carb swap questions

[Grim Reaper]

Originally Posted by screwballl

The adapter plate also came with the fuel line adapter that allowed me to connect the regular rubber fuel line to the steel line and it included a standard fuel filter that attaches inline with the fuel line, not on the carb.




As it was a 28 year old carb i would rather replace it now and be done with it rather then continue screwing around with the old one again and again and again just trying to get it to work properly.

Alpha, I already have it, its been installed for over a week now and is doing awesome!!!

thnaks for the help everyone!

The Rochester on my 70 Pontiac I have ever done more then change the fuel filter. Ran great! The quad on my 75 I rebuilt because it sat and the accelerator pump rubber got stuck to the bore and pulled off. That was 5 years ago and I haven t touched it and it's sat for a month. I know it will start just fine when I take it wheeling this month.

I stand by my statement. New doesn't mean better. The only two big problems Rochesters have is the shaft wear (an thats all carbs have that same problem and even FI has it) and the rest is usualy error on the part of those working on them. Overtighten them and they warp the castings and are forever screwed. Other wise sitting and dirty gas are the only things that cause issues and that's is a accross the board problem as well.


Now I also offroad and the Carter is pain in the butt off road. The quad is far better. I am so sick of my one boddies ford running a carter. to get it to run off camber he has it so rich it makes me want to puke. On the street they don't suffer that problem.

[screwballl]

well it seems that when my truck is parked with the front end lower than rear end such as on a slight hill or parking space, even after sitting for 8 hours, it either floods it or starves it of fuel, not allowing the truck to start like tonight... with starting fluid it almost catches but doesn't start. ?Next is to replace the fuel pump, probably my next day off, Sunday. I am sure it was the combination of carb and fuel pump to begin with, a trusted mechanic said that is the most liekly scenario and hes sure thats the problem.
I got the new carb already and running good (when running) and now need the fuel pump. Just going for stock replacement from AutoZone or Advanced Auto... i tend to have better luck with Advanced locally.

If this doesn't fix it then i am totally stumped as to why it will start while still warm but wont start on a decline. Next i would guess the distributor???
Whats the suggestion from y'all?

[screwballl]

ok i dont know what the hell is going on, it started fine this morning and drove/ran fine going to work. I started it on ym luch break without a problem, i started it 45 minutes before leaving work just to make sure its doing ok... i tried starting it when i got off work and it wouldn't start. Tried starter fluid, no change. Why would it start at 5:45 and not at 6:30??? this is really pissing me off about this truck. My next step i was going to try was the fuel pump but im not sure that will fix this problem.
Maybe the distributor? Maybe needs complete rebuild because its not getting the compression to start? Maybe fuel sending unit in the gas tank since my fuel gauge bounces and it always displays 1/4 tank higher? This is just bugging the hell outta me.

Earlier someone said a choke problem.. well now its same problem but with new carb and electric choke. What else could it be? its a basic engine so not much should be able to be causing this problem.

[blitz'd]

Originally Posted by BigGMCDaddy

O.k., I have a Q-Jet #17085290 in my 1986 GMC K2500 pickup. I sent an e-mail to Edelbrock and they are telling me that my carb is computer controlled and Edelbrock doesn't make a replacement Q-Jet for that type of carb. I asked because I couldn't find my carb on their cross-reference sheet.

Will the #1400 work on my truck? I'd like to go with the 600cfm. My baby needs a new carb NOW and I'm at a loss. Your help is greatly appreciated!

Id like to know this too.

[Jonboy]

I don't see why it wouldn't. You would lose the "computer controlled" aspect, but I don't think that would be much of a downside. Do the ESC mod on www.73-87.com and lose that headache at the same time.

[screwballl]

if you look at http://edelbrock.com/automotive/carb_index.html it says for the 600cfm:
"600 cfm Carburetors
Street Legal, Electric Choke
50-state street legal for all 1980 and earlier General Motors V8s (E.O. #D-215-10). Calibrated for maximum fuel economy. Includes timed vacuum ports, EGR and fuel vapor outlet. Not for computer- controlled engines. Comes with the following jets, rods and springs: Metering Jets – Primary .098, Secondary .095; Metering Rods – .073 x .047; Step-Up Spring – orange (5" Hg). Includes carb studs and hardware."

For alot of the mid-80's vehicles especially GMs, they had a carbureted engine but had an electric throttle body, basically a carb with the standard jets removed and a computer controlled external injector on top or just inside... The computer balanced the O2 sensor, intake, amount of air and fuel in the system and a few other things to continuously adjust the fuel flow making it richer or leaner depending on the needs. If you were to put on a new standard Edelbrock carb, you would have to remove the computer completely including the O2 sensors and anything else that is hooked up to it.
A better suggestion for you might be to get a replacement QJet, remove the jets and use your existing (or new) throttle body injector...

[1976Scottsdale]

I cannot complain about a 750. My 350 is going to be running a 750 Q-Jet that has been totally rebuilt. It will be mated to my Edelbrock Performar intake. I hope to get at least 10 MPG. I am running 58cc heads and a 443/443 cam. Should do okay.

[86-C10-V6]

Edelbrock told me the same thing about my truck and they were wrong. My 86 has a M4ME quadrajet and it is not computer controlled. The M4ME has a dual capacity fuel pump that is controlled by a thermastatic switch, so there will be a electrical connector at the top of the carb, this is not computer control. Take a close look at your carb and identify it before you take Edelbrocks' word that it's computer controlled.
It took a lot of research, but I talked to a carburetor design engineer at Magneti-Marelli in Sanford NC and they told me that the Edelbrock 1904(which they designed) could be used on my truck. By the way Magneti-Marelli also designed the Quadrajets for GM, this guy read me the jet sizes and other specifics off the spec sheet after I gave him the GM part number.
I purchased a 1904 off of ebay but have not installed yet. The 1904 does not use the dual capacity fuel pump, so the thermostatic switch connector is not used, but based on what I have read I am sure it will bolt in with no problems.
As Swervin and others will tell you, the 1904 is a good Qjet replacement, reliable and tunable.

[screwballl]

new replacement OEM QJets are suitable replacements but i wanted soemthing better than just a simple replacement carb. I am very happy with mine but it is still a personal decision...