1971 360 question

[neilyoung561]

1/2 the vacuum on a PV is the standard. Even Holley states that on their videos and tech support. I had a 6.5 PV in it originally and it would bog off the line, now it doesn't. The only issue now is the idle. There is a big difference in the idle between P or N and in drive.




Hmmmmm, didn't check that, but when I mash the gas peddle, it launches.

I would disconnect your gas peddle linkage and check if you are able to drop the idle down A body throttle cable doesn't have enough travel in the peddle I perches a secondary linkage to get full throttle part number 20-122 and a throttle lever extension modal number 4014412 to also get more travel if i didn't get these 2 things i would lot have full travel in my carb im just thinking your cable is too tight and keeping your throttle open a little bit and the RPM drop is because of the trany load RPM should be able to set as low enough to stall out the engine

 

[AJ/FormS]

IMO, your idle-timing is your problem.
Coupled with, most likely, a partially open Secondary throttle, and Primaries that are too far closed.
There is NO GOOD REASON to run big idle-timing numbers, NONE. People do it to get the stall-timing right, cuz they don't know how to properly modify the distributor. Or, they're just lazy.

BTW, I run a 12.5PV on my 360 with a 276/286/110 cam (230/237@050), and she will idle down to 550 in First Gear(A833) and pulling herself around the parking lot at 5* timing advance. She'll go down to 500 if I ride the brake a hair.

Fix your timing

 

[neilyoung561]

IMO, your idle-timing is your problem.
Coupled with, most likely, a partially open Secondary throttle, and Primaries that are too far closed.
There is NO GOOD REASON to run big idle-timing numbers, NONE. People do it to get the stall-timing right, cuz they don't know how to properly modify the distributor. Or, they're just lazy.

BTW, I run a 12.5PV on my 360 with a 276/286/110 cam (230/237@050), and she will idle down to 550 in First Gear(A833) and pulling herself around the parking lot at 5* timing advance. She'll go down to 500 if I ride the brake a hair.

Fix your timing

Exactly what i was thinking. Throttle is partially open

 

[72bluNblu]

The timing is off the scale, not sure where, but I would guess around 20 degs.

Not knowing the idle timing is a problem. You have to know where you’re at, exactly, regardless of who you’re gonna listen to for the rest of your troubleshooting and tuning.

Holley has been wrong about power valve selection going on 50 years, at least as long as I've been involved with cars.

You have a tune up problem with 400-500 rpm drop from p/n to in gear. Hillbilly timing tape the balancer so you know where you sit for initial and total timing.

C’mon man. They’re not wrong about PV tuning. Lots of different tuning philosophies out there, and they don’t all apply to every build.

Their method of selecting a PV is a recommendation of where to START tuning, not where to end it.

And it’s meant for the average user. Hell some builders will put a plug in the PV and do all the carb tuning with the jets. Good way to lose gas mileage and run rich at cruise on a street car, but for a car that’s always wide open on the drag strip that’s not a problem.

IMO, your idle-timing is your problem.

lol, the PO doesn’t even know what it is.

Coupled with, most likely, a partially open Secondary throttle, and Primaries that are too far closed.

Could be, still not enough info to determine that for sure though

There is NO GOOD REASON to run big idle-timing numbers, NONE. People do it to get the stall-timing right, cuz they don't know how to properly modify the distributor. Or, they're just

Complete bullshit. There are absolutely reasons to run higher idle timing than what the factory recommends, and that can be very build specific.

Sure, not every build should have 20° advance at idle, but not every build is gonna be right at 10° either.

BTW, I run a 12.5PV on my 360

A perfect example that one size does not fit all. On my 340, that would mean the PV would be open at idle.

And hey, maybe your 360 has a vacuum of 20 inHG at idle and that works for you, but it absolutely wouldn’t work for everyone.

 

[RustyRatRod]

1/2 the vacuum on a PV is the standard. Even Holley states that on their videos and tech support. I had a 6.5 PV in it originally and it would bog off the line, now it doesn't. The only issue now is the idle. There is a big difference in the idle between P or N and in drive.




Hmmmmm, didn't check that, but when I mash the gas peddle, it launches.

Holley has gotten it wrong for over fifty years.

 

[RustyRatRod]

C’mon man. They’re not wrong about PV tuning. Lots of different tuning philosophies out there, and they don’t all apply to every build.

