Best Carb combo for stock 85 318

[rodrju]

Hello-

Looking for some general opinion regarding carb size and timing specs.


1985 Factory stock 318 with first year roller lifters and new style heads.

Edelbrock Performer Intake
Stock single exhaust with no cats
Standard Mopar electronic ignition conversion

Currently setup:

Edelbrock 1406 600 CFM
10 degrees BTDC


Runs well. Minor Low/mid throttle bog. Does well wide open

Carb was used..I have no idea if it factory set or has different jet/rods

Have an air/fuel gauge on order to get more info about what is going on.

Would like to get rid of the bog….Im wondering if this could be the condition of the carb or maybe too much carb for this setup..?

While I have read many times the 318 and the 1406 are a good match…most of the endorsements seems to be with the 70s style heads. I wonder if the later (post 85) style engine would do better with a 500 cfm 1403.

Also timing..?

Thoughts on this setup while keeping a stock engine.

Thanks!

 

[Aspen500]

You may need to use different jets and/or metering rods, metering rod piston springs, etc.

Wait until you install the a/f ratio gauge to change anything. You probably should get a jet, rod, and spring kit for the carb. It can be touchy getting the jets and metering rods dialed in.

 

[Camtron]

400cfm carb, a/f ratio gauge, jet/spring/metering rod kit. Drive it, monitor a/f ratio, change jets/rods/springs accordingly…you could do the same with your 600cfm carb but it will have a little less port velocity than a 400cfm carb. You’ll get better performance and economy with a smaller, well tuned carb with how anemic the stock engines are in these cars.
Actually, if you do the “builder math” and take our engine size, Max operating RPM and volumetric efficiency, a 400cfm carb is still a little too big for these cars…but 300cfm carbs (good ones anyway) seem to cost about twice as much as most 400+ CFM carbs that we see more commonly used.

 

[69-]

All said.
I had a similar slight bog and got rid of it with a metering rod spring - just one step stronger.
Get the adjustment kit, try the spring one step harder (e.g. slightly more fuel when vacuum decreases just slightly) and feel the engine. Then O2 sensor does help to do the fine tune.

Don't change everything at the same time, you easily loose grip of the tedious process.

Timing is rather conservative at idle, but all-in mechanical timing should be closely watched (without vacuum advance, though). Low compression engines can accommodate a little more advance than high comp.

Example: I run my 69 A100 318 with like 17 at idle and all-in at 33. Vacuum adds another 8. Runs very strong.
And it feels that the engine can take quite some more.

 

[Camtron]

Of yea; Timing, I was also running 15 btd and 32-33 all in. Like 69 mentioned, the stock 318s really respond nicely to it. You’ll get compliments about how nice the car sounds and people won’t believe you when you tell them it only has 140ish HP. At least my experience when I had my 318/eddy intake and header/dual exhaust.

 

[Remow2112]

The 1406 will work. More initial timing is good. On factory stuff we would set initial as high as we could till it fought to start. (Too far advanced) then backed it off 2 degrees. Make sure that all in (4k - 6500 RPM) you do not exceed 36 degrees total timing.

There is a limited pump shot on the the 1406. It is a 3 hole arm in the front right of the carb when you look at it installed. What hole is the arm in?

You can also check out Thunderhead289 on Youtube. He has a video on setting up and tuning Eddy carbs. Good stuff.

 

[rodrju]

Update:

Moved the throttle arm into the lower most position on the carburetor.

Gave it some more timing, but to be honest, I don’t exactly know how much. The dampener on my engine only shows 10°. And I just have a very basic timing light. I moved it just a little bit past 10 I would guess but it is not anymore than 15 but I need to get a better timing light to help me figure out where exactly I’m at and total timing.

The result is much more responsive at low medium throttle. Just seems like it runs better overall. But still working on getting things tuned.

Air / fuel meter is next. That should tell me what I need to do with the carb. Carb spring/rod kit on order.

Thank you all for the great replies