5.0 and 5.7 Discussion, 89 Brougham carb needs rebuild... in Cadillac Engine Technical Discussion; Hey guys, the carb in my 89 Brougham needs a rebuild. I'd rather not deal with having it rebuilt by ...
Hey guys, the carb in my 89 Brougham needs a rebuild. I'd rather not deal with having it rebuilt by a shop and getting it more screwed up. My question is this, do any of the after market carb companies such as Edlebrock or Holly make a carb that would work for the 5.0 in these Caddys? If so what is pricing and is it a direct fit?
To answer your original question, I'm not aware of any aftermaket carb that's designed to bolt in as a replacement for the Electronic Qjet. You can get non-feedback carbs, but not one with the computer connection. If you use a non-feedback carb you'll need to bypass the computer, change the distributor to one with a vacuum advance, and come up with a switch for the lockup torque converter. You'll also need to figure out how to get that past emissions testing.
Yup, find a good shop to rebuild, or do it yourself and save $400.
I have done a couple E4MC's and find them just as easy as any other Q-Jet. They are far from hard to rebuild if you have good technical ability. I don't use a rebuild kit often, but I also have a bunch of parts already in my stash to pull from. So get a kit, they are only $30-$40. Only replace the electrical parts that are bad, 98% of the time they are good and last a very long time.
Name of the game with a carb is cleanliness. Spray the carb cleaner (I highly recommend only Gumout brand, most others are very harsh and strip the varnish off the carb) down each and every orifice, making sure everything is spotless. Being it is a pressure differential device, dirt in an orifice wreaks havok with metering.
In my experience, #1 failure is accelerator pump seals. #2 is float. #3 is people messing with it who think they know better than GM/Rochester Engineers.... If you don't have a FSM for it, get one or get someone to copy it for you, you won't have any problems.
Make sure you're armed with the carb's part number, when it's time to order the kit. That you'll find on the left side of the carb stamped vertically where the secondary chamber is. It's a nine-digit number beginning with "1".
IIRC all E4Mx carbs were 1705xxxxx. They got the 9 digit #'s after 1974 I think. That was when they went from 4M to M4 carbs. Then in 1981 the first electronic Q-Jet E4 series. These were the 3 major breakpoints of the carbs. Most parts interchange in the families 4M, M4 and E4.
TPS and Mixture Control Solenoid. The MCS is the heart of it, instead of vacuum pulling the "power piston" up and down with the primary metering rods on it, it has metering rods with a small and large end of the rod and it goes up and down controlled by the ECM, so the ECM can make it richer or leaner as needed as the O2 sensor reads. The TPS tells it where the throttle is, idle, off idle or WOT. TCC lockup is significantly affected by TPS. Canister purge (pretty much open and anything non closed throttle) and EGR (many other factors too) are both affected too.
I would never buy a rebuilt carb, waaaay too much $$ for what little needs to go into it. I would say that is a 400% to 600% profit margin item easy.
You might be able to get a rebuilder to do it for less than the $430.
I got an ex-Cad mechanic to do it with parts for about $350 here in the Chicago area. He said rebuilding the carb designed for the engine is the way to go. I sure don't know.
Really runs well after the rebuild though.
Sheesh, I should go buy a ton of E4MC's and E4ME's in the boneyard and rebuild them and sell them!
If you have any technical ability, take $30 and rebuild it yourself first. Then if you can't get it to run right then and only then look for a rebuilder. Unless you have that much $$ to part with easily.
Lets look at it this way. Rebuilding a carb is 1hr worth of work, maybe 30 min tops of alignments. The rebuild kit is around $30 now, so that puts it at $300 to $400/hr labor....