vacuum for mopar 509 cam....

[1974dodgecharger]

Im lost. ...maybe....but I was at another forum non mopar specific talking about tuning and power valves.  I recieved a message saying my engine is all messed up and that my vacuum is too low amd I have engine issues. 

My vacuum is 6.5 to 7 with this 509 cam
My timing I cant remember off top off my head 16 amd 35 total


Point being this guy told me my engine is messed up and my vacuum should be at 15 to 20?   I was like oh crap really? He said I need to retime my car for higher vacuum amd he said I should haveore power.  I told him my engine has 500hp on engine dyno stand.....with that vacuum.   He said if I could getore vacuum I would have a 900hp engine?

So what is the vacuum norm for mopar 509 for big block?

[firefighter3931]

That's about right for that cam in a 440 based engine. The 509 has 76* of overlap so it's not going to make a lot of idle vacuum. 

The only way you could ever possibly make 900hp with that cam would be with some type of power adder ; blower/turbo/nitrous etc....



Ron

[c00nhunterjoe]

Peak tune on my 383 with a similar grind to the 509, mine is a little more agressive rate, but the end specs of .510 lift and 292 advertised remains the same.

[Troy]

I have a "purple shaft" cam in my Six Pack. I don't remember exactly which but I thought it was a 509. I can get it to 12-15 but the car runs like doo doo. It seems much happier around 8-9. I believe there are much better cams on the market these days.

As for the guy thinking 6-8 degrees of vacuum will get you anouther 400 HP... try not to take any of his advice. The guys here will steer you straight.

Troy

[XH29N0G]

Peak tune on my 383 with a similar grind to the 509, mine is a little more agressive rate, but the end specs of .510 lift and 292 advertised remains the same.

I guess your gauge says your motor isn't a normal.    

(I also don't have a 509, but similar lift at 280/296 rated duration and similar lift/vaccum (9-10 inches) too - running with a pcv.)

[BSB67]

If your gauge reads 21" of vacuum with a 509 cam in a 440 at less than 1000 rpm, your gauge is broken.

[1974dodgecharger]

Thanks for info I know you guys know your stuff here, but I registered at another forum because a member there was considered a blower expert in that community so I wanted to chit chat with him.  Along the way I started asking other questions on other things and one thing leads to another. 

yes COONHUNTERJOE my vacuum is like what you have and reads just as a tad lower than yours im sure we are about the same.

BSB67 no the guy told me my car should be reading 15 to 20 on vacuum and that my engine is messed up with such a low vacuum reading. 

thanks again guys....

[BSB67]

Thanks for info I know you guys know your stuff here, but I registered at another forum because a member there was considered a blower expert in that community so I wanted to chit chat with him.  Along the way I started asking other questions on other things and one thing leads to another. 

yes COONHUNTERJOE my vacuum is like what you have and reads just as a tad lower than yours im sure we are about the same.

BSB67 no the guy told me my car should be reading 15 to 20 on vacuum and that my engine is messed up with such a low vacuum reading. 

thanks again guys....

And the guy on the other forum is an expert?  You cannot change the fact that it has 76° overlap.  The 509 ground on a 114° will have a better idle, but still has 64°.  Which one do you have.

[1974dodgecharger]

Thanks for info I know you guys know your stuff here, but I registered at another forum because a member there was considered a blower expert in that community so I wanted to chit chat with him.  Along the way I started asking other questions on other things and one thing leads to another. 

yes COONHUNTERJOE my vacuum is like what you have and reads just as a tad lower than yours im sure we are about the same.

BSB67 no the guy told me my car should be reading 15 to 20 on vacuum and that my engine is messed up with such a low vacuum reading. 

thanks again guys....

no didn't know the guy....just came into the discussion and told me to get a PRIUS afterwards...because I forgot what my timing was.....its something I don't keep in my head....only thing I can think of is he is some young buck who thinks he has photographic memory or something.....either way an Ass 
And the guy on the other forum is an expert?  You cannot change the fact that it has 76° overlap.  The 509 ground on a 114° will have a better idle, but still has 64°.  Which one do you have.

[1974dodgecharger]

Thanks for info I know you guys know your stuff here, but I registered at another forum because a member there was considered a blower expert in that community so I wanted to chit chat with him.  Along the way I started asking other questions on other things and one thing leads to another. 

yes COONHUNTERJOE my vacuum is like what you have and reads just as a tad lower than yours im sure we are about the same.

BSB67 no the guy told me my car should be reading 15 to 20 on vacuum and that my engine is messed up with such a low vacuum reading. 

thanks again guys....

And the guy on the other forum is an expert?  You cannot change the fact that it has 76° overlap.  The 509 ground on a 114° will have a better idle, but still has 64°.  Which one do you have.

http://www.summitracing.com/parts/dcc-4120237ae/overview/make/dodge

engine was built back in 08....this was the one....don't have the receipt thrown away along

[c00nhunterjoe]

That one is ground on the 108, your vaccum readings are correct.

