Need Help Choosing Heads and Intake

[Cwhite7089]

Hello guys I’m new here and need some help. I recently picked up a 1984 C20 with an 85 350 in it, currently auto 3 speed.
I want to make this 350 into something fun and usable. As in more than necessary torque, the kind to surprise passengers or other folk. Without cutting gas mileage in half, all while on a budget compared to going all out.
I was thinking along the lines of a 383 or 408 (4” stroke, go to choice right now), with a very small cam as far as aftermarket goes, cheap heads, intake, and a 650-75cfm carb, short headers.
Here’s my dilemma, I’m new to all this and not sure what the best route is. Ideally I’d like to maintain or improve mileage under light throttle driving, “taking my time”/“grandpa on a Sunday drive” but have the torque to wind a friend :3

So here’s my questions:


1) Would a 408 (4” stroke) be too much for gas mileage even under featherweight throttle?

2) 670 Holley spread bore, 650-750 Holley or edelbrock square bore, or factory quadrajet?

3) I looked into summit vortec heads but I want to keep the compression no higher than 9.0 to 1 to use 87 octane. I will be in rural Montana before long and don’t intend on struggling to find 91 or paying for it haha.
So I need to stick to 75-80cc heads it seems after doing some calculations using the rods and pistons of choice.
I saw the Dart Iron Eagles SS? I’d really like to keep it hydraulic flat tappet which I can with these, unless going roller would really matter that much?
The problem is intake selection for these, according to google searches, only reveal the racing style intakes from Dart and Brodix. I DO NOT want that. Am I able to use others such as Weiand Street Warrior or Edelbrock Performer?
If not, what hears are recommended? I don’t care what material so long as it’s 75cc minimum chamber size.


4) I was planning on swapping the 3 speed auto for a Muncie m22/sm465 for cost and keeping it in era. Which would be better suited for my setup? I was also thinking 3.42 rear end?


Any help with any of it is greatly appreciated. I’ve never built a setup before so I’m pretty lost with my goal being what it is

 

[Cwhite7089]

I found a solution to the cylinder head and compression ratio issue and In turn the intake issue and sticking with the QJet at least for now.

 

[SquareRoot]

At this stage, I'd seriously consider an LS swap and not look back.

 

[Bextreme04]

The cylinder head is everything. The second you stick with stock 75cc heads with no work you are not going to have anything near "wind your passenger" power. I'm running almost exactly what you are talking about running and it is a great running motor with plenty of low end grunt for driving around town or towing. But it is just barely as fast as my 2011 Suburban with a stock 200k 5.3L and 3.05 gears.

Mine is a 350 bored .030 over with flat top pistons and .020 taken off the deck. I am running stock 802 heads that have minor pocket porting, bowl blending, and a slight chamber polish. Summit K1102 cam and factory quadrajet. long tube headers to dual 3" exhaust and flowmaster 50 series big block mufflers. It's 9:1 static compression and 8.05:1 dynamic compression.

It's in my 1980 K25 pickup with factory TH400/NP205 and 14BFF rear with 4.10's and a Yukon Grizzly locker.

I'm still breaking in the motor, so I haven't had the chance to really romp on it. I also haven't dialed in the carb all the way yet, as I'm running a wideband sensor and need to hook up the computer and do some street tuning.

 

[Raider L]

@Bextreme04,

Yeah, you did it right, but here's the key word @Cwhite7089 used..."BUDGET"

 

[Raider L]

@Cwhite7089,

I thought you wanted to build a budget mild performance 350??? What you are talking about stroking it and Brodix heads and all that kind of stuff will sink the ship!! You want "light throttle", for what you were saying I hope you have a fat bank account especially at today"s gas prices!! And 650 -750 big carbs like you are talking about are NOT known for their "sipping gas" attributes.
I don't know who you've been talking to but they are leading you down the path of full race engines, not "grandpa" putting down the street. I'm not trying to talk you out of doing what you want to do, or use what you want to use although I know it sounds like I am, I'm not. I'm trying to get you to put the brakes on and slow you down before you spend huge money and none of the things you wanted will be way behind you when you realize where you are.

First off, take a good look at what you have and do some research into what can be done with what you've already got. I think, and @Bextreme can correct me if I'm wrong, but I think '85 350's were vortec already if not one of the LT engines?
As far as heads, you may be better off taking a few thousandths off your heads to up the compression to 9.0:1. Do a angled valve job on it to improve flow, the necessary polishing or whatever to improve flow even better. Get the rotating parts blue printed and balanced. Find a set of flat top 2 valve relief pistons and that alone will up the compression with no milling.
Then do the simple math to find out exactly what cfm carb you need, and I have the formula. don't just throw a "750 double pumper" on it just because somebody told you that would make a 350 really go! Do the math.
As far as intakes are concerned Edlebrock Performer, NOT the "RPM" will be more than enough for a mild performance 350.
Then Hooker makes a inexpensive set of long tube headers that will give you added horse power and torque.
Cam? Dang there are so many, it just depends on what you want to do with it. But if you want good HP and torque and save your gas stay within the .215 IN-.223 EX at .050" , .450" lift should be enough to give you the snap you want out of your motor and be no slouch on the street or track. It ain't no racing cam but it's enough for some light towing and still maintain some fair gas mileage.
Combind all the above with an H.E.I. distributor and a better quality set of plug wires along with a MSD "Blaster II" coil and you'll be burning rubber at 20 miles per gallon, maybe??

How's that sound @Bextreme04? Conservatively speaking and concidering a "budget" of course.

