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carb too big?

mightymopar

mightymopar

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I have an Edlebrock 1405 600cfm carb and an Edlebrock alum. intake on my stock 318. It runs pretty strong for a small block, but man oh man the exhaust. Not much of a carb mech. is it way too big, can I back it off or just go to a smaller one.
 
For a street driver that is stock I would say the 600 is way more than you need.
 
I am running dual Eddy 500cfm's on my mild poly 318 and it runs great. I'm no carb guy either but From what I read the vac secondary carbs limit the flow to what the engine asks for, (by vacuum) so it is some what difficult to over carb in a sense. You just don't use the full potential of the carb. I know someone will correct me if I am off base here,
 
Hmm...I'm running the Edelbrock 650 on my Poly 318 and it seems to like it quite well. If you are comparing (I assume) the exhaust smell to a newer car, yes there is more 'odor'. That is because the older cars do not have catalytic converters to burn up any unused fuel in the exhaust. You can try closing down the mixture screws a bit more. Edelbrock does have videos on their website for making carb adjustments. I think tuning is in the middle of the page. Take a look. http://www.edelbrock.com/automotive_new/misc/tech_center/install/tech_vids.shtml
 
I have a 73 318 that I have no reason to believe has any other mods than the permormer intake, carb and headers. It runs just fine.

Those are pretty common mods that lots of people do.

What exactly are you complaining about?

is it running extremely rich, and you are smelling that in the exhaust?
 
What you need to do is tune it. The carb size is fine. Get the jet and rod kit.
 
I'm in agreement with rumbleratfish360 and RustyRatRod--this carb simply needs some minor change in the jets and metering rods. Get the kit from Summit and follow the instructions--they'll come with the kit and are also available online. EASY FIX.
RustyRatRod said:
this ^^^^
Click to expand...
 
Guys, we really still don't know what the actual probalem is-

"...man oh man the exhaust..." is not exactly the most descriptive explanation.
 
Edelbrocks usually come a tad rich out of the box for their own liability. They do not want someone to melt a piston and blame them. Just get a tuning kit (rods and jets), and tune it yourself.
 
Most ALL square bore carburetors are rich. That's because the primaries are the same size as the secondaries. This is why I love a Thermoquad on the street. You can run them lean as all get out on the primary side but have 850 CFM on demand when you want it.
 
mightymopar said:
I have an Edlebrock 1405 600cfm carb and an Edlebrock alum. intake on my stock 318. It runs pretty strong for a small block, but man oh man the exhaust. Not much of a carb mech. is it way too big, can I back it off or just go to a smaller one.
Click to expand...

A 1405 is a 500 CFM
A 1406 is a 600 CFM
 
That carb is fine for a 318. I have a 670 truck avenger on my almost dead 318 in our 1970 W100 trail rig. It works perfectly.
 
Thanks guys for all the help. The reference to the exhaust was indeed the odor. I did turn the carb adj. screws all the way in and back them about 2 1/2 turns (thats all I know about adjusting carbs) and the smell seemed to get much better. Havent had much time to try it out yet, been rainy here, and am doing the valves seals now, again a first for me.
 
The best way to adjust your idle mixture screws is with a vacuum gauge and a hand held tach. Edelbrock's you- tube video is a very good primer as to how to do this. I usually start with the mixture screws lightly seated (in all the way) and then backed out 1 1/2 turns. The final adjustment usually comes in about 3/4 to 1 1/2 turns out. Good luck with your project.
 
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