Manifold vacuum and power brakes

[greatscot3]

Hello all

I've have a couple of problems and I could use some advice with my power brake booster and engine vacuum situation.
My car is a '74 Cuda 440 clone that used to be a 318 car.
It's now got a Tremec 5 speed OD with a semi mild pro-built 440 with a Holley Street Dominator single plane intake and 750 Holley 4150.
I've got flat topped forged pistons at about 9:1 compression because I was going to run carb baseplate nitrous and pump gas but ran afoul of the insurance Nazis.
I've owned the car since 1987 and have never driven it.
I'm just getting ready to break it loose from the garage and have been working on it a little every day to finally get it going.
It's been running for a while and I'm playing whack a mole with various problems such as just getting it running and observing power steering fluid pouring out of the steering box etc. etc. etc. etc.
I had the PCV hooked up to a fitting on the no. 8 intake port runner and read a post here about a guy that tee'd his PCV off of his brake booster line coming from the rear carb baseplate fitting.
Then I read another post that said it's a bad idea to run a brake booster off of a carb fitting and you should only use direct manifold vacuum.
At the time, it seemed like a better idea to use intake plenum vacuum from the carb baseplate rather than using one intake port runner and possibly messing with the A/F ratio on one cylinder.
Then I got myself an el cheapo vacuum gauge to adjust the carb A/F mixture screws and noticed my inches of HG are only about 9-10 inches at an 700-800 RPM idle. I read online that some power brakes need about 16-19 inches of HG. If I open the throttle a little I get from 19-23 inches of HG.
The cam in the car is not very lumpy and is a similar grind like the original purple shafts. I attached a pic of the original cam spec. card.
I've got a rebuilt brake booster and master cylinder and I think it's a 10 or 11 inch single stage booster or whatever was stock in a 318 car with stock front discs. You can see part of it in the attached picture. Since that picture was taken I added Edelbrock aluminum heads partly to get the compression ratio up and also add a few ponies.
I guess I have a couple of problems.
That 9-10 inches of HG seems low for the cam and setup I have and is probably too low for a power brake booster.
I've read that vacuum accumulator cans are just okay and can fade out if you don't get the vacuum high enough between times when the brakes are used such as in stop and go driving.
I've also read that a hydro booster or electric vacuum pump is the way to go but I really dread trying to put in a hydro booster. I just got done having a custom high pressure hose made for the power steering and I'd just about rather have a whole mouthful of root canals than go through that nightmare all over again.
There is only one guy around where I live that has the tools to make hydraulic hoses and to get a single hose made right by this guy, I had to make no less that ten trips to his shop to get him to simply do only what I asked him to do.
Besides that, it's very tight in there next to the power steering box.
Has anyone reading this run up against these kinds of problems and which way did you go to solve your problem?

Thanks in advance for any advice on this.

View attachment CompetitionCamsSpecs 001.jpg

 

[Chryco Psycho]

Comp Cams are always a bad choice in Mopars , lack of power & vacuum can be attributed to the cam for sure , A cam swap would help the situation a lot , a vacuum canister will help for sure . Personally I would swap the cam but that is a lot of work.
Hydroboost is kickass , you always have the boost assistance there with any cam .
The PCV should be on the base of the carb to equally distribute the waste gasses , the brake booster can run off, the intake runner without issue .

 

[greatscot3]

Comp Cams are always a bad choice in Mopars , lack of power & vacuum can be attributed to the cam for sure , A cam swap would help the situation a lot , a vacuum canister will help for sure . Personally I would swap the cam but that is a lot of work.
Hydroboost is kickass , you always have the boost assistance there with any cam .
The PCV should be on the base of the carb to equally distribute the waste gasses , the brake booster can run off, the intake runner without issue .

Chryco

Thanks for your reply.
I bought that Comp camshaft back in about 1988 or 1989 and I bought it because they advertised it as being similar to the Chrysler purple shaft cams. I wanted something that would not beat the engine and valve train to death but maybe last for a while.

