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Old 09-04-2017, 04:45 PM   #1
Sawlog
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Cam vs mpg

I have a 69 c10 with a 350
65 cc iron heads with 2.02 and 1.60 valves. 165 cc runners
Performer dual plane intake
600 cfm carb
Headers and 2.5in dual exhaust
Th400 tranny with stock converter
12 bolt rear end with 3.08 gear and 30in tire.
My current cam is 204-214 @.5 and 420-440 lift with 112 lsa.
My question is... what would be the best cam for performance and milage?
In getting 18 mpg now if I keep my foot out of it. Wouldn't mind going a touch bigger if it won't kill me.
Thanks
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Old 09-04-2017, 06:13 PM   #2
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Re: Cam vs mpg

18 mpg in these old bricks is great. How much mpg are you willing to lose?
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Old 09-04-2017, 06:32 PM   #3
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Re: Cam vs mpg

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18 mpg in these old bricks is great. How much mpg are you willing to lose?
Not much, I drive it alot. I was just kinda wanting to go up a step on my cam.
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Old 09-04-2017, 09:46 PM   #4
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Re: Cam vs mpg

I would leave it alone and brag about the gas mileage if it was mine. If you change the cam you are going to lose gas mileage and take the chance of creating a problem where there is no problem.
Just my $0.02 worth.
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Old 09-04-2017, 10:48 PM   #5
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Re: Cam vs mpg

Crower used to sell a system in the early '80s with really high static compression ratio pistons and special custom cam with late intake valve closure to manage the peak pressure without knock. I forget what he called it. I think Hot Rod tested it and they would up making 25mpg in a street rod.

It was a neat idea to market it, but he wasn't the first to invent it. Sometimes called the Miller cycle.
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Old 09-04-2017, 11:00 PM   #6
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Re: Cam vs mpg

I agree with leaving it alone.

But if you must change the cam, I would go with a more modern grind and stay with a 112 LSA. Call a few cam companies' tech dept and get their input.
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Old 09-05-2017, 08:47 AM   #7
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Re: Cam vs mpg

The cam/specs you have now IS the best blend of performance and mileage. If you get a big enough cam to actually notice a difference over what you have now (like 218* @ .050" or bigger), you'll need a higher than stock stall in the torque converter to get the most out of the new cam and then your mileage will start to suffer.

In my '65 Bel Air station wagon (daily driver) I have a small cam in it similar to what you're running and I get 17mpg in it with 3.08's & TH350 w/stock converter and 28" tall rear tires. It's a 350 with an Edelbrock performer intake & Holley 650 vac sec 4bbl carb.

In my '05 GMC w/5.3, I put a 215* @ .050" cam in it, mileage stayed about the same (18), but then I installed a 2600rpm stall torque converter to take full advantage of the bigger cam and promptly lost 2 mpg.

18mpg in your truck with a strong 350 is great. If you're happy with it now, I'd weld the hood shut and drive it.
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Old 09-05-2017, 09:02 AM   #8
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Re: Cam vs mpg

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Originally Posted by mattfranklin View Post
Crower used to sell a system in the early '80s with really high static compression ratio pistons and special custom cam with late intake valve closure to manage the peak pressure without knock. I forget what he called it. I think Hot Rod tested it and they would up making 25mpg in a street rod.

It was a neat idea to market it, but he wasn't the first to invent it. Sometimes called the Miller cycle.
In the 80's this would have been a great thing to have. Most big trucks or cars rarely got above the 17-18 mpg on the highway. Rumors have it that big oil would buy out the inventors of high mileage devices and lock them up in a vault never to be heard of again. I suppose others just didn't live up to their billing.

Regarding cam swap. I agree with above posts. If the truck is getting 18 mpg on the highway I wouldn't tweak one thing. As a poster once said "weld the hood shut and leave it alone."
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Old 09-05-2017, 05:15 PM   #9
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Re: Cam vs mpg

I'd agree with not touching it. ..18mpg from a smallblock and without a od trans is like finding a unicorn. ..or bigfoot......or bigfoot riding a unicorn
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Old 09-05-2017, 11:36 PM   #10
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Re: Cam vs mpg

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I'd agree with not touching it. ..18mpg from a smallblock and without a od trans is like finding a unicorn. ..or bigfoot......or bigfoot riding a unicorn
That's funny right there I don't care who ya are!

It's funny because it's true!

