Cam vs mpg

[Sawlog]

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

[Boog]

18 mpg in these old bricks is great. How much mpg are you willing to lose?

[Sawlog]

Originally Posted by Boog

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.

[garyd1961]

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.

[mattfranklin]

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.

[Captainfab]

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.

[BossHogg69]

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.

[68gmsee]

Originally Posted by mattfranklin

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."

[mongocanfly]

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

[GASoline71]

Originally Posted by mongocanfly

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!

Gary

[DieselSJ]

Keep the cam and swap in a 700R4.

[gearheadperkins]

I would have to agree.. leave it alone and drive the wheels off.. that is great mpg..

[Sawlog]

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

[garyd1961]

Originally Posted by Sawlog

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.

[Sawlog]

Originally Posted by garyd1961

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.

[garyd1961]

Originally Posted by Sawlog

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.

[Boog]

Originally Posted by garyd1961

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.

[Captainfab]

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

Originally Posted by Sawlog

I know I know, I was just wanting to go 216 216@ .5. 110 lsa. Sounds like I better leave well enough alone.

[toolboxchev]

Originally Posted by Captainfab

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.

[BossHogg69]

Originally Posted by Sawlog

I know I know, I was just wanting to go 216 216@ .5. 110 lsa. Sounds like I better leave well enough alone.

Going to a 216* can @ .050" really isn't going to give you much 'lope' at all.
You might be able to tell that it has a mild cam, but definitely not the fender shaking crackle/thump/lope that you might be hearing in your head.

Just leave it like it is and enjoy a reliable daily driver with the good mpg you're getting now.

[toolboxchev]

Originally Posted by BossHogg69

Going to a 216* can @ .050" really isn't going to give you much 'lope' at all.
You might be able to tell that it has a mild cam, but definitely not the fender shaking crackle/thump/lope that you might be hearing in your head.

Really sounds like you have a great combo working on this right now. I wonder if those cam companies are engineering their product just for an idle sound?

I would hope that engineering's first priority would be HP/Torque at WOT then mileage on light throttle similar to a VVT tuned engine would be. I know some are ground this way yet there is a ton to understand to get there.

[cadillac_al]

Originally Posted by Sawlog

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.

[mattfranklin]

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.

[toolboxchev]

Originally Posted by Sawlog

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?

[Sawlog]

Originally Posted by toolboxchev

What kind or type of fuel do you have to run everyday?

Just regular 87 octane