Their method of selecting a PV is a recommendation of where to START tuning, not where to end it.

And it’s meant for the average user. Hell some builders will put a plug in the PV and do all the carb tuning with the jets. Good way to lose gas mileage and run rich at cruise on a street car, but for a car that’s always wide open on the drag strip that’s not a problem.

I'll go along with that. I think most scoff at Holley acting like there's only one way to skin a cat. Although what you say makes sense and I agree 100%, nowhere at any time have I seen anything in print from Holley that backs up the idle vacuum method as being a "starting point", though it does make perfect sense. There's many ways to skin this dog. I like cats, so.......

 

[72bluNblu]

I'll go along with that. I think most scoff at Holley acting like there's only one way to skin a cat. Although what you say makes sense and I agree 100%, nowhere at any time have I seen anything in print from Holley that backs up the idle vacuum method as being a "starting point", though it does make perfect sense. There's many ways to skin this dog. I like cats, so.......

They should definitely say something along the lines that they’re making a basic recommendation for the average user, not an “end all be all” declaration that all PV’s must be half the idle vacuum.

But they’re a big company. Lots of people that buy their carbs open the box and install the carb and if they get as far as changing the jets up or down a size or two they’re doing good.

To me, any of those basic manufacturer recommendations are a starting point for your tune, nothing more. Your car idles at 20 inHG? Well that off the shelf 6.5 PV your carb came with may not be right. Your car idles at 10 inHG? Again, probably gonna have to look at that PV. That’s all it is.

It’s not “wrong”, but it won’t be right for every application either. Just like some of the advice here isn’t right for every application.

 

[RustyRatRod]

They should definitely say something along the lines that they’re making a basic recommendation for the average user, not an “end all be all” declaration that all PV’s must be half the idle vacuum.

But they’re a big company. Lots of people that buy their carbs open the box and install the carb and if they get as far as changing the jets up or down a size or two they’re doing good.

To me, any of those basic manufacturer recommendations are a starting point for your tune, nothing more. Your car idles at 20 inHG? Well that off the shelf 6.5 PV your carb came with may not be right. Your car idles at 10 inHG? Again, probably gonna have to look at that PV. That’s all it is.

It’s not “wrong”, but it won’t be right for every application either. Just like some of the advice here isn’t right for every application.

Puzackly.

 

[Newbomb Turk]

They should definitely say something along the lines that they’re making a basic recommendation for the average user, not an “end all be all” declaration that all PV’s must be half the idle vacuum.

But they’re a big company. Lots of people that buy their carbs open the box and install the carb and if they get as far as changing the jets up or down a size or two they’re doing good.

To me, any of those basic manufacturer recommendations are a starting point for your tune, nothing more. Your car idles at 20 inHG? Well that off the shelf 6.5 PV your carb came with may not be right. Your car idles at 10 inHG? Again, probably gonna have to look at that PV. That’s all it is.

It’s not “wrong”, but it won’t be right for every application either. Just like some of the advice here isn’t right for every application.

Once again, the power valve can open at idle but it won’t flow any fuel.

No one should be setting power valve opening from idle vacuum. That makes ZERO sense because it doesn’t have any affect on the idle and it’s not influenced by idle vacuum or anything else.

To CORRECTLY set the STARTING POINT for a Holley power valve you need to know IDLE CRUISE VACUUM because that’s where the power valve functions.

You should start power valve opening 3-4 inches below CRUISE VACUUM.

Holley knows it’s wrong to use idle vacuum as a starting point.

That’s one reason why guys have fucked up, sorry running Holley carbs.

They get the power valve opening late, so they use a massive pump shot and every time they touch the throttle it slobbers fuel into the engine when it doesn’t need it.

I can’t believe it’s 2025 and guys still say there’s more than one way to skin a cat when it comes to this. It’s crazy to perpetuate the wrong.

Idle vacuum and power valve opening have no connection whatsoever.

Do what you want but doing what you say is wrong.

 

[mopowers]

I've never owned a car where choosing a PV based on half of idle vacuum was a good starting point. They're better off just choosing an arbitrary number as a "starting point," which is pretty much what Holley does since most new Holley's come with 6.5 PV's.

Anyone willing to tune the PV should know that the opening event is based on vacuum when actually driving, not sitting at idle. Using idle vacuum as a starting point is just ignorant.

