Carb guru's, need to bounce something off you....

["MrEd"]

did you clean the main body and the metering blocks?
i know at one time i was running in circles with a similar situation,i had the ignition practically sitting on the work bench while running the car. (wasnt the problem)
swapped on another carb, problems went away at idle and part throttle (cruising speed).
so i tore my 750 back apart and cleaned it and blew out all orifices in the main and metering blocks, some trash came flying out of one the metering blocks.
bam fixed it
good luck

[SSMAN]

did you clean the main body and the metering blocks?
i know at one time i was running in circles with a similar situation,i had the ignition practically sitting on the work bench while running the car. (wasnt the problem)
swapped on another carb, problems went away at idle and part throttle (cruising speed).
so i tore my 750 back apart and cleaned it and blew out all orifices in the main and metering blocks, some trash came flying out of one the metering blocks.
bam fixed it
good luck

Mr Ed, congratulations, You get the grand prize. Partially obstructed front metering block. I cleaned every thing with carb cleaner. But I put the air hose to it this time and put some pressure behind it. Seems to be running fine now.

I am one happy camper. It only took taking the carb off 4 times. LOL

["MrEd"]

Lol!!
Good deal glad I could help...
hopefully you didn't change a bunch of stuff to the carb,being that it was working fine originally.

[SSMAN]

Lol!!
Good deal glad I could help...
hopefully you didn't change a bunch of stuff to the carb,being that it was working fine originally.

Oh no. It is all the same. I learned a long time ago , change one thing at a time. It has run good for too long. I knew everything else was set right.

This was kicking my ass though. I ran by the local mechanic that is a friend of mine here in Burleson. He is a smart SOB. He said it was the metering blocks too. I guess I needed more pressure to blow it out. Plus the fact he loaned me his 750 hp and that confirmed beyond a doubt it was the carb.

Thanks everyone.

[SSMAN]

Its a flutter but a hard cut out, enough that it kicks the truck like a hard shift kinda feel. i have a lazer thermometer. Ill check it out and see. It doesnt feel like ignition or mechanical related. Almost acts like if for example you were flipping a switch off and on constantly. but if while its doing this, i push the gas farther 1/2-3/4 throttle it quits and takes off.. really weird..

Any word on your situation?

[Blackpony]

Any word on your situation?

Not yet man. I took the carb off today to clean it up and replace a few things. I had taken it off and put on another truck to see if the problem was the same, and that truck popped through the carb and killed my pv. After couple hours and couple cans carb cleaner its back on. Still cuts out at part throttle, about 1/8 ish but wot and acceleration with more then 1/8 throttle is much better. Also before when wot about 4500 ish it would begin to kinda fade out and loose power. That is much better and it pulls pretty good all the way through now. need to richen it up a bit maybe. I'm gonna try an 8.5 or 10.5 pv to see if that helps. Forgot to get my laser temp gauge from the shop, so i will check that on tuesday and report back with my exhaust temps.

[jyro]

I may have missed it but

I didn't see anyone ask what his fuel pressure is.

[mustang87]

I know you said you replaced the power valve, but with my dealings with Holley over many, many years I have found that power valves are the week spot in a Holley. Was your rebuild kit a Holley brand or after market?, if so after markets may have the wrong PV in the kit and to many times I have installed a new Holley PV and it was bad, That's why I have always run a power valve blocks in my carbs. Power Valves work off carb vaccum and with a big cam you may not have the right valve for what your carb vaccum is producing. Good luck, Holley carbs are great carbs, but when they start giving you shit they can be a pain in the ass. If you want, call Rob Camp at CS Motorsports in Plano he is by far one of the best Holley guys I have been around. Had a Chuck Nutton Holley on my 87 363 and never could get it to Idle right and it had a tip in hesitation that even Chuck could not fix and Rob had it running great in just hours after doing some ajustments.
Hope that helps.

[mustang87]

I didn't see anyone ask what his fuel pressure is.

Good point

[Blackpony]

Yea I used a Holley rebuild kit for vacuum secondarys. Put a 6.5 pv in it. I am getting about 12" vacuum at idle. After the rebuild last nite and performing a few tricks that I found online it runs a ton better but did nothing to help with the part throttle issue I am having. I plan to get a few different pv to try maybe a 10.5 or so and see if the fuel needs to come in a little earlier. Our tuner Sean at the shop is great with carbs just haven't had a chance to take the truck up and mess with it.