Carb Questions

"BJohnson11" (brettjohnson01) 09/24/2013 at 00:53 • Filed to: Truck Project

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So I had my truck running ok, but I knew that I was tempting fate by driving around with a very choked down sounding carb that had sat in a field for 4 years. And sure enough, whilst towing the Formula SAE car to an event (luckily it was after I dropped the car off and was no longer needed), the truck (now named ScarJo) decided to die. After a tow home from a friend, I did some inspecting. Fuel was getting up past the fuel filter, but none was actually being squirted into the carb. So the ole Quadrajet probably needs a nice going through, but this brings me to my question...

I was planning on my first major performance upgrades being a new intake and carb. My dad very nicely picked up half the tab for rims and tires, so I have $550 coming back to me, and coincidentally enough, the intake, carb, carb studs, intake gaskets, and accessories I want for the new intake and carb come out to pretty much $550, give or take maybe $20. The intake is a Weiand Street Warrior that is, as far as I can tell, the ONLY intake manifold on the market with ports that match the peanut port heads I have. The carb is just a 750 cfm Edelbrock unit for nice bolt on reliability. So do I pull the Quadrajet off, clean it to the best of my abilites while not springing for a rebuild kit, or do I do a full, and very treacherous rebuild of the QJ, or do I just say, hey, I was gonna get the intake and carb anyways, why not do it now?

Thoughts Oppo? I'm leaning towards a combo of both. Order new parts, and tomorrow, with my day off (MWF classes is great. The days off will come in handy for work and homework, but seeing as the first day of class was today and the machine shop doesn't open till next week, I'm free for now) take off and clean up the Quadrajet.

pdthedeuce > BJohnson11 09/24/2013 at 01:04

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i say go ahead and order the parts, and clean up the q-jet in the meantime. also, here's a link to a bbc build up using peanut port heads. pay attention in particular to the 4th paragraph, referring to intakes. good luck !

http://www.carcraft.com/techarticles/c…

BJohnson11 > pdthedeuce 09/24/2013 at 01:10

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Hrmm. I'm dubious of their not liking the Peanut Port intakes. From a purely fluid mechanics discussion, having ports that dont match up is going to cause a good deal of turbulence that will disrupt flow into the combustion chamber. I know that with some work and some port matching, an oval port intake can be made to have no flow interference, but I'm a little skeptical.

That, and I don't know how much I trust CarCraft's writeups. I read another article where, with just a cam, intake, and carb, they somehow made like 570 hp on a NA, no nitrous engine. Hmmm. Sure. Whatever you say.

That said, doing some reading on forums, a good number of guys do run Edelbrock performer intakes on the peanut port heads, so who knows.

Yowen - not necessarily not spaghetti and meatballs > BJohnson11 09/24/2013 at 08:34

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Reading your posts about this older truck are inspiring me to take on a project of my own, I came very close to buying a cheap old truck over a year ago, but got sidetracked because I had to replace me daily driver. Perhaps it's time to go on the hunt again.

I'd say if you are planning on doing the upgrades anyway might as well do them now, unless you really need that $550 for something else. Everyone's situation is different.

CammedCTSV > BJohnson11 09/24/2013 at 08:35

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Don't try to rebuild the q-jet. The 750 will be close out of the box, just get the box of jets from edelbrock

427zeo6 > BJohnson11 09/24/2013 at 08:36

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Quadrants are great carbs. If your involved with F SAE I take it that you can possibly read. Get the Doug Roe book on Quadrants, look over at the Corvette Forum on the problems with the accelerator pumps put into modern rebuild kits and find the right part number to use. Save your $$$ don't do the peanut port intake swap, plan on installing a set of older oval port heads and Edelbrock intake on your 454. I have an Edelbrock intake and set of good 1972 oval port heads and Edelbrock intake for a Qjet$450 and they are yours with a fresh valve job. Email zeohsix "at" gmail plus the "dot com"

Bruno Martini > BJohnson11 09/24/2013 at 09:00

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I hate to say this, but why not pick up a TBI unit from a junk yard and a ford e-series van pump and a megasquirt and convert her to EFI? You can still hide it like its a carb, but you have efi, and if properly tuned, you will get more power and less fuel consumption. I believe the TBI units can be run with the cheapest megasquirt. That should be about the same price as the carb and intake.

