Holley Quadrajet EFI

I've used the Holley system (their TBI system) on an S-10 with a 355 in it that was warmed over and run on nitrous (this was my buddy's dad's truck, we installed it). It works fantastically well, the kit we had used a wide-band and was self-tuning. It was extremely reliable and provided a big improvement in gas mileage and behaviour, I'd highly recommend it.
I like the idea of FI on older classic cars. Do you recall the camshaft profile that was used? Early in the aftermarket FI game a wider LSA (113 vs 110) was recommended because of the need for vacuum. Perhaps current systems can be programmed without the need for higher engine vacuum??
 
I like the idea of FI on older classic cars. Do you recall the camshaft profile that was used? Early in the aftermarket FI game a wider LSA (113 vs 110) was recommended because of the need for vacuum. Perhaps current systems can be programmed without the need for higher engine vacuum??
The system did use a MAP sensor, so that's a good question (it was speed density). We used a Comp XE series, not super wild due to the nitrous, MIGHT have been an XE 268H? This was a roller engine, it was the replacement for a carb'd 357 that had a Lunati Voodoo in it. The roller mill had much better manners.
 
Yep, the Q-Jet stood the test of time with GM and eventually saw it’s grave in the 1990s. It was, alongside the Aisin and Keihin carbs on Toyota and Honda an electronically-controlled carb in the 1980s.

Pretty much any carburetor used on cars and trucks in the 80s is electronically controlled. A 3-way catalyst, required by emissions regulations starting in (if I recall correctly) 1979, cannot work correctly without the shift from slightly lean to rich and back again provided by a fuel system controlled by an oxygen sensor. Some trucks may have been exempt from the requirement for a 3-way catalyst prior to about 1982-1984, which I why I say "pretty much".

The usual way this was implemented was an o2 sensor connected to some sort of ECU that controlled a mixture control solenoid in the carb. As I recall, Chrysler called their ECU the "spark control computer" but it controlled more than just spark.
 
Pretty much any carburetor used on cars and trucks in the 80s is electronically controlled. A 3-way catalyst, required by emissions regulations starting in (if I recall correctly) 1979, cannot work correctly without the shift from slightly lean to rich and back again provided by a fuel system controlled by an oxygen sensor. Some trucks may have been exempt from the requirement for a 3-way catalyst prior to about 1982-1984, which I why I say "pretty much".

The usual way this was implemented was an o2 sensor connected to some sort of ECU that controlled a mixture control solenoid in the carb. As I recall, Chrysler called their ECU the "spark control computer" but it controlled more than just spark.

My C20 '85 Suburban could even run leaded fuel, No catalyst or ECM controlled spark/QuadraJet, I've seen '86 model 8,600 & up GVW models set up the same way.
 
I put gm tbi on my 78 k20 that had a quadrajet. If i had to do it over again i would have kept it stock. While the fuel injection is fine and im sure the holley system is great i really like the simplicity of the carburetor. Have you considered buying a remanufactured carburetor? Also make sure the camshaft is ok if its original along with the timing chain. Worn lobes can do weird things with it running and a loose chain can cause timing to jump around causing bogging.
Oil analysis was clean so I don't have any reason to suspect the cam. Timing chain could be loose, I have no history of repair on it. As far as a reman carb I am leery of it. I am afraid I'll get something that's worn out worse than what I already have plus looking at the cost of $200 to $400 I'm that much closer to fuel injection. The thing is I'm not good with these carbs and there's only one guy left around here that is. I know that I can make FI run well.
 
Um timing? Is it a mechanical or vacuum advance? Poor mileage, unwilling to pull under power, great idle...dieseling kinda sounds like a whacked up timing issue to me.
Pretty sure it has both but again it's been over a year since I was into it. The carb guy checked the timing. I don't know what it was at but he made no mention of an issue.
 
My C20 '85 Suburban could even run leaded fuel, No catalyst or ECM controlled spark/QuadraJet, I've seen '86 model 8,600 & up GVW models set up the same way.
No electronic controls on this one besides the wire to the choke. No cats on it either. It's just an old 5.7l. I kicked around the LS swaps, kicked around a 6bt and 4bt swap, even looked pretty deep into an R2.8 Cummins swap. My biggest problem is I don't have a good place to tackle that kind of project at the moment. Hoping I could slap some form of bolt on fuel injection in a weekend and have it running good again.
 
just for a test unplug the alternator control plug (in 86 should be whiteish 2 pin plug). See if it still diesels. There is diode somewhere in the harness to prevent that.

Rod
 
Oil analysis was clean so I don't have any reason to suspect the cam. Timing chain could be loose, I have no history of repair on it. As far as a reman carb I am leery of it. I am afraid I'll get something that's worn out worse than what I already have plus looking at the cost of $200 to $400 I'm that much closer to fuel injection. The thing is I'm not good with these carbs and there's only one guy left around here that is. I know that I can make FI run well.
Reason i bring this up is because my truck had the those issues. The timing chain was very loose and was causing bogging issues and the worn camshaft had slowly worn over time and didnt show itself visibly in the oil. It may have if i did a uoa. You can watch the rockers move and see if they look even to get an idea of the cam condition.
 
EFI would be great, but you gotta have proper fuel delivery. Make sure your local smog laws allow for a conversion.
If you can rip all the smog stuff off, you might just wanna try a new carb like this Street Demon.

All depends on what you wanna end up with and, of course, your budget.
I love Q-Jets, but finding an unmolested one or a good rebuilder is difficult.
You can look up Lars Grimsrud, Henry at Ole's Carb or Cliff Ruggles.
 
EFI would be great, but you gotta have proper fuel delivery. Make sure your local smog laws allow for a conversion.
If you can rip all the smog stuff off, you might just wanna try a new carb like this Street Demon.

All depends on what you wanna end up with and, of course, your budget.
I love Q-Jets, but finding an unmolested one or a good rebuilder is difficult.
You can look up Lars Grimsrud, Henry at Ole's Carb or Cliff Ruggles.
There’s no smog inspections or anything where I live. I just had a truck inspected for license renewal today and they checked lights, horn and wipers. Never even popped the hood or got under it. I’m looking for a reliable daily driver that starts at the turn of a key. Nothing more, nothing less. The fuel injection is definitely an investment but the truck fits the bill for what I need and to replace the truck would exceed the cost of the system. I’ll install the Holley tank and pump if I go this way.
 
The car I did, the guy bought the whole kit from Speedway with the tank and pump. The tank was fine but he hated the pump. Said it was noisy and drove him crazy. We ended up removing the pump that came with the kit and installing a different one. He's happier now with the new pump.
 
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