What's your favorite camshaft without going completely full race apes**t?

 

[Chryco Psycho]

Lunati VooDoo 702 or 703 great lift & Power , good vacuum .

 

[moparleo]

You say you haven't driven the car since 87 ? Is the engine even broken in yet.
Looking at your picture a few things jump right out.
#1 -The power brake booster is supposed to be connected where you have the pcv hose connected.
#2 -The PCV should be connected to the base of the carb. CORRECTION Rear.
#3 -The Vacuum line from the distributor goes to a port on the right side base of the carb, not the metering block.
This information came with your intake manifold instructions and everything you need to know is available on line.
#4 - I also notice no choke plate or shaft. You will get no measurable benefit from this as this is not a highly tuned race car.
You have a lot of things going on that should be addressed first.
The hydro boost would probably be your best bet. It looks like you don't mind spending money and a total conversion would be well worth the money.
Hoses are simple to get made by " The Hose Man" .Many locations and many, many years of experience.

Locations – The Hose-Man

 

[greatscot3]

You say you haven't driven the car since 87 ? Is the engine even broken in yet.
Looking at your picture a few things jump right out.
The power brake booster is supposed to be connected where you have the pcv hose connected. The pcv should be connected to the base of the carb. Up front. The Vacuum line from the distributor goes to a port on the right side base of the car, not the metering block. This information came with your intake manifold instructions and everything you need to know is available on line.
I also notice no choke plate or shaft. You will get no measurable benefit from this as this is not a highly tuned race car.
You have a lot of things going on that should be addressed first. The hydro boost would probably be your best bet. It looks like you don't mind spending money and a total conversion would be well worth the money.
Hoses are simple to get made by " The Hose Man" .Many locations and many, many years of experience.
Locations – The Hose-Man

Not only have I not driven the car since I bought it in 1987, I've never driven it at all. I ditched the 318 back in '87.
It sat in storage after getting the 440 built for it for any number of reasons I won't bore you with. Just two maybe. I lived on a houseboat in the California delta for 10 years, then bought a house on an island in the delta, fixed it up, had kids and the car faded away in importance. S**t really happens doesn't it?

I have to clue you in on a couple of other things. The picture you saw was taken in a past iteration of the setup it is now. I posted the picture to show the brake booster.
I said that was an old picture and now I have Edelbrock heads on it and the vacuum hoses have changed positions because of suggestions and advice from this very forum.

Certainly not your fault, my fault for not being clear enough.

Everything I needed to know about that manifold was NOT online. I bought it 27 years ago. I wanted to buy the EGR block off freeze plugs and they told me I had to use 1/8" pipe plugs. WRONG and I'll show you why. The holes were machined as through holes with shoulders to support freeze plugs being driven in. When I contacted Holley, they no longer even had the engineering drawings, much less the freeze plug part numbers. I had to find them myself, buy some that wouldn't fit and dremel tool the others until they would fit.
See the pic of the EGR holes for yourself. You tell me how easy it would be to drill that hole out and tap it for a pipe plug like Holley said to do. In this case, with the old, brand new manifold I had, Holley and their gen X techs were worthless.

You say I seem to have a lot of money. I'm still laughing about that one as I sit here. I'm 66 years old and on a fixed income.
What I am is a stubborn old son of a ***** that refuses to give up on something I started 35 years ago that was a dream and I'm using up my life's savings.
My clock is ticking down and these days I have trouble even walking.
You have no idea what a MF this has been trying to tie together 30 year old parts to work with new parts to make a 48 year old car work in 2022.
I probably have two cars worth of parts I've bought sitting around because I decided or had to use others.

Your email irritated me and I still think you don't have any idea what 35 years of trying to get a car running is like.
I get that you think I am an idiot and it's really hard to appreciate your comments.
It took me two years and more aggravation than you have probably had in one liftetime just trying to get the title and registration straightened out with the effing tards at the CA DMV.