QJetMoan > pdthedeuce 09/24/2013 at 09:54

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I would say that simply cracking open the carb and giving it a little clean up would likely be a wasted exercise. There are too many little quirks of the Q-jet that are likely causing problems (warped airhorn, warped mainbody, leaking well plugs, junk trapped under the idle feed tubes, leaking primary throttle shafts). In fact, I recently had to put a Q-jet swap on hold when I discovered it would easy take over $250 to whip it back into shape. That doesn't make it junk IMO (as most cores will have the same problems), just to too spendy for me now. But I should mention that it is my opinion that a properly rebuilt/calibrated Q-jet is the very best 4 bbl carb for any street engine where performance, drivability, and gas mileage matter.

If you have your heart set on an Edelbrock carb I would go for the 800 cfm AVS unit. Not too much carb for a stock BBC and you get an easily adjustable secondary air valve. Also the Quickfuel Slayer is about the best bang for the buck Holley 4160 variant on the market to today. I'd say it's primary advantage over the Edelbrock is adjustability. Sometime in the future, I may be going with this carb for my 350 as well as a wideband gauge for tuning.

Look into that David Vizard guy. He offers some highly regarded (by top professional engine builders) easy to digest advice in his books.

CobraJoe > BJohnson11 09/24/2013 at 10:40

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Personally, I don't like the Edelbrock carbs, they have a very limited range of adjustment and that means a very limited possibility for upgrades. I'd say to keep the Qjet, possibly with a full rebuild (which should be cheap), and then save up for something that'll match what you eventually want to build. No sense in spending $300ish on a carb that will become obsolete after a head and cam swap, if that's what you want to do.

Same goes with the intake, if you want to eventually do a headswap, then don't spend your money on an intake that won't fit it.

Of course, that's just my opinion, and I don't even have much experience working on chevys.

BJohnson11 > CobraJoe 09/24/2013 at 12:28

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Well the intake I was considering is made for the heads, hence, the reason I'm looking at it.

In terms of carbs, yes, the Edelbrock is less tunable and offers less performance, but it trumps a more expensive Holley or Demon or Quick Fuel for out of the box ease of use. Plus, while a new cam is on the slate for maybe a few months from now when I have more time to tear the engine out, I'm not sure if new heads/a full engine rebuild is really an option. The goal of the truck is keep a driveable little street truck that has a host of projects that last only a weekend or two at a time. Intake and carb swap can be done in a day, maybe two depending on how many beers are consumed. Full engine build is a much more lengthy (and expensive) project, and I have other places to spend money on before I get to that.

That said, I am considering a Holly 750 HP (4160 series) for about $500. It's a much more tunable carb, and will support more power, but I don't know if it's the right application for my build.

BJohnson11 > Yowen - not necessarily not spaghetti and meatballs 09/24/2013 at 12:32

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Good! The goal of the truck was to give me something to work on while in college. Yes, having a project car in school isn't necessarily the best idea, but it keeps me out of trouble and keeps me busy. The projects planned for it are cheap, short projects (intake carb swap is probably one of the most expensive—cam swap when I get more time adds to that as well). Things I want to do are: get a set of full length headers and then buy an exhaust builders kit and build it all myself, do a roll on bedliner in the back, maybe swap in a LSD into the factory 12 bolts, Install drop spindles and drop shackles, big brake kit for the discs up front.

The idea is that I have a perfect vehicle for exploring all areas of the vehicle. I'll do some bodywork, some engine work, some wiring, some suspension work, etc.

It's a lot of fun, and I highly recommend it.

BJohnson11 > 427zeo6 09/24/2013 at 12:35

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Hmm, very tempting. And I know the general consensus on the PP heads is that they're best used as doorstops, but for the type of build I'm doing, I think they're the right heads. Reading on forums, they have some decent power potential, and make gobs of power and torque on the low end of the RPM range. So while keeping my build on a budget, I can feasibly get a 400 horse, 500 ft-lb engine. Sure, the peanut ports won't support much horsepower after that, but I'm not looking to spend that much money on the engine, at least for the next few years (and by that time, who knows if I'll still have the truck).