 

[67Dart273]

If that 71 360 still sports the original ONE YEAR ONLY pistons, then it has higher compression than ANY other year LA 360 and probably DANG CLOSE to the 5.9 Magnum, because they had one year only pistons with a taller compression height and that gave those engines around a true 9:1 "or so" compression. So yeah, it'll suck that 750 down and blow it out the tail pipes.

I had a 71 hi compression. My understanding, perhaps not correct, is that some were high and some low. Maybe early/ late, etc.

 

[Wicked4659]

Are running ported or non ported vac advance....

I'm using the timed spark port above the idle mixture screw.

Alright. So I'll take that to mean "The timing is where it is all else be damned and I'm not gonna verify a damn thing" Sounds good to me. Have fun with it.

Do you yell at the sky and tell kids to get off your damn lawn? With your attitude, I don't need your help. I'll get this squared away, with out your input, have a great weekend.

 

[nutz]

Ha I'm sure he dose ......
Sounds like my wife.....better close the doors on the cabinets
But she dose get the point across

 

[Wicked4659]

The only point he got across is, "I'm not here to help, but to berate other members". We all ask for opinions, because there might be a solution we didn't think about and a fresh set of eyes might pick up on it. This is supposed to be a forum, where like minded people work together, to accomplish a goal. There was no need for his attitude, if you're not here to help, move on.

 

[nutz]

Think he wants base timing #s

 

[Newbomb Turk]

The only point he got across is, "I'm not here to help, but to berate other members". We all ask for opinions, because there might be a solution we didn't think about and a fresh set of eyes might pick up on it. This is supposed to be a forum, where like minded people work together, to accomplish a goal. There was no need for his attitude, if you're not here to help, move on.

So letting wrong information go uncorrected so feelings don't get hurt?

Got it. But that's exactly why stupid, incorrect and wrong information like setting power valve opening at half idle vacuum continues to spread like VD.

I hope this doesn't hurt your feelings.

 

[65 Cuda 340]

The only point he got across is, "I'm not here to help, but to berate other members". We all ask for opinions, because there might be a solution we didn't think about and a fresh set of eyes might pick up on it. This is supposed to be a forum, where like minded people work together, to accomplish a goal. There was no need for his attitude, if you're not here to help, move on.

Coming in here with 19 total posts and attacking an old hand with over 100,000 posts is not a good look. And yeah, RRR can be kinda grumpy at times, and no one is always right, no matter how often they post. But he knows a lot and genuinely tries to help. After a while he can, like many of us, get tired of newbies coming on here seeking solutions to a problem they're having, but when knowledgeable people ask for more information so they can make a reasonable stab at diagnosing the problem, all they get is a run around.

I'd say yours is the attitude we don't need.

 

[AJ/FormS]

And hey, maybe your 360 has a vacuum of 20 inHG at idle and that works for you, but it absolutely wouldn’t work for everyone.

Even 318s don't always idle at 20.
I've never had any 360 idle at 20.
more like 8 or 9 maybe up to 11 if I really advance it.
But not at the 12>14 I run.
But see, My 11/1 engine is tuned to run on 87E10, so I run a 2-stage curve that I pirated out of an old 318, and just set up for my application.
But the thing is, as I stated, I can tune to idle at 5* timing.
and what I said was;
"There is NO GOOD REASON to run big idle-timing numbers, NONE. People do it to get the stall-timing right, cuz they don't know how to properly modify the distributor. Or, they're just lazy."
I never defined "big" . What you imagined, came from inside your own daymn head.
So as usual, you jumped in with your blinders on.

I don't recommend ANY IDLE TIMING numbers for the simple reason that any number given may upset the Transfer slot to Mixture-screw synchronization, which leads to drivability issues.
On my engine, with properly synchronized T-slots, and a stable fuel-level, it runs on any Idle-timing from 5 to 25, the only difference being the Idle-Speed, and a small change in throttle response. By 8 degrees, I can slam that DP and expect instant tirespin, so, there is no good reason to run more. I run 12>14 cuz it gets me 28*@2800 on the first stage, which is slow enough to not cause detonation on 87E10. From there it goes to 32>34 at 3400. which is late enough to go WOT at any speed in any gear except overdrive which is geared for 144@5000, so not going there on any public road, lol.

