So there will be less fun shortly...
Thread Starter
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
So there will be less fun shortly...
I'm thinking about downsizing back down to 350 cubes since I'm really taking a hit on gas mileage each time I decide to have fun. Just this week, I went from about 14 mpg to like 9 mpg from opening up the throttle just a tad more that I should. Unless it is the double pumper carb I have on, I really don't know what to do next. This motor might be for sale shortly to whoever wants to try it out. So for you 350 gurus, it is possible to create a heads/cam 350 combo where I can use the cheap gas, still have the capability to trap 95 mph or better in the 1/8th and get good mileage and drivability around town? Perhaps 15 mpg with moderate driving? Anyone here do such a thing? Thanks!
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
I would think that the carb is hurting you on gas mileage a good bit. I get 15 mpg with my minirammed 383. It has been tuned real well, and that number is best case senario(driving like a grandma), Its about 18-20 highway and 10 in town.
What kind of gas mileage do you get in your T/A?
What kind of gas mileage do you get in your T/A?
Thread Starter
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
I would think that the carb is hurting you on gas mileage a good bit. I get 15 mpg with my minirammed 383. It has been tuned real well, and that number is best case senario(driving like a grandma), Its about 18-20 highway and 10 in town.
What kind of gas mileage do you get in your T/A?
What kind of gas mileage do you get in your T/A?
When I played around with the Miniram, I was getting 14 mpg playing around, and 18 grannying. But that is combined with the problems associated with a chopped up 18 year old wiring harness. Not good either.
So the T/A is a different story. It weighs 3450 lbs and gets 11 mpg all the time on 87. I have to run it richer at 12:1 full time to prevent it from knocking.
Since my Vette now weighs 2700 lbs stripped out, I just want it to have decent fuel economy as light as it has become, but I think running premium and the 383 seem to cut the fuel mileage quite a bit.
I'd just want to know if there are any other high performance carbed combos out there that can do better than 15 mpg on a light car. Hopefully so.
Burning Brakes
Joined: Sep 2006
Posts: 1,142
Likes: 0
From: Spring Grove Illinois
Hoobly....Ya got her dialed in well??? I run a 383 with Dart 215 runners and a BG 750 blow thru with a S/C as still get 15 around town..Now don't ask about getting in it..
Timing and carb set up is very important..Does everything match in your engine??..ie Heads to Intake and such...You realy should get better than what your getting..Come on over and we'll dial it in.....
JMHO
Timing and carb set up is very important..Does everything match in your engine??..ie Heads to Intake and such...You realy should get better than what your getting..Come on over and we'll dial it in..... JMHO
Burning Brakes
Joined: Sep 2006
Posts: 1,202
Likes: 3
From: MD
Is the engine fully broken in (a couple thousand miles)? Usually a new engine does pretty bad on gas mileage until ti's really good and run-in. Also, do you have a manual trans or an auto? A D/P carb is really best for a manual trans. If you have an auto you'd be better off switching to a vac-secondaries carb.
Racer
Joined: Jun 2007
Posts: 486
Likes: 0
From: Sandy Ut
Hoobly I got a 92 dodge Daytona POS (yes that is Piece of Sh--) stick shift sitting in the driveway that I drive as my daily when I have to. I allow $100 for gas each pay day to feed the Vette, and try to watch the weekly driving and that way I have it for Friday's and the weekend. Being Married and having kids, I do not make daily trips in it much, and that works good for me. I either drive the Daytona (That gets really great mileage of around 30 Hiway) when I have to, or if I am going out to the field to make a field visit (I am a home designer) I drive a suburban and my Vette actually gets better mileage than the suburban. I tell them if I have to drive the beast out to the field often, they need to give me a gas allowance and it worked. I get an additional $100 each payday for gas just incase I have to go to the field. (Amazing the number is the same isnt it?) I put up with the POS for daily driving because I do not have to drive too far in it.
Le Mans Master
Joined: Aug 2004
Posts: 5,141
Likes: 7
From: Metairie Louisiana
Although I don't think I could handle driving a 4cyl daily after being in the Vette daily for 4 years. You could always build a mild 350 setup built to handle a ton of spray.
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Racer
Joined: May 2005
Posts: 461
Likes: 0
From: East Northport New York
I was in the same boat, drove a Mazda GLC (goes like crap) daily and cruised the vett when I needed to have some fun. On top of the gas advantage my insurance was less for two cars then it was for just the vett. Mazda was my primary everyday car and vett was listed as my second car. Insurance company liked that better then me driving the vett everywhere.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Ya gotta pay to play 
Are you running the 650 DP with mechanical secondaries? If so, we used to call it a DP 4 squirter, very little throttle and all four barrels were dumping fuel, unlike a carb with vacumn secondaries. If that's the case...change carbs, you'll see an increase in MPG. Hate to show my age here, but there's also the Qudra puke (as some called it) more accurately Quadrajet. Small primaries and huge secondaries, used alot on older carbed boats, primaries for fuel economy and the huge secondaries for power.
Yep, I'm one of those guys that drive a 4 banger daily, and use the vette for enjoyment. Same as above, and that insurance savings can put alot of fuel in the tank!
