back to square one.

Not worth setting the timing limit yet either (32 - 36* or whatever), with WOT tests, coz you haven't dialled in the engine yet.

The 'timing curve' has to be verified first. Period.

Once the curve has been verified as correct, I.E. linear, then you can start fine tuning the curve rate, top limit, idle limit, and vacuum advance.

How do you know how much vacuum advance timing is being provided, if at all ?

Look up several more spark plug technical sites, and look out for 'when to read a plug' and 'compression changes effect on plug heat range '

It wouldn't hurt to read up on lean and rich carb mixtures as well.

I say several technical websites, coz some write crap, and if the majority are saying the same thing, chances are they are correct.

Reading up some more will help you when you get to conflicting messages, like your existing plugs being too rich, lean, or ok.

Talking of conflicts, you've just been told that your plugs are too hot AND too cold.

Your engine will actually give you the correct answer.

I would try 24's, drive around and read them in the exact same manner as you read the 25's, and see what's what.

I say in the same manner so as to compare apples with apples.

24's instead of 23's so as to take one step at a time.

When I look at your plugs, I see the air filter is blue and nicely matching the valve covers.

Just for info, the blue air filters give 23.76 HP more than the red ones.

Not only can a lean mix or too much timing cause pinging, as already mentioned, but so too can a poor choice of pistons and cam !!

What's the part numbers of your new pistons and cam ?

If the block and/or intake manifold were machined, how much was taken off ?

I'll consider that while you work on the plugs and ignition wire voltage.

I'm off now to season the blocks of ice and fresh snow for this evening's bar-b-q with my Mum.

 

Well, some rather horrible advice has been disseminated in this thread.

You want to get the advance fully in by at least 3000 rpm. That is the typical street engine curve. in performance build you'd maybe want it all in by 2500 RPM. But getting your curve adjusted so it all in before 3000rpm is the first thing you do before anything else.

Once that is done you can dial in your mech advance for what the total is going to be. Set this by doing full-throttle acceleration from an idling rolling start and bringing engine rpm up past 3000 rpm. (or where ever the mech is fully in) keep advancing the timing till you start to get WOT detonation then back it off 2-3°. The 2-3° back off will ensure that you won't get detonation from varying environmental conditions.
I suspect you will end up closer to 34° once you have kicked a few degrees back from WOT detonation. I had a similar build back in the day and I was dialed in for 34° total.

Once you have done that you can adjust your available mech if you need to dial back your base. Again ideally you want your base around 8-12° this will ensure easy starts even if the battery is a bit weak.
All these settings and adjustments are done with the vac advance disconnected.
This is the way timing curves have been done either on a machine or in the vehicle since mech advance was widley used in the 1920's

Now you do you vac advance. The vac advance is the last and least important thing you should be worrying about it only there to wring the last mpg or so out of the motor at cruise.
And you are shooting for no pinging when lightly loading the engine under cruise conditions.

And again your plugs are fine your mix is basically perfect, white insulator with just a hint of tan really you could not ask for a more perfect fuel air mix for fuel economy. Many of the plug references you see online today are of no use cause they are for pre ethanol fuel/modern fuels. Modern fuels even non-ethanol do not read the same as they are much lighter and less energy-dense.. 40 years ago your plugs would be considered a bit lean, but it is not 1980 and we are not using fuel formulations from 1980.
The body of your plugs in the combustion chamber is carbon-coated indicating that the plugs are not heating up enough to prevent deposits indicating they could be a heat range hotter. But I would not be too worried about it. And those are old plugs also and have been in use for a while..... And once you advance the mech your plugs may just be fine as you are going to raising combustion temps when moving the curve. To be really accurate plug reading should be done after WOT runs.

A wideband AFR Meter is always a wise investment for a carbed vehicle especially when you have no idea where your AFR is..

 

To the Op, please ignore everything that I have posted, and accept my apology for providing horrible advice.

I had noticed that everyone was only mentioning the timing 'range' and 'speed of the curve' ,as in the start to finish, idle to wot, and springs.

I must have misread your Thread title when I read timing 'curve'.

Do not plot the curve first or at all, and rather advance your timing with softer springs NOW so that it is all in as suggested already.

The electronic ignition manages the actual curve between the start and finish points which the owner sets.

It was wrong of me to suggest checking that the electronic ignition is actually doing its job, by observing, recording, and plotting a graph. Oops !

I've just learned that the actual curves have not been tested since the 1920's.