Furthermore; when I said;

"BTW, I run a 12.5PV on my 360 with a 276/286/110 cam (230/237@050), and she will idle down to 550 in First Gear(A833) and pulling herself around the parking lot at 5* timing advance. She'll go down to 500 if I ride the brake a hair."

Please note, I said BTW which, if you don't know it, means; "By the Way".
Then I continued, with information that could be helpful once OP figures out his cam. Nowhere did I command OP, or even recommend OP, to run a 12.5pv
.
BTW,
I run the 12.5PV for two reasons;
1) so I can run a smaller MJ so I can cruise lean, made possible by my custom timing curve that allows up to 50* at 2240, and on the previous cam, I squeezed 32 mpg out of that 11/1 engine, geared 65=1600. and
2) cuz the transition from PMJ to PV is dead smooth.
I got a double pumper set slightly rich on the back to compensate for slightly lean on the front; and it's a manual trans, so the engine is always humming, I gotta try to save gas wherever I can. Plus lean is mean.

Finally; if your 340, at idle, with a 12.5PV already flowing, your tune has a problem. You should consider a 360 like mine;
which has no problem with that 12.5,
right down to 550rpm,
and nicely crawling along on it's own, at 4mph.

So you know, if you can't get sense from my posts, whose fault is that?
Just put me on ignore.

 

[72bluNblu]

Even 318s don't always idle at 20.
I've never had any 360 idle at 20.
more like 8 or 9 maybe up to 11 if I really advance it.
But not at the 12>14 I run.
But see, My 11/1 engine is tuned to run on 87E10, so I run a 2-stage curve that I pirated out of an old 318, and just set up for my application.
But the thing is, as I stated, I can tune to idle at 5* timing.
and what I said was;
"There is NO GOOD REASON to run big idle-timing numbers, NONE. People do it to get the stall-timing right, cuz they don't know how to properly modify the distributor. Or, they're just lazy."
I never defined "big" . What you imagined, came from inside your own daymn head.
So as usual, you jumped in with your blinders on.

I don't recommend ANY IDLE TIMING numbers for the simple reason that any number given may upset the Transfer slot to Mixture-screw synchronization, which leads to drivability issues.
On my engine, with properly synchronized T-slots, and a stable fuel-level, it runs on any Idle-timing from 5 to 25, the only difference being the Idle-Speed, and a small change in throttle response. By 8 degrees, I can slam that DP and expect instant tirespin, so, there is no good reason to run more. I run 12>14 cuz it gets me 28*@2800 on the first stage, which is slow enough to not cause detonation on 87E10. From there it goes to 32>34 at 3400. which is late enough to go WOT at any speed in any gear except overdrive which is geared for 144@5000, so not going there on any public road, lol.

Furthermore; when I said;

"BTW, I run a 12.5PV on my 360 with a 276/286/110 cam (230/237@050), and she will idle down to 550 in First Gear(A833) and pulling herself around the parking lot at 5* timing advance. She'll go down to 500 if I ride the brake a hair."

Please note, I said BTW which, if you don't know it, means; "By the Way".
Then I continued, with information that could be helpful once OP figures out his cam. Nowhere did I command OP, or even recommend OP, to run a 12.5pv
.
BTW,
I run the 12.5PV for two reasons;
1) so I can run a smaller MJ so I can cruise lean, made possible by my custom timing curve that allows up to 50* at 2240, and on the previous cam, I squeezed 32 mpg out of that 11/1 engine, geared 65=1600. and
2) cuz the transition from PMJ to PV is dead smooth.
I got a double pumper set slightly rich on the back to compensate for slightly lean on the front; and it's a manual trans, so the engine is always humming, I gotta try to save gas wherever I can. Plus lean is mean.

Finally; if your 340, at idle, with a 12.5PV already flowing, your tune has a problem. You should consider a 360 like mine;
which has no problem with that 12.5,
right down to 550rpm,
and nicely crawling along on it's own, at 4mph.

So you know, if you can't get sense from my posts, whose fault is that?
Just put me on ignore.

I get "sense" from your posts, it just seems to me that you have a narrow understanding of a complicated topic and think that repeating the same very specific advice to everyone is good for them regardless of the situation.

You say you don't recommend any idle timing numbers, but yet you'll brow-beat anyone that uses more than you- very helpful. I didn't say 20º advanced was "big", I said- "not every build should have 20° advance at idle, but not every build is gonna be right at 10° either". I said that because the OP said his timing was "around 20 degs". The OP's words (post #45), not anything out of my "own daymn head" as you say. Maybe read the thread before you regurgitate your same advice and come after me?

