Roller-cam Vortec 357 TBI build

[Chris]

I am upping the fuel pressure and tuning it with my Autoprom. I actually have a Walbro 255 sitting around waiting for my EFI conversion on the Camaro that I could use. From what I have read, the stock fuel injectors still work well up to about 25psi...which would be about double the lb/hr they are now. Granted I haven't actually done this yet, but I don't see it being a big problem and should be fine. I guess we shall see.

A stock Vortec 350 is rated at 255hp, and my engine will have more cam, more compression, headers and a more traditional intake. I know it will be over 250.

Good boy.

You should be able to get it tuned fairly decently, until you get bored and switch to MPFI and an 0411 PCM. :read: I would suggest sourcing a 7.4L throttle body because they flow much better, and you'll have finer control with smaller injectors at higher psi. (the 7.4L injectors ran at 28-30psi stock) When I was still fairly into tuning TBI stuff, I switched philosophy on that and it made a world of difference. It's easy to tune cruise and WOT logic, but part throttle acceleration and off idle gain are things that take a little time. Any plans to convert to MAF, or stick with SD? I wound up sticking with SD because I had a little better control over lean cruise.

Just my opinion, but I would gone with a different cam choice. I know the b-body LT1 cam and GenII Vortec cam are nearly identical, but what small differences there are don't necessarily add up to more power. Everyone and their brother throws an LT4 hotcam into these things, for good reason. They're cheap and lots of info about how to tune them. New valvesprings are cheap, and you don't even have to machine the heads if you don't want to. (If you run LS6 springs and ditch the umbrella seals)

 

[woody80z28]

The manifold adapter, spacer, and stock 350 throttle body I have are all the same size, so I don't plan to switch. I think it will be fine for the low RPM this engine will spend its life since it won't be needing a million cfm. And running the stock 350 injectors at a higher pressure should do the trick as far as lbs/hr is concerned. I've done some homework.

The LT1 cam I'm using is from an F-body, so it's bigger than the B-body or L31 cam. It's basically the max you can safely run with the stock valve train. Remember, this is a budget build for my beater, and all the extra gearing I get with the NV4500 should make it feel like a monster down low.

I'm sticking with speed density, because it's what I'm familiar with on the Beretta and it's the plan for the Camaro too. You have to get your VE tables right, but it's a simple system. Simple is good.

 

[MOBS]

Hmmmmm, if ya like "gearing" then do away with that nv4500 and get a Clark 280 just kidding, that's overkill.

 

[Mike]

Great pics and shop. Keep it up.

 

[woody80z28]

One forward two back...

Got the block honed and it looks brand new. However, both Vortecs I just got are cracked. Magnaflux picked it up. That means four total, and no good ones. WTF

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So this morning I bit the bullet and bought a pair of brand new ones. I'm sick of waiting around and need to slap this thing together.

http://cgi.ebay.com/ebaymotors/ws/e...0588476951&viewitem=&sspagename=STRK:MEWNX:IT

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[woody80z28]

Got the heads today and they are definitely legit GM, I'm happy.

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Pistons look good at home too!

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My Summit order should be here tomorrow with all the gaskets I need to assemble this thing. Picked up new bearings for the bottom end too just for *****&gigs since I have it apart.

 

[MOBS]

Sorry if i missed it, but what type rings did ya run?(chrome, moly, iron, etc)

 

[woody80z28]

All my gaskets, etc came in from Summit yesterday so I got the shop all cleaned up & organized so I can start assembly tonight hopefully. I cleaned up and painted some of the little stuff too like the valve covers, timing cover, oil pan, intake manifold...etc. It should look good for at least a week or two. hahaha

The rings are Summit-brand iron. All the other gaskets are teh good Fel-Pros, including the #1094 .015 head gaskets and the Perma-Dry metal/rubber intake gaskets.

 

[MOBS]

Good deal, I've always ran iron for longevity. Funniest thing I've ever heard aside from "3/4 cam" was someone claiming to run chrome-moly rings. I myself have never heard of such a thing, there's either chrome or moly.

 

[woody80z28]

Assembled the engine last night and it went pretty well. I took my time since it was my first time doing a bottom end. Started at about 6 washing the block and got done with it at about midnight.

I'll get some pics up tonight.