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1bbl vs. 2 bbl. for mpg
https://slantsix.org/forum/viewtopic.php?t=45914		 Page 1 of 3
Author:  raPoM [ Wed Aug 10, 2011 9:29 pm ]
Post subject:  1bbl vs. 2 bbl. for mpg
What do you guys say for MAX mpg 1bl or 2bbl carb? Building up the 69 Dart for daily driver.Plans so far:

1969 Dart Custom 4 door
904
7 1/4 with 2.9x
185/75/14 tires
Manual steering
A/C
1978 225 with the holley 1945


Was thinking about finding a aluminm 1 bbl intake,and rebuilding the holley 1945 thats on the car.Already have the HEI ignition comming together.Only other changes are to rebuild the head,MAYBE some mild porting/casting clean up,and shave it to get a true 9:1 comp ratio. Top it all with a 2 1/4 exhaust off the stock manifold,and a nice quiet muffler with decent flow(dynomax?)

What do you guys think? Like I said before this is going to be a daily driver/gas miser so I want max mpg over performance.

Thanks :D
Jared
Author:  Dart270 [ Thu Aug 11, 2011 6:06 am ]
Post subject: 
Hard to say. I've had good results with 1 bbls, 2bbls, TBI, big cams, small cams...

The 1945 should work well if in good condition, and will likely return very good mpg - about 23-25 mpg hwy if everything is working well together and you are driving properly.

Lou
Author:  SlantSixDan [ Thu Aug 11, 2011 6:22 am ]
Post subject: 
I agree with Lou. The 1945 gets a bad rap, but most of the driveability issues it's blamed for are actually a result of tuning. The design of the carb is actually rather good. Put in a brass float (Walker #100-48 ) and go through the carb with a good quality kit.
I like the improved inlet needle/seat design that comes with the kits from www.daytonaparts.com .
Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.

The rest of your recipe/shopping list looks good. I can't recommend any of the "performance" mufflers such as Dynomax -- loud/droning exhausts get old in a hurry. Just use a larger-than-stock, stock-type muffler.
Author:  Rug_Trucker [ Thu Aug 11, 2011 7:04 am ]
Post subject: 
The best MPG I got with a 1bbl on my Duster was 29.5. That was with no header, split dual exhaust and 3:23's.
Author:  raPoM [ Thu Aug 11, 2011 10:25 am ]
Post subject: 
Thanks everyone! I am going to stick with the 1bbl,since its what I have on hand.

I have heard/seen a few post with people dumping on the 1945,but I have used them before with good results.

Dan,by larger than stock,you mean larger dia. inlet/outlet,or were you reffering to the overall size of the muffler case? Just trying to clarify.

Rug, dang that is a nice number. Was everything else stock on the car? No interal engine work? Electronic ignition?

Lou, I plan on driving this thing like a grandma. Not going over 65 on the highway,and using some of the "safe" hypermilling techniques. Ive done the whole hot rod the slant thing before,and its loads of fun,but this time I just want a nice daily driver that I can afford to drive. Its going to be my goal to get the best mpg I can get.
Author:  raPoM [ Thu Aug 11, 2011 10:27 am ]
Post subject: 
Also thinking about an electric fan,or clutch fan set up. Do you guys think a clutch fan from an F body would work if I ran the thinner radiator from the same car?
Author:  SlantSixDan [ Thu Aug 11, 2011 10:31 am ]
Post subject: 
It is really tough to fit a Mopar-type clutch fan in an A-body with a slant-6. See here for a workaround. Electric fans are nice, but would require some pretty comprehensive charging system upgrades; they are very power-hungry.

Don't skimp on radiator capacity!

As for the muffler: Both! Larger in/out and larger body diameter. Try out a Walker #21110 or AP/Goerlich #2087 main muffler (2¼" in, 2" out), and if you want it good and quiet without highway drone, AP/Goerlich #2092 resonator.
Author:  raPoM [ Thu Aug 11, 2011 10:47 am ]
Post subject: 
Thanks for the info Dan. I am also wary about electric fans because of the possibility of failure. When you live in Tx and the temps are 100+ for 50 straight days,you dont want to have your cooling fan go out on you!