That pretty much takes care of getting you @Cwhite7089 much nearer to what you were talking about without the expense and more of a heck better motor that will LAST than Dart and Brodix heads and all that other. I hope that helps get you started and keep us up on what you choose and what you are doing with PIC'S!!!

 

[Raider L]

@Cwhite7089,

Oh yeah, and welcome to the forum from Louisiana!

 

[QBuff02]

No replacement for displacement, Big Block it! Lol

 

[Catbox]

I would go with the Summit Vortec heads and the compression they have.
With the better heads the extra compression should not be a hassle with regard to the cheap pump gas you will want to use.

I plan on using the L-29 Vortec bottom end for the roller cam and currently my cylinder head choice is the AFR Enforcer line of heads. Inexpensive China aluminum casting, but finish worked here in the USA with quality parts.

BUT, I am building for a car, not a heavy truck.
The smaller but super fast ports of the Vortec's should serve the usage quite well as they were made for trucks and other heavy vehicles.

Beyond the heads you will want to match the MAX lift to your heads with the cam as well as the engines operating range.
There is no point in having a cam that will lift to .550 if your heads are done at .500.
Same with the RPM range, keep it sane as it is a truck.
No need to have to run a stall converter like a drag vehicle.

 

[Catbox]

Or you could source a big block and stuff it in there.
I cannot tell you how much fun it is to drive my truck with all that brute force under my right foot.
And mine is fairly stock, with only an "RV" cam put into it by a rebuilder in the 90's.

I can tell you that the SM-465 is not a performance oriented transmission.
It shifts as fast as a heavy duty truck transmission designed in the '70's should, slow.
They used it in dump trucks after all.

I am planning on switching mine out for an auto one of these days.

 

[Bextreme04]

@Cwhite7089,

I thought you wanted to build a budget mild performance 350??? What you are talking about stroking it and Brodix heads and all that kind of stuff will sink the ship!! You want "light throttle", for what you were saying I hope you have a fat bank account especially at today"s gas prices!! And 650 -750 big carbs like you are talking about are NOT known for their "sipping gas" attributes.
I don't know who you've been talking to but they are leading you down the path of full race engines, not "grandpa" putting down the street. I'm not trying to talk you out of doing what you want to do, or use what you want to use although I know it sounds like I am, I'm not. I'm trying to get you to put the brakes on and slow you down before you spend huge money and none of the things you wanted will be way behind you when you realize where you are.

First off, take a good look at what you have and do some research into what can be done with what you've already got. I think, and @Bextreme can correct me if I'm wrong, but I think '85 350's were vortec already if not one of the LT engines?
As far as heads, you may be better off taking a few thousandths off your heads to up the compression to 9.0:1. Do a angled valve job on it to improve flow, the necessary polishing or whatever to improve flow even better. Get the rotating parts blue printed and balanced. Find a set of flat top 2 valve relief pistons and that alone will up the compression with no milling.
Then do the simple math to find out exactly what cfm carb you need, and I have the formula. don't just throw a "750 double pumper" on it just because somebody told you that would make a 350 really go! Do the math.
As far as intakes are concerned Edlebrock Performer, NOT the "RPM" will be more than enough for a mild performance 350.
Then Hooker makes a inexpensive set of long tube headers that will give you added horse power and torque.
Cam? Dang there are so many, it just depends on what you want to do with it. But if you want good HP and torque and save your gas stay within the .215 IN-.223 EX at .050" , .450" lift should be enough to give you the snap you want out of your motor and be no slouch on the street or track. It ain't no racing cam but it's enough for some light towing and still maintain some fair gas mileage.
Combind all the above with an H.E.I. distributor and a better quality set of plug wires along with a MSD "Blaster II" coil and you'll be burning rubber at 20 miles per gallon, maybe??

How's that sound @Bextreme04? Conservatively speaking and concidering a "budget" of course.

That pretty much takes care of getting you @Cwhite7089 much nearer to what you were talking about without the expense and more of a heck better motor that will LAST than Dart and Brodix heads and all that other. I hope that helps get you started and keep us up on what you choose and what you are doing with PIC'S!!!

Vortec heads on SBC and BBC started in 96.

I agree, the second he mentioned Brodix heads and budget in the same sentence he lost me.

I built my mild 9:1 compression 355 for about $1800 all-in, including getting the 4-bolt main motor. It runs good and strong, but isn't what I would consider hi-performance by any means. You would be money ahead and have way more potential from just dropping a stock 454 with an RV cam in it. But of course fuel economy will suffer. Even the MPFI 454's with a good tune are lucky to get 12-14mpg. If you get a wideband and dial in the tune on your carb with a 350, you could maybe expect 14-17mpg depending on the weight, gearing, and driving conditions you are driving in. Around town with a 6,000lb, 3/4 ton, 4x4 you would probably be at the 10-12mpg range regardless of what engine you have.

 

[Raider L]

Yep. Correct. I always forget about rear gearing. You could have a stock motor and put a 5.56 gear behind it and you'd think it had twice the motor in it.

 

[Rusty Nail]

Dude ditch the perimeter heads and buy centerbolt - all of those heads are better to choose from AND youd get to buy a schmancy new intake manifold.

I just bought a pair of GM #801s for a K5.

Basically the secret is this:
The more F-body parts you can bolt into your truck, the better you'll like it.... It's really that easy. All you gotta do is take the truck parts OUT and put Camaro parts IN.

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[CoggedBelt75]

I reckon Caleb really didn’t need the help. His loss.

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[Rusty Nail]

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