68 289 C code engine tips!

Crs

Member

May 7, 2004

182

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16

San Francisco, CA

Jan 24, 2007

#1

• Jan 24, 2007

• #1

I'm in the process of getting my engine rebuilt. I'm looking for a healthy combo with excellent throttle responce that will give me the most out of my block without being a gas hog. I have 3.50 gears in the rear with a C4 2500 stall(I may ditch to smaller stall). I just sold my 393 stroker.....so i'm building my original 289. Thanks!

 

Cobain03

Active Member

Aug 27, 2003

996

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36

Lexington, Ky

Jan 24, 2007

#2

• Jan 24, 2007

• #2

my mods are in my sig and i only get 10 mpg in town.

 

Crs

Member

May 7, 2004

182

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16

San Francisco, CA

Jan 24, 2007

#3

• Jan 24, 2007

• #3

Are you still using stock heads? Is there anything with your combo that you would change if you could?

 

J

JEE740

New Member

Oct 21, 2006

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1

Jan 24, 2007

#4

• Jan 24, 2007

• #4

Crs, what kind of MPG were you getting with your 393? I'm just curious, since people can have different opinions on what a "gas hog" is. Also, what kind of performance were you getting from your previous combo?

 

Cobain03

Active Member

Aug 27, 2003

996

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36

Lexington, Ky

Jan 24, 2007

#5

• Jan 24, 2007

• #5

stock heads, but worked a little bit. there are slightly larger valves.

i have a weird situation where i think i have the wrong headers and i had to jack my engine up about an inch for the secondary tubes to pass the inner fender towers, also my hood scoop is bolted on with about 1 inch bolts sticking on the underside of the hood. i dont even want to explain why cause there is no resonable answer.

because of that i have major clearance issues. if those two items were out of the way, i would go performer RPM intake with performer RPM heads to match the specs on the cam (same as the performer RPM cam). i would put 3.50s in the rear (currently 2.80) with a 5 speed. the RPM package dyno sheet from edelbrocks website says 367 horse 340 torque. thats QUITE a bit difference lol.

 

Crs

Member

May 7, 2004

182

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16

San Francisco, CA

Jan 24, 2007

#6

• Jan 24, 2007

• #6

On my 393 , i was getting 7-8 MPG normal driving with occasional flooring of the pedal. The person who built the engine said it was a 400 hp motor with a mid 12 sec capability...........................never took it to the track though!

Thanks for your input Cobain ! I was thinking about a Crane Energizer 272 or a similar Comp Cam, with my stock heads cleaned up and the comp ratio bumped up a bit . Maybe the Edelbrock Package might not be a bad option either........... but i wonder how fuel efficient it is?

 

C

C0V3R

Member

Feb 14, 2003

524

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16

Australia

Jan 25, 2007

#7

• Jan 25, 2007

• #7

An overdrive will do as much for you as any build ever will. Consider putting in an aod or a t5 at the same time if you can stretch the extra.

 

Crs

Member

May 7, 2004

182

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16

San Francisco, CA

Jan 25, 2007

#8

• Jan 25, 2007

• #8

I will consider

 

jadesville

the polarbear conservation corps protects a polarb

20+ Year Stangneter

Oct 8, 2003

2,189

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47

Gresham, OR

Jan 25, 2007

#9

• Jan 25, 2007

• #9

The C4 is what is killing you, I could only best 6-7mpg on highway with mine.

Overdrive, AOD or T5 will be a major improvement. Vacuum secondary carb (with an automatic), later model heads.

 

Cobain03

Active Member

Aug 27, 2003

996

0

36

Lexington, Ky

Jan 25, 2007

#10

• Jan 25, 2007

• #10

in all honesty, if your building for gas mileage, your building the wrong engine lol. get a 4 banger

 

dennis112

15 Year Member

May 15, 2005

1,561

36

79

Amish Wonderland of Central PA.

Jan 25, 2007

#11

• Jan 25, 2007

• #11

The 393 in my sig gets 14-15mpg with careful (boring) driving and normally around 11mpg with lots and lots of flogging--with a 1:1 ratio toploader, 3:70 gears, and 26" tall tires.

When I had a basically stock 351w in the 65' it got 19mpg using 3:10 gears.