Not really sorry, but cut me some effing slack here.

Helpful comments like Chrycos welcomed.

 

[moparleo]

Sorry about your situation. I am older than you and still have one under a tarp since 88 with a garage full of parts to boot.
Of course many other cars along the way.
The info for where the vacuum lines go is on line, that is where I got the info to post.
You said nothing about the egr. I agreed that hydro boost is the way to go and gave you the place to get lines made. As far as money I see a lot of expensive parts and your talk of "Tremec 5 speed" Nitrous, Edelbrock aluminum heads, Serpentine belt drive and other stuff I can see as well as your descriptions. A lot of money to me who is also on S/S with no pension. And you haven't driven it but seemed to keep putting money into it. Sell those other parts.
In my experience people waste a lot of money because they don't know better. Not lack of enthusiasm. Age having nothing to do with it. Just that most questions should be asked before the money is spent.
If you haven't driven it yet I ask again is the engine even broken in yet ? and have you tested the brakes up on jackstands or ?
Nothing personal, I don't even know you.
Maybe a current picture would help. Showing an old setup was just confusing now..as you say everything is different, which you didn't say at first.
The focus should be on one thing at a time. Hard to fix many things at once since a lot of things are related ,you want to go a step at a time so you know you are going in the right direction. Change too many things at the same time and you won't know what was good and what wasn't.
Good luck. Experience costs both time and money...
I know about DMV. Learned that before you buy an out of state vehicle and you live in California to find out about title transfer and registration requirements first. I bought an out of state federal 1978 B-200 Dodge van back in 85. Had to take it to a State Referee after it failed smog. They required all California smog equipment to be installed before I could have it re inspected. It was not from California so I would have to hunt the recycle yards for all the parts, install them and then have it visually looked at. It still wouldn't pass smog so no title. It has been a storage shed for parts in my back yard since then.

 

[greatscot3]

You say you haven't driven the car since 87 ? Is the engine even broken in yet.
Looking at your picture a few things jump right out.
#1 -The power brake booster is supposed to be connected where you have the pcv hose connected.
#2 -The PCV should be connected to the base of the carb. Up front.
#3 -The Vacuum line from the distributor goes to a port on the right side base of the carb, not the metering block.
This information came with your intake manifold instructions and everything you need to know is available on line.
#4 - I also notice no choke plate or shaft. You will get no measurable benefit from this as this is not a highly tuned race car.
You have a lot of things going on that should be addressed first.
The hydro boost would probably be your best bet. It looks like you don't mind spending money and a total conversion would be well worth the money.
Hoses are simple to get made by " The Hose Man" .Many locations and many, many years of experience.

Locations – The Hose-Man

#1 -The power brake booster is supposed to be connected where you have the pcv hose connected.

The power brake hose will be hooked to the fitting on the no. 8 cylinder port runner through the new vacuum reservoir I am buying.

#2 -The PCV should be connected to the base of the carb. Up front.



#3 -The Vacuum line from the distributor goes to a port on the right side base of the carb, not the metering block.
This information came with your intake manifold instructions and everything you need to know is available on line.
#4 - I also notice no choke plate or shaft. You will get no measurable benefit from this as this is not a highly tuned race car.