On the radiator capacity, I believe the slant six F body a/c rad has the same or more capacity that the A body sl6 a/c rad. It is thinner but it is also wider,I put one in my 70 Dart when I installed an electric fan in it about 9 years ago,and it worked great untill the fan failed :evil:

I will look into that muffler!
Author:  raPoM [ Thu Aug 11, 2011 10:53 am ]
Post subject: 
Hmmm a mercedes clutch fan huh? Did you ever end up trying one out Dan?
Author:  Aggressive Ted [ Thu Aug 11, 2011 12:11 pm ]
Post subject: 
I ran the MOPAR clutch fan for a few years on my 74 Dart. It worked well but you had to pull the radiator to install it then carefully slide the radiator back in.

I switched to a 16" electric fan and ran that for about 5 or 6 years. It worked great and only drew about 12 amps. The bearings started to go so I just purchased two 9" fans and mounted them at the top near the tank. They are much easier to mount, no interference with the engine and work very well and draw much less current.

My radiator is the stock 18" wide unit with a square shouldered tank. With a little trimming on the fan shroud flanges they just fit! They are triggered by a switch screwed in the top tank. The switch is a stock unit used on GM cars the last 15 years or so.

To deflect more air through the radiator I built a air dam or deflector at the bottom of the radiator. It is bent at 120 degree angle and works like a scoop to push more air from under the bumper up to into the radiator. When running a electric fans I find they rarely come on unless I am stuck in traffic.

On mileage with a 1920 Holley Economaster version the best to date has been 26 mpg with a #57 jet. My 74 Swinger is pretty boxy and weighs over 3600 lbs.
Author:  raPoM [ Thu Aug 11, 2011 12:26 pm ]
Post subject: 
Ted,have any pictures of your new setup? Where did you buy the fans?
Author:  Aggressive Ted [ Thu Aug 11, 2011 12:34 pm ]
Post subject: 
Not yet, I should probably take some pictures this weekend when the sun is out and add them to the link. It has been pretty cloudy out here in the foothills.

The fans just came from DNAmotoring off eBay. I thought I would give them a try since they draw less and have nice deep flanges.
http://cgi.ebay.com/ebaymotors/ws/eBayI ... K:MEWNX:IT

So far I like them over the single 16". Every time I put my hand behind the 16" fan the bottom would be cold and the top would be hot. So I went with the idea of the two smaller fans to pull more air from the top of the radiator. So now I get way more air flow through the top which cools much quicker.
Author:  raPoM [ Thu Aug 11, 2011 12:40 pm ]
Post subject: 
Wow,those are cheap for a pair of new fans! How do you have them wired up? If you get a chance to take some pictures,let me know I would love to check them out.

I hear you Wa guys are having a very mild summer. Makes me miss Wa when im in this Tx heat,I use to live in Grays Harbor.
Author:  Aggressive Ted [ Thu Aug 11, 2011 12:47 pm ]
Post subject: 
Grays Harbor......oyster country! Heading down there with the Dart for a vacation in a few weeks.

Yes, it has been a very mild summer so far.....the tomatoes are just getting ripe.

I have the two small fans wired in parallel and they still draw less than the single 16" fan. You can buy better quality small fans but I wanted to try this idea out first to see if it was sound. The past few weeks of testing, I have been very pleased so far. The wiring schematic is posted in the Engine FAQ section.

The bottom of the radiator is still very cool.
Author:  raPoM [ Thu Aug 11, 2011 1:19 pm ]
Post subject: 
Yep :D Used to go get razor clams with my grandpa out at ocean shores,then go fishing for trout at aberdeen lake and have a heck of a meal!

Thanks for all the info.
Jared
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