I put in a cam and heads on a 454 , I was trying to break in the cam . well the motor will
die if i let up on the gas. if i give it gas it stays running and its not poping ,or shaking
it will run ok as long as keep the rpm's at about 2000 or higher once i let off the gas it dies , i was able to break in the cam . so now i would like to fix this idle pain . its a holley 850 dp
i got it used but looks brand new.
any help please :confused:

Check to make sure you have enough initial timing in the engine 16*to18* at idle with vacuume advanced unhooked and plugged at the carb or intake so you don't create a vacuume leak.If that checks out to be ok I would check float level make sure it's to the bottom of the plug in carb.If you look at the bottom of carb the transfer slots should look like squares at the throttle blades if they look rectangular there open to far if you can't see them there not open far enough.Turn the idle screws out 1 1/2 turns from seat,this should put you in the ballpark for your car to idle. graemlins/waving.gif

Turning the motor over and using a timing light
its at 10 btdc,and it will only start to run if i give it gas. so i should turn all the idle screw
in then out 1 1/2 turns for starters.
i will try all that you have listed
thanks

Sounds like you have a HUGE vacuum leak. Look at the carb baseplate on the rear. Might be an open hole there.

Sounds like a vacum leak to me. Check the intake at the back. A notorious place for leaks. I know for years I have just chucked the front and rear gaskets in the trash and used a nice RTV bead. Lasts longer and dont blow out.
L-Jo

I'M GOING OUT THE CAR :D WITH CAN OF STARTING FLUID
IF THERE IS ONE I WILL FIND IT .I WILL GET BACK TO YOU ASAP

Bob,as mentioned above if your running a perf cam the 10 btdc intial advance you say you motor is at is TOO RETARDED,you need to be in the range of 16-18 deg btdc initial advance so crank in 6-8 more deg timing.

Your idle should definately improve with 6-8 more deg of initial timing but if you still have idle issues after that adj then look into a possible vacuum leak as mentioned above.

If you have a vacuum leak large enough to stall the car unless your foot is in it @ 2k rpms it would have to be a fairly big leak and make a lot of suction noise so listen for it and good luck.

Scott

WELL i sprayed starter fluid alone the bottom of the carb.and alone the intake front and rear as my son ran the carb around 2000 rpms and the motor did not speed up, i feel as of now i don't have a leak. i used a lot of sealer on the ends of the motor and intake, i have a new victor jr intake so i didn't want oil leaks .
as always as soon as i let go of the gas its dead no low idle no spudder ,dead!!
but like i said it runs and sound good when i gas it ,no missing , alittle pop if i run the throttle
high.how can i start from step 1 and go back and make shure that my cam is in correct working order (timing) what is going on with the rockers
when the #1 piston is at tdc are they up and the
valve closed??? no spring pressure??? I NEED HELP
I KNOW ITS SOMETHING SIMPLE BUT I'M LOST
I NEED TO START SOME WHERE.. I WILL RIP THE UPPER HALF DOWN IF I HAVE TOO. I WANT TO DO THIS RIGHT I WANT TO KICK THIS SO I CAN SLEEP EAT AND WORK
OH YA AND SEE MY WIFE AND KIDS!!!!! :eek: :eek: :eek:

I'm no expert on this matter, but i had the same problem, and it was that my air to fuel mixture ratio was not correct. The needles on your carburetor need to be adjusted while the car is running. I hope that helps.

I did the 1 1/2 turn on all 4 screws like i was told as a starting point. i will look in to that
and see if that helps. the fuel is at the bottom of the veiwing hole ,ok the slot in the base looks
like a small square i can see it in the front part of the carb ,not the back not till i open the throttle wider, :confused:

If the engine is on the compression stroke yes both rockers better not be holding valves open, roll the engine to the tdc exhaust stroke and both will be open (perfomance cam). Make sure valves are set correct. If timing is correct, I would try a different carb, idle curcuit could be varnished up, air bleeds, idle curcuit needs cleaned or blowed out. Mark

sounds to me like a carb problem. if you're not getting any popping or anything when you let off the gas, and no idle speed up with starting fluid, i would go with another carb.

You will have to adjust the secondaries to get the metering sysytem right turn the carb over and adjust the small screw that goes through the base plate and hits the arm on the secondary blades until they are square to.

TODAY I'm going to my friends shop and he is going to let me try on his holley 750 dp
I know it work fine ,its on his running car i will also test my carb on his motor,that should let me know if its my carb.I WILL POST THE OUT COME LATER . thanks ;) for all your replys

Well I tryed my carb on my friends motor and his car did not idle with my carb.but it did with his .now i tryed his carb on my motor and it did not idle , and i couldn't keep it running run like i could with my carb???? well i'm so lost
one thing i did find is that with the valve covers off and if i crank the motor over with the
starter (bump)i hear a woosh sound coming from the drivers side head. it sounds like it is coming from the rockers or springs .but its hard to tell at this point maybe i'm hearing things????
well its too close to XMASS to spend money on a pro to have a look (low on money)so maybe i will go back to step one and start from removing the wires ,distrb. checking the firing order checking my cam lift all the fun stuff.its cold out here in AURORA IL. 30 deg. so if anyone has anything to add feel free :confused: :confused:

Hi Robert. I am by no means an expert. In fact kind of a beginner but had a similar problem early on with my 454. Maby what I found will help you.

My problem was in the gas. I was starting the motor on the motor stand and realized that the gas can I was using had some regular gas that had been sitting for 3 or 4 months. Just out of a whim I went to the station and got some premium and added some octane booster. The moment the motor cranked on this fresh fuel I was able to idle it down to a much more acceptable rpm. I did not have a tach on it but my guess is that I was origionally somewhere around 1800 rpm. The motor would just die anywhere below that. With the fresh fuel it would idle down somewhere around a thousand. Anything below that and my cam is a little to "lumpy" so the engine would slowly kill itself unless you just bumped the accelerator every few seconds.

Some of the more technical guy's might say this was only coincidental and should not have made that dramatic of an effect. I still don't know why it worked like it did but it worked for me. Just thought you might want to hear what my "shade tree" remedy was. Once again I am only a beginner as is obvious by the topic I have going with some demons of my own. Hope this helps you. Good luck and don't get too discouraged. I know that's easier said than done sometimes.

Billy graemlins/waving.gif

I GOT IT !!!!IT TURNED OUT THE FUEL PUMP WAS LOSE
AND IT WAS NOT GETTING A GOOD GAS FLOW , i still have to play with timming and tuning in the carb
seeing that it sounds like its idle a little high
so any help to on the basic timming info. and carb
tunning would help i got a 850 dp on a 454 with
larger valve on my 781 heads ;) tongue.gif