Sorry about your situation. I am older than you and still have one under a tarp since 88 with a garage full of parts to boot.
Of course many other cars along the way.
The info for where the vacuum lines go is on line, that is where I got the info to post.
You said nothing about the egr. I agreed that hydro boost is the way to go and gave you the place to get lines made. As far as money I see a lot of expensive parts and your talk of "Tremec 5 speed" Nitrous, Edelbrock aluminum heads, Serpentine belt drive and other stuff I can see as well as your descriptions. A lot of money to me who is also on S/S with no pension. And you haven't driven it but seemed to keep putting money into it. Sell those other parts.
In my experience people waste a lot of money because they don't know better. Not lack of enthusiasm. Age having nothing to do with it. Just that most questions should be asked before the money is spent.
If you haven't driven it yet I ask again is the engine even broken in yet ? and have you tested the brakes up on jackstands or ?
Nothing personal, I don't even know you.
Maybe a current picture would help. Showing an old setup was just confusing now..as you say everything is different, which you didn't say at first.
The focus should be on one thing at a time. Hard to fix many things at once since a lot of things are related ,you want to go a step at a time so you know you are going in the right direction. Change too many things at the same time and you won't know what was good and what wasn't.
Good luck. Experience costs both time and money...
I know about DMV. Learned that before you buy an out of state vehicle and you live in California to find out about title transfer and registration requirements first. I bought an out of state federal 1978 B-200 Dodge van back in 85. Had to take it to a State Referee after it failed smog. They required all California smog equipment to be installed before I could have it re inspected. It was not from California so I would have to hunt the recycle yards for all the parts, install them and then have it visually looked at. It still wouldn't pass smog so no title. It has been a storage shed for parts in my back yard since then.

I kind of jumped on you and I apologize. I did mention I was an old fart and I have kind of proved that I'm also grouchy.
Let me back up and explain a few things. Yes, it's got some expensive parts on it. The heads were bought last year by my wife as an anniversary gift. She knows how I am about this POS.
And yes, you are right. I ought to sell lots of s**t just taking up room in the black hole (garage).
I'm forgoing an expensive paint job and going with "rat rod" and a Roadkill Garage (big fan, love those guys) attitude.
It might not look too great but everything and I do mean everything has been replaced or rebuilt on that car bumper to bumper over 30+ years of tinkering.
The Tremec, pedals, transmission hump and shifter were put in fifteen years ago when I still had an income.
The engine was built in 1989.
I bought a Holley 4150 without a choke because I found one for sale brand new cheap. It starts right up with a couple pumps of the gas pedal no problem.
I also have one other distraction and money pit besides the Cuda. It's a 1970 Challenger base model I got from an old girlfriend's parents in 1993. I really like it. It's a lot of fun to drive and goes pretty good for a slant six car.
I even sacrificed my other baby and sold it to buy parts for this Cuda. It was/is a 1975 Jeep CJ6 I used to haul my twin boys all over hell and back in the Sierra Nevada mountains as they were growing up.

The thing with the DMV was awesomely stupid and it really did actually take more than two years to get the registration sorted out with them. It even came from Kalifornia originally. I had my checks and paperwork kicked back at me five times.
I want to show you a letter I got from some imbecile named Jeb at the CA DMV that looked at all of my correct paperwork and my check and sent it back one of those times saying they didn't have any record of the car.
Evidently, Jeb the Jenius was running his bosses office the day my paperwork came through for the fourth time. Lucky me you bet.
YES JEB! I KNOW THAT THERE IS NO RECORD OF THE CAR! IT HASN'T BEEN REGISTERED SINCE 1986! That's what all those pretty pieces of DMV paper with all that writing and signatures are for!
Those papers are sent to the DMV in order to get a new pink slip and registration you effing moron! I didn't actually say that but I sure wanted to.
I just gritted what are left of my teeth and sent the same paperwork back again trying to get them in front of someone with more than one active brain cell.
I finally got the pink slip and registration and insured the car. I almost threw a party.

Back on the subject, yes the car has been started and I'm playing whack a mole with various problems.
I take care of one problem which leads to two more.
I decided to order a vacuum reservoir and try that before having to buy a vacuum pump or hydro booster. It's the easiest, cheapest way out and maybe I'll get really lucky and it will work.
I am tentatively planning on driving the Cuda for the first time maybe next week after I get the vacuum canister installed if everything goes well. HAH!

