I can’t say what RPM for certain. It’s not my car. The OP needs to determine that, these are all suggestions & estimates to try and help him.
Recommended total engine timing
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That’s not what I asked you.
I want you to explain how a drag race engine differs from any other engine’s timing requirements.
Explain how a drag engine doesn’t need a curve even though timing is based on load and VE.
Explain how the physics of this changes when you install an engine in a drag car.
Again, use your own words and give details of the physics of how a drag race engine differs from a street/strip engine.
I’m willing to learn.
You make the claim.
I’m saying I used to do it that way and I was WRONG.
You again are running your mouth out of utter ignorance.
You can’t change physics.
I was wondering how long it would take for you to spout the ignorance comment or similar because that is all you have.
The one thing you have said that is correct: you cannot change physics. You also cannot change history & history has the runs on the board...
The hole you are figging is getting bigger...
The one thing you have said that is correct: you cannot change physics. You also cannot change history & history has the runs on the board...
The hole you are figging is getting bigger...
You make far too many assumptions to be taken seriously.
My problem is you spew bullshit wherever you go without proof.
The fact is you or anyone else can’t over come physics.
To that end I’ll say this.
There are people today at race tracks all over the country who can’t use a timing light.
You assume the fictional people you quote actually knew about slew rate and how much and when the ignition box retards.
I’m sure many guys (myself included) locked out timing and went quicker. That doesn’t make it the correct way to tune.
You always have the option of making me look stupid by putting your junk **** on a dyno and proving locked out timing makes more power.
I can walk out to my shop and prove it does NOT.
My testing matches the physics. Your testing…wait…you don’t test anything.
Edit: you need to leave the thread NOW because once again you are derailing a thread where people can learn.
Turk,
This thread is about total engine timing, & that is what I am talking about. I am not derailing anything, except for maybe the BS train....
And now you say you locked the timing on YOUR engine & went quicker? That is what I am saying, so what are we arguing about? There is only ONE quicker, not quicker quicker. I run a locked dist [ 35* ] on my engine which is street driven. Been that way for about 18 yrs, & idles at 48* using MVA.
The internet is full of examples of people that have gone faster....with locked timing.
This thread is about total engine timing, & that is what I am talking about. I am not derailing anything, except for maybe the BS train....
And now you say you locked the timing on YOUR engine & went quicker? That is what I am saying, so what are we arguing about? There is only ONE quicker, not quicker quicker. I run a locked dist [ 35* ] on my engine which is street driven. Been that way for about 18 yrs, & idles at 48* using MVA.
The internet is full of examples of people that have gone faster....with locked timing.
Let me explain it one more time. And I’m taking about total timing and a curve.
If you have no clue about skew rates and ignition boxes retarding, then locking it out is probably best BECAUSE YOH DONT KNOW ANY BETTER.
It’s 2025 and people STILL don’t understand this because people like you **** up everything the people that do know try to teach.
Here’s one for you smart guy.
Bill Jenkins KNEW long BEFORE 1975 that ALL engines wanted a curve. He also sorted out that for the combustion chambers of the day, the rod to stroke ratios and the compression ratios they were using then wanted a “creeping” curve of 1.5 degrees/1000 rpm.
That is still very close to what I’m seeing today. Some of the faster chambers may want 1 degree/1000 rpm but the very low rod/stroke ratios affect that as well.
The fact and the physics are on my side.
The bullshit is on yours.
And you still can’t explain how an engine knows it’s in a drag car. Because you can’t.
Now stop ******* up ANOTHER thread.
I am not f/up another thread because all my comments are relevant to the topic. Nice try by you to protect your b/**** comments. Several people on THIS THREAD other than me have supported locked timing, just the amount varies.
You haven't presented any 'facts & physics', just your opinion....which we get so often..& is WRONG.
And then you introduce slew rates/reading timing lights into the thread when the thread is about locked timing...& you have the gall/stupidity to accuse me of derailing the thread!
You haven't presented any 'facts & physics', just your opinion....which we get so often..& is WRONG.
And then you introduce slew rates/reading timing lights into the thread when the thread is about locked timing...& you have the gall/stupidity to accuse me of derailing the thread!
Mattax
Just the facts, ma'am
The internet is full of BS. Just like in real life people claim they had 'full race' cam in their hemi powered Goat and it was so fast their buddy couldn't hold onto their dash. And guys who claimed they machined a GM distributor to fit in BB Chrysler.
When you know guys who ran stock eliminator and similar where ET is the only thing that counts and you see real times on real slips, now you got people who may have something really worthwhile to share, if they are willing. Not many people willing to spill all their secrets, especially if they are still in the game.
When you know guys who ran stock eliminator and similar where ET is the only thing that counts and you see real times on real slips, now you got people who may have something really worthwhile to share, if they are willing. Not many people willing to spill all their secrets, especially if they are still in the game.
