Moparchat - Home of MOPAR enthusiasts worldwide!



Go Back   Moparchat - Home of MOPAR enthusiasts worldwide! > Technical Forums > Performance Talk

Click here to search for Mopar cars and parts for sale.


Reply
 
Thread Tools Display Modes
  #1  
Old 04-19-2002, 11:45 PM
Tim_K Tim_K is offline
Registered User
 
Join Date: Oct 1999
Location: Southwest Pennsylvania
Posts: 899
Smile Holley or TQ for 318 mileage ?

I'm going to be putting a 4 bbl. on my 318 '72 Dart 4 door (727, 2.76 gears). This is my new beater car which will haul me 42 miles ONE WAY to work each day, so mileage is important! I'll be putting on a larger exhaust to help mileage (anyone got some shorty headers for a 318?), and I've had 4 bbls get better mileage than 2's in the past on 318's.

A guy I know has a variety of carburetors for sale cheap. I'm thinking of either an 800 TQ or a 600-650 Holley vaccum secondary. I've had TQ's run good for me before, but I wonder about tuning it well for mileage. I know a Holley can be tuned for just about anything, but would it get better mileage than a TQ?

Current mileage with the BBD is 15.5 mpg, mostly highway driving. I'll be using cheap 87 octane in it.
Reply With Quote
  #2  
Old 04-20-2002, 12:06 AM
Ausydad's Avatar
Ausydad Ausydad is offline
Inactive User
 
Join Date: Jul 2001
Location: Ft. Wayne, In.
Age: 57
Posts: 1,024
Default

I think you'll be happier with the performance and mileage out of the Holley 600. If you have to do emissions testing on the vehicle, the Holley may not be legal because of bowl vents, etc.
Reply With Quote
  #3  
Old 04-20-2002, 12:46 AM
Tarrbabe Tarrbabe is offline
Inactive User
 
Join Date: Jan 2002
Location: Cumberland Plateau
Posts: 1,972
Exclamation Gas Mileage

I had a 340 in a 78 Volare' with 727 & 8 3/4 with 2.76 gear. When I put it in with the Thermoquad, I got 18 mpg and switched to a Holley 650 DP Spreadbore and got 19.5. This was with a Crane 284 cam and Hooker headers. My results may be diffrent from yours but you must look for good vacume to indicate the engine will retard itself to get the mileage. My cam was advanced 6 degrees and sounded almost like a stock cam sitting at the lights.
P.S. - When the Volare was new with 318/2 bbl and 2.4 rear axle I got 25 mpg from Detroit to Cookevlle, TN.
Reply With Quote
  #4  
Old 04-20-2002, 01:15 AM
Tim_K Tim_K is offline
Registered User
 
Join Date: Oct 1999
Location: Southwest Pennsylvania
Posts: 899
Default

I should have mentioned that there is no emissions junk on the car except for the PCV valve. The car is older than 1975, so it's exempt, but even if it weren't, I'd still take the emissions junk out!

It has points ignition and no vaccum advance on the distributor. The one time I hooked it up, it just made the engine go surge,die,surge,die. So I just set total timing at 35 with no vaccum advance mechanism. I don't believe changing from points is worth the effort.

What is the diameter of the throttle plates on a 600 or 650 Holley? Any certain list numbers to watch for?
Reply With Quote
  #5  
Old 04-20-2002, 11:45 AM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

If theres one thing I know for sure is that going from a non-vacumm to a vacumm distributor is going to add miles to the car. I frimly believe that a newwr system is better than points. Nothing wrong with points, just that theres better equipment out there that will add a few MPG's over points.
IMO, dump the points for a new MP adjustable vacumm advance distributor, add a MSD box (min.) or better, open up the plug gap till performance falls off. Start with a gap of .050.
This has allways produced the best results for me. Of course adding a a set of low restance wires can only help. MSD or Jacobs has excellent wires for the task.
Other things to look for would be the headers you inquired about. The shorty headers are a good start. Full lenegth tubes are better. Exhaust of no larger of 2 1/4 with at least an "H" pipe, "X" being better, with a good muffler. For this app. I would recomend a set of Hooker Aero Chambers. Run the pipes to the bumper.
The intake should be a Edel. Performer, the best for a 318.
If you do anything to the heads, just freshen them up. Larger valves aren'y needed.
On my 360, I used a Carter 625 with a factory 4bbl and a stock '73-340 K&N equiped air cleaner, 2 1/4 "H" pipe exhaust and MSD. I came up with 20 MPG's in a '79 Dodge Magnum.
2.76 gears and 26 inch tires.
Reply With Quote
  #6  
Old 04-20-2002, 02:11 PM
Tarrbabe Tarrbabe is offline
Inactive User
 
