Here are my motor stats

310 c.i. block (L69 bored .030 over)
heads shaved to 56cc
204/214 dur.- ,420/.442 camshaft
Edelbrock performer intake
STOCK QUADRAJET
open element
Accel: coil, cap, rotor, wires
Msd 6A
Edelbrock headers, gutted cat, Flowmaster 2 chamber
T-5 and 3.73's


My stock Quadrajet seems to be holding this motor back, I would guess that if a stock L69 runs 190 hp, I must be at at least 250 by now at the crank, maybe a little more. I think if I throw a vac advance distributor on there and an Edelbrock 1406 600 cfm, It will run better, my check engine light loves to come on on long trips, drives me nuts. Plus I would expect maybe 8-10 horsepower from the change, not to mention the reliability and how easy it will be to tune.


What do you guys think? Who has put a carb on the ol' L69, and how did it run??

 

No, your QJet is a perfect match for the 305. It will support well over 400 hp.

Go to the Tech Articles and read the one on tuning the QJet. That will sort out your problems.

 

No, I don't think so, and I'll tell you why...

the first thing is, the only things on there that I really see that would add horsepower would be the camshaft and the headers.

Boring the engine .030 over, and the performance intake definitely add horsepower, I'm not doubting that, but certainly not like what the camshaft and the headers add for performance.


The cam, headers, and intake are a good package... did you get the Edelbrock Performer package? Usually on an otherwise stock 305 V8, it would add about 40-45 horsepower.

I used to think that by putting in a cam, BAM 25-30 hp right there, a set of headers, heck.. another 30hp just like that! Unfortunately the numbers don't add up that nicely...

Even still, it sounds like you have a NICE motor.

The QuadroJET is made in some cases, with as high as up to 800 cfm. I see them lying ALL OVER the junkyard. If you think your car can handle more air, then I suggest looking for a higher flow carburetor.. stock that is... possibly one from say a mid 80s Caddy, those usually had like 700 cfm carbs in them. I think your car would do perfect with a 600 cfm though.

You can also send your carb in to have it modified, or you can do it yourself.. sometimes it's just a matter of adjusting the carb plates so that they open all the way.


Todd

 

Check the tech articles for optimizing the q-jet. After you've done those practically free mods (if you even have to), get it out of your head that the q-jet is holding you back.

You never said what code is being set on these long trips when the check engine light comes on. What code is being set?

Buying a different carb and distributor will have the effect of lightening your wallet and decreasing economy and performance.

 

i was in that same situation with the q-jet.. dude take that crap off your car, i put a vacuum advance dis. and a edlebrock 600cfm and it DID make a difference, those stock q-jets are horrible.. definately go with your orignal plans to replace it

 

No, that's not the best way...

the only reason why your Edelbrock carburetor works better is because it's NEW, and because it's already tuned.

I can assure you, that with the right adjusting, a 600cfm Rochester Quadrojet will be a LOT more efficient than an Edelbrock 1405 or 1407.

I have a 1405 on my 81 TransAm, but if the car HAD the computer still on it when I got it, I would have gone with a Rochester Qjet.


Todd

 

The da#m computer will not tell me what the trouble code is. For some reason, the code will only remain on and come on consecutively at night when the air is colder. My guess is that it is either a lean or rich exhaust sensing, not sure though, the computer just flashes code 12 all day??? If any thing I would think it's a lean circuit, but it definately doesn't run or smell like it's running lean. And I don't want a 1405 or 1407, I want a 1406, 600 cfm elec. choke.

I have a 625 cfm Road Demon on my car in Hawaii, it runs real good on the top end, but produces the infamous stumble at the bottom a bit, (also because I still have the stock T.C. with a high duration cam-)

I just hear that those 1406 carbs kick *** for the street, and tuning them is like making a P.B.J. sandwich.

 

330hp_91RS, It's true... they are easy... you can convert any 1405 by the way to a 1406 or 1407. You just have to order extra parts.

You should get a service manual.. like a Haynes or a Chiltons, they have charts inside that give the engine codes.

I'm really suprised that this site doesn't actually have a list of the ODB-1 engine codes...

I used the computer on my Fiero to tell me what's wrong, and I use a code list I've got from several Fiero sites, and I just couldn't live without knowing it...

Todd

 

Thanks for your advice BUT...

Shaving the heads to 56cc increases the compression- adding horsepower

Adding five cubic inches to your engine- adds horsepower, but moreover, torque


I am not the kind of guy that thinks that every time I add a mod I just added 20 horse.

I don't see where you get off thinking that the only mods that are really giving me horsepower are my cam and headers, it's kind of funny actually. That intake will add at least 8-10 peak horsepower and headers don't do much if you don't have a nice exhaust behind it.