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furrystump
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I’m pretty sure the distributor is locked at 38 degs, but he is pulling timing out with the box. The box can only delay the timing event. So mechanically the distributor is locked at the highest advance point you would want the engine to ever see. Then based on RPM or time, the box pulls a programmed amount of timing. Which is here nor there. I know LA’s are very sensitive to timing and 38 is a ton. I would start at 30 then run it, add 2 degs until it loses MPH. Then back up 2 degs. MSD actually tells you to lock the distributor if you want to run 10 degrees or less mechanical advance. Kinda silly bandaid.
The way I read his posts the timing is locked at 38. I didn’t find where he said anything about pulling timing anywhere.
At this point the thread is so fucked up it down matter.
If the OP was smart he’d just figure it out on his own than come here and get idiotic *** backwards information.
MopaR&D
Nerd Member
He has a separate thread with a link to a video he made showing how actual timing retards with RPM when using an MSD-style ignition. Locking out the timing to a fixed number can work "OK" but there can be more performance gained by having a curve that advances past peak torque. Just because everyone did something a certain way 50 years ago and got good results doesn't mean there isn't a better way to do it now.
TT5.9mag
Two atmospheres are better than one
It’s pretty simple physics really. The engine speed is continuously variable, we alter the ignition timing because the engine speed increases and the time to burn the mixture gets smaller and smaller. Not only that, but volumetric efficiency changes throughout the rpm range because of things like runner length, plenum design, header length and all order of pressure waves, and as VE goes up or down the burn characteristics in the chamber change because of the density of the charge. Locking the timing only makes the engine happy at ONE single place in a very wide window. Kinda like a broken clock, only that’s at least correct twice.
TT5,
I disagree with your assessment. Locked timing worked decades ago... still works today & has not changed. Locked timing [ or a lot of timing ] works on the low end & the top end for different reasons. I am making the assumption here that the engine has been 'hotted up', ie all the go fast goodies like headers, big cam, better intake have been fitted.
At the lower end, the extra duration/overlap from the cam causes poor/rough combustion which shows up as a rough idle. That mixture takes more time to burn, to burn as completely as it can. Hence the requirement for more timing, to make this happen. At higher rpms, the denser mixture burns more completely...& takes less time. But to give the correct amount of burn time with an engine that is rotating faster requires advancing the timing to let this happen.
I disagree with your assessment. Locked timing worked decades ago... still works today & has not changed. Locked timing [ or a lot of timing ] works on the low end & the top end for different reasons. I am making the assumption here that the engine has been 'hotted up', ie all the go fast goodies like headers, big cam, better intake have been fitted.
At the lower end, the extra duration/overlap from the cam causes poor/rough combustion which shows up as a rough idle. That mixture takes more time to burn, to burn as completely as it can. Hence the requirement for more timing, to make this happen. At higher rpms, the denser mixture burns more completely...& takes less time. But to give the correct amount of burn time with an engine that is rotating faster requires advancing the timing to let this happen.
TT5.9mag
Two atmospheres are better than one
@Bewy locked timing does work, in fact there are circumstances when locking the timing is perfectly fine but in almost all cases building a curve will make more torque at peak and more Hp at peak. The engine wants different timing at those two places for sure. I’ll give an example. When my twin turbo BBC was on the dyno I argued with Steve Brule (a man way smarter and way more experienced than me) about locking the timing on it. I wanted a curve in it. He showed me how an engine in a jet boat will be loaded and unloaded by the pump using the dyno and proved to me that the engine will never operate and be loaded (key word there) in the range where I wanted the curve. The rpm on a jet boat moves so quickly passed peak torque with no load (almost like a loose converter in a car) that the engine didn’t really care where the timing was. We swept it all over and it made zero difference during a pull. So, certain situations locking the timing is perfectly fine, sure, but in ANY case where the engine will be loaded and swept through peak torque and peak Horsepower there is much more torque and power to be had with a curve that caters to both of those ranges and takes in to account the slew rate of the electronics.
Was wondering how the cam profiles interacts with the ignition timing required.... any information for my own knowledge and understanding would be highly appreciated.
This is exactly the way my MSD box and locked distributor are functioning.
Jax,
The cam profile/type has little effect on the WOT timing. At idle, & just off idle, the cam has a big effect. More overlap, duration & lower CR requires more idle timing. The most I have used on a big cam-med engine was 48* at idle. It turned a dog into something that had a reasonable idle @ 900 rpm, in gear, & able to run power brakes. More timing increases vacuum.
The cam profile/type has little effect on the WOT timing. At idle, & just off idle, the cam has a big effect. More overlap, duration & lower CR requires more idle timing. The most I have used on a big cam-med engine was 48* at idle. It turned a dog into something that had a reasonable idle @ 900 rpm, in gear, & able to run power brakes. More timing increases vacuum.
The camshaft directly affects cylinder pressure. Cylinder pressure directly affects timing curve.
It also affects where peak torque and peak power occur. That matters too.
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