Need some thoughts/ideas/guidance

[centexk5]

I'm getting ready to build an engine for my k5. It's lifted 9" on 38's on 1 ton axles with 3.73 gears and a th350 with a stock stall. I've hit a bit of analysis paralysis on how to move forward on the build and could use some thoughts. No, I'm not doing an LS swap.

Currently it's got a 4 bolt 350 bored 60 over in it with stock heads and pistons and a flat tappet RV cam in it. It works but meh. I've got a set of vortec heads I'm having cleaned up to throw on here to help for the time being.

The truck is just a toy. I drive it around town, I take my kid in it, I take it rock crawling, I drive it to work. But I'm a power junky and just finished my dad's 77 bronco with a nasty little 306 in it and can't have him beat me.

I've got a 350 block with stock crank sitting around. My initial thoughts on the build are I beam rods with arp bolts, balanced rotating assembly, forged flat top pistons (thinking around 9.5-10:1 compression), main studs and girdle, aluminum heads, cam, roller rockers, dual plane intake, Holley sniper EFI. I like rpm and like to over build. I haven't ruled out forced induction or nitrous (because how cool would that be) but I'd be surprised if I did either.

Here is where I'm hung up. Should I go ahead and have the vortec heads I'm putting on the original engine machined for higher lift and screw in rocker studs and pocket ported instead of aluminum heads? Am I wasting my time with the 350 rotating assembly and should I just jump to a 383? Is the girdle a waste of money? What about the I beam rods and bolts? I'm thinking something around 6000-6500rpm redline but it's gotta be smooth enough that my throttle isn't on off and the cam so radical that I can't control it while on a 30* incline.

Thought, opinions, comments? Tell me I'm an idiot or I'm way off base. I'm just stuck on how to proceed and need some ideas bounced around. No, I'm not doing an LS.

 

[nvrenuf]

3.73’s with 38’s makes it pretty under geared, any thoughts on backing off the motor some and stepping up the gears? 5.13’s would make it pretty frisky with a moderate motor and the moderate motor would perform better in the rocks than a hot 6k+ motor.

 

[centexk5]

I'm stuck there to. Part of me wants to drop it to 5" lift and 35" tires and the other part wants to regear. 1 tons with 35s is kind of a waste but 38s are a bit of a bitch for something that sees more street than rocks.

 

[dyeager535]

For the cost of aluminum SBC heads nowadays, I wouldnt spend time/money on vortecs unless you had no choice. They are good heads, but for really making power in higher rpm ranges, probably every aluminum head out there would make more power out of the box, plus have the right parts.

Have you looked at the Ramjet 350? Considering it's already injected, compared to the crate 383, it puts up some pretty respectable numbers. I've not heard much in the way of issues with the Ramjet injection like I have with most/all aftermarket systems (to be fair, Ramjet was not a production automotive injection system either), and for the cost of machining and going injection on your own block, it might be a candidate.

https://www.chevrolet.com/performance/crate-engines

Unfortunately building your own engine anymore is not cost effective compared to crate engines. Difference is, you know what goes into one you build yourself, and you can put it together with whatever combo of parts you want.

 

[centexk5]

I'm building the engine myself so I can teach my daughter and because it's easier to spread out the cost.

And I should correct my previous post, I am going to regear this thing for sure because it is a dog with the 3.73's. Just haven't decided if I want 4.88's or 5.13s.

 

[6872xtc]

I bought Edelbrock aluminum heads for a 350 rather than having a set built from used ones. I have been pleased so far. It pulls pretty decent in my opinion. I have a 354 which now has lots of Edelbrock parts, the hydraulic flat tappet cam, the heads and Proflo4 injection. Then 700R4, 203/205 doubler 4:56 gears and 37" MTR tires that measure 35.5". I am at 4600' elevation.

But I am definitely a fan of cubic inches as I am a fan of the 400 SB. I've never had a problem keeping any of them cool. So I wouldn't be afraid to go 383 and gain some torque.

I would also recommend getting good measurements off of the 3:73 gears before you pull them as apparently lots of guys are looking for them.

@Bent77 do you have any help on this?

 

[Bent77]

Cut it



oops wrong question
I agree with @dyeager535 about the heads, and also would like to know the actual cam grind. Some of these “rv” cams are decent, some are crap. Actual timing and lift numbers are critical to making a flat power ban

35s are more more useable and agreeable. If you really want 38s, go 4.88 or numerically higher

engines stuff, stock rods are fine as are cast pistons. It’s not a drag car, you won’t gain anything there
Is Girdle to mean stud girdle? You don’t need that either. Engine will probably spend less that 5% of its life over 5000 rpm

build torque, and a 383 is a good way to do that

 

[centexk5]

RPM range: 800-4200
duration: @ 0.050" 206/212
Lift w/ 1.5 rocker: .425/.440
LSA: 108*

 

[Bent77]

RPM range: 800-4200
duration: @ 0.050" 206/212
Lift w/ 1.5 rocker: .425/.440
LSA: 108*

Just use an Edelbrock performer plus then if you are replacing it

 

[centexk5]

I've got no desire to hot rod the current engine anymore than the vortec heads. It's flat tappet and bored 60 over and I don't want to screw with it much. That's why I've got a spare block I'm building up.

 

[1-ton]

The only way you are going to get more HP that you will notice is more cubic inches. Adding a bunch of bolt-on parts to your 350 will not add any noticeable HP. When building a stroked small block for more cubic inches proper block clearancing is the part that trips people up. The Scat "Pro Series I-Beam rods" are what you want to use when buying a small block 383 rotating assembly stroker kit. Not the H-Beam or Super Stock rods. Those will cause clearance problems with a standard journal diameter cam. The Pro Series I-Beams will not cause a problem with a standard journal size cam. If you look at the picture I posted you can see the large end of the rod has cutaways along the bolt shoulders, in order to clear a standard size journal cam.

I also agree with @dyeager535 about the heads. GM factory heads crack easy, and a reman set of Vortecs heads will not last long before they crack from age and metal fatigue. It is better to get a set of aftermarket heads that all have a deck thickness that is twice a thick as a set of GM factory heads.