I have a bad TPS sensor in my E4MC qjet and I figured I should just rebuild the entire carb while I'm in there. I want to stay with the qjet for mileage and so I don't have to replace the dizzy and maybe the intake.

What are the differences from year to year for E4MC carbs? I have an 88 Cutlass Supreme with an E4MC and looking to buy another E4MC, but I wanted to know if there were any differences. I've heard metering rods could be different? Do I simply have to have the same carb numbers?

 

I would contact Everyday Performance. He can do a total overhaul of your ekectronic carb including throttle bushings and plating. A reman carb is a huge risk on quality and a big gamble.

 

There were minor changes each year, but the biggest change was the move from a two-point to a three-point adjustment on the mixture control solenoid and bowl vent. I don't know how this change would impact the programming in the PROM, but it likely wouldn't be a positive change. The later carbs are all three-point. And I'd also shy away from any commercial rebuilder on these carbs. There's no guarantee that the work is done properly, and given the very fussy internal adjustments that these carbs require, I'm doubly doubtful that these would be done correctly. Of course, even a rebuilt carb requires the comprehensive on-car adjustment process that's detailed in the CSM. Even a properly rebuilt E4MC is unlikely to run correctly on a specific motor until it's adjusted properly.

 

I think you would be much happier with a traditional carburetor in the long run. Rebuildable cores aren’t expensive, neither are regular distributors. They will give you the ability to tune it yourself and you will notice the improvement in drivability.

 

Consider replacing your TPMS, air horn gasket, the needle valve, seat, float, accel pump, fuel filter, adjust the TPMS, clean all exposed passages with carb cleaner and compressed air all with the carb in place.

Good luck!!!

 

I'm hoping that after nearly three years, the OP has it fixed.

 

Nope...supply chain delay...parts just arrived.

 

Just an FYI, the 88 Cutlass 307 Quadrajet is a 2 point calibration. Only the VIN 9 Olds is a 3-point on the 307. VIN Y engine carb air horns do not have the hole drilled and tapped for the rich stop adjustment screw because there isn't one. The rich stop is made into the lean stop adjustment screw setup, meaning it's a fixed distance. So as you adjust the lean setpoint, you're also adjusting the rich setpoint at the same time. All done with a single screw. Not 100% sure if the early Y engines had 3-point or not, but I know 85-up don't.

You can make it a 3-point by putting a VIN 9 top on a VIN Y float bowl (body) and swap the 2 point lean stop screw/limiter with a 3-point lean adjustment screw.

 

The Qjet on the VIN Y 307 in my 1986 Caprice wagon was three point. The one on the VIN Y motor in my 1984 Custom Cruiser was two point.

 

I seem to recall drilling a hole in an air horn on my friend's 87 Salon to make something adjustable. This was 17 years ago or so. It was near the accelerator pump pivot arm. Would that be this 3 point thing?

 

That was the cap on the adjusting screw for the TPS.

 

Probably not. It most likely was drilling the plug to use a screw or something to pop it out to reach the adjustable screw for setting the TPS voltage. If you didn't have to do any tiny-thread tapping just in front of the air horn from the inside, you wouldn't be adding a rich stop. To me it looks pretty difficult to add one. Seems simpler just to use the 2-point as the 4/32" setting window is built in.

The three-point setting was adjusting the carb on the car. The Idle Air Bleed Valve (IABV) that has a letter stamped on top is set by a gage setting and left alone, and then there's your lean stop, rich stop, and idle air bleed adjustment screws at the front base of the carb. Usually the base screws are sealed from the factory with steel plugs, but the seals can be chiseld/drilled out for access.

Had to drag out the tech info for this. An 86 Y with a 3-point sounds odd. According to the ACDelco tune-up specification guide, I was mis-remembering. The 86-87 442 carburetor is showng as a 2-point carb as there is a "-" (dash) showing as a rich stop adjustment. Same for all the 85-up Y engine carbs. The 85 442 (17085554) was the last 3-point 307 carb listed, which makes sense, since it was just a restamped 84 H/O carb. Regardless, all rich stops were supposed to be adjusted to 4/32 total travel. It used to be a tad tighter than this, but CCC components and settings were constantly updated and revised, even in the middle of production runs.

Page 3-21 of the 1981-88 GM Computer Command Control Carburetors training manual (7/87 printing), one of the new for 1985 notice was the 2 point carbs for all 2ME/4ME/4MC except Chrysler 318, and 307 with the 442 package only, which had 3-point. H and G chevy engines had a 4 point adjustment, meaning you had to include the IABV in the equation as well when making final on-car adjustments.

According to the ACDelco 81-87 SD-100A, (7/87 printing) Tune-up Specifications Manual, page 129, all 2-point 2MC/4MC carbs for 81-87 260/307 engines are as follows:
17085282
17086008
17086009 (were used on 86-90 VIN 9, as some Cadillacs used VIN 9 307s after G-body ended)
17086077

That's it. 84 and back originally all had 3-point adjustments. If yours is something different, check the carb number. Does it really matter? No. You either have a rich stop, or you do not. But it helps to know if your IABV has a letter stamped on top of it or not. If you don't know what you're doing adjusting these carbs, you can find yourself in a world of hurt real fast.