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Old 09-06-2017, 01:26 AM   #11
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Re: Cam vs mpg

Keep the cam and swap in a 700R4.
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Old 09-06-2017, 01:05 PM   #12
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Re: Cam vs mpg

I would have to agree.. leave it alone and drive the wheels off.. that is great mpg..
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Old 09-06-2017, 06:40 PM   #13
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Re: Cam vs mpg

Well I was really wanting to put a bigger cam in it so I could get that lopy idle sound I like so much and not lose performance.
Thank you all
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Old 09-06-2017, 06:54 PM   #14
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Re: Cam vs mpg

When I eventually get mine going it will have an equivalent to the classic 1970 Corvette LT-1 cam (GM p/n 3972178) in it. I'll post how that goes. Of course I don't have the "before" case, only the "after" case.
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Old 09-06-2017, 08:49 PM   #15
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Re: Cam vs mpg

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Well I was really wanting to put a bigger cam in it so I could get that lopy idle sound I like so much
This has been the ruin of many of good motors.
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Old 09-06-2017, 09:04 PM   #16
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Re: Cam vs mpg

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This has been the ruin of many of good motors.
I know I know, I was just wanting to go 216 216@ .5. 110 lsa. Sounds like I better leave well enough alone.
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Old 09-07-2017, 07:14 AM   #17
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Re: Cam vs mpg

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Originally Posted by Sawlog View Post
Well I was really wanting to put a bigger cam in it so I could get that lopy idle sound I like so much and not lose performance.
Thank you all
I lean out the idle circuit a little bit to roughen the idle a tad to imitate a big cam. It sounds cool idling through the fairgrounds. As soon as I touch the gas it's smooth as silk though. I have about the same cam with 3.08's in my truck and Impala. This is on my hot rod Impala not my work trucks though.
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Old 09-07-2017, 08:52 PM   #18
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Re: Cam vs mpg

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I know I know, I was just wanting to go 216 216@ .5. 110 lsa. Sounds like I better leave well enough alone.
I am not an expert but I just spent a lot of money on a motor with a big lopy cam just to learn it was basically worthless in my truck. With a big lopy cam you need a big stall converter and big gears in the rear. What you end up with is a truck that is good for going WOT for a short distance but you sacrifice low end torque and gas mileage.
If you want a big lopy cam get a light weight car and build you a drag racer. If you want a good cruising truck with power in the low rpm range where you need it leave your motor alone.
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Old 09-07-2017, 09:39 PM   #19
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Re: Cam vs mpg

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I am not an expert but I just spent a lot of money on a motor with a big lopy cam just to learn it was basically worthless in my truck. With a big lopy cam you need a big stall converter and big gears in the rear. What you end up with is a truck that is good for going WOT for a short distance but you sacrifice low end torque and gas mileage.
If you want a big lopy cam get a light weight car and build you a drag racer. If you want a good cruising truck with power in the low rpm range where you need it leave your motor alone.
That's solid advice right there.
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Old 09-07-2017, 11:25 PM   #20
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Re: Cam vs mpg

You just have to ask yourself if having that lopey idle is worth loosing maybe 5 mpg's or more depending on the cam.

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I know I know, I was just wanting to go 216 216@ .5. 110 lsa. Sounds like I better leave well enough alone.
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Old 09-08-2017, 02:13 AM   #21
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Re: Cam vs mpg

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You just have to ask yourself if having that lopey idle is worth loosing maybe 5 mpg's or more depending on the cam.
After listening to these guys the 210-218 total lift at .526-.522 sounds like I would be losing out on mileage without gaining much if anything.
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Old 09-08-2017, 02:14 AM   #22
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Re: Cam vs mpg

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Originally Posted by Sawlog View Post
I have a 69 c10 with a 350
65 cc iron heads with 2.02 and 1.60 valves. 165 cc runners
Performer dual plane intake
600 cfm carb
Headers and 2.5in dual exhaust
Th400 tranny with stock converter
12 bolt rear end with 3.08 gear and 30in tire.
My current cam is 204-214 @.5 and 420-440 lift with 112 lsa.
My question is... what would be the best cam for performance and milage?
In getting 18 mpg now if I keep my foot out of it. Wouldn't mind going a touch bigger if it won't kill me.
Thanks
What kind or type of fuel do you have to run everyday?
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Old 09-08-2017, 06:21 AM   #23
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Re: Cam vs mpg

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What kind or type of fuel do you have to run everyday?
Just regular 87 octane
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Old 09-11-2017, 01:25 AM   #24
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Re: Cam vs mpg

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Just regular 87 octane
Thanks for getting back, One more if you do not mind. Who is the manufacture of the cam?
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Old 09-11-2017, 06:38 AM   #25
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Re: Cam vs mpg

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Thanks for getting back, One more if you do not mind. Who is the manufacture of the cam?
It's a summit k1102
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