Good, simple carb choice for modified 318...

[ViperMan]

I know this could lend itself to being a HUGE topic, but I need to start budgeting to replace my carb on my (now known to be) factory 318.  Thing is, it's not wearing the factory carb now - it's got a 4-barrel on it.  I know it's been modified - besides the 4-barrel, it has a full set of headers, and aftermarket valve covers (which in itself means nothing, but could mean that other things internally are modified.)  And it's obviously been yanked, as the A/C was removed and the block was painted red.

SO, I probably need to stick with a 4-barrel, but I know NOTHING about judging CFM's, functionality, etc.  I don't want anything fancy, Hi-Po, or high cost - just something to replace the worn out hunk-a-junk that's on it now.

Any idea where to start?  Any idea on how to determine what's on it now with relative ease that might give me some better ideas?

Jeff

[422STROKER]

Any numbers on the carb?  There are mainly two aftermarket types.  Holley with side hung fuel bowls or the Carter/Edelbrock type carbs.  Does the carb run ok now?  I would think something in the 600cfm range would be good for your 318.  I have a 600cfm Eddy on mine and it runs pretty good.


Tom

[ViperMan]

My carb is CRAP...  The base (is that the right word?) plate is shot - I've been told...  It doesn't rest at idle right.  When I'm driving and let off the throttle say at a red light, it idles real high - I have to tap the throttle to let the spring pull back the plates enough.  When you adjust the idle setting, it doesn't actually change anything right away.  Plus the connections for the choke were all screwed up - this thing was bastardized.  I had a guy fix it who does a LOT with muscle cars - he did the best he could, but said I need a new carb to really make a difference.

I'll check for numbers - any idea where to look?  I know a lot about cars, but almost NOTHING about carbs.  Let's just say all I know I learned from Nitro R/C cars.  They don't have much in common!

Jeff

[422STROKER]

Well take a peek at holley's web site and edelbrocks site to start see if you find anything that looks similar.  Then again if the one you have is junk, you could just order one up from Summit Jeg's or even the local Auto parts store and swap one in an hour or so.  Auto Zone usually has a couple in stock.

Tom

Holley is usually a 1850 carb 600cfm and Edelbrock is 1405 carb 600cfm

 

[70challengerrt]

I know chyro doesnt like them but an edelbrock will give you trouble free/ maintenance free driving. I very rarely have to adjust mine. On the other hand a Holley is harder to initially set but is a better performing carb IMO. I would go with a 600-650 cfm.

[ViperMan]

Sorry for double-posting, but also, how do I know what type of choke to use?  I thought manual chokes were the kind that you had to actually open and close with a cable inside the car.  Electrics are of course, electric.  I'm pretty sure mine now isn't electric - I thought it was vacuum controlled.  But, unless I'm wrong on my definition of a manual choke, mine isn't manual.  Or is it?  I don't have to adjust anything - it adjusts on its own.

Jeff

[70challengerrt]

I don't know about holley but the edelbrocks have electric choke, all you have to do is run the choke wire to a power source when the key is on and its pretty much all set. Set your idle mixture, idle speed and your good to go. If it has a hesitation when you hit the throttle you adjust the plunger linkage to hte next hole and that is it.

[422STROKER]

You could have a Thermoquad carb.  It would possible be controlled by a choke cup and bimetallic spring to choke horn.  Either way opt for a Electric Choke Carb.  Makes for simple turn the key and go diving.

Tom

[GoodysGotaCuda]

Simple? That leads striaght twords edelbrock or carter in my opinion. I have a 650cfm AVS Eddie carb and love it. 

[CrazyPete]

years ago i did a 4 bbl swap on my 70 gran coupe it had then 318 2bbl.  I did the carter 625 cfm ele choke(and a 360 cast iron intake) and that thing was awsome.  Pretty much just had to throw it on the car and only a very little fine tuning was needed.  Worked awsome years of great service as a daily driver.  Good luck

[MEK-Dangerfield]

Jeff,

  Whatever brand you choose, definitely go with an electric choke. It sounds like your current carb might have a vacuum leak somewhere. If your engine is believed to be stock internally, then 600 CFM is just fine.


  Mike

[Mopar73340]

Another vote for the eddie as I run the avs style on both of my 340's. Like said easy to tune and once done you can forget about it. Go with the electric choke #1406 if you go with the 600cfm, or 1806 for the 650.

[ViperMan]

Well, it's got headers instead of the standard manifold, so with the ability to breathe out better, it can probably breathe in better - I'm leaning towards a 650cfm...

[Chryco Psycho]

the 318 doesn't respond well with big 4 bbls , I would get a small 1850 Holley with an electric choke , the Eddys carbs simply will not allow much adjustment

[Super Blue 72]

Well, it's got headers instead of the standard manifold, so with the ability to breathe out better, it can probably breathe in better - I'm leaning towards a 650cfm...

I think one of the big mistakes people make with carbs is "bigger is better" which is not always true, unless you plan on doing high RPMS or what not.

A bigger than needed carb will give you bogging on take off, where as the smaller carb may be snappier off the line.  My vote is like the others, go 600cfm.  If you poke around on craigslist or know someone with an extra carb you can try different carbs and see what works best for you.

Tom mentioned a Thermoquad.  This is a pic of one.  It has the characteristic "phenolic" black main body.


These are classified as "spread bore" carbs, as are Rochester Quadra Jet carbs.  (GM stuff).  They have smaller primaries and large vacuum operated secondaies and are supposed to be aimed with economy in mind, hence the small primaries.  I actually had a Rochester Quadra Jet on a 318 a while back ago.  I think it was a wee bit too big and off the line was not that good.