40 -45 added horsepower???? I think not, I've raced and beat:

2- 89-93 5.0 stangs (smoked them bad)
1- 95 5.0
3- 4.6l stangs

The list goes on... ( I left the rice out...)

190hp plus 40-45 equals 230-235hp

ARE YOU KIDDING ME???

go do your homework, and I think I've made up my mind, I"ll try to tune this quadrajet and if i still can't get it right, I'll yank it off infavor of the 1406 Edelbrock.

 

Umm, I don't know what you're talking about..

I am the ONE that suggested you KEEP the QuadroJET.....

So.. I don't know where you see that I said you should ditch the jet and get an Edelbrock.

I SAID that I own a 1405 Edelbrock on my 81 TransAm... BUT.. since your computer for the most part still works.. it would be MUCH more efficient in your case to KEEP the QuadroJET and just tune it and modify it.


And by the way, the Edelbrock Performer package WILL add 40-46 horsepower..

The Edelbrock Performer package includes a set of TES Headers, a new Edelbrock Camshaft, and an Edelbrock 3701 or 2102 intake manifold. To reap the full benefits, you would need a free flow catalytic converter.. replacing the muffler on your camaro does almost nothing at all... you gain MAYBE a horsepower or two.. most of the power you gain is at really high rpms... it's the free-flow cats that make the biggest difference in an exhasut system (with the exception of the headers).

You seem to have confused everything that I said, with everything that someone else said.. so let me re-iterate so you don't think I'm a dumbass...


I think you should... KEEP the QuadroJET.

And get yourself a Hanes or Chilton's repair manual. It has a list of service codes INSIDE the manual that will help you diagnose what's wrong with your car's computer. Most likely it could be anything from a BAD map sensor, to a failing Oxygen Sensor.


Todd

 

I'm not trying to get pissed, just scroll up and you'll see what you said, YOU SAID THAT THE ONLY THINGS THAT I'VE DONE TO MY CAR THAT REALYY ADD HORSEPOWER WERE MY CAM AND HEDERS, you wrote it, not me

Furthermore, I DO NOT HAVE AN EDELBROCK CAM, I have a larger lift and duration than the one offered for 305's by edelbrock. and I have a GUTTED cat, that better than any cat you can buy!!!

It almost seems like you think I'm the guy who takes his car to jiffy lube to get my oil changed, I put this motor in myself!!!

Don't kid yourself, 1-2 horse for a muffler??? There can't be a person on this board that will agree with that.


And by the way, READ WHAT I WROTE AGAIN, I never said that you told me to ditch the Quadrajet. And it quadrAjet not quadrOjet.

 

AND I HAVE A *** DA#N MANUAL, AND THE *** DAM# CODE IS 12. UNDERSTAND, NO OTHER CODES, THAT IS WHAT A CAR WITH NO CODES IS SUPPOSED TO DO, CODE 12!!!!!

 

WHERE DID YOU GET THAT HOOD???? i was just checking your car out on the rides section, you should check my Hawaii car out, you'll like the original paint scheme.... I like yours!!

just search for it under my user name.

AND, did you feel a performance gain after you installed that carb on your ride??

 

Dude, chill.... I never said you didn't know anything about cars, don't be so sensitive.

Todd

 

Oh yeah, 330... you'll probably get offended by this too...

But yes, your car's computer will flash the code 12 THREE times... This means "OK".

Then, it will flash any other codes that are in the system.. each one only 3 times.

And then it will flash the 12 again.


Todd

 

https://www.thirdgen.org/newdesign/faq/thirdgen.shtml

Towards the bottom of the page.

 

Wouldn't it be nice if they were the same for all GM cars with the ODB-1 computer? That way we'd only have to remember one list of codes.

They usually are fairly similar though.


Todd

 

Calm down for a second.

My car has done that too. It seems like it's real picky about whether or not it stores certain codes. Almost like they have to be set for a certain duration, or something.

The two codes my car doesn't like storing are rich and lean exhaust. The only way I spotted it was hooking a scan tool up while the car was still running--if I shut it down, it lost the rich code (but it was more than happy to store other codes, like the loss of distributor signal you get when setting the timing on a CCC car, so it isn't the memory).

Coming on on long trips suggests it's likely a rich code. Mine was doing that, and my Olds does that. The Camaro wa a matter of having blown the needle off the seat and connecting the vacuum to the WRONG side of the charcoal canister (yes, I had engine vacuum sucking directly on the tank, oops).

It wouldn't hurt just to replace the O2 sensor. That massivley cuts down on the codes. Failing that, the MC sensor may have come out of adjustment, the float level could be too high, any number of things.

