low vacuum issue-cam or ???

Hello,
First I want to say sorry to Holley for my mispelling(Holly-oops!).Ok, on to my question.I'm running a well used ram air 3 engine with across the board compression of 125 all cylinders.The engine smokes a little, but revs thru rpm range smoothly enough. I don't have the build history of engine, but can logically guess it's built(doug thorley headers,holley street dom. intake,holley 4 barr. carb, elect. fuel pump, unilite ign. w/ blaster coil ect, 456 rear gears, traction bars, trans cooler, ect...  I bought the car not knowing what cam might be inside, but can tell by the rumpity-rump & power level that it's cammed. I don't know enough about built engines to diagnos. I have to advance timing to get engine to idle(1800 rpm). I just put a new 3310 vac secondaries man choke Holley on and am having trouble getting idle. My vacuum is 5 inches. Im pretty sure I don't have any vac leaks.Can the cam cause this low vac condition. I am also going to replace the power valve with low vac replacement. Can low vac affect secondaries. Any help greatly appreciated- Thanks Darren  

What color is the smoke?
Yes it could be the cam effecting the vacuum.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

The smoke is light.It is blueish.smells rich.This is at idle(1800).I forgot to mention there is a stall converter of approx 2000rpm & I have to run High octane (110 works best)or else it pings.I'm trying to get the engine to be freindly enough to drive around and have some fun.The car is 1969 H.O 350 firebird.The oil pressure is 50 psi.The 5 inch vac. is making it not so street friendly,but the novelty of such a setup built many years ago and still running is way cool !Thanks.Any info greatly appreciated.So far the carb you recommended seems like a good choice.Darren  

I forgot to ask- does low vac affect how I set up the secondaries.Thanks Darren  

If it is blueish smoke then it is burning oil also 125 psi cylinder pressure is kind of low.
What is the block and head codes.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Hopefully these are the codes.If not let me know how to decode please.

block-0215537  WS

head-  4 8  

Yep! correct.
You not have a 1969 350 HO.
It is a 1969 400 R.A 3 366Hp 10.75:1CR.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Sorry about the confusion.It's a 400 R.A. in a 1969 firebird.You suggested the 750 3310 carb to run on this engine.I,m trying to dial it in as best I can under the circumstances.I know the engine is somewhat worn,but still seems strong enough and sounds pretty tight (valve train not rattling apart).I still want to know how 5 inhes of vacuum might affect my secondaries set up.Thanks,Darren  

Holley vacuum secondaries will work fine down to 2" vacuum at idle. The biggest thing to do is change the power valve on the metering block to 3.5. Then you can start setting the idle mixture.

14-16 deg initial timing is ideal.

125 compression is low, and sounds like it is due to worn rings and not from an over sized cam. The only way to tell is by doing a leak down test on all the cylinders. If the leak down is less then 30%, then yes the cam is part of the low vacuum problem.  

I just came in from testing(in driveway) engine after replacing power valve (I installed a # 25) and I'm happy to report 7 inches vacuum,idle down to 1300,and engine very responsive to throttle.The smoke comes & goes & isn't too big an issue.I think the leak down test will confirm worn rings.I will be able to try it on the road soon.Thanks for good,quick knowledgable responses.It's nice to have help like yours...Darren  

In reading your original post it sounds like the car was built for the eigth mile drags and will never be street friendly until you "calm" it down a bit.No pontiac needs 4.56 gears unless it's race only. I'm guessing it has a big stall converter,3500+,as well. At highway speeds It is going to run way too many RPM's with these gears. I'm also guessing it has a few hard passes due to the smokeing and low cylinder pressure.Without pulling the cam it's impossible to tell what you have but I'm again guessing it's not the original RAIII, probably a race only design thats been put in.The idle even at 1300 is still real high.The vacuum also tells me the cam is too big. The secondaries shouldn't be affected at idle but when they come in at WOT they may not be opening all the way.I guess it depends on what you want out of the car but if you want to drive it on the street you need to detune the motor and drivetrain quite a bit.  

I agree with creepyracing and your idle should not be over 1000RPM's in park.
Even if it is race only it still doesn't need 4.56 gears.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

I agree on the racecar theory.Yes it is too low geared.I am restoring the car over time,and the engine in the car is something I'm not used to.It is interesting to learn about & very powerful.I want to drive it like this just for kicks for awhile!The car will be sold in a couple years & I'll probably let the naxt owner decide what to do.I like getting info & conversation on this site-Thanks Darren  

A question rolling around in this cavern behind my forehead is....

Are you running a vacuum advance on the distributor for street use? Has the idle mix screws been balanced to get the best vacuum reading ?  The way I understand the beauty of the Pontiac motor is that they like lots of advance and if you can tune them with the proper amount of advance and keep the vacuum up, even with lumpy cams, the throttle response is quicker and it gets the torque of the Pontiac in sooner.

I have seen in many other cases on other engine types that jet and accelerator pump nozzel size increased to get throttle response up on an engine with low vacuum.  The excess fuel washes oil from cylinder walls.  Been guilty of this myself. 8 to 10 inches of vacuum at idle on a rough idle cam is possible.  Got one in the garage now that pulls 12 inches at idle and you should see what it's drawing it through.

Just trying to open up suggestions....  

I know I'm not helping you with your question but I am looking for someone to help me with mine. I have a 79 Formula that I have replaced the hood with a T/A hood and scoop. Now my scoop sets off center to the right half an inch. Really need help with this one.