Tire spin as a reason to not add idle timing? Give me a break! That's a lousy reference. I could blow off the tires on my Challenger with a boring 318, a 625 carter OOTB, 2.76's and a 904 with a stock converter. No where near an idle tune. If you couldn't spin the wheels up running the all season tires you run, in an A-body with a 360 and a 4 speed I'd tell you to do a compression check not change the idle timing. And that's before we get to a lack of traction not implying a perfect tune.

Not every engine needs to be tuned the same. Not every engine will perform best when tuned the same, because not every engine build is the same and not every application is the same. You want to tune for absolute gas mileage? Neat. Someone else might want to tune for maximum power, and that will be a totally different set up.

Regardless of what you or the banned member formally known as Yellow Rose say, there are A LOT of different ways to tune a carburetor. Some are definitely better than others, but there's a lot in the middle too. And what works best in one particular car will depend on the engine build, car weight, gearing, vehicle use and even the drivers style and preferences.

Saying I'm "lazy" because my car doesn't run best at 12º advance at idle and won't tolerate a 12.5 PV just shows that you only understand a very small window of a very complicated topic. I'm no expert, but it's pretty obvious you aren't either.

 

[Newbomb Turk]

I get "sense" from your posts, it just seems to me that you have a narrow understanding of a complicated topic and think that repeating the same very specific advice to everyone is good for them regardless of the situation.

You say you don't recommend any idle timing numbers, but yet you'll brow-beat anyone that uses more than you- very helpful. I didn't say 20º advanced was "big", I said- "not every build should have 20° advance at idle, but not every build is gonna be right at 10° either". I said that because the OP said his timing was "around 20 degs". The OP's words (post #45), not anything out of my "own daymn head" as you say. Maybe read the thread before you regurgitate your same advice and come after me?

Tire spin as a reason to not add idle timing? Give me a break! That's a lousy reference. I could blow off the tires on my Challenger with a boring 318, a 625 carter OOTB, 2.76's and a 904 with a stock converter. No where near an idle tune. If you couldn't spin the wheels up running the all season tires you run, in an A-body with a 360 and a 4 speed I'd tell you to do a compression check not change the idle timing. And that's before we get to a lack of traction not implying a perfect tune.

Not every engine needs to be tuned the same. Not every engine will perform best when tuned the same, because not every engine build is the same and not every application is the same. You want to tune for absolute gas mileage? Neat. Someone else might want to tune for maximum power, and that will be a totally different set up.

Regardless of what you or the banned member formally known as Yellow Rose say, there are A LOT of different ways to tune a carburetor. Some are definitely better than others, but there's a lot in the middle too. And what works best in one particular car will depend on the engine build, car weight, gearing, vehicle use and even the drivers style and preferences.

Saying I'm "lazy" because my car doesn't run best at 12º advance at idle and won't tolerate a 12.5 PV just shows that you only understand a very small window of a very complicated topic. I'm no expert, but it's pretty obvious you aren't either.

I haven’t seen an engine that can actually use 1/2 of idle vacuum and have it be correct.

No where have I read Holley claim it’s a starting point, and if they have they never tell how to tune from there.

Even Holley doesn’t practice what they preach. How so you ask? I can find several examples of OE Holley carbs that came with 12.5 inch opening power valves. That would mean the idle vacuum would be over 24 inches.

Of course you’ll say that they started at 1/2 vacuum at idle and then tuned back to a 12.5 power valve. I’ve never seen how they got there though.

Interesting note for those who care. If I get this wrong maybe @Mattax can come in here and clean it up.

Not long after Colt Industries bought out Holley they did what all these buy out/merger/acquisition companies do and that’s cut costs. And of course, most of the tooling was old and used up and Colt wasn’t going to spend a bunch of cash retooling.

This is when the faulty power valves started showing up. And this is about the same time all these articles and books were being written and when the “half idle vacuum” started.

Once that was put down on paper it was the de facto method of power valve tuning. And of course it’s wrong. How else do you explain he above reference of the OE Holley carbs using a 12.5 power valve.

Let’s also remember (I forgot to mention it was an OEM GM carb) that the vast majority of testing for the carb was done by GM.