But you have to find out first if it's rich or lean.

 

I won't get offended,

IF I KNOW HOW TO CHANGE A MOTOR, DON'T YOU THINK I WOULD KNOW THE CORRECT SEQUENCE FOR TROUBLE CODES/// USE YOUR HEAD, I ALREADY KNEW EVERY THING YOU TRIED TO EXPLAIN TO ME.

EVERYONE ELSE:

Now, last night I tried to fiddle with that A/V flap that is in the tech part of this site. any way my carb definately did not cooperate.

I loosenedthe set bolt (the one underneath), and mine was the one with the torx bit insead of the allen head. I proceeded to turn the screw on the side of the carb counter clockwise like the article said, well it never flopped open on it's own, it didn't seem like anything was loosening at all. anyway before i screwed anything up, I tightned it back up and made sure everything was cool. It felt stronger, didn't bog, and now it chirps the hell out of 2nd - 3rd. Beats the hell outta me!!!

I still am going for the non computerized setup though.

Regarding the carbon canister and such, am I going to need to utilize a different fuel passage arrangement like you do with F/I swaps?, I'm not going to pull the smog stuff off, just change the dist. and carb.



Thanks, Matt

 

No, you shouldn't have to change any vacuum lines if you convert to a non-computer setup...

 

330, you obviously are getting offended, otherwise you would have simply just not responded to what I said... assuming you already know the knowledge, you'd simply just ignore anything that wasn't new information to you.

Anyway, now I'm REALLY confused...

So you've definitely decided to junk your computer?

Why then HAVE you decided to stick with a QuadraJet? My only reasoning for staying with the QuadraJET was BECAUSE you had the computer, and because it was still working. But now, since you're changing to everything anyway... why not just get an Edelbrock?


Todd

 

Edelbrock? Faugh. Stick with the Qjet or go with a Holley. No other real options IMO.

 

Well, the 1405-1407 carb is nice because it rids you of the guess work. You can actually install them straight out of the box, and they're tuned to within 85% efficiency.

For real performance though, I suggest optimally tuning it, and or going with a high performance Holley. But this is just a street driven car, and not something that lives on the dragstrip.


Todd

 

Okay, so Edelbrocks are good for people who can't turn a wrench. How does that make a good carb?

They're down on gas mileage compared to a Qjet
They're down on power compared to a Qjet
They're WAY down on power compared to a Holley.

I'm missing the part where they're good?

 

Here's my plan:

I have a funtioning computerized setup as of now, except I don't like the carb.

I am not going to junk anything, just simply remove the Quadrajet and replace it with a Holley or a Edelbrock carb, along with a non-cc distributor.

See this way, I can just through the other stuff back on for smog time.

Make sense, I'll get the reliability of a carbed car, but everything will remain intact for smog purposes.


BY THE WAY, ALL OF YOU GUYS KEEP SAYING THAT Q-JETS OUTPERFORM EDELBROCK/CARTER CARBS. I WOULD REALLY LIKE TO SEE SOME TESTING ON THIS.

I DON'T WANT TO SEE ARTICLES FROM HOT ROD WITH NON-CC QUADS THOUGH, CAUSE THATS NOT WHAT WE HAVE. I KNOW THEY MAKE LESS POWER THAN NON- COMPUTER CONTROLLED SETUPS.

I AM SICK OF WONDERING IF IT'S MY CARB OR MY COMPUTER SETUP THAT IS OUT OF TUNE, THATS WHY I WANT AN EDELBROCK. I'M NOT THAT FOND OF HOLLEYS CAUSE THEY ARE PAIN TO TUNE ON A 305 AND EVERY ONE THAT I HAVE HAD HAD HESITATION ON THE BOTTOM END, SURE YOU CAN GET RID OF THIS WITH PROPER TUNING, BUT YOU'LL PAY FOR IT AT THE GAS PUMP.

 

330_91RS, that makes good sense....

I personally like the QuadraJET carbs.. but for ease of use... an Edelbrock or something is just a much easier way to go as you know.

I mean, with the Rochester, there's like over a million different vacuum lines, etc... and there's soo many differnet ones, it's hard to know what goes where.

With the Edelbrock, there's GOOD documentation... and it's just so much easier to tune.

I agree with you about the Edelbrocks.... I think QuadroJETS CAN be made to perform as well as Edelbrocks... but you'd first need to completely rebuild them, buy new jets for them, do all the research.. etc.. and tuning necessary to get the right combination of jets, etc... all that's already been done for you in a brand new inexpensive Edelbrock carb....

 

There's plenty of article that show that the Qjet outperforms the Edelbrock. Look around. The comp controlled Qjet actually makes power just fine compared to the non computer controlled one.