HELP! Carb problems
Elder User
Joined: Aug 2000
Posts: 597
Likes: 0
From: Burke VA
HELP! Carb problems
Hi all,
I dropped a 351W in my 78 with dual 2 1\2 inch pipes, factory 4bbl intake manifold and a rebuilt My buddy rebuilt it) 4 bbl holley 600 CFM carb.
Started it up and it runs like crap. Barely idles and will hardly take a load (ie dies if I put it in gear). Timing is about where it should be. We pulled the plugs and they are wet (gas). Gas is also coming out the tail pipe. My buddy leaned out the jets to no avail. I have taken the carb off and readjusted the floats but I don't think they were bad enough to make the engine run this bad. Could the jets be bad? they're 48's.
Help! a new carb costs about $200 and i'd like to avoud that if I could.
Jay
I dropped a 351W in my 78 with dual 2 1\2 inch pipes, factory 4bbl intake manifold and a rebuilt My buddy rebuilt it) 4 bbl holley 600 CFM carb.
Started it up and it runs like crap. Barely idles and will hardly take a load (ie dies if I put it in gear). Timing is about where it should be. We pulled the plugs and they are wet (gas). Gas is also coming out the tail pipe. My buddy leaned out the jets to no avail. I have taken the carb off and readjusted the floats but I don't think they were bad enough to make the engine run this bad. Could the jets be bad? they're 48's.
Help! a new carb costs about $200 and i'd like to avoud that if I could.
Jay
Senior User
Joined: Aug 1999
Posts: 166
Likes: 0
HELP! Carb problems
Sounds like a bad power valve in the holley. Mike.
1977 F-100
300 I-6 / C-4 (soon to be AOD)
Offy intake w/Edelbrock 500CFM
Hooker Ceramic coated headers w/duals
MSD6
Whiter whites/Brighter brights
1977 F-100
300 I-6 / C-4 (soon to be AOD)
Offy intake w/Edelbrock 500CFM
Hooker Ceramic coated headers w/duals
MSD6
Whiter whites/Brighter brights
Post Fiend
Joined: Sep 2000
Posts: 8,238
Likes: 3
From: Oregon
HELP! Carb problems
I'd vote for the power valve too. Its opens up under load for flow and if its blown it will be shooting way too much gas through your carb at idle.
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE428 @ 400 ponies , 4-speed, custom suspension w lift, mud on black.
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE428 @ 400 ponies , 4-speed, custom suspension w lift, mud on black.
Elder User
Joined: Aug 2000
Posts: 597
Likes: 0
From: Burke VA
HELP! Carb problems
You were right. Replaced the power valve (it was blown) and the truck ran great... for about 3 minutes. The floats were set too high. so tomorrow I'm going to try to reset them. I pray to god it runs good after this.
Thanks for the help!
Jayson
Thanks for the help!
Jayson
Trending Topics
Senior User
Joined: Dec 2000
Posts: 435
Likes: 0
From: Nebraska Farm
HELP! Carb problems
Another power valve note, if you ever backfire through the carb, it could blow the power valve again. The new Holley street avengers have a check valve to prevent this. There also is a kit to add a valve to your old Holley.
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 never will be finished.
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 never will be finished.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Thread
Thread Starter
Forum
Replies
Last Post