Join Date: Jan 2002
Location: Cumberland Plateau
Posts: 1,972
Default Mileage

Running a dist. with vacume advance can get you 2 - 3 mpg. The vacume retards the timeing and allows the engine to run easier and place less demand on the carb. You will save money with a daily driver and it will still run great if you get the right dist.
Reply With Quote
  #7  
Old 04-20-2002, 09:33 PM
dave571's Avatar
dave571 dave571 is offline
Inactive User
 
Join Date: Feb 2001
Location: carstairs,alberta,canada
Posts: 2,809
Default

I've never had any luck getting mileage out of a holley.

The electronic ignition is a good idea, for sure, and you should be able to do it cheaply with wrecker parts(this is a beater right?)

Make sure the vacuum advance is hooked up to a ported vacuum supply, not manifold vacuum, or it won't work right.
Reply With Quote
  #8  
Old 04-20-2002, 11:54 PM
Tim_K Tim_K is offline
Registered User
 
Join Date: Oct 1999
Location: Southwest Pennsylvania
Posts: 899
Default

I don't know why the vaccum advance didn't work right, but I had this same carb on a built /6 with no problems before it was put on this 318. With the vaccum hooked up, the engine would idle ok, but opening the throttle even a little made it do the 'surge die' thing. Nowhere close to being driveable.

Yes, this car is a beater.

My plan for the exhaust is 2-1/4" pipes to a Flowmaster reverse Y, then a single 3" tailpipe through a Flowmaster muffler. What companies make shorty headers? I don't want to put full length headers on this car for clearance and servicability reasons. The current exhaust is the factory small pipe with a 2 foot glasspack and no tailpipe. The glasspack is actually pretty quiet, and it has been on the car for at least 5 years.

When the time comes for head work, I'll probably keep the stock valves but do a moderate porting job on the heads. If / when I do, I'll post flow numbers on this forum.

I tried a metering rod experiment with the BBD for mileage. I found that putting the rods all the way down at curb idle got me 16.07 mpg, insane overheating, and white spark plug side electrodes and insulators. Too lean! After raising the rods twice, it seems to be doing better. I'll check the plugs in a day or 2 and see how they're doing, and if I need to go leaner or richer again.

When I rebuild this engine eventually, I want to put in a mild cam, but will keep it under 220 at 50 for mileage and daily driver reasons.
Reply With Quote
  #9  
Old 04-21-2002, 12:03 AM
George G. Leverette George G. Leverette is offline
Inactive User
 
Join Date: Jan 2000
Location: Lancaster, Ca USA
Posts: 2,061
Default

If you run the T. Q. you want the Edelbrock performer because it is built for a spread bore carb. The Holleys are square bore carbs and a manifold to fit the carb without an adapter should be selected. I have a hollet 750 CFM carb on a performer RPM intake on my 340 engine and gas mileage sucks, Demonsizzler please returm my T. Q. so I can get some decent mileage with performance and get rid of the gas fumes the vent into the air cleaner. If you can get a T. Q. its the best if not a carter 600-650 I have no luck with Holleys except bad.
Reply With Quote
  #10  
Old 04-26-2002, 03:21 AM
Mister Fiberglass's Avatar
Mister Fiberglass Mister Fiberglass is offline
Banned
 
Join Date: Jan 2000
Location: MI, TN, FL
Posts: 1,988
Default

find an SP2P intake and a TQ.............and if you fiddle with the TQ - you should get 3 to 5 over that Berri ANYDAY !
Reply With Quote
  #11  
Old 04-26-2002, 05:43 AM
Fast One Fast One is offline
Inactive User
 
Join Date: Dec 2001
Location: Adelaide South Australia
Age: 66
Posts: 329
Default

And you can start a fire on cold mornings..
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
holley/demon carb gas mileage tricks party340 Performance Talk 2 11-15-2008 07:09 PM
Gas Mileage w/V10 4x4 QC gthomas Ram Truck Chat 3 03-27-2003 10:48 PM
Rebuild the Holley or Replace the Holley ThePsychologist Performance Talk 12 01-13-2002 04:44 AM
Why is my gas mileage so bad? 00DakExCab Dakota Truck Forum 6 01-21-2001 07:37 PM
Gas Mileage Jason Peel Ram Truck Chat 9 03-15-2000 02:57 AM




All times are GMT -4. The time now is 03:24 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
. . . . .