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Author Topic:   ??????HOW TO MAKE MY PURE STOCK PULL VACUME?????
eric5
Member
posted November 09, 2004 09:33 PM
Increase the idle speed.

Use a 2 barrel intake instead of a 4.

Increase valve lash.

Advance the timing as much as you dare.

Change to a cam that has more lobe seperation. 110 lobe seperation should do it.

Or, so I have heard, just add a smog pump. I guess this is supposed to give you tons of vaccum.

engineman
Member
posted November 10, 2004 06:15 AM
quote:
Originally posted by eric5:
WE HAVE TO PULL 16 INCHES OF VACUME IM PULLING 8 HOW CAN I GET THE REST OUT OF THE MOTOR WITHOUT CHANGING IT

Smallrock98 is right, you need another camshaft....a 110 lobe sep. or one with less Duration, or both will get you there.

Like he said, you can turn the idle up...but if it is mesured at a certin RPM that aint gonna work either.

you can also play with the cam timing....but dont expect to get much out of it.

You may prove me wrong, but I dont think all the tuning in the world is gonna get you 8 more in. of vac. without changing the camshaft.

Call a good cam company that will work with you on what you need(a real good one sponsers this site).

Good Luck

------------------
Mark's Racing Engines

(903)883-0196

www.northtexasracing.com

engineman@northtexasracing.com


waltonjr1
Member
posted November 10, 2004 06:51 AM
You can get about 5 inches switching to rhoades or comp anti pump lifters. How far after zero lash did you go when setting the valves? Unless you have a seriously big cam you should be able to more than 8 inches.


eric5
Member
posted November 10, 2004 09:57 AM
I may be mistaken but I am pretty sure a vaccum pump is the same as what I have heard called a smog pump. They come stock from the factory with the engine for what I think is used for some form of pollution control. They look like a tiny alternator and they seem pretty common in 80's vehicles. Once I was thinking about doing this but setting it up looked like too much of a pain to me. I would just check out the local junk yard. Since these came stock anyway, there should be no reason why the tech guy should frown upon it.

[This message has been edited by smallrock98 (edited November 10, 2004).]

streetstock82
Member
posted November 10, 2004 10:50 PM
If you do use a smog pump on your motor, you'll probably have to run it in reverse rotation from it's stock set up. Those pumps are generally used to push air into the a.i.r valves to dillute emissions in the exhaust. It might take a little ingenuity to make it work. But by running it reverse, it should **** air instead of pushing it depending on whick side of the pump your hooked to.


FlyNLoIMCA17
Member
posted November 10, 2004 11:38 PM
you could also use a pump off either a chevy 6.2 or 6.5 liter diesel or ford 6.9 or 7.3 liter diesel, They are fairly stout and any parts store should have them.


eric5
Member
posted November 11, 2004 09:52 AM
any tech guy with "half a lick" of sense is going to know something isn't right when your hoopty is thumpin' like top fuel dragster and still pulling 16 inches of vacuum...


Dixon
Member
posted November 11, 2004 02:22 PM
streetstock82 is right on the money regarding the A.I.R. pumps, and I'm not sure that it could be converted to pull vacuum. The pumps actually pull air in from the units themselves, and I don't see anyway to connect a tube to run to the crankcase, intake, carb, or whatever you'd hook it to. I don't know how the valving works inside them, but I doubt reverse rotating them will work.

I think those A.I.R. pumps are interesting. The EPA says "reduce emissions" so the car makers build a device that pumps fresh air into the exhaust, which reduces the harmful particles on a "parts per million" scale, which satisfies the EPA, because they don't have a clue, but doesn't actually reduce the actual emissions produced.

b4racing
Member
posted November 11, 2004 03:48 PM
get a vac. gauge and start messing with your air jets do one side at a side and reset the idle screw as you do it. Earl Parker has a whole cd that is a great tool you might think about. I have a big cam and can get close to 16. Also mess with your ignition timing. You could leave the distributer a loose enough you can turn it by hand and find the spot that you can pull the most vac. Mark it and mark the racing spot before the tech gets there turn it real quick. Bobby


engineman
Member
posted November 12, 2004 03:57 AM
quote:
Originally posted by outlawstock17:
any tech guy with "half a lick" of sense is going to know something isn't right when your hoopty is thumpin' like top fuel dragster and still pulling 16 inches of vacuum...


You got that right! ROFL!

The tech guy....

------------------
Mark's Racing Engines

(903)883-0196

www.northtexasracing.com

engineman@northtexasracing.com


rico 08
Member
posted November 12, 2004 07:15 AM
The easy way to bust the vacuum pump setup is to rev the motor a little,about every tech man i've seen does this,a normal engine will drop vacuum when you throttle it..the vacuum pump just keeps pumping the set vacuum,My setup pulls 14 easy:
lift .488-.510 dur 234-244 @.050 112 LC
It's the lobe center and the rhoades lifters that do it.
BTW i really don't need to pull vacuum anymore so if you want this setup just say so..i'll sell it or i will trade for a more conventional circle burn cam


jello
Member
posted November 13, 2004 09:38 PM
I have been working on this vacuum thing
myself. My class requires 12 inches at
1200 rpm (Also, .450 lift cam rule) I recently got what was supposed to be the
trick cam. I put it in and got a whopping
8 inches of vacuum. After playing with this
thing all day--air bleeds, timing, valve lash
etc--I got it up to 12, But to get this I have my valves set at about .005. Is that
gonna give me any motor problems with it being that loose?? And does anyone have any
experience with the Rhoads anti-pump lifters?
Do they really raise vacuum?? I am hoping they will put me over the top. thanks for any info.


zero5334
Member
posted November 14, 2004 03:08 AM
quote:
Originally posted by eric5:
WE HAVE TO PULL 16 INCHES OF VACUME IM PULLING 8 HOW CAN I GET THE REST OUT OF THE MOTOR WITHOUT CHANGING IT

rad. cams don't work well with stock intake and exhaust manifolds. talk to a good cam grinder about your setup.

rico 08
Member
posted November 14, 2004 09:02 AM
Jello,the Rhoades work really well,you know i'm not sure if they are anti-pump.You can run em that loose if you have anti-pumps,the old standard lifter with the regular retaining clip will blow apart without any preload.


jello
Member
posted November 14, 2004 09:14 AM
Thanks Rico, I think I am gonna give 'em
a try.


iowatoolman
Member
posted November 15, 2004 10:18 PM
on a roller setup i advanced the cam 2* and opened the lash up by .006 and gained 4" that would get you half way there also total seal rings add 2-4" so that could make up the difference

tuning the carb right helps also
with a vacuum rule tuning the carb is the most important job

drive hard or drive home

eric05
Member
posted November 18, 2004 03:01 PM
thanks guys


speedwrench
Member
posted November 21, 2004 08:35 AM
Run solid lifters on the hydraulic cam and lash it at about .020 to .024 that will tame the lumppy and bring up your vaccum