Many many years ago during my youth I built a 77 c10 with a 454 engine and motor combo, pafter I sold it I slowly tapered being into classic vehicles due to college and life and my father getting severely sick and almost dying about 5 times along with working in the gun industry for 10 years . Since early last year I've been looking for a classic vehicle since it's in my blood and I've wanted to reward myself for the hard work and dedication I put into many things thru the years. While looking for a 62-64 impala I came across this truck on craigslist and fell in love with it. It wasn't a short bed like I truely wanted, but it was clean enough that I couldn't pass it up for the price I got it for. Apparently he bought it three years ago from the same area here in orlando / Kissimmee and would love to find the original builder if they happened to see it online .

Here are the specs from what I've noticed

-400ci block according to casting number , (could be a 383 ? Guy I bought it from didn't know ish about the truck , just bought it and drove it )
-Edelbrock air gap intake
-holley 850cfm carb
-long tube headers
-MSD DIstributor, coil, and ignition box
-Unknown cam, crank , compression ratio
-700r4 transmission, sfi rated flexplate, unknown stall converter
-posi rear
-17" American racing wheels and tires
-factory front power disk brakes
-factory power steering
-CPP lowering springs

Interior :
-Aftermarket grant steering wheel
- complete black interior including full headliner
-full aftermarket stereo
-original AC cab but shaved firewall
-door rubber and felts in good condition
-solid inner and outer rocker panels, floor pans and support braces.
-factory gas tank in factory location

I'm probably going to do a lot of led conversions just for personal preference. I thinking the motor may need a 650 instead of an 850 as my race friends say normally the 850 is reserved for big blocks and really lumpy cams, this motor is definitely street friendly. I'm also probably going to do a rear disk conversion, vintage air gen 4 AC unit , and still debating aftermarket radiator with electric fans, and do I leave long tube headers on there or go with shorter headers to tuck up the exhaust. But it's gonna be a work in progress. I thought maybe someway of integrating a Bluetooth setup or iPad mini in a custom center console.

For the carb, as mentioned it's a Holley 850, I think I saw it was a performer series ? I didn't see any electric chokes on it and I couldn't tell if you if a mechanical or vacuum secondary. The truck sat for a year and the guy didn't know that gas went bad and the carb wouldn't let the truck run right. ( you know that conversation in the craigslist thread where someone would rather deal with a not knowing owner than a bullshit artist dealer, well this guy didn't know anything about it , he just bought it and drove it ). Do you guys recommend rebuilding the 850 and running it, as he said it was a gas hog, do I sell it and get a 650 ( what brand do you recommend ) and anyway to clean up the carb connection where the gas pressure gauge is and filter (kinda seems autozone parts to me, would prefer a little more professional level stuff )  

if its a 400cid casting bock, its a 400, 383 is a 350 block with 400 crank, and a 400 block with 350 crank is a 377

Really clean truck.  Keep an eye at the rockers and cab corners for rust.  

FIRST you don't do ANYTHING to the carb


Instead you buy a AEM wideband A/F ratio gauge and see what some basic tuning can do for the one you have.

The very first thing my wideband gauge taught me was the no matter how good YOU or your local carb gurus THINK they are at tuning the reality is they're just guessing and really don't have a clue.


ETA: you expect us to tell you about the carb yet don't even show us a pic of it?

Well the carb needs a rebuild since it's been sitting for a year

The fucking icing on the cake today, I go snooping for numbers on the carb to see which exact carb is on there, since the guy I bought it from didn't know shit about the motor, and I look around for casting numbers on the heads, and I see four letters that make my day, DART . looks to be dart iron eagle heads on this maybe 400 motor. Last 3 digits on front numbers on block are CLK

Buy this carb and be done with it. You don't need a 850 unless you are racing it. If you spend 99% of the time driving below 6,000 rpm, this carb will do you just fine. It will give you great street driveability and still give good performance on the top end when you decide to get down on it.

Take a serious look at this one

750, electric choke, tiny primaries for good efficiency, clean design, simple adjustments, gone with two of the 625's so far and I love them. With yours being a 400ci you could go with the 650 for better economy or the 750 for a little more power. For a street truck that won't be raced the 625 is probably the better choice, just depends on your loud foot preference.

Don't make the mistake of buying into the calibrated for XXX application bullshit.

I guarantee if you put a wideband on the two posters carbs above it will show an absolute dog ass lazy pig rich condition at ALL rpm and throttle inputs. Because that's how carbs come from the factory so they aren't responsible for the possibility if burning up someone's motor with a lean condition.  