At any rate, the idea that idle vacuum or anything related to idle vacuum is even a good starting point is at best wrong.

I see it all the time. Carbs with the MAB so big it would swallow a golf ball and a power valve opening at 6.5, which has now become the de facto starting point for guys who don’t even bother to use a vacuum gauge.

That big MAB starts the booster way too soon, and if you couple that with an “early opening” power valve you get a nasty, slobbering, pig rich condition. The actual fix is correcting the MAB first and then tuning power valve opening timing.

That never happens. Or at least it happens so little that it’s like it never happens. Does delaying power valve opening help with the massive MAB? Certainly. Is that the right or correct way to tune these carbs, taking into account that while there are exceptions to the rule (which you freely admit) the answer is an unequivocal NO.

I can’t tell you how many engines out there that I know of that have an idle vacuum so 7-8 inches. By the wrong method they should be STARTING with a 3.5 power valve. Of course, at a cruse most of these engines have vacuum of 14-16 inches.

It doesn’t take a rocket surgeon to see the HUGE delay in opening the power valve. And that SHOULD cause a lean stumble. And it will IF the MAB is sized correctly.

You can be butthurt all you want. I couldn’t care less. The fact is it’s wrong to keep perpetuating the myth of half idle vacuum to start power valve opening.

To start tuning power valve opening the MAB sizing needs to be checked and remedied before anything else. I’m not going into how to size the MAB but if the MAB is bigger than an .028 on most 4150 carb’s you need to find out why that is. Then the car needs to be driven with a vacuum gauge hooked up and look at cruise vacuum under various loads and conditions. Then you can pick a starting power valve. Which should be 2-3 inches LESS than cruise vacuum to start.

Annular booster tune differently than down leg boosters and down leg boosters tune differently than straight boosters.

Which leads to this last statement. I know guys love a good hack. A corner cutting time saving hack. This is a bad place to use a hack.

I’d bet a lot that most guys won’t bother to get enough hose to run from the engine compartment to the cabin to read the gauge while driving. They can use the half idle method which is quicker and requires much less effort.

That’s why the dreaded “Holleyitus” is so prevalent. It’s one reason for sure. I would think at some point we’d be wanting to correct this way if tuning. Of course, tuning correctly takes way more time and thought and effort and maybe that’s why it isn’t being done.


TL;DR using half idle vacuum to start power valve opening is a fools errand.

 

[Mattax]

Guessing a little bit on the history but that's about right.
It's certainly possible that the 1/2 idle was something they could tell the average mechanic to do when 'tuning' the aftermarket holley 2 bbl or 4bbl. With a basically stock engine could get away with it, or at least be close.

Tuner has written about the low opening power valve myth and how that came about when fuel changes were eating rubber parts. So that ties in there. Drag racers for the most part don't deal with part throttle as long as they can get the engine to go to full throttle off the line, getting the part throttle acceleration fine tuned wasn't considered important.

IMO, what anyone interested in the subject needs to know is that for driving; idle should be moderately rich, off idle should similar or leaner, getting leaner with more throttle. Increasing throttle for acceleration or up hill, or higher speed cruise (interstate) continues to get leaner.

As the engine load approaches the maximim it can produce at a given rpm, that's when enrichment is needed. The better the fuel distribution, the later this enrichment is needed. A very efficient truck engine may only need enrichment when the vacuum drops to 5 or 6 inchs of mercury. A hot rodded engine with intake and carb and exhaust that doesn't have great part throttle distribution maybe it really does need enrichment at 12"Hg. Chevy's 396 with the 3310 came with a 10.5 (p) and 8.5 (s) PV. All of the Chrysler's performance engines that came with Holleys in '67 and '68 list a 8.5" PV. Relatively speaking the Chrysler's were a bit better (and arguable a little less radical).

Vacuum advance goes completely away about the same time enrichment is needed. So that's another place hot rodders can get the tune messed up. It's best to test for a part throttle dead spot with the vac advance disconnected and a mechanical advance that looks something like the factory's. Ideally a nice open road when one can squeeze on throttle from 50 mph or higher, then do it again but squeeze deeper.
If crusing with 16", should get more acceleration as throttle increases and vacuum drops. It's a little tedious. it's why we say tune to the point that you are satisfied. Some people want to squeeze all they can out of a setup, and others are happy of the car waddles down to the Sunday coffee and donuts.