 

[moparleo]

Nice Challenger. Jeb wasn't wrong technically......
My first bad DMV experience came back in 1974.
I used to do some side work for a towing compoany on my days off. I would do brake services, clutch replacements, u-joints etc... in exchange I would get to raid the impound yard for unclaimed cars for anything short of the Vin-ed chassis that they had to scrap.
I was at another tow yard when I saw them stacking cars on a flat bed and asked how much they get for scrap? They said $100. per car. I saw a 57 Chevy wagon in line for scrap and asked if I could buy it for the $100. They said yes but also that it was an out of state stolen/ recovered with no engine or trans.
So I bought it, they towed it to my house. I went to the tow yard I worked for and they had a 69 Chevy Impala wagon in the impound yard with a 427/Turbo 400. Console, bucket seats and console with the horseshoe shifter. I took all those parts and transplanted into the wagon.
I then went to DMV for a title transfer and to register it. They told me since it was an out of state vehicle that I had to bring it in to have it inspected and vin verified. So I brought the car in. I talked to the same person again and told them that the car was there. The first thing he said was " how did you bring it here?". I said I drove it. He then said "you should have had it towed on a trailer, now you owe all back registration fees and penalties from when the car was last registered because the tires touched the roadway."
That was more than I had invested in the entire car.
I asked why didn't he tell me that before I drove it in, he just said because I don't have to...I almost came over the counter at him.

 

[greatscot3]

Nice Challenger. Jeb wasn't wrong technically......
My first bad DMV experience came back in 1974.
I used to do some side work for a towing compoany on my days off. I would do brake services, clutch replacements, u-joints etc... in exchange I would get to raid the impound yard for unclaimed cars for anything short of the Vin-ed chassis that they had to scrap.
I was at another tow yard when I saw them stacking cars on a flat bed and asked how much they get for scrap? They said $100. per car. I saw a 57 Chevy wagon in line for scrap and asked if I could buy it for the $100. They said yes but also that it was an out of state stolen/ recovered with no engine or trans.
So I bought it, they towed it to my house. I went to the tow yard I worked for and they had a 69 Chevy Impala wagon in the impound yard with a 427/Turbo 400. Console, bucket seats and console with the horseshoe shifter. I took all those parts and transplanted into the wagon.
I then went to DMV for a title transfer and to register it. They told me since it was an out of state vehicle that I had to bring it in to have it inspected and vin verified. So I brought the car in. I talked to the same person again and told them that the car was there. The first thing he said was " how did you bring it here?". I said I drove it. He then said "you should have had it towed on a trailer, now you owe all back registration fees and penalties from when the car was last registered because the tires touched the roadway."
That was more than I had invested in the entire car.
I asked why didn't he tell me that before I drove it in, he just said because I don't have to...I almost came over the counter at him.

Sometimes I think they get off making someone's eyes bulge out of their head with some ridiculous bill.

Something similar happened with the Challenger. I parked it when I had cut the exhaust off of it to put all Clifford Performance goodies in it and paid the registration for years after that, then let it lapse and did not file a non-op.
Long story short, they got me for nine years of back registrations because I had made the mistake of registering it every year since it started sitting.
If I had stopped registering it every year since I parked it, it would have fallen off the records. As it was I ended up paying to have it sit there and also paying all those extra years when it sat there after I stopped registering it also.
That thing with Jeb though? I had gone around and around and around after getting the VIN verified because I was told I needed this form and I needed that form and half the advice I got from the DMV phone monkeys was wrong.
Each time they kicked it back took MONTHS because they don't do anything fast, then all the BLM riots started happening in Sacramentato and they furloughed the DMV personnel for weeks also.
Then I put one too many signatures on one form and they kicked it back at me AGAIN.
The version of the paperwork I sent them and Jeb intercepted was actually right in every respect. He just didn't have any idea what he was looking at.

On the original cars subject, I was looking at a thread on timing and vacuum advance on B Bodies Only and found an interesting article pasted into that forum. I am attaching the article below because the author seems to know what he is talking about.
He has a website/store (4secondsflat.com) that looks like it has some good stuff on it too. I'm considering having him look into my vacuum advance can and make recommendations if it needs anything.