Yowen - not necessarily not spaghetti and meatballs > BJohnson11 09/24/2013 at 12:35

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Awesome! I keep using my living situation as an excuse and to an extent it is. Having a garage is so much nicer when working on something. But if I get something drive-able, there is no excuse for me to get out to the apt parking lot and work on my truck, even if it's small projects until I get a garage.

Is your goal to have a capable tow/haul vehicle by the time you have it built how you want?

CobraJoe > BJohnson11 09/24/2013 at 12:45

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I'm just trying to stick some considerations of future upgrades in your thoughts. If you're planning on keeping the heads and want some more intake flow, then by all means go for the intake.

As for the Edelbrock carb, I'm sure there are plenty of people who like them, I'm just not one of them. It probably would work fine on a stock or near stock engine, but is it enough of an upgrade from the Qjet? (or would the Qjet even fit on the new intake?).

I think if I was in your position, I'd keep the Qjet, give it a good cleaning or rebuild, stick it on top of that new intake, and save the rest of the money for something else fun, like the cam or exhaust. After all, as long as you don't have to remove any adjusting screws, it will be a lot closer to being tuned correct than any out of the box carb, and I doubt the flow and fuel delivery difference would be enough to make a noticeable difference (based on exactly zero experience with Qjets.).

BJohnson11 > CobraJoe 09/24/2013 at 12:54

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Definitely a good consideration. I'll pull the Qjet off today and give it a good cleaning and take it down as far as I can go without getting a rebuild kit. If it turns out an internal component is broken, I'll consider a rebuild kit. The problem is, a full rebuild kit for a Quadrajet (beyond just gaskets and plastic parts) will reach up into the $200s. So at that point, a new carb might be one to consider.

CobraJoe > BJohnson11 09/24/2013 at 13:18

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Ouch, I didn't know they were that expensive. At that price it does make more sense to get a new one.

BJohnson11 > CobraJoe 09/24/2013 at 13:20

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Well it all depends on what's broken inside, so I'll take it off and tear into it a little first, but yea, a full rebuild would be pricey.

CobraJoe > BJohnson11 09/24/2013 at 13:30

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True. Not sure what you could buy separately for repairs or what only comes in a kit, but it also could be a non-broken problem. Old fuel can turn into a sort of a varnish that can easily clog ports or jets, so some carb cleaner really helps clean this up.

Yowen - not necessarily not spaghetti and meatballs > BJohnson11 09/24/2013 at 14:08

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Is it me, or does this seem like a NP:
http://grandrapids.craigslist.org/cto/3955346792…

BJohnson11 > Yowen - not necessarily not spaghetti and meatballs 09/24/2013 at 14:33

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Definitely seems like a nice price, but I'd be wary of rust and bondo. I mean, body work and a nice paint job alone for that truck would be upwards of 10 grand, so I'd be wary of bondo and a cheap Maaco job.

That said, if it is as advertised, definitely NP.

Yowen - not necessarily not spaghetti and meatballs > BJohnson11 09/24/2013 at 14:49

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Haha yeah, I have some research to do of earlier vs later 70's F series. As they had either 390, 351M or 400M engines. I seem to recall the 351/400M are rather low on power. This '73 has a 390 that could make decent power with a 4bbl 600 Edelbrock, exhaust manifolds (bottleneck on this engine) and a timing change from its fuel crisis era configuration. Oh and an ignition system upgrade. Sounds like a fun project! Probably would try to find a truck for half that price, haha.

BJohnson11 > Yowen - not necessarily not spaghetti and meatballs 09/24/2013 at 15:17

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Yea mine cost me $2100 and with just the rims, tires, bench seat, and various little parts, I'm only about $3700 into it. So I have a decent amount of change laying around to focus on performance.

Yowen - not necessarily not spaghetti and meatballs > BJohnson11 09/24/2013 at 15:27

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Cool, just went back through your tag and found your bench seat, that does look really good!