[1974dodgecharger]

That one is ground on the 108, your vaccum readings are correct.

I know its a hated cam....with 10.5 to 1....oh well plan to put a 871 blower on it..and blow it up with 5lbs of boost see what happens  

thanks again guys for the help and confirmations.....seems some folks still think the vacuum is low and something is wrong....seems this other forum has never seen vacuum that low?  A veteran engine builder guy who claims he has put lots of 509 cams in mopars claims the vacuum is low....claims lowest he ever saw is 12 in all his years. 

[c00nhunterjoe]

Peak tune on my 383 with a similar grind to the 509, mine is a little more agressive rate, but the end specs of .510 lift and 292 advertised remains the same.

I guess your gauge says your motor isn't a normal.    

(I also don't have a 509, but similar lift at 280/296 rated duration and similar lift/vaccum (9-10 inches) too - running with a pcv.)

The gauge is designed for a stock engine. The print on it is to be ignored when you start modifying things. My readings are with pcv, torker single plane intake, 1200 idle.

[GPULLER]

I have an old 484 Mopar cam, want to say my vac is around 10".

[BSB67]

That one is ground on the 108, your vaccum readings are correct.

I know its a hated cam....with 10.5 to 1....oh well plan to put a 871 blower on it..and blow it up with 5lbs of boost see what happens  

thanks again guys for the help and confirmations.....seems some folks still think the vacuum is low and something is wrong....seems this other forum has never seen vacuum that low?  A veteran engine builder guy who claims he has put lots of 509 cams in mopars claims the vacuum is low....claims lowest he ever saw is 12 in all his years.  

No reason to hate the cam.  It is a great cam in my book.  It can make a bunch of power in the right motor.  It does not have great low speed idle characteristics for the average street guy.

[c00nhunterjoe]

I love my racer brown version of it. Is it a tire burner from idle? No, like bsb67 said. But the midrange is incredible. Its like in the fast and furious when they spray "nos" and the cars come alive and throw them in the seat. Now its not a total turd down low, its very snappy, but it does like the extra gearing. 4.10s would be the minimum i would run with that cam. Run those gears and a loose converter (or 4 speed in my case) and it makes a very fun car.

[BSB67]

I love my racer brown version of it. Is it a tire burner from idle? No, like bsb67 said. But the midrange is incredible. Its like in the fast and furious when they spray "nos" and the cars come alive and throw them in the seat. Now its not a total turd down low, its very snappy, but it does like the extra gearing. 4.10s would be the minimum i would run with that cam. Run those gears and a loose converter (or 4 speed in my case) and it makes a very fun car.

4.10s and a 4 speed.....perfect.

[c00nhunterjoe]

Well.... 4 speed, 4.88's and a 29.5 tall tire on mine...


And yours would still walk all over me...

[69wannabe]

The outside numbers on that gauge are cm/hg vacuum and the inside numbers are in/hg vacuum which read about right for a 509 or similar camshaft. It is reading 8-9 in of vacuum.

[BSB67]

Well.... 4 speed, 4.88's and a 29.5 tall tire on mine...


And yours would still walk all over me...

I've done 3.91 and 4.10 with 4 speeds on a few cars....it is the definition of fun in my book.

[BSB67]

The outside numbers on that gauge are cm/hg vacuum and the inside numbers are in/hg vacuum which read about right for a 509 or similar camshaft. It is reading 8-9 in of vacuum.

Duh...thanks

[XH29N0G]

The outside numbers on that gauge are cm/hg vacuum and the inside numbers are in/hg vacuum which read about right for a 509 or similar camshaft. It is reading 8-9 in of vacuum.

Duh...thanks

Just a question, do you think the guy who originally said 15 -20 could have been thinking in cm of mercury instead of inches?   

[1974dodgecharger]

No.......they said mercury.......and clearly 10 people said my engine is fcked up even after I told them I have a 500hp engine they said get vacuum up I will have 900hp.....either they r all joking or they dont know mopar.

[c00nhunterjoe]

No.......they said mercury.......and clearly 10 people said my engine is fcked up even after I told them I have a 500hp engine they said get vacuum up I will have 900hp.....either they r all joking or they dont know mopar.

Its not a mopar specific problem. It is science and physics.... the specs of the cam dictate the avg vaccum it will pull. That grind in a ford chevy or mopar will behave almost the same. Whoever those guys are, stay far far away.

[XH29N0G]

I meant inches of mercury as opposed to centimeters of mercury.  76 cm is about 30 inches and that is what the air pressure is.  Vacuum is just how far below that it gets.  You can see that Coonhunter's gauge has both, and the inches of mercury we are seeing corresponds to about 15-20 cm of mercury.