From Don Gould at 4secondsflat

Ported or Constant?
Let me try and give you an explanation in layman's terms.... Generally, emissions equipped vehicles use Ported and they are connected to a computer, OBD1 or 2 to retard the timing based on information gather from a multitude of sensors in the vehicle.

Non-Emissions Hot Rods and Street Muscle Cars Pre-emissions use Constant. Many vehicles were built with specs that designated Ported, that was fine in 1975 when we used real gas and we could set the total advance to 25 with 5* initial and have the vac can pull the timing to 34 under load and fuel economy, formulations and costs were not an issue. These cars ran horrible and got terrible fuel economy, more gas ran out the tailpipe than got burned in the combustion chamber.

GM always used Constant Vacuum and built over 300 different set-ups for all there product lines until computers were introduced and everything changed to meet EPA emissions regulations.

So Your Hot Rod gets connected to CONSTANT manifold vacuum and the distributor needs to be set up properly to burn today's fuel formulations. The Vacuum Can needs to be adjusted to pull enough timing in the motor to allow it to burn the today's fuel and limiters installed to set the part throttle cruise timing numbers so they don't pull the timing too high and cause a lean miss at cruise, it's a delicate balancing act to get it all correct.

Your carb has 4 Venturi's, as the air speed or velocity increases with throttle position a venturi creates high pressure in the center to fracture the fuel into small particles and "Opposite and Equal Reaction" is negative wall pressure.

The negative wall pressure is what draws the fuel through the booster and feeds the engine based on throttle position or air velocity. A carburetor is a simple metering device that delivers fuel and mixes it with the air to create clean combustion, the higher the velocity the more negative pressure the more it delivers, it's a pretty simple device.

Ported vacuum: With that thought in mind consider if the distributor hooked to Ported Vac, as air speed increases the ported vac activates and starts to pull more and more timing in the motor as velocity increases. So if you set you total timing to 34* at 3000RPM that's when the ported starts to do it's job and advances the the timing to the total stroke of the vacuum can arm, usually 12-18* (without Limiters) so now have your total of 34* PLUS the stroke of the Canister arm of say 16* net result=50* of total timing under hard acceleration and your motor WILL "Detonate". If you had a OBD1 computer it would pull that timing back to the 34* as all the sensors feed information to it.... and no detonation.

Now to Constant: At idle/part throttle cruise you have high vacuum, the carb is nearly closed causing a restriction which creates the high vacuum level. Under this light load condition and lean AF ratios the motor needs more timing to burn the fuel (Lean Mixtures take Longer to Burn than rich mixtures) so you need more timing at idle and cruise to burn the fuel correctly and completely. When you stomp the throttle you have NO manifold Vacuum so you have NO vacuum timing and at NO time under high load will it ever advance more than the mechanical "All In" numbers. Stop pointing your finger at the carb for rich idle and top end lean conditions.. It's In Your Distributor Tuning! If your Buddy tells you to hook your Hot Rod distributor to Ported Vacuum, find a new friend because that guys advice is going to blow your crankshaft through the oil pan. Same goes for the guy who say's to disconnect it, they obviously have no idea of how it works or what it does or why we use it.

This not hear-say or an opinion its engineering, based on physics formulas, calculated by people who are a lot smarter than me and I know that so I do what they tell me. They come up with the numbers, we set them up accordingly.

Rule of Thumb: If the Motor Makes 8" of vacuum at Idle with 30* of timing in it then it needs a properly calibrated Vacuum Can, we have Mopar and GM vacuum cans that will read 7" of vacuum. most stock or aftermarket Vac cans will only read down to about 15", the odd one (1 out of 100) will read to 12"

We manufacture Mopar vac cans that will read to 7", our Lane Choice Gold Plated VC-1 BB or VC-1 SB

There's all sorts of unqualified guy's on the "Internet" and so called "engine builders" who will try and argue this point with me, I have given up trying to argue with these folks. They have no understanding how a vac can works or what it does, if they did they would realize how ridiculous they sound to us, Jim and I account for over 100 years experience with well over 10,000 happy customers.