Now

If you're interested in making a carb run RIGHT and have throttle response that feels like EFI you're going to need two things

A wideband 02 gauge

And a carb with changeable air bleeds IE the quick fuel slayer 750

A demon or Holley carb would be the absolute last carbs I would consider for a vehicle that I cared how it ran


ETA here's my thread about the adventure you're about to undertake. Read it as it contains a wealth of valuable knowledge

http://ls1tech.com/forums/carbureted-lsx-forum/1715966-c-mon-guys-walk-me-through-step-step-krochus-es-carb-tuning-thread-o-doom.html

I would stick to a big carb since its a big engine and for brand I like my edelbrock carbs...

Are you sure that isn't an Edelbrock carb?

You act like someone here said it wouldn't have to be tuned.

You know, I never said it shouldn't need tuned or adjusted once install. I basically said it was easy to do with the street demon carb. Its a great design, simple to adjust and tune, and nice to the wallet. OP wanted to know.......... rebuild or dump the 850, I'd dump it quick as its far too big for his use/motor. For a daily driver the 625 will make him smile and it will give him a long easy life.

But that's my point you can't tune it


Without changeable IFR AND air bleeds you cannot do but the most rudimentary tuning

And without a wideband you cannot even begin to tune any more accurately than rolling bones across the shop floor

Once you start playing with the air bleeds you will be adjusting on a daily basis. Carbs are imperfect . With barimetric changes you will be changing bleeds constantly . What is a good setting at midday will be crap when the sun goes down and the temps drop. Any tuning on a carb is a compromise for a daily driver

My experience with tuning via wideband disagrees. Perhaps for the "experienced" tuner making wild ass guesses based on smell and plug appearance witchcraft it is the norm

Out of the box the tuning is crap at all times.

Finding a good compromise state of tune us vastly superior to whatever you happen to end up with from the carb manufacturer (generally a pig rich lazy revving motor)

Again OP no wideband = no carb tuning PERIOD

Carb tuning predates widebands.  Don't listen to the guys saying you can't tune without one.  

From your pic you have some sort of Holley, if it has a cone hanging off the passenger side near the body then it is vacuum secondary.  If it truly is a 850 then it will be a double pumper and way too big.

To the guy saying it has to be a 400, they can be destroyed to a 383.  Rare but possible.

Me personally I prefer Edelbrock carbs.  No gaskets below the fuel level, easy to adjust, and damn drivable right out of the box.  To tune one hook up a vacuum gauge and adjust your mixture screws for the most vacuum.  Your rpm will go up as you do this so you will have to turn it down, readjust, repeat.  Now put new plugs in the motor and drive it around the block then pull a couple.  Black is rich, bone white is lean, you want a brown look to your plugs.  If all is fine and dandy toss a couple of new ones in and do a few wot passes and read the new plugs.  

To tune an Edelbrock you will need a tuning kit.  In order to richen it, put skinnier rods under the caps on top, to lean it out use fatter rods.  The springs control the rate of how fast it richens up the mixture.  If you are getting lean pops or bogging on the top end you should put in a lighter spring.  The accelerator pump arm has three spots, this controls your tip in response.  If you have off idle bog increase the shot size until you no longer have it.

Happy hot ridding!

I was once you!


Carb tuning does predate widebands

Correct carb tuning does not

All the old school carb tuning indicators from the vacuum gauge to plug appearance will lead you to tuning a carb pig ass rich. Untiill you tune via wideband you cannot comprehend how wrong you were when you thought you were right. It was an eye opening experience for me.. A properly wideband tuned carb will give throttle response and economy nearly on oar with EFI and one hell of a lot better than a pig rich guesswork tuned carb.

BUY a wideband, they're only. $150 nowadays and not only will it allow you to bring carb tuning out of the Middle Ages it will also tell you if something has gone wrong with your fuel delivery system in real time. A handy feature in of itself. I PROMISE any of you guys that $150 spent on a wideband will bar none be the best $150 you EVER spend on your rig. The results you can get out of one are that good


Brown plugs are pig rich probably 11-12 AF ratio or less. Running correct mid 14-1 air fuel ratios the plugs will be bone white as they would be on any modern vehicle any other color = RICH RICH RICH

So here's the pics of the carb off the motor. Still don't know what the f I have, I do know that the carb main body says pro form on the side and 11092 on bottom. Flaps say 172 and 173.

Well I can tell you it's a mechanical secondary double pumper carb.

