Getting ready to start my tbi vortec build.

[bgwhtahoe]

I have been lurking around here for some time trying to absorb as much info as possible. I plan to source another tbi engine for my 95 tahoe. I will build this one up to replece my stock 350. My current engine is stock except for ultimate tbi mods and mid length headers. The plan for the new engine is as follows

Block will remain stock bore if possible. If I have to bore it out then .030

Stock rods crank and pistons cleaned and tolerances checked.

For the cam I'm going with comp cams extreme energy 08-422-08 hydraulic roller cam.

Vortec 350 heads reworked with new valves seals screw in studs and Scogg and Dickey heavy duty z 28 valve spring kit for .600 lift.

I have push rod guide plates and some Harland Sharp 1.6 roller rockers. Not sure if these will be too much for this build or not.

Intake is a GM Performance dual plane part number gm12486570.

I plan to run my factory tbi or a 454 tbi if needed, a vortec fuel pump, and my tbi already has an adjustible regulator installed.

What do you guys think of this combo? Pros cons tunability. I know i will need a stall and better gears than 3.42's. I drive it daily right now, around 8 miles round trip to and from work. I have tuner pro rt and a autoprom, aldldroid and a bluetooth adapter. Datalogs and tuning shouldnt be too bad of a problem with some good advice and gudence along the way. I am eager to get in to it and learn. I still need to get a wide band o 2 sensor.

[Roadknee]

What are your performance goals? Where do you want to set wot shift rpm ? Is part throttle response and economy or wot upper rpm power more important?

[jester8798]

Subscribed as I'm working on a similar build myself!

[bgwhtahoe]

What are your performance goals? Where do you want to set wot shift rpm ? Is part throttle response and economy or wot upper rpm power more important?

Hp goal is 300-375. Wot shift rpm is 4800 now, will move it to suite cam. Looking for mid to top power, more on the mid side.

[BLG355]

For the cam I'm going with comp cams extreme energy 08-422-08 hydraulic roller cam.

Vortec 350 heads reworked with new valves seals screw in studs and Scogg and Dickey heavy duty z 28 valve spring kit for .600 lift.

I have push rod guide plates and some Harland Sharp 1.6 roller rockers. Not sure if these will be too much for this build or not.

That cam has enough lift to worry with Vortec heads. With the valve seal on these heads, you can run out of room between the retainer and the seal. With a 1.6 rocker, you need to make sure there is some extra clearance in there. With a .060" safety buffer and .536 lift on the exhaust side, you would want it to have .620" between the seal and the retainer. Any good machine shop should be able to machine them for you for the proper clearance.

Barry

[Roadknee]

I think you can meet your goal with about 10 degrees less cam and have better part throttle response and economy. The zz4 cam would be a good choice and is easy on the valve train. If you want a more aggressive lobe any of the comp extreme energy or extreme 4x4 with 206-210 duration @ .050 on the intake would work well and pull to 5500 rpm.

Our local machinist claims the tbi blocks usually need to be bored, but cranks can be polished. I recently tore down a 1995 350 with 140k and it had a lot of ridge.

[bgwhtahoe]

That cam has enough lift to worry with Vortec heads. With the valve seal on these heads, you can run out of room between the retainer and the seal. With a 1.6 rocker, you need to make sure there is some extra clearance in there. With a .060" safety buffer and .536 lift on the exhaust side, you would want it to have .620" between the seal and the retainer. Any good machine shop should be able to machine them for you for the proper clearance.

Barry

I have a local machine shop that will be doing the heads for me. They should be able to handle it since they build many race engines. They are one of the best around my area. I will make sure they know what my plans are so they can check for all the proper clearances.

I think you can meet your goal with about 10 degrees less cam and have better part throttle response and economy. The zz4 cam would be a good choice and is easy on the valve train. If you want a more aggressive lobe any of the comp extreme energy or extreme 4x4 with 206-210 duration @ .050 on the intake would work well and pull to 5500 rpm.

Our local machinist claims the tbi blocks usually need to be bored, but cranks can be polished. I recently tore down a 1995 350 with 140k and it had a lot of ridge.

I have already purchased the cam. It was between that cam and their 08-502-08 grind or the gm LT4 hot cam. The part throttle response won't be that bad will it?

[Roadknee]

I think it will run fine, just not as strong below 3500 rpm compared to the smaller cam. It might take some extra tuning effort to get your cam to idle well. However it should pull really strong to 6k. I'd spend some time tuning shift points to hold it in the lower gears longer. There probably won't be much point running overdrive below 60 mph.

[bgwhtahoe]

There probably won't be much point running overdrive below 60 mph.

Even with swaping to 3.73 gears,which should push my od cruise rpm from 1200 to 1600. Who ever had it before me had swaped out all the drive terain. Had a 700r4 when i got it, now running a built 4l60e like it should have been.The rear axle is from a truck i think. I have a new narrowed axle that I'm going to build.

[Roadknee]

Some of it comes down to personal preference. I have a stock 1995 k1500 with 3.73s that I've rrtuned to stay in third till 48 mph. You won't know for sure till you start tuning but I guess it will get better economy in drive than it will in OD below 2000 rpm

[bgwhtahoe]

I think mine has 2.73 right now by the calculations, haven't pulled the cover yet. Doesn't matter they are coming out for better ratio.