Your "Engine builder" may be the best in the world but he's an Engine Builder and very seldom do they know anything about the fine tuning of the vacuum can or distributor mechanical advance system

 

[greatscot3]

Comp Cams are always a bad choice in Mopars , lack of power & vacuum can be attributed to the cam for sure , A cam swap would help the situation a lot , a vacuum canister will help for sure . Personally I would swap the cam but that is a lot of work.
Hydroboost is kickass , you always have the boost assistance there with any cam .
The PCV should be on the base of the carb to equally distribute the waste gasses , the brake booster can run off, the intake runner without issue .

Chryco

I had one more question. I assumed that the fitting on the baseplate of the carb fitting in the rear which is 3/8" barb would be the correct fitting to use for the PCV since they are the same diameters. The front port on the 4150 baseplate is a 1/4" barb.
I figured the controlled leak by of the check valve in the PCV would keep the amount of vacuum from being too big and causing vacuum loss problems.
I had tried to find out more about different kinds of PCVs and flow rates on each for vacuum and the information is semi proprietary and not readily available.
I decided to just by one for a 440.
Is the rear baseplate 3/8" barb port on the carburetor the one to use for the PCV?

Thanks

 

[Chryco Psycho]

Yes that is the correct prt to use for PCV

 

[moparleo]

I corrected my post on that fitting. When I looked at the baseplate on the 4150 the view was from the bottom which means when you flip the carb over the front and rear get reversed,
The PCV valve is a valve that is vacuum actuated ,no vacuum, closed no leak.
They are designed/tuned for specific applications. Not advisable to just pick and choose. They do make adjustable PCV valves though.
Again try not to make too many changes until you get the rings seated properly and running as smooth as is possible.
Start making tuning changes after you get a stable baseline.

 

[MoparCarGuy]

Your original question was about engine vacuum with your existing cam and how to get good vacuum for the power brakes. You said you saw a vacuum increase when you "opened the throttle a little". That makes me think your idle RPM may be too low and, if raised, might help get you the 19-23" you measured. Let us know what the idle RPM is and what RPM you saw the 19-23". If you really cannot permanently raise the idle RPM slightly, then go to Plan B.
Chryco Psycho or moparleo may have some insight on the state of your tune (timing and carb setup) and how that might get you the highest vacuum reading, at least at idle.

Plan B: I used an electric vacuum pump (LEED Brakes VP002 ELECTRIC VACUUM PUMP KIT - BANDIT SERIES) and mounted it under the battery tray. I supplied switched 12V power (RUN position at the key switch) to the relay that comes with the pump and that gives me 21" of vacuum all of the time. First picture is before wiring it up for switched power. Second is after battery was re-installed. Those A/C lines are Classic Auto Air. Florida heat requires A/C!
This solution will work for any cam and is hardly noticeable. The pump is available direct or on Amazon.

 

[SDChallenger]

Not only have I not driven the car since I bought it in 1987, I've never driven it at all. I ditched the 318 back in '87.
It sat in storage after getting the 440 built for it for any number of reasons I won't bore you with. Just two maybe. I lived on a houseboat in the California delta for 10 years, then bought a house on an island in the delta, fixed it up, had kids and the car faded away in importance. S**t really happens doesn't it?

I have to clue you in on a couple of other things. The picture you saw was taken in a past iteration of the setup it is now. I posted the picture to show the brake booster.
I said that was an old picture and now I have Edelbrock heads on it and the vacuum hoses have changed positions because of suggestions and advice from this very forum.

Certainly not your fault, my fault for not being clear enough.

Everything I needed to know about that manifold was NOT online. I bought it 27 years ago. I wanted to buy the EGR block off freeze plugs and they told me I had to use 1/8" pipe plugs. WRONG and I'll show you why. The holes were machined as through holes with shoulders to support freeze plugs being driven in. When I contacted Holley, they no longer even had the engineering drawings, much less the freeze plug part numbers. I had to find them myself, buy some that wouldn't fit and dremel tool the others until they would fit.
See the pic of the EGR holes for yourself. You tell me how easy it would be to drill that hole out and tap it for a pipe plug like Holley said to do. In this case, with the old, brand new manifold I had, Holley and their gen X techs were worthless.

