Idling/carb question
Thread Starter
Heel & Toe
Joined: Jul 2009
Posts: 15
Likes: 0
Idling/carb question
Hi - I have a 71 with 350, 4 speed manual...I just put an Edlebrock 1405 on, changed wires, changed plugs, changed filters, new throttle return spring and top V belt. After warmed up, the engine ramps up RMPs from 6oo to 1000 and sort of go's back and forth. It's as if someone is hitting the throttle a touch and then letting off. When I am driving and try to decel, the same thing happens...it's as if it the gas is stuck just a tad.
Any guesses on where to start?
Any guesses on where to start?
Drifting
Joined: Feb 2005
Posts: 1,879
Likes: 38
From: Los Gatos CA
Do the throttle blades close completely? If you back off the idle speed adjust and the engine does not idle down and die, you have a vacuum leak. Air must be getting in somewhere. I bet this is the problem.
Advanced
Joined: Apr 2011
Posts: 82
Likes: 0
From: Newington Ct
do you have a manual choke or an electric choke?. if neither is hooked up then you must wire the choke plate in the open position.The butterfy could be moving from partaly open to partaly closed.take a length of mechanics wire secure to the cable holder and loop it through the choke linkage in the full open position.just a thought, I've been there. I this isnt the case, you might have a vacum leak at a carb fitting or a cracked hose
Thread Starter
Heel & Toe
Joined: Jul 2009
Posts: 15
Likes: 0
Jeff & CT Roadster:
I put a new gasket in on the base plate, seems like a very snug fit. I will double check the hose from PCV port to block. That is the only vacuum that is hooked (the timed vacuum and manifold vacuum ports are plugged with pieces that came with kit). no power brakes. Could my PCV be shot? Also, the throttle blades do return nicely, I don't notice anything strange with that...this decel issue is intermittent. I used teflon tape to seal the thread of the power brake inlet too. also this is a manual choke
another detail I just thought of....the edlebrock air filter does not fit (not enough clearance under my hood,..I have an LT1 hood, not original to the car that I can tell bc it is a 350....the block sits up too high for me to use it...so I had to use the lower profile version I had on my Holley before. Could this be having the impact?
I put a new gasket in on the base plate, seems like a very snug fit. I will double check the hose from PCV port to block. That is the only vacuum that is hooked (the timed vacuum and manifold vacuum ports are plugged with pieces that came with kit). no power brakes. Could my PCV be shot? Also, the throttle blades do return nicely, I don't notice anything strange with that...this decel issue is intermittent. I used teflon tape to seal the thread of the power brake inlet too. also this is a manual choke
another detail I just thought of....the edlebrock air filter does not fit (not enough clearance under my hood,..I have an LT1 hood, not original to the car that I can tell bc it is a 350....the block sits up too high for me to use it...so I had to use the lower profile version I had on my Holley before. Could this be having the impact?
Advanced
Joined: Apr 2011
Posts: 82
Likes: 0
From: Newington Ct
you say you have a manual choke, is the cable connected and working properly? do you have the vacum hose for the headlights hooked up? There is a 3/8 nipple of the front of the carb that goes to your PCV if you shake the PCV up and down you should hear the valve clanking if you dont hear anything then its gummed up and needs to be cleaned or replaced but dont think this is the problem. My money says its a vacum problem