I also learned that the seasoning on the ice blocks was strong enough to make me light headed enough to write rubbish.

I'll ask my Mum later if she gets light headed too.

So, to ensure no more errors, IGNORE THE CURVE, you can 100% trust that it's control is in proper working order.

 

I have an update/correction to make. I took the Bronco for a spin again yesterday and apparently I’m still pining at 14* idle timing. When I initially set it at 14* (down from 18*) I took it for a drive and gave it the same amount of throttle coming off a stop light as I did before I adjusted the timing and there was no pinging, so I assumed the pinging issue was resolved. But when I drove it yesterday I decided to test for pinging by giving it more throttle than I did before and it was pinging again. So now I’m back to square one.

Matthewq4b—I did see that disclaimer, but wouldn’t the coloration patterns and things to look for when reading a spark plug be the same weather your drag racing vs cruising down the road at a steady throttle? Won’t they both produce the same signs of whether a plug is too hot vs too cold, signs of being too rich or too lean, and signs of detonation or not…..am I correct with my assumption? I understand this article is geared toward drag racing, but it was my understanding that they are looking for signs based on WOT runs, which is why they said to shut down the engine immediately once the race is over. But the signs you’re looking for on a plug is the same even on a street driven vehicle….correct? Or am I wrong? Logic tells me it would be the same, but my logic could be wrong. It wouldn’t be the first time. That’s why I’m on here asking questions.

I used this article because it gave an excellent description and clear detailed pictures of what to look for when reading a spark plug. I compared it to my plugs and I assumed my plug was too hot because the color line on the electrode was only about 1/3 the way up from the weld, not half way up the electrode like the article stated would be a good heat range. That reasoning, and the fact that I’m getting pinging at part throttle, along with your guys suggestions made me think my plug might be one stage too hot. It’s been mentioned that too hot a plug could contribute to pinging, so my logical train of thought was to resolve the plug issue first and see what happens. I’m also going to start using supreme w/no ethanol gas and that should help also, but I still have a half tank of cheap crappy gas to use first. You mentioned my plug looked too cold and now I’m confused because according to the article I read, that is the opposite of what it suggests based on where my color line is on the electrode. Can you explain why you think it’s too cold? What are you seeing on my plug that makes you determine it’s too cold?

I looked at the MSD website and Summit Racing and I could not find an adjustable vacuum advance canister for my MSD 8477 distributor. And nowhere in the literature does it say the canister I have is adjustable. Maybe I’ll just get out my allen wrenches and stick it in the vacuum snout and see if I can determine if it’s adjustable nor not. Any idea what size allen wrench an adjustable canister screw takes?

6 by 8—I have to confess something….I found our conversation extremely hilarious and since I know my wife has the same sense of humor as you and I and the fact she has thick skin and doesn’t get butt hurt over stuff like this, I thought it would amuse her if I caught her up on our conversation, so I read it to her just now. She laughed her *** off and had a comment or two of her own to throw out there. She said, “you both are assuming I would want to have a conversation with you”. And she also wanted to know how old your mom is since you’re 93…..LOL. And then she picked up on the fact you have a basement in an igloo, which means you must be doing well for yourself if you can afford an igloo with a basement…..LOL.

Yes, I could have the wife help me with the timing curve. I think that sounds like a plan that would get done much sooner than getting my son to come over and help. Good idea. I’ll see if I can talk her into it; that is if she “wants” me to talk to her….LOL.

I too feel the A/F gauge will be a great tool and I’ll probably take your advice on getting a vacuum gauge also. FYI…my vacuum gauge reads 18 at 800 rpm, so I have really good vacuum with this RV cam. I’ve tried dialing in the A/F mixture and jetting with a vacuum gauge and tach and it’s not as easy as some make it sound, especially if there are fluctuations with the needle. But I have done the best I can and I think I have it close. The A/F gauge will give me more accurate data, but the gauge I want is $300, which is why I haven’t bought it yet. But I feel it would be a great investment.

Not bringing the timing curve in sooner just yet makes sense to me since I’m still having issues with pinging. First thing to take care of is to determine the timing curve (as you and others have suggested), then deal with the pinging and then adjust the timing curve, correct? Am I understanding this correctly??? At the same time, I want to start over with a fresh set of plugs since I have swapped carbs. I’m not sure if what I’m seeing on the plugs is a result of the 750 carb or the 600 carb. Speaking of installing new plugs….how many miles do I need to put on the new plugs before I am able to see the coloration patterns for a hot vs cold plug, jetting and pinging? Since I’m still pinging at 14*, should I back the timing down to 12* and then drive it? Or leave it as is? If too hot of a plug can contribute to pinging, then logic tells me to leave the timing as is and see if a colder plug solves the issue. Am I on the right track with my logic? After all, you guys say to do one thing at a time, right?

