I need a mild cam for my 393!

Crs

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Oct 29, 2005

#1

• Oct 29, 2005

• #1

I want to down grade from my Isky 280 mega (.517 lift....232 duration@.050), to a more milder daily driver type cam on my 68. I still want it to work with my World Heads, Performer Rpm Intake, 2400 stall and 3.50 gears. Hoping to get better than 9 MPG. Any suggestions?

 

69Rcode_Mach1

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Apr 20, 2004

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Salt Lake City, Utah

Oct 29, 2005

#2

• Oct 29, 2005

• #2

That seems like a pretty mild cam to me. Especially for a 393, I think you could go with compcams XE268H if you want, but that doesn't give you much room to spin, or too much lift for a 393. I would stick with that cam.

 

Crs

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Oct 29, 2005

#3

• Oct 29, 2005

• #3

I'm just trying to downgrade on the cam so if i start driving it daily i get better mileage out of it..........that's only if i decide to baby it. Does your 69 get better that 9 mpg?

 

69Rcode_Mach1

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#4

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I haven't driven it on the road yet, but hopefully next week I will. I just got all my safety inspection stuff fixed up today. I would hope it does, since I put in a 5 speed. We will see though.

 

iskwezm

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May 24, 2005

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Rowland Heights,California

Oct 29, 2005

#5

• Oct 29, 2005

• #5

try something with less duration,but the same lift and about a 112-114 LS???

I would think my combo get more MPG then thatmeven thought its only a 349.

 

jerry S

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Sep 3, 2003

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Oct 29, 2005

#6

• Oct 29, 2005

• #6

Crs said:

I want to down grade from my Isky 280 mega (.517 lift....232 duration@.050), to a more milder daily driver type cam on my 68. I still want it to work with my World Heads, Performer Rpm Intake, 2400 stall and 3.50 gears. Hoping to get better than 9 MPG. Any suggestions?

Click to expand...

better mpg can be had by

1. stock TQ
2. 3.00 gears
3. 650 cfm vac. secondary carb (I just assume you have a bigger carb on there, like a 750 DP or sumfin)
4. same cam
5. steping on the accelerator with the same amount of force you would use to step on your own testicles.

or just no. 5

 

Max Power

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Jul 31, 2003

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St Paul

Oct 29, 2005

#7

• Oct 29, 2005

• #7

My 393 has the Edelbrock RPM package, which has a similar cam, and I am running a stock TC and 3.50 gears. I am getting about 15mpg on the highway.

You might want to look at why you are getting 9mpg with the package you have. I think it's more than the cam. A Comp 268 would be an OK choice, but it won't get you from 9mpg to 15 on that alone. Something else is up.

 

Crs

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Oct 29, 2005

#8

• Oct 29, 2005

• #8

I've been trying to figure out why i get crappy mileage out of my set-up and i just cant figure it out. I assume that i just have a rich cam, because my plugs are very fouled (black), and my carb (Holley 4160), and timing is okay.
Will a 108 LS = a rich cam?

 

iskwezm

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May 24, 2005

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Oct 30, 2005

#9

• Oct 30, 2005

• #9

Crs said:

I've been trying to figure out why i get crappy mileage out of my set-up and i just cant figure it out. I assume that i just have a rich cam, because my plugs are very fouled (black), and my carb (Holley 4160), and timing is okay.
Will a 108 LS = a rich cam?

Click to expand...

you need to re jet your carb.A cam cant run rich,its the carb supplying the amount of fuel.I have a 108 LS and my plugs arent black.

 

ddonaca351

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Dec 1, 2002

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Camas Washington

Oct 30, 2005

#10

• Oct 30, 2005

• #10

I run 218/228 .536/.536 in a 306 and get just shy of 20mpg on the hwy. The cam you have seems mild for a 393... are you sure you dont have a vac leak or carb adj problem?

Dave-

 

Max Power

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Jul 31, 2003

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St Paul

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#11

• Oct 30, 2005

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You have carb problems, not a cam problem.

 

Crs

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San Francisco, CA

Oct 30, 2005

#12

• Oct 30, 2005

• #12

I have a 750 Vac sec, 3.5 Power Valve ( 7-8 inches of vacuum), and stock 72jets in front. After changing jets in the front do you still have to mess with the mixture screws?

 

jerry S

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Oct 30, 2005

#13

• Oct 30, 2005

• #13

Crs said:

I have a 750 Vac sec, 3.5 Power Valve ( 7-8 inches of vacuum), and stock 72jets in front. After changing jets in the front do you still have to mess with the mixture screws?

Click to expand...

I think that you have a vac. issue somewhere. I have a bigger cam in my 351W than that and I had 13 inches of vac. I bet there are guys with superchargers who pull more vac. than 7-8 inches. Your low vac. could be related to your poor fuel economy.

 

69Rcode_Mach1

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Oct 30, 2005

#14

• Oct 30, 2005

• #14

Yeah your vac is pretty low. It is definitely a carb problem. This part can get tricky. Just gotta start eliminating possibilities.