Here's my solution to that issue,
The older style are a lot nicer to plug wires. Never understand why the engineers went back to over port manifolds on passenger cars & some trucks.
Quadrajet or Aftermarket?
- Thread starter TheSaint
- Start date
The older style are a lot nicer to plug wires. Never understand why the engineers went back to over port manifolds on passenger cars & some trucks.
My shop buddy had a 1985 Chevy 350 pickup shop truck. It ran like crap. I said it had a miss but he would not believe me. I built him a Q-jet from a Suburban. Still missed. Then I rebuilt his Q-jet from the truck, it had the enrichment solenoid. Still missed. Finally one of his workers and I snuck in on a Sunday and gave it the treatment. What do we find? The #7 cylinder wire had laid on the exhaust pipe way back out of sight. It was totally burnt to a crisp. After a new set of wires- PERFECT! No more miss. And with the rebuilt Q-jet he said it never ran better. Oh....well.....
Mark,My shop buddy had a 1985 Chevy 350 pickup shop truck. It ran like crap. I said it had a miss but he would not believe me. I built him a Q-jet from a Suburban. Still missed. Then I rebuilt his Q-jet from the truck, it had the enrichment solenoid. Still missed. Finally one of his workers and I snuck in on a Sunday and gave it the treatment. What do we find? The #7 cylinder wire had laid on the exhaust pipe way back out of sight. It was totally burnt to a crisp. After a new set of wires- PERFECT! No more miss. And with the rebuilt Q-jet he said it never ran better. Oh....well.....
It goes to show you how easily something like a bad plug wire can be overlooked. Well, at least he came out of it with a rebuilt Q-jet.
But back to the OP's question. I had a friend with a 1969 Chevelle convertible. It had the two barrel 327 on a 3 speed Saginaw manual trans. We found him a 4 speed to swap in and that was better. He also swapped on a two plane 4 barrel intake. He knew nothing about Q-jets so he bought a Holley. It ran terrific. Why? Because it was a 550 cfm tiny Holley with an electric choke. So, yeah, aftermarket carbs can work, as long as you resist the temptation to plop the hugest carb you can afford on it. As always- fit the punishment to the crime.
I've run a Holley 600 cfm #1850 electric choke carb for probably over 30 yrs. It ran pretty well and was dependable for the most part. I tore it down once for a cleaning/ overhaul. It had been daily driven for all those years. I gotta say, I really like the Q-jet better. It's more responsive with the smaller primaries.
However, the Holley has it's advantages for ease of tuning and overhauling..
Jack, doesn't that include the 'need' for tuning? I only say that because everyone I know that runs a Holley, complains that from day to day, it acts differently. And needs constant adjustments. My buddy with the 1968 Firebird 400 used to come home from work and re-adjust that Holley carb almost every day. But he was running the 068 cam which did not make enough vacuum. Have you experienced that? At the same time I set a Q-jet- and forget it. In fact all that a simple cleaning requires is to screw in the idle needles, writing down how many turns to bottom out, then unscrewing them and blasting the idle ports with carb cleaner. Then just screw them back to what they were before, and carry on. Years of double checking with the vacuuum gauge taught me that whatever it was before, no change needed after cleaning.
I found the same with the Holley. My first new vehicle was an 80 GMC 4x4, I switched out the Q-Jet for 600 double pumper, mechanical choke. Night and day difference plus it increased fuel economy tremendously. Went from about 7mpg to 12 mpg average. Doesn't sound like much, but percentage wise, it was over 50% increase.
7mpg sounds terrible by today's standards but back then 10mpg was average. My GMC was 350/TH400 with 4.10s as it had the snow plowing package from the factory.
Everything on the car is a system. So when you get that system in balance, you have a dynamite car.
7mpg sounds terrible by today's standards but back then 10mpg was average. My GMC was 350/TH400 with 4.10s as it had the snow plowing package from the factory.
Everything on the car is a system. So when you get that system in balance, you have a dynamite car.
Holleys and most aftermarket carbs are built to run on everything with a generic tune and a whole mess of adjustments to get close enough. Qjets on the other hand were built for each factory engine application they were put on with a specific tune for each powertrain application and various OEM options.
Funny engough, EFI is the same way. OEM EFI is built for specific factory applications while aftermarket EFI are built to run on everything but not well on anything.
Funny engough, EFI is the same way. OEM EFI is built for specific factory applications while aftermarket EFI are built to run on everything but not well on anything.
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Mark,
I've never had to re-jet the Holley, like you said an occasional mixture adjustment. It was pretty much close to being dialed in out of the box. It was a bit of a gas hog. The Q-jet is a much more efficient running carb. My old 305 had a Q-jet on it and it ran quite well. I had it overhauled by a local shop at the time.
Too bad i didn't keep that carb. I gave the engine away to a friend and it still ran good at under 100,000 miles but I wanted a little more oomph which the 350 provided.
You're right about the Q-jet, Set and forget. In the few years that I installed that carb I never had to adjust it.
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