I will definitely look up more articles. In fact, I started doing that last night. I have the same method as you when it comes to determining good info vs bad info. I look for the majority with the same info and then add a little of my own knowledge and sprinkle a little common sense on top of it and come up with an answer or solution. But sometimes that offends people because they think you don’t believe what they’re saying. But that’s not the case whatsoever. It’s just that when you have opposing information, how do you determine which is correct? What seems to work for me is looking for the majority of the same info.

Here are the pistons I’m running. https://www.tmeyerinc.com/product/piston-set-ford-400/

Here’s my cam & lifter set https://www.summitracing.com/parts/cca-cl32-242-4/overview/make/ford

Here’s my distributor https://www.summitracing.com/parts/msd-8477/overview/

Here’s my coil https://www.summitracing.com/parts/msd-8202

The block and intake were not machined. But with that said, read the notes on the pistons regarding deck height. However, my heads were surfaced when I had them rebuilt. Not sure how much “surfacing” takes off, but if my memory serves me correctly, I think the machine shop guy said he took off about .010”. I’m not sure how much more compression that adds to the 9.3 compression the pistons provide.

It has long since been determined that dyno results prove if you run a matching blue air filter with a blue Ford engine, you gain more hp and torque. If I was to paint the engine Chevy orange and run a blue air filter, I’m not sure the engine would start at all, let alone have any power….LOL.

 

Most of the " horrible advice " is exactly the same as the new and improved self proclaimed expert advice. you gotta love the internet.

 

So true. Determining good advice from bad advice when you don't know the answer yourself is the challenge.

 

Yes but you are not just driving at steady throttle. Unlike on a dyno where the fuel air ratio static at WOT when you are driving the fuel-air ratio is quite dynamic it will go from max as per your jetting to extremely lean when you back off the throttle and will vary with manifold pressure RPM and throttle position. Again why the article clearly stated this can only be used for Dyno tuning as on the dyno there is basically 2 throttle positions idle and WOT
and it is that WOT fuel-air that counts as that is when the engine is working the hardest and generating the most combustion heat and where the risk of doing damage is the highest..

See below for the simple dummy version of plug reading. And look where yours sits. Again you are NOT drag racing, you do not run the same heat ranges racing as you do on the street you typically would run hotter on the street to keep the plugs clean as you have varying fuel-air ratios from cold to hot and unlike racing the plugs are not changed every or every couple races nor are subjected to continuous full thorttle, plugs on the street need to be hot enough to burn off accumulated deposits under the varying driving conditions street vehicles see. You are better off being a range too hot than one too cold.

Your part throttle pinging has NOTHING to do with your plugs zero zip nada, plugs at part throttle can not cause that unless they were excessively hot like hot enough the ground strap would be burned off and the porcelain blistered.
Your plugs are the absolute last thing you should be worrying about.

Your part throttle pinging is ALL due to the vacuum advance. Disconnect the vaccum advance and I can almost guarantee it goes away.
Also IIRC the MSD distributors use a GM style vac advance so something like the Moroso 72315 or equivalent should give you an adjustable vac advance. Regardless the Allen wrench size for all them to adjust is 3/32"

 

Ya especially from the dudes that think ignition timing affects the delivered fuel-air ratio of the carb, Those self-proclaimed experts should put a sock in it till they get half a clue.

 

Your wife's comment is very clever and very quick.

Hmmm, be wary (afraid!). I can see HER driving the truck and YOU sitting in the back ! LOL

My Mum is old fashioned and says that one should never ask a woman's age, but seeing as it's a woman asking, I'm sure she won't mind me sharing her age.

She's 109.

Yeah, I know, she had me at a very early age.

Now I'm not one for ego or showing off, but I have to share with you that the igloo is in a fact a 'multi story igloo'.

We also have a first floor, which is where Mum's bedroom is.

She keeps fit by using the stairs.

I'm not the affluent one.

Mum made her millions selling paintings of snow and ice bergs.

I've been out of work since I was, well, since I left school.

That's enough about me and my Mum.

