Hi Guys Thanks for looking I was a member awhile ago don't know what happened to acct Anyway
been having trouble keeping my 1971 Olds 442 running on a idle when i stop or sometimes put it in drive seems i lose vacumm when the car gets hot put a new 1411 Edlebrock carb on and made no difference put back on the Rochester and flushed coolant and seems to be better but still lopes in a idle or when in drive any help would be great i do have a mild cam and bored 30 Over Thanks Joe

 

Won't idle when hot sounds more like vapor lock or weak fuel pump to me, but I'm don't really know what a vacuum leak might act like so could be that too. Are you sure you've got good fuel pressure? I seem to recall 5-7 psi being the norm.

 

new fuel pump new alternator new voltage reg new carb new vac lines took the themostate to 160 runs great cold warms up and lopes thanks

 

i figure you are on an iphone or something but your posts are really confusing could you use punctuation because i can't tell if your last post says you took the thermostat out and now its fixed and runs great or if you are still having the problem and you took the thermostat to 160 and it runs great until it warms up and then it has the lope problem you see it is really confusing to read try to convey the information as clearly as possible so those of us that would be trying to help you dont get frustrated and give up on you because of a communication error it might help if you look at the tips for successful troubleshooting thread in the newbie section to give you an idea of what kind of things help people help you JMO

 

Sorry just really frustrated can not keep my 1971 olds 455 from stalling when it get hot, car never over heats just hits about 210 rebuilt factory rochester and still stalled when hot and in gear or at a stop, bought a 1411 Edlebrock and it made no difference, when it got hot. So the i flushed the radiator and it seemed to get better , then intalled a 160 thermostat , ran a lot cooler, but when the car idles for a time it seems i lose vacumm ,when it gets hot (i ordered a new vac guage so i can state the actual reading)s, car ran like crap with edlebrock . but off idle with my foot in it runs great with Rochester Thanks Joe

 

How are you seeing the vacuum loss? Brake pedal? In other words how do you know it's a vacuum problem and not a fuel problem?

When you put new vacuum lines on is it possible that you left one off or didn't plug a vacuum port?

 

One easy but a little dangerous way to find a vacuum leak is to use carburetor cleaner and spray it on any area that could leak. Such as the intake where it connects to the head and the base gasket of the carburetor and all the vacuum lines. When the carburetor cleaner comes in contact with a vacuum leak it is sucked into the engine causing it to run at a higher rpm. However this method is dangerous so if you decide to do this make sure you have a fire extinguisher or something to put out a fire handy.

 

I'd check both the timing chain and valve springs, after warm-up.
Both can be problematic when hot, with a lot of miles on them.
Get a 3/8 carb gasket for the Q-jet, to eliminate that.

 

Don't blame the iPhone - I use one all the time, and post from it every now and then, and it is just as easy to punctuate with it as with a keyboard (maybe easier because it inserts some punctuation for you).

I wouldn't call it dangerous.

You can also do the same thing with car-starting ether and with propane from a propane torch. Same thing - if you've got a vacuum leak, the leak will suck in combustible material and increase the idle.

I agree that this does not necessarily sound like a vacuum leak - it could be a lot of things. Although it is possible for something to cause a vacuum leak only when warm, it is not a usual characteristic of vacuum leaks to behave that way.
You need to go over everything from scratch, including dwell angle, ignition timing, vacuum and centrifugal advance, and compression.

... And when you say, "... i do have a mild cam..," exactly what cam is it?

- Eric

 

Thanks for the replys, Attatched vac gauge and cold was about 18lb
after about a half hour , when the carb kicks down and starts to lope the gauge reads 10to 12 lb. Note: The car will stall but will start right up, if i 2 foot the pedal i can keep it running. Tried the carb spraying around the intake and did not change ,sprayed the wires with water, no arc or change. Timing advanced to about 15 degrees .Motor was built about 12 years ago with limited mileage put on , about 25 to 125 per year, sorry i am stll looking for the paper work for the cam,it was the next one after stock for a 1971 olds 455 Crane Cam, Thanks for all the help


Joe

 

Joe you might have bad gas when the car is cold the choke is causing it to run rich enough but when the choke opens it stumbles.

Eric I hear you and agree some people think starting the car with the air cleaner off is dangerous. Not knowing the skill level of the person I would rather be on the safe side.

 

It's either the gas or your carb gaskets have dried out.
While you've the carb off to install the 3/8 gasket, tighten all the carb screws!!

 

is it normal for the left bank 1,3,5,7 to be higher than the right 2,4,6,8 left is 175 and the right is 145 consistent thanks on a 1971 olds 455

 

The normal reading is that the lowest cylinder should not be less than 70% of the highest cylinder, and no cylinder should read less than 100 psi.

For 175 psi being the highest, the lowest you can have is 122.5 psi. However, if your compression is that consistent across the board and one side is consistently 30 psi less than the other I might be asking myself why.

What is the history of this engine? Did you rebuild it or was it rebuilt before you got it?

 

it was rebuilt 10 years ago but driven very few miles less than 100 a year did not put hardened seats in heads looses vacumm from 20 to 8 when hot and then stall at lights run great cold thanks Joe

 

Are the heads the same on both sides?

- Eric

 

Or mismatch the pistons?

 

no they are the same

 

Back to the posted problem - try tightening the manifold bolts after the the engine is hot.
If it gets worse, have the intake zygloed.

 

okay will give that a try today will keep it posted thanks

 

okay checked intake bolts all were tight no change

 

At the carb, disconnect everything that is vacuum operated and cap the ports. If it improves then start replacing lines 1 by 1 until it acts up. If it is not at the carb, then move to the manifold ports and repeat.

Also disconnect PCV and spray some ether (starting fluid) into each valve cover opening and down the oil filler tube to see if that affects your idle.

 

It might be a good idea to check the vacumn hose,s that run to the dashboard heating unit. I had a similar problem and found out that the dashboard heater control unit was bad and caused a vacumn leak; also the vacumn motors on the heater box was going bad and causing a vacumn leak. This was on a 1965 dynamic 88 with air conditioning. I could hear a hissing noise coming from under the dash so it might be helpful.

 

thanks i will