On that alone unless the trucks primary function is RACE I would recommend a different carb. such as this

Ya, that is a double pumper, probably a holley with a proform main body swapped onto it.  A vacuum secondary carb would be much more useful for a street motor.  To see if your carb is too small hook up a vacuum gauge and if you are pulling vacuum on the top end under wot then your carb is too small.

so I got this on the truck forum I belong to

and I measured and according to my cheap micrometer its 42.46mm or 1.6715in depending on which mode its on, using the inward measuring ears, so technically 1 43/64 , so safely assume it is an 850 ?

and new guy question, why vacuum secondaries over mechanical secondaries ?

To be fair, a cheap way to tune is just using an O2 sensor and multi-meter.  Plenty of online resources to figure out how to do it.  BUT a lot of the wideband sensors out now are pretty damn slick, and have a lot of benifits like data logging and such.



Technology>guesswork.

That's a 750-850 carb and too large for what your wanting to do in my opinion.

You should be able to get $150-200 bucks for it though.

Double pumpers give it the full load, great for WOT.  Vacuum secondaries give it what it needs, great for the street.  I would venture to say you could get 300+ for that carb, it really is a drag piece.

Got more numbers for you guys, Front metering block looks to be 11173 with a 3 below it for numbers on it , and the rear one nearest the firewall shows 11166 with 3 below it. And throttle linkage plate seems to say 70645

Yep, sell the old carb. Pull the spacer, and get either an Edelbrock or Street Demon. I still lean to the Street Demon for ease of tuning and simplicity. They are similar designs. If you want it absolutely perfect, then yes a wide band o2 will get you there. Decent drivable can be done easily without it. For a daily street truck the 625 to 650 range will be best drivability, and for top end power the 750 gets the nod. But unless it's primarily a race truck, the smaller carb will work MUCH better.  

Drive the shit out of it.

Nice truck!

You need some more era-appropriate rims for it!  

I love those 69-72 chebbies.

Before dumping a ton of money into that engine, considering pulling it and selling it and getting the drivetrain out of a late model GM truck and swapping it.  It would be fast enough to be entertaining and several magnitudes more reliable and easier to live with.  Local craigslist has several engine/tranny combos with low miles for well under $1000.  Think about it, over 300 horsepower, 87 octane fuel, starts every time, no distributor to mess with, no carb jets, no power vavles, on and on.

EFI conversion using Megasquirt or whatever superseded it.

[flame_suit_ON]

The Luddites are coming unhinged cause I suggest getting a $150 part that will let them have way more power and better mpg with their carb.

They're gonna burn you at the stake.

I plan on doing a 5.3 if this motor ever goes.

A 5.3 would be a great motor for it.  

There is nothing wrong with a WBO2, it just does not fit this application.  You do not tune wot to pull 14.7 anyway, you want around 12.5-13 for max horsepower.  What the OP needs is great drivability, you don't buy a truck like that for gas mileage.  Cater to your audience my friend.

You simply do not comprehend. A street vehicle is where the wideband shines brightest

You can tune the ENTIRE fuel curve using a wideband with a tunable carb. Even at part throttle the difference in response and chrispness between as minuscule a change as 12.5/1 to 14 would blow your mind. You cannot come anywhere close to guessing in a carb at all the throttle, load and throttle ranges you can using a wideband.  You can actually see how the different enrichment circuits interact with one another and make changes accordingly.  

GET A WIDEBAND. I promise you that you won't be sorry. The old saying goes "lean is mean" and you can't get there guessing plug color. There's more to tuning a carb my friend than mixture screws and jet changes.

When you get a wideband you too will agree with me on its value. But as it stands you simply do not comprehend how much better your car can run with near optimal air fuel ratios

So I went to the local speed shop and they recommended a qft 750 , vacuum secondaries with electric choke, but they did say since I had already driven the truck with the previous carb aka Frankenstein carb that I might not be as happy with throttle response with the new one over the old one(since vac secondaries it might have a bog feeling like driving an 80s caddy, and yes he said you can dial in the vacuum secondary to activate quicker but throttle response wouldn't be as quick as my current carb) . So I haven't bought one yet as I'm still researching what I want so I don't have buyers remorse afterwards, they also did recommend a BLP weekend warrior 750 which apparently flows 930? But that's $7-900 , plus side is that they are local and one of my buddies is sponsored by them so might get slight cash break, but still a lot of $$ for a weekend truck

If you get a 750 qft and get it dialed in I promise you won't be disappointed over the current setup. Not in a fairly heavy truck with a small stall and not super low gears

No you do not comprehend that the guy isn't sure how a carb works and you are wanting him to buy a tool that he may not be able to use.  Save the WB for injection where you really can tune the entire map.  Would you suggest he get a dynometer too, after all it's the only way to truly tune your vehicle for max power?