This thread topic is about timing curve setup.

But it could also be 'what is the root cause of my pinging?'.

The recent posts mentioned ascertaining good advice from bad, so let's have a look at :

The first sentence way back in post 6 by 440 sixpack.

The 1st and second sentences in post 19 by AKsilvereagle

Good advice right there.

But why exactly does the engine ping now ?

Your OE engine prior to the rebuild had a compression ratio of +/- 8.4, less than optimal 'squish', less than optimal 'quench', less than optimal 'Dynamic compression' and lowish cylinder pressures.

That setup doesn't mind cheap gas (low octane).

Your new engine now has a higher compression ratio of +/- 9.4 which produces a much better, efficient squish, significantly higher cylinder pressures, but still less than optimal quench due to the 'open chamber' OE heads.

The new setup needs more octane. Period. And premium gas, with the higher octane and better quality, will solve the pinging problem immediately.

Luckily you agreed to using premium back in post 21.

Problem solved. Yeeeeeee-haaaaaaaa.

If you're curious as to what the cylinder pressures are, get a compression gauge and read each cylinder on a warm engine.

The OE engine would have produced +/- 140, and the new engine should be +/-160, as guidelines.

You've read enough about the timing curve to get a good understanding of it, so now it's time to convert that theory into practice.

MatthewQ4B was correct in his sentence one in post 30, and he just mentioned it again.

Seeing as you still have cheap gas in your tank, may I suggest this :

With the dizzy exactly as it is now, plot the timing curve. (14 to 32 all in at 3,500rpms)

If the curve is crap, and reflects a faulty dizzy, enough said.

If the curve is linear, and appears to be similar in shape as the diagrams advertised by MSD, great, you can keep it coz it works.

Move the idle to 12 (32 will automatically become 30) and go for a drive.

How does the power feel and do you still have pinging ?

Then change it to 10, pinging or not, and go for a drive. (feeling the power loss yet ?)

Once you have no pinging, change it back to 14 and disconnect/plug the vacuum advance, and drive it like that until you can fill up with he good stuff.

No vacuum advance ruins gas mileage by up to 20% !! But we don't care in this case.

Assuming your air/fuel mix is in the ballpark, once you've filled up with the octane mojo, go for a decent length drive, and on your way home, find quiet roads, and from a standstill give it WOT.

There should be zero pinging at any throttle position throughout the drive.

Next up, change one heavy spring with one light spring.

Ask The Boss, I mean the wife, to assist you again, and plot a new graph.

Let's say the all in timing is now at 3,000rpms, go out and drive the same again.

If still no pinging, change the other heavy spring to a medium spring, plot the graph, and go out again.

Once you get to all in at 2,500rpms, say, with no pinging, you can advance the total timing in increments of 1 until you get pinging at WOT, then lower it by 2.

You get the picture.

You keep plotting a graph coz how else will you know if the actual springs are crap or not !!

During these dial in tests, you should start feeling more power, more responsive and smoother.

The 25 spark plugs will be just fine during this dial in period.

Reading the plugs again now will be a waste of time coz the octane and timing are about to change !

Your engine will tell you if the plugs are fine or not, heat range etc.

Read your plugs every say 100 miles until you are happy with them.

Once you install the AFR gauge, you can fine tune the idle, cruise, and WOT circuits.

Your reading of 18'' at 800rpms is excellent. Did you get a steady needle at this reading ?

Is your engine equipped with emission control bit's 'n pieces ?

If not, would you like to see 21'' at 800rpms amongst other benefits ? No extra cost, and takes 3 1/2 minutes to achieve.

Once you're done with the 400, you'll have the confidence to do the same to the 460, and by the looks of it, the 460 can be improved.

Right, time to do my hair and trim the beard coz Mum and I are off to a snow man building competition. Yeah, early start !

 

" especially from the dudes that think ignition timing affects the delivered fuel-air ratio of the carb, Those self-proclaimed experts should put a sock in it till they get half a clue"

If you're too dumb to understand ignition timing effects fuel burn you're not nearly the expert you think you are.

When you parrot other people's advice it doesn't make it original just because you ridicule them first. but what should we expect , Americans design and build everything then you take it and try to figure out how it works and call it yours.

