904-gas mileage?

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1973Barracuda

1973Barracuda

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So, I had a 318 with a 500cfm on it, got crappy mpg(10-11)-tuned ok. Changed to a 360(mild), 650 eddy, tuned decently, 10-11 mpg. When first started, takes a bit to get it moving, is that the pump? Anyway, thinking the tranny is part of the cause of my mpg , thoughts? BTW, 36 total, about 18 initial. 3.55 gears.
 
Could be the converter.
As transmissions go the 904 wastes less HP than the 727.
A worn out converter can make it seem to have to work too hard, and get crappy fuel economy.

If the pump was causing it the trans would be toast.
 
toss your carb. the people that made the carb you have dont know how to jet a carb. jet it like a chrysler AFB, that was on a chrysler with a engine like yours. warring if the jet does come out easy DONT force it. there is a trick to get it out, but to long to put here. idea: any time you have trouble: check what Chrysler did, ill bet they did it right.
 
I have 360 with 355 gears new trans and converter Im only getting 10-11.
 
i think the 3.55 gear is more the problem then the carb..

my stock 360 had a 780 on it and i got as good as 17mg on the way to carlisle. usually got around 15mpg. but i was also running a 2.94 gear with a 28"tire.
 
I know I won't get 20 mpg, just think the 10 or 11 mpg is low with a 360 that is fairly mild. Unknown cam, was told 268ish, AirGap, 650 Eddy thunder. When I first start the car, after warming up a bit, I put it in drive and give it some gas, the car barely moves, then starts to move and slowly gets better, probably a 20-30 second time period.
 
Yes in neutral.. Just a few seconds should be plenty to get her juices flowing..
 
It only takes a second or two to fill the converter, so even 10 seconds of running is WAY plenty of time to fill it.
Even in park the pump still runs and circulates fluid, but doesn't return it to the pan.

There is somthing else wrong, or something you are missing.
Like the choke being on too much, or something.
That is a myth about having to let them warm up in neutral, and the ones that do have to be done that way are just worn and have hardened rubber seals.

I can fire mine up in park, drop it in gear and go without any issue's at all except the choke still being on all within 5 seconds. (these cars didn't hesitate when they were new either)
 
no choke. with me feathering the throttle and letting it warm, it still takes a few seconds for the car to move after putting it in D. Car revs and then starts to move-and kinda builds until it gets moving, if that makes any sense.
 
1973Barracuda said:
no choke. with me feathering the throttle and letting it warm, it still takes a few seconds for the car to move after putting it in D. Car revs and then starts to move-and kinda builds until it gets moving, if that makes any sense.
Click to expand...

Makes total sense, and it's not right and usually because of older cold rubber seals.
A worn converter bushing and/or sloppy pump clearances just adds to it.

Still, they can last a long time like that.
 
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