This is going to be my first engine build for me. I work at a benz/cad/chev dealer and in the service department, Im a service advisor, so I have tools, resources, equipment, parts, available to me.

So here's the run down.

I have a core vortec L31, paid $50, for the long block. Today, well in about an hour, were going to tear it down and see what were workin' with. The story on the core: intake leak, washed down, lower end knock, about 100k on the motor. Outwardly the water jackets an oil passages look clean. Pulled a plug and it looked good, so we might be in good shape, but we'll see.

So were going to complete the tear down today, hopefully, all things well, we will send the block, crank, rods, and to the machine shop on monday.

Going to go with the .030 overbore, 3-angle valve grind. Hence the 355ci. I'm not sure if were going to increase the valve sizes in the head, I'll come back to that in a moment because I'd like some educated responses on vavletrain setup. I will be posting pictures as this thing progresses.

So here's were your advice will help. I'm not building a monster engine, but a reliable, streetable, somewhat economical, kick in the pants engine that is a step up over a stock l98. Were going to re-use the TPI(after its cleaned and rebuilt and obviously with a vortec manifold for TPI. I am unsure on what cam I should use that would yeild good numbers, work with TPI, and just be cohesive with the whole setup. Obviously, what valve sizes, rocker ratios to go with the cam are needed. I just would like to know your success or failure stories or I wouldn't mind knowing your similar setup.

Thanks in advance,
Scott

will be posing images later today.

 

Having done extensive work on a new SuperFlow 1020 flowbench with Vortec 350 heads, here's my advice, take it as you please:
Intake ports. Get them clean. That's it.
Exhaust ports: 5-angle valve job for 1.60" valves, with the seat as far out on the valve as possible. Then carefully port away that ridge on the port floor (short-turn) and blend the 75-degree cut into the bowl, trying for ca perfect radius, however tight the radius may have to be. Tapering the guides makes no difference at this level, so leave them be. Polish entire port, all 8 exhaust ports.
Valves: Get good aftermarket stainless, 1-piece, swirl-polished, undercut valves. The best deal is from www.competitionproducts.com at $80 for all 16.
Be sure you're ordering 1.94"/1.60" Have the machine shop put a small 30 degree back cut on them.
At this point, the heads will work best with a cam having 6-8 extra degrees exhaust duration at 0.050", and no more than 0.480" advertised intake lift with 1.50:1 rocker arms.
Rocker arms: 1.50:1 only, for the intake side, unless the cam is advertised at less than 0.450" lift.
This is the ultimate bang for the buck with these heads.

 

Sorry, no pictures yet. We got the enigne torn down. Everything was good, except for the crank shaft. Has about a 1/16 grove on the #1 journal under the bearing. So the crank may not be salvagable. we'll see. ALL parts are in the parts washer.

Scott

 

If the crank is toast, plan on going 383.

 

The TPI does not breath very well at high rpms so I would look for milder cam one with small duration and around a .480 lift. I would use the stock rocker arms and valves.

Personally I would go with a carb and an intake that would flow decent at higher rpms than the tpi would, this would allow for a bigger cam and more power. I just built a 355 vortec motor and I ran it with a HSR and carb setup and its a pretty mean street motor.

 

Okay, heres a stupid question. So my current bottom end has about 60k on it and it shows no sign of weakness. What if I just replaced my current head with the vortec's, which are at the machine shop today. If I kept the current cam and just changed my heads with the vortec base and the TPI uprades. Is this even worth while? My question revolves around the lack of ability of the TPI system itself. My cam choices are limited while at the same time trying not to turn this project into a runaway train. I'm still going to do this, but am exploring my options as we go.

Its pretty much determined that were going to keep my bottom end as it is. but i am exploring my options, as this is NOT an exotic engine build. But driving my 02 ss really made me realize how much this z28 could use some engine love. Other than that I love my hunk o crap 3rd gen!!!!

Scott
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Oh Oh. I am set on keeping the TPI system, so please do not recommend a carb or another injection setup. This is not a flame to any of you, but just a heads up. All of your edjucated advice is greatly appreciated. So I thank you to you all.

 

Scoggin-Dickey has come up with a TPI setup for a 350, using the GM "HOT" cam and Edelbrock TPI base and runners, on Vortec heads, that delivers 357 hp and 417 ft-lbs. This might be something for you to investigate farther. Just don't use 1.6:1 rockers on the intake side. You won't really lose anything, because when you lift the intake valve too much, the port stalls, and you lose flow from that point until the intake valve closes to 0.200" opening.

 

What about the groove in the rod journal?

I don't think it would be worthwhile to swap heads and keep the same cam. I would look into a mild performance cam.

If you are set on TPI you're going to be limited on cam choices and remember that you are going to have to computer tune the PROM for it all to work.

 

I don't know much about TPI but I know enough to go carb on my last 355 build. I used a 350 block 4 bolt and a set of vortech heads with 5 angle valve job and I pumped the compression to 10.5-1 and it was a beast to about 5800-6000 and loved the juice. Problem was it used way to much gas and was good for a trip to the strip and a couple runs then fill up and come home with 15mpg avg hwy. Ohh and it loved to eat 700r4 transmissons specificly 2nd and 3rd gears so a th350 with some mods was swapped and it secured a low 11 and high 10 with a 2 stage.

 

Well here is my final setup:

vortec heads: new springs, guides, retainers, seats, decked, 3 angle grind, ect. O.E. rocker arms

Crane Came 2032:
Crane Cams 104224 "PowerMax" hydraulic roller camshaft
Fits 1987-1992, 305-350 cu.in. Chevrolet V8Crane Cams has been designing and manufacturing high performance camshafts for the street and the race track since 1953. Their cams can be found in every major race series and on streets and drag strips all across the country.
Crane "PowerMax" emission legal hydraulic camshafts produce significant increases in power and torque, and improved throttle response. They are fully compatible with OEM computers and also work well with aftermarket performance chips. These cams are suitable for cars and light trucks, both 2x4 and 4x4. RPM Range: 1,800 to 5,800
Duration @ .050" lift: 214/220 (int/exh)
Valve lift: .452"/.465" (int/exh)
For Corvette, Camaro, and Firebird with factory TPI
Recommend adjustable fuel pressure regulator.Crane Cams 104224 • Strong powerband without sacrificing idle or throttle response
• Dual pattern for balanced intake and exhaust flow
• Produces maximum low end, mid-range, and upper rpm power
• Many PowerMax cams make the most of nitrous and supercharged applications

Scoggin Dickey vortec tpi base manifold. EGR deleted.

Home ported tpi plenum, runners, ect.

Adjustable fuel pressure regulator.


Thats pretty much it.

Obviously, new timing set, vortec O.E. valve covers, gaskets, and some hard parts in the parts washer.

I am going to go this set up.

Any comments. I'm thinking that this may be a nice upgrade from what I'm working with now. Maybe a 30-40hp upgrade and a 50ft lb upgrade while maintaing a stock lock and power band. What do you all think?

 

The cam says 5800, and that'd be true with a Mini-Ram or HSR, but you're still gonna be rpm-limited by the TPI. The porting will get you more torque in the 2500-4500 rpm range.
I'd add in a set of stamped steel 1.6:1 rockers.

 

Any updates on the build?? I have a set of vortecs I got for free and may do something similar.