 

Matthewq4b—Your explanation of part throttle vs WOT makes logical sense. Also, I looked for an adjustable vacuum advance, including the one you mentioned, and so far I can’t find one that comes right out and states it will for sure fit my MSD 8477. When I searched for adjustable vacuum advance canisters, I get a variety that fit different distributors, but one doesn’t fit all. I have also been reading Q&A’s on each canister looking for details on my specific distributor and so far the only mention of the 8477 was someone that stated that MSD doesn’t make one for the 8477. However, that doesn’t mean Moroso or another brand won’t fit, but I want to get confirmation before I spend money on something that I don’t know for sure will fit. So I did send an email to Summit Racing asking if they know which canister will fit the 8477. I’m waiting to hear back. I’m also in the process of sending the same e-mail to MSD/Holley. We’ll see what they say. But I am on board with changing the canister to an adjustable one (if I can find one) because I believe you’re right about the vacuum advance causing pinging issue. Oh and for the record, my current vacuum advance canister is not adjustable. I took a 3/32 allen wrench and checked it last night.

6 by 8—My wife is pretty smart, and that fact is proven by her decision to marry me…..LMAO. I’m not too worried about her driving my truck. She can drive a stick shift, but as she mentioned last night, my truck is way too big for her to feel comfortable driving (78 F150 Super Cab w/6” lift on 37’s w/gear vendors overdrive). The size, height, and the GV overdrive makes her nervous enough that she doesn’t want to drive it. So it sounds like I’m in the clear…..Whew!!!!

So your mum was “getting busy” at 16? That’s not acceptable behavior of society 109 years ago. Sounds like your mom was an outcast for having you at 16. She probably got kicked out of the village, and country for that matter, and explains why you live in an igloo in Antartica…..LMAO. But it sounds like she made the best of it and worked her butt off to afford a “multi-story igloo”. Gotta respect hard work. Good for her!!!

The wife got a real good laugh at your comments this morning, and so did I. Although this is all in fun, your choice of words in your comedy skit (mum, multi-story with bedroom on the first floor) has my wife curious as to where you’re from. She was guessing either Canada, England/GB, Scottland or Wales. I mentioned that I thought they used the word “mum” in Australia also, which puts you close to Antartica, so the move out of the country wouldn’t be that far…..LMAO.

The steps you outlined to do is perfect. With information overload setting in, that’s exactly what I needed. First thing I’ll do is determine my timing curve, then I’ll work on doing the steps you suggested. I won’t be able to do it today, as we will be helping my sister and brother-in-law tear down a barn. Depending on what time we get done and how exhausted we are, I might be able to talk the wife into helping me with the timing curve tonight. She already agreed to help, but not sure if we’ll get to it tonight. We’ll see. If not tonight, I will shoot for tomorrow after work. When I figure out the curve, I'll do the driving test, then I’ll report the results and go from there.

No, I’m not running any smoq equipment. And from what I remember, the needle was pretty steady when I took the vacuum reading (which was a few months ago when I first got the 400 built and installed. There might have been a little fluctuation, but it wasn’t very much if my memory serves me correctly. Question…..you mentioned you would like to see 21” of vacuum at 800 rpms. I believe I got that 18” of vacuum with the timing at 18*. So to get 21”, I assume you are shooting for the idle timing to be somewhere north of 18* once all is said and done???

 

Update…..Ok, so I was able to do some testing this afternoon and was able to determine my timing curve. It looks pretty consistent to me. What do you think?

14* @ Idle

16* @ 1500

23* @ 2000

27* @ 2500

30* @ 3000

31* @ 3500

After charting the timing curve, I took the Bronco for a drive with the idle timing at 14*, the vacuum advance disconnected and plugged. No pinging even at WOT. Then I adjusted the timing to 12*, reconnected the vacuum advance and took it for a drive. It did ping at WOT, but just barely and not for long. It seems that once I get past a certain rpm, it quits pinging. Then I adjusted it to 10*and took it for a drive again. No pinging at WOT whatsoever. I left it at 10* for now, but once I am able to use all the crappy gas and fill it with supreme, I’ll see if I can advance it back to 14* without pinging. In the mean time I sent Summit Racing and MSD/Holley an email about an adjustable vacuum advance that will fit my distributor.

 

LMAO Ignition timing-induced fuel burn efficiency has NOTHING to do with the fuel-air ratio that the carb delivers. THAT is what you claimed, do we need to post the quote again for a reminder...
And still waiting for you step up already and explain in-depth how ignition timing affects the fuel-air ratio delivered by the carb.
Or are you doing a back peddle on that now that you got called on making stupid clueless statements?