Well shit. Let's just throw the timing light away too. After all you can get it close enough for "the street" by guessing.


I'm amazed how a hot rodder whose ultimate goal is to get his stuff to run as good as possible like yourself is willing to let personal bias stand in the way of really good advice.

I didn't want to go there but you are simply IGNORANT of what you speak. And you will remain that way till you try both ways as I did.

OP here's how this will work.

You'll get a wideband and notice your stuff running pig rich all the time.

You'll search, ask and learn

You'll tune your carb to not be pig rich and in the process your motor will absolutely come alive

You'll then take pride in doing something right and how impressed everyone is with how good your toy runs

No afraid not, see that car in my avatar?  I probably make more horsepower than you do and it is throttle body injected.  I entirely see the value in a WBO2, I am tuning with narrow band at the moment but as long as I keep my BLM in the 128 range I am running stoic.  For what the OP has a O2 is just not needed, cater to your audience.  A carb just does not have the tuning range to take advantage of it.

Pig rich as you put it is where he will make the most power, that argument is moot.

I have had your engine before MULTIPLE TIMES. You ain't making more power than anybody with a 305/350 TBI with cranked up fuel pressure and timing with a few ghetto bolt ons. My stuff made more power than you before I turned the first bolt on it.

You will not make the most power pig rich. You will have a lazy unresponsive engine. Your "power" AF will be slightly rich but your part throttle response will be best at near ideal AF/ratio. Think of it as the difference in a car you have to make spin the tires and one that you have to be careful not to.

If the OP buys the QFT carb me and his speed shop is suggesting there isn't a single part of the rpm-throttle range he can't tune.  Just because YOU can't doesn't mean it can't be done.

My engine is not bolt ons and my throttle body is bored out.  The only thing factory on my motor is the crank.  Again I am probably making more power than you.

No your not. You are just making yourself look bad





A STOCK aluminum 5.3 HO is 325 by itself.

BEFORE all sorts of internal work, big cam, exhaust, porting, milled heads ect.

In a 2800 lb fox mustang.

7000rpm 400 horspower worth of lightweight high flow awesome vs your 4500 rpm face falling boat anchor. And yes I've jacked with a lot if TBI stuff. Back in the day when Clinton was president...I swapped TBI onto an impala along with a 325 horse "hot cammed" vortec headed mercruiser 5.7 it ran ok but it was no LS. Heck my 7.3 diesel probably makes more horse power than your car not even counting torque


What are your specs on your TBI wonder motor?

You can make believe all day long that one engine makes more power than another...





Till you two put numbers up it's all just bluster.
 

388hp 357ftlbs

8.2 1/8et

I for one am looking forward to the next few months when I get the cash scrounged up to replace the 30 year old headers on my Mach 1.





Definitely getting an o2 bung welded in.  



351CJ running right and tuned to ideal?  Yes please!  

It's an amazing tool that teaches you so much. It gives you an appreciation for how amazing a piece of equipment a carb is seeing a number showing what it's doing as you drivr

What suprised me is how much difference that last point and a half of air fuel ratio makes in performance and how everything you were taught to read when tuning was wrong!

That and after a couple carb changes how rich they are with factory tunings.

Yup.  





The funny thing is, is people still trying to gauge rich or lean running based on spark plug color with modern gasoline.  



 

Hey just cause those chillton books use that same illustration from 1973

I think I have you by a little bit.  My motor is a copy of humble pie with a bit more compression.  

I think you are not paying attention to the OP.  The WB needs to stay on the shelf until he gets more experience.  I never said it was a bad thing, intact they are great.  I am saying for what the OP is doing right now he does not need one.  If he is buying a new carb you are insisting that he spend a few hundred more on something he may not be able to use.  Cater to your audience.

750 Speed demon #1402020VE Vac secondary electric choke. Simple, adjustable, Street carb is what I recommend if you want to stay in the Holley world
Understand that Holley always stated that when using a double pumper carb that you can use 100 cfm less than if you were using a vac sec carb. So that BLP that really flows 930 would be a pig of a carb
Don't discount the Edelbrock carbs 1407 750cfm or the 1413 800cfm

To the tires through a th400?

But you don't know?