today i drove about 2 hours on the highway and about 10 min left of highway time my car starts dropping rpms by its self, feels like i am letting off the gas but i am not (like she was going to stall out)she never did though. the only way it would stop doing it is if i slow down, i was doing the speed limit though. then i got off and took it easy and it was fine, so i went and tested it by flooring it and it started doing it again and even when i was doing 80kph it was doing it. also every hard stop i would make the car would almost stall > one time it did. is my carb doing this from getting to hot or something? or is egnition related? oh i have a holley 750 vs.

 

Sounds like the carb is flooding.

remove and clean the fuel needles and seats and install a paper inline fuel filter.

 

i'll clean that stuff up tomorrow. i have a fuel filter but its in the fuel line, i should get the one that goes in the carb? also if it is flooding how come it only does it when i am driveing higher speed for a long time?

 

A good inline paper type filter will do the job.

there are little paper and bronze type filters that go in the carb fuel inlet fittings too. These work good at trapping the fine dirt and grit that can infect the carb. A good idea. Go for it.

This is a common cause but not the only one.
The problem very well could be ignition related.
I'd look at the coil , module and pick up coil and little connection wires as suspects in a heat related intermident fault like you discribe.

it could also be sticking valves. The valves can stick open
cause the stems are gummed up especially if the motor is getting too hot while running down the hyway.
Could be a cooling system problem, A fuel delivery problem ( too lean) causeing the motor to run hot or just gummed up valves.

had a old Chevy Chevette that would stick a valve open when ever you ran it on the hyway for about an hour.
The car would start bucking a missing and you'd have to pull off the road. Shut the car off and let it cool down and you could literly hear the stuck open valve suddenly click shut , They off I'd go for another 1/2 hr of hwy driving and it would do the same thing.
would happen about two times on a trip to Toronto on the QEW.

The car eventually died of cancer (rust), solving the sticky valve problem forever.

Could be a sticky valve.
Does the motor run hot?

 

Not saying that it's not happening, but the chances of the valve getting stuck open are pretty slim.. It's most likely that it's either an ignition problem or a flooding problem. Maybe replace the coil and cap, see if that clears up the problem. While you're at it, might as well replace the plug wires, check the spark plugs for buildup, etc. If you don't have much money to spend then try as F-Bird'88 said first, and clean the needles and seats, and replace the fuel filter. If that doesn't do it, like I said, replace those ignition parts. It certainly won't hurt it, and if that still doesn't do the trick, let us know. Good luck.

 

Are you running an HEI dist? If so, check the module in the bottom of the dist. That's how they act when they're going away.

 

the modual?? tomorrow i plan on putting a new accel supercoil,aceel roto and cap on.....what is the modual? and ya i do have HEI.

the problem is getting really bad now everytime i go hard on the gas it starts doing it, and keeps doing it till i shut her off for a hour or so. i have to drive around like a granny lol.

 

If you're going to buy aftermarket tuneup parts for your HEI get MSD stuff....

Way better than Accel. Tthe only good Accel HEI parts are the caps and rotors. Get a MSD coil and module or a stock GM replacement module. Be sure to replace the stock carbon resistor type center post with a MSD solid non resistor center post.
(its in the cap under the coil) Its required when you upgrade to a high output coil like the MSD.

 

i already have the accel coil cap and rotor i got a really good deal on them and i cant take them back. but i have not got the moduals as yet. i wanna get them on friday, so u say i should just get the stock moduals rather then accel even if i have a accel coil??
is there anything else i should know of? i though i had everything covered then some said modual, so is there anything else??
oh if this does not fix the problem, then would it be my carb??

thanks for all the help guys. i never knew what a modual was untill this post lol.

 

The best set up is the matching MSD coil and MSD HEI module.
The second best setup is to have a MSD coil and a Stock GM module.
Either way you go be sure to replace the carbon centerpin in the distributor cap with anew solid steel center pin. MSD.
You even need one for a Accel cap.

The MSD coil is better than the Accel coil.

 

my holley did that, something got stuck in the carb n jammed the floats...

took it apart n cleaned her, ran like a dream

 

i brought the car in the shop had them tune my carb and set my timeing and intall new stuff. car seems fine now, and i did not replace the moduals, i have a feeling it was my carb out of tune or something