I just want to see what everyone else is getting in gas mileage. I had an Edelbrock 750cfm carb on my '85 350 Regal with a metric 3 speed tranny and whatever the factory rearend gear is. I pulled that carb off because I was only getting 10 to 12mpg. I went with a Q-jet from a '73 Olds 455, so I'm guessing it's an 800cfm. Now my gas mileage has jumped up to 13 to 14mpg. I thought it would be a whole lot more. The details::Smarty: I drive 15 miles to work. 13 miles of that is on the freeway at about 75mph. The rest is city driving. I don't drive it too hard otherwise. Should I be getting better mpg? Is there anything I can do to help? I want to switch to a 200 R-4 tranny and go with a higher rearend gear but I'm really afraid my gas mileage will take the blunt of it. Thoughts? What are you getting? MARK
jeez...i probably was getting around 20 in mostly cityish driving. 750 qjet, 200r4, 3.42s. it's probably dropped now that i did a few things and had to jet the carb up a lot, but 10-12 with mostly highway is definately low.
Your mileage sounds about right, maybe with a bit more tuning you can get it a bit better, but not a whole lot. Your Regal probably has a 2.41 rear in it. If you switch to a 2004R trans with a better gear, say a 3.42, your performance will be better, but your mileage will probably stay the same, its kind of a trade off, going from an economy rear gear, to a performance rear with the overdrive trans. The G body Regal, depending on options arent THAT much lighter than the 68 to 72 Skylarks/GS's. A well optioned 87 Turbo Regal will weigh around 3500 to 3700 lbs. My 71 GS 350 weighs 3780lbs. A base Regal, not many options is around 3300 to 3500 lbs. The cars are downsized from the the earlier A bodys, but they have alot more sound deadining, heavy bumpers, and more bracing for crash protection. Hope this helps yah a bit, Mark
Mark, If you have tall rear gearing(2.41), I'd say your gas mileage should be better. You're probably taching about 1900 RPM@60 M.P.H. , that's great for mileage, not good for performance. How is your advance curve in the distributor set up? Are you running vacuum advance? Is the Q-jet jetted rich, and are you sure you have no vacuum leaks? I would throw a vacuum gauge on it just to see what it's pulling at idle.
I don't have a tach so I'm not sure what RPM I'm running. I'm running vacuum advance and I'm pretty sure there are no leaks. I'm pulling 18 on the vacuum gauge when I connect to the manifold. I'm not sure if I'm running rich or not. I don't see black smoke. I'll check my plugs in the morning to see if they are black or white. Although, I didn't check them after I removed the Edelbrock so I might have to clean them off then check them later to get the correct results. Thanks, MARK
I've never gotten mileage above 15mpg with a mix of city and highway driving. ONE time, I got 23 mpg when I was driving home from Flint, but I was driving 60mph the whole way and never flogged it out of the hole. City alone, I get 12....if I'm lucky. I like to have fun around town.
I do remember "back in the day" when we would pull the Olds diesels out of Cutlass's and drop in the gas Olds 350, those things liked to suck gas big time. that was in the Mid 80's, boy do I feel old:eek2: What type of exhaust are you running? Hope its not the Factory style, the V-6 had a hard time breathing thru that. A good true duel, or even an aftermarket style GN ( Y-pipe to duals 2.5 inch) would work great, Or have the crossmember modified to run true duels:beer Mark
I modified the crossmember to run true duals. They are 2 1/2 pipes to thrush turbo mufflers. I wish I could have fun in town. The car sounds good but doesn't go anywhere with that lame rearend gear I have. Maybe I can do like what was mentioned above and switch to a 200 R-4 trans with a 3.42 gear. MARK
Here's the update. I cleaned the plugs Tuesday morning before I drove to work. I have driven 75 miles between Tuesday and today (Thursday). I pulled plugs 1,3, 2 & 4. They all were equally blackened quite a bit. So I guess I'm running rich??? How do I correct this or make it leaner? Also, I noticed when I was jumping on the freeway, I heard my secondaries open up. When this happened, smoke poured out of the exhaust. As soon as I let up on the throttle, it went away. I went a little further down the freeway and tried again. I just slowly pushed down on the pedal until I heard the secondaries open up (but didn't down shift). Once again there was smoke. It really doesn't look like oil burning, but I can't be certain, and it doesn't look like a blown head gasket. I see no other smoke at any other time. Even when I accelerate pretty fast without opening the secondaries there's no smoke. Any ideas? SHould I open a new thread? Thanks folks, MARK
I would suspect the spring tension for the secondary air doors is out of adjustment, not enough tension, so the doors are just flopping open instead of progressivley opening as the engine demands more air. Check your float adjustment also. How old is the carb? On Quadrajets, its real common for the upper air horn to warp and not seal completely. It may seal around the perimiter of the carb, but may not seal the passages inside well enough, then you have fuel dribbling over into the secondary or primary side all the time, basically fuel going where its not needed at the moment. I replaced mine with the Holley 750, while that carb works great, I prefer the Q-Jet for all around driving. The Secondaries on the Holley are a pain to tailor for each application. The jetting on the Q-jet from the 455 Olds may be a tad rich for the 350, I dont remember what the stock jetting for the 350 GS was, but you may also pick up a wee tad more mpg, plus better drivability. Mark
I'm not sure if the carb has ever been rebult since 1973. Probably hasn't although it looks very clean. I'll check the float. I was actually thinking the spring to the secondaries was too tight. I could be wrong though. Everyone was preaching about better fuel mileage with the Q-jet and I'll agree, 1 or 2 mpg is better, just not what I was expecting. MARK
