AVS 650 hesitation

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Slantsix64

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I have a mild 318 9:5 compression mild ported heads 260/264 duration camshaft 430/453 lift forgot the exact numbers. Got a new AVS 650 edelbrock car hauls *** and smokes them up, but at a dead stop and if I gun it it has a second of a hesitation, if I’m rolling 35mph then gun it, it will hesitate some times not all the times.

things I have checked

#1 clean gas clean fuel filters
#2 float level
#3 ignition timing has always been the same
#4 I ended changing the rods to be a lot richer and it got worse. Came with .101 jets with 70x37 I installed 68x57
#5 now I have 73x47 rods and it seems better but the hesitation is still there

I might try some thicker rods I can’t find the edelbrock chart for the 1905 carb online.

also I have the stock fuel pump, and the stock 273 commando air cleaner but I doubt it these might be issues.
 
Sounds like the accelerator pump is not kicking on right away. Look down the carb and press back on the pedal linkage the accelerator pump squirt should start immediately, if not then there is an issue with the accelerator pump system.
 
Sounds like the accelerator pump is not kicking on right away. Look down the carb and press back on the pedal linkage the accelerator pump squirt should start immediately, if not then there is an issue with the accelerator pump system.
I inspected it, it is the stock one should I upgrade it with the better one edelbrock makes? I tried moving the slots on slot made it worse the other just about the same
 
I inspected it, it is the stock one should I upgrade it with the better one edelbrock makes? I tried moving the slots on slot made it worse the other just about the same


under the hood with the engine off, what happens when you push on the linkage- like you are pressing on the pedal. you should get gas out of the accelerator nozzle in the carb right away.

I had a 750 cfm that I replaced the plunger in the carb during a rebuild and it would hesitate every time, took me a minute to figure it out, but the 650s and the 750s have a different plunger. More than likley hopefully not your problem but you never know.
 
Have you tightened the secondary air valve spring?

Agree with this!

I was having a hesitation when going part throttle to WOT last week... tightened up my secondary air valve 2 turns... maybe 2.5 and now no more hesitation.

Or.... Get a double pumper lol.
 
This made me literally LOL while trying to put my kids to bed :rofl:

I now see the humor in that ...

But AJ does a great job of explaining the steps and reasoning behind tuning .
Lots of guy say to do this or that but not why and when .
 
I now see the humor in that ...

But AJ does a great job of explaining the steps and reasoning behind tuning .
Lots of guy say to do this or that but not why and when .

I agree he does do a very good job of explaining things. A lot of times I have to read it multiple times to make sense of it all, but its worth it when you start to understand what he is talking about.
 
Tell him why AJ .
AJ's guide to Transfer Port Synchronization

To set the idle fueling; such that the carb does not hesitate on gentle tip-in, you gotta balance the fuel delivered from the primary low-speed fuel delivery circuit, namely; the transfer slots, TO; the idle mixture trimmers, namely the idle discharge ports.
When you do this, you will find that, to get it right, there is a very small window of adjustment on the transfers . And in most cases, a street cam will idle too fast with the timing all your friends will tell you, has to be like as much as possible until the starter kicks back. But that is not true!
The engine will tell you what it wants for idle-timing; if you just listen to the clues. You should not force what is, IMO, massive amounts of idle-timing on your engine. Below the stallspeed, it simply does not matter. I have run the same ancient Holley 750DP on a 292 cam as on a 270 cam, in the same engine. The only change to the idle circuit, was to the bypass-air.

Now, if the stumble occurs later, after the carb gets up on the mains, lots of good advice has been given.

Never underestimate timing;
Your engine has exactly ONE timing requirement which is to get the max cylinder pressure delivered to the crank at very nearly just one time,in degrees,which is in the neighborhood of 25 to 28 degrees ATDC. Your job is to start the fire,at the right time, under all conditions, to make that happen.
To break it down, your engine has these timing requirements;
A) Idle-timing
B) Power-timing
C) stall-timing
D) Part Throttle timing, and
E) cruise timing.
ok , I'll include; for manual trans cars
F) closed throttle decel-timing, and
G) low roadspeed timing

Of all of these;
Power-Timing is the most important and also the easiest to figure out.
Idle-timing is a little more involved.but
Part Throttle is the toughie.
And cruise-timing will surprise the heck out of you.
Stall timing is often whatever comes out in the wash, but that is not right! Timing at stall is what you are forever gonna be feeling, every time you mash the pedal. Too much and the engine will detonate. Too little and the engine will be lazy. Stall timing to power-timing is where you are gonna spend most of your time in tuning,and where brain is gonna get it's exercise.

Bed time/ I'm passing out while typing!
 
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One problem I have seen on these edelbrocks is the check ball for the accelerator pump will stick and you get no pump shot. If your not getting any spray from the accelerator pump, check this first.
Have you tried changing the springs for the plungers circled in the pic? Sorry, cant remember what they call these. Anyways, these are held down by vacuum and when you stab the throttle they lift from the absence of vacuum which then opens the jets. Too heavy of a spring will hold them down too long and you get a lean bog.

001826_v2_1.jpg
 
What's yur Idle-timing?
And stall speed
Aj, it’s idling at 650 12 degrees of initial and 18 in the distributor. Stock 318 torque convertor running 3.91s in the rear

also adjusted mixture with a vacuum gauge, what I noticed is that the engine will not die with the screw all the way in, but does run rough, does that mean my primary jets and too fat?
 
No it indicates too much of the fuel at idle is coming from someplace other than the idle discharge ports.
Main Jets have practically nothing to do with idle.

A Carter idle design is different than a Holley only in that it has a second bleed and second restriction.
My guess is what AJ has already said, the throttle blade position is too far open at idle. Too much fuel is coming through the transfer ports.

Mopar offered a great intro to the carbs systems. May 1966 is a good one to start with Master Technician Service Conference - Chrysler's Training for Mechanics
There's another version a couple years later that touches on emissions and Holleys. Also good.

1. Check fuel level in bowl.
2. Adjusting the idle mixture is going to require repeating steps as each change effects rpm which in turn can effect vacuum which effects mixture.
a. Timing
Measure timing at lowest rpm it will run, then measure what rpm it starts to advance. If the timing is changing with rpm at idle speeds, it makes the rest of the tuning more difficult. In other words it could be 12 at 650 but 10 BTC at 600 rpm.

b. Idle mix
Do not use highest vacuum in neutral as the final determinant. It will result in the mixture too lean for the load with the transmission engaged. The engine is only a making a few horsepower at these rpms. Just engaging the transmission increases the load signifcantly relative to the maximium power that can made at these rpms. See the '66 Carburetor fundementals.

Richen the idle mix screws, then reduce the throttle opening. Readjust the mix screws for strongest idle. Check by placing in gear with foot on the brake. Looking for the least drop in vac and rpm. Use which ever is the easier to read/work with.
Repeat as needed.
If the rpm is dropping off after said attempts, then add a couple of degrees to the initial timing.
This assumes a PCV valve is already being used. If not, then that is the way to bleed more air in and allow the reduction of the throttle opening at idle.

Once the throttle position is more ideal, then the off-idle throttle will respond more as it should.
 
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Agree, t/blades open too far at idle if screwing in mixture screws does not kill the engine. This needs to be corrected before further tuning is done.
 
I feel like an idiot! I figured out what it was,




The damn air filter was clogged I forgot that I had been using that one and reusing it off my daily driver slant six car!!!!!
 
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