Edelbrock tuning issues

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blackdart75

blackdart75

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I have a 318 set up with a edelbrock preformer cam. weiland intake, edelbrock 1405 and a pair of manifolds from a 360.

The issue is that on this setup i would think that i should have more power.

I first thinked that the carb was too big and started to jet i down and no effect. If the jetting was too low then it just started to struggle and seamed that some syllinders would not fire.

Im just wondering if im doing correct and if my theory of the carb is too big is correct.

What is youre opinion on the carb setting?
 
Jetting only effects the Air Fuel Mixture (Lean or Rich)

It will make no discernible difference in the
Air flow (CFM).
 
Sounds like you have a good set up. Make sure your Timing is good.
 
TF360 said:
Is the Cam too big? What are the Spec's
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if it's the performer then it's not very big at all. they spec it out as 420/420 and 204 @ 50

unless it's a performer plus... then it's an entirely different beast and likely too big for what he's trying to do.
 
junkyardhero said:
if it's the performer then it's not very big at all. they spec it out as 420/420 and 204 @ 50

unless it's a performer plus... then it's an entirely different beast and likely too big for what he's trying to do.
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The cam was allredy installed when i bought the car. But i really do not think its a preformer plus.

Could it be too lean on the mixture?
 
It’s also counter intuitive, a carb that is too big will run lean, not rich. The velocity of the air through a too big carb is slower so the signal is weaker. That equals leaner. That carb it’s fine.
 
Gears, torque converter, what are we working with?


If you're going down the road at 3500 and stomp on it, is it still "too slow"?
 
well, lets start with some basics:

have you done a compression check? what is the cranking PSI, that could give us an idea of what kind of compression you have.

what's the over all condition of the motor? slap wore out with a million miles? are there any vacuum leaks? is it sucking oil?

what kind of ignition or distributor does it have?

do you have any way to measure the valve lift at the rocker arm/valve to kind of ascertain what cam you may have.

have you done any additional tuning beyond the carb? messed with the timing, etx?
 
The Edelbrock 1405 and 1406 carburetors are pretty much bolt on and go with the exception of idle speed and tuning the mixture screws. You need to start with the basic tune up in the car and see what is going on with that.
 
To throw a wrench in things, on Edelbrock carbs, especially 1400 series, I jet the carb up 2 sizes. I had a good mopar buddy show me this when I had a hesitation/ stumble issue. I've done this on numerous vehicles with great results. Last one I did was on a 56 Chevy wagon with a 350. Customer was extremely happy. Said it never had such response.
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I think the 1405 is a perfect match. I don't believe the problem is the carburetor. Put it back stock and look elsewhere.
 
I would do a quick timing test, grab a timing light. A 318 with a cam that is behind on timing (ignition) becomes a big dog. Learn a lot in 60 seconds under the hood.
 
Hopefully you have the 40 year old heat riser flap removed from the passenger exhaust manifold.

When that engine goes cold, that flap rolls shut. If it is rusted and stuck shut from sitting, that will kill any power that you are dreaming of making.

Dual Exhaust?

Hold a wrag over each tailpipe at the rear of the car after it has warmed up good, to see if there is a pressure difference between the 2 pipes.

Stuck flaps or animals getting up into the mufflers and building nests?

Needs to breath properly to make power.

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☆☆☆☆☆
 
Basics:
- is the carb opening fully.
- choke hanging up will prevent secondary t/blades from opening. Check for this.
- what is the ign timing
- carb size is perfect for this engine.
 
I have an Edelbrock 1405 on my 318 and it runs great! I suggest you go online and look at some of the YouTube videos on these carburetors. I went on Amazon and got a knock off Chinese tuning kit (sorry guys!) that allowed me to go richer or leaner from the factory tune. Edelbrock has a chart that recommends different jet and metering rod combinations depending on if you need to go richer or leaner. I suggest you go back to the factory setting for the primary jets, metering rods and metering rod springs. You’ll need a vacuum gauge to determine your vacuum at idle for the metering rod springs. They are actually very easy carbs to tune once you understand how they work.My only complaint is, they are very sensitive to ethanol fuel and will be hard to start when hot unless you run a spacer underneath to isolate the heat. We have a gas chain here called QT that sells ethanol free 90 octane and that’s how I solved the problem
 
318willrun said:
I would do a quick timing test, grab a timing light. A 318 with a cam that is behind on timing (ignition) becomes a big dog. Learn a lot in 60 seconds under the hood.
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What degree do you suggest i set it on. Its a nightmare to see the degrees on the damper because the degrees disepares under the waterpump..
 
Funny how so many people think poor performance is the fault of the carb. So many other things to check BEFORE messing with carb settings. LIke 318willrun said, check the engine timing and let us know what it is set to currently. Does the distributor use vacuum advance? If so, ported or manifold? What kind of ignition are you running? Points, electronic? Stock distributor or aftermarket? What kind of car is engine in? What is the rear gear ratio? Automatic or manual transmission? See, we need more info to point you in the right direction.
 
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blackdart75 said:
What degree do you suggest i set it on. Its a nightmare to see the degrees on the damper because the degrees disepares under the waterpump..
Click to expand...
What vehicle? You can just turn the distributor counterclockwise just a little and see if the RPM's pick up. If they do, take it around the block. See if it gets noticeably better. I don't have a degree to suggest, but your engine will. Actually, I just did a video on baselining your timing. It would be beneficial to you to watch it.
 
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