You say I seem to have a lot of money. I'm still laughing about that one as I sit here. I'm 66 years old and on a fixed income.
What I am is a stubborn old son of a ***** that refuses to give up on something I started 35 years ago that was a dream and I'm using up my life's savings.
My clock is ticking down and these days I have trouble even walking.
You have no idea what a MF this has been trying to tie together 30 year old parts to work with new parts to make a 48 year old car work in 2022.
I probably have two cars worth of parts I've bought sitting around because I decided or had to use others.

Your email irritated me and I still think you don't have any idea what 35 years of trying to get a car running is like.
I get that you think I am an idiot and it's really hard to appreciate your comments.
It took me two years and more aggravation than you have probably had in one liftetime just trying to get the title and registration straightened out with the effing tards at the CA DMV.

Not really sorry, but cut me some effing slack here.

Helpful comments like Chrycos welcomed.

Your response reeks of Cali! Rude, crude, etc.. Lighten up.

 

[i_taz]

Your response reeks of Cali! Rude, crude, etc.. Lighten up.

That's what the left has done to them.... and the rest of us by the looks of things

 

[greatscot3]

Your original question was about engine vacuum with your existing cam and how to get good vacuum for the power brakes. You said you saw a vacuum increase when you "opened the throttle a little". That makes me think your idle RPM may be too low and, if raised, might help get you the 19-23" you measured. Let us know what the idle RPM is and what RPM you saw the 19-23". If you really cannot permanently raise the idle RPM slightly, then go to Plan B.
Chryco Psycho or moparleo may have some insight on the state of your tune (timing and carb setup) and how that might get you the highest vacuum reading, at least at idle.

Plan B: I used an electric vacuum pump (LEED Brakes VP002 ELECTRIC VACUUM PUMP KIT - BANDIT SERIES) and mounted it under the battery tray. I supplied switched 12V power (RUN position at the key switch) to the relay that comes with the pump and that gives me 21" of vacuum all of the time. First picture is before wiring it up for switched power. Second is after battery was re-installed. Those A/C lines are Classic Auto Air. Florida heat requires A/C!
This solution will work for any cam and is hardly noticeable. The pump is available direct or on Amazon.

View attachment 95189 View attachment 95190

MoparCarGuy

Thanks for your reply. I decided to try Chryco's suggestion about the vacuum canister. I got one from Summit and threw it in. Canister vacuum gauge shows steady 15-17 inches HG. Brakes work really well.

 

[heminut]

I decided to try Chryco's suggestion about the vacuum canister. I got one from Summit and threw it in. Canister vacuum gauge shows steady 15-17 inches HG. Brakes work really well.

The vacuum canister is a good solution. When I rebuilt the 340 in my first Cuda I put a Mopar Performance 484/284 Purple Shaft cam in it. It was marginal on the vacuum for the power brakes. My first wife had a habit of pumping the brakes when coming to a stop, and would run out of vacuum. There weren't any aftermarket vacuum canisters back then. I sourced a canister off of an Olds Toronado (vacuum operated headlight doors) and it solved the problem. My ex was still afraid to drive the car, so when we split up she got the 67 Impala SS and I kept the Cuda!

 

[Dodgeboy]

Just FYI if you don't do anything

I now have 6" of vacuum @ idle (I used to have 0") and a max of 12" at hwy cruise. I have power brakes and the only issues I have are stopping in repeat stop & go traffic, or coming to a complete stop and then inching forward a few feet. Slowing down/stopping when your coming off of the hwy is not a problem. My car trips are usually short or in low traffic. I have gotten used to it but this is a issue that should be corrected, I myself will eventually do a cam swap.