Are you running the 650 DP with mechanical secondaries? If so, we used to call it a DP 4 squirter, very little throttle and all four barrels were dumping fuel, unlike a carb with vacumn secondaries. If that's the case...change carbs, you'll see an increase in MPG. Hate to show my age here, but there's also the Qudra puke (as some called it) more accurately Quadrajet. Small primaries and huge secondaries, used alot on older carbed boats, primaries for fuel economy and the huge secondaries for power.Yep, I'm one of those guys that drive a 4 banger daily, and use the vette for enjoyment. Same as above, and that insurance savings can put alot of fuel in the tank!
Instructor
Joined: Jan 2008
Posts: 163
Likes: 1
From: Idianapolis Indiana
There isnt much you can do about it. Gas out here in socal is getting ridiculous. Especially considering their "premium" is cheap *** 91 octane that wont support a 383 with 10.5:1 cr for more than a week w/o detonating. Youll find the gas pump wont hurt you as much when you have a little beater japanese car for driving during the week.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
It isn't the 33 extra inches³ between the 383 and the 350 that is the cause of the horrible gas mileage. Swapping your combination on the a 350 short block will show no noticeable improvement. As you've noted, probably the biggest cause of your excess fuel consumption is your driving style. If you want to play, you have to be willing to pay. Also, you have isolated another big cause for excess consumption.
Replace or repair that wiring harness and go back to the EFI. Even when playing, as you pointed out, it uses less gas with EFI. Properly set up you should easily get better than the 14/18 mpg you were getting with the Miniram and a defective wiring harness and no MAF. Fix it correctly and you will be the benefactor.
RACE ON!!!
Originally Posted by hooblyboobly
When I played around with the Miniram, I was getting 14 mpg playing around, and 18 grannying. But that is combined with the problems associated with a chopped up 18 year old wiring harness. Not good either.
RACE ON!!!
Thread Starter
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
I know I have a 0 fun factor Corolla as a "far trip daily driver", but I'm still thinking that it could be that my fresh 383 still has about 4000 miles on it. But though my "hot rod" cars are streetable, its just annoying that gas mileage isn't as great as I'd like it to be. I might have to go with a spread bore carb with vac secondaries if this DP is gonna start killing me. But thank you all for some of those suggestions.
The Trans Am is another project. Though I still run very good times with it on crap 87 octane gas, it will still get 11 mpg no matter where I'm at.
This wiring harnesses on both cars was quite chopped up from insulation stripped out to just bad connections on some areas so it might be harder to go back to EFI. I could only dream about LSx swaps at this point, but at least that would be with a much never, better harness than before.
The Trans Am is another project. Though I still run very good times with it on crap 87 octane gas, it will still get 11 mpg no matter where I'm at.
This wiring harnesses on both cars was quite chopped up from insulation stripped out to just bad connections on some areas so it might be harder to go back to EFI. I could only dream about LSx swaps at this point, but at least that would be with a much never, better harness than before.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by hooblyboobly
This wiring harnesses on both cars was quite chopped up from insulation stripped out to just bad connections on some areas so it might be harder to go back to EFI.
RACE ON!!!
Safety Car
Joined: Nov 2004
Posts: 4,991
Likes: 5
From: The Pines South Jersey
I'm thinking about downsizing back down to 350 cubes since I'm really taking a hit on gas mileage each time I decide to have fun. Just this week, I went from about 14 mpg to like 9 mpg from opening up the throttle just a tad more that I should. Unless it is the double pumper carb I have on, I really don't know what to do next. This motor might be for sale shortly to whoever wants to try it out. So for you 350 gurus, it is possible to create a heads/cam 350 combo where I can use the cheap gas, still have the capability to trap 95 mph or better in the 1/8th and get good mileage and drivability around town? Perhaps 15 mpg with moderate driving? Anyone here do such a thing? Thanks!
Safety Car
Joined: Nov 2004
Posts: 4,991
Likes: 5
From: The Pines South Jersey
Thread Starter
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
His combo is 4000 stall, Miniram, stock 350 with ZZ9 cam and ported 113 heads. I had a very similar combo, but the best I could muster was a 12.80 @ 116 mph, with premium. I'd like to do just that, but use 87 octane. Does Vic'89 use premium gas?
Thread Starter
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
I would love to go back to EFI, but time will probably not allow for the next few years or so. I would consider a FAST EFI system, but heck it is too pricey for the time being. That stock wiring harness would be a royal PITA to replace since it is entangled and integrated with some of the other harnesses out there, i.e. A/C system wiring harness, gauges, in dash, body, etc... So much work for too little benefit.
Melting Slicks
Joined: Mar 2004
Posts: 2,141
Likes: 2
From: Pittsburgh Pa
weren't you the one going on about how great of gas mileage you could get with a carb and that efi is just a bunch of trouble and a waste of money to pursue cause of the high cost of parts?? funny how fast that went out the window.. i bet you the harness isn't as hard to replace as you think.. if you can change a heater core in 2 hours i think you may be able to change out the harness.