454 Throttle body or 46-47mm modified 350 TB?

[1990Z71Swede]

Have started collecting parts for a very mild upgrade package for my daughters truck.
What I want to achive is just a little more better everywhere, to match, or possibly ever so slightly, outperform the performance of a stock 454ss but with 350 fuel consumption

I'm hoping to get there on stock heads, long tube headers, better flowing cat(s)
Lt4 cam(to hot?), 1.5 roller rockers and a modified to 46-47mm stock TB or a 454 throttle body, possibly on an eddy 3706 Q-jet manifold and the GM Q-jet to TBI adapter.

I have both a 454 Trottle body and a spare unmodified stock size 350 TB. I read somewhere that apart from different connectors the IAC setup on the 454 TB could be problematic on a 350. Even If I decide to use the Big Throttle body, I'm planning to run the 350 injectors. (With a Vortec pump, raised fuel pressure and the at that point unavoidable chip)

Is the IAC thing a real issue? And if so, has anyone modified it to work well on a 350?

 

[L31MaxExpress]

I have run them without issues.

 

[1990Z71Swede]

Great, thanks! That makes it SO much easier. Did you run 454 or 350 injectors? And what manifold?
The runners on the Stock TBI looks OK. A little bit better than the cast iron Boat anchor I have that came on 1968 275hp Gross Camaros. But the "plenum" looks absolutely terrible on the TBI.
And speaking of boat anchors, that TBI manifold is a heavy Sumbitch

 

[tayto]

what is your power level?

 

[L31MaxExpress]

Great, thanks! That makes it SO much easier. Did you run 454 or 350 injectors? And what manifold?
The runners on the Stock TBI looks OK. A little bit better than the cast iron Boat anchor I have that came on 1968 275hp Gross Camaros. But the "plenum" looks absolutely terrible on the TBI.
And speaking of boat anchors, that TBI manifold is a heavy Sumbitch

I ran marine 30 psi injectors. 46# @ 30 psi for 74# and 61# @ 30 psi for 104#. Different power levels.

My manifold was aluminum OE bored to 2, then a 3704 bored to 2", then a performer rpm with an adapter and finally a 2913 single plane with an adapter.

 

[1990Z71Swede]

what is your power level?

Whatever it takes to get it from 0 to 60 in 7.2 seconds or less. And if it ever went to a track (it won't. It's my daughters Daily Driver) make it over the line in 15.7 Seconds or less. I' m guessing that means somewhere around 290 at the Flywheel. I'm REALLY reluctant to give up ANY of the low RPM tourque or mileage, hence hoping to get there with the 193 heads. If I can find a spare set I will give them a slight workover to gain some of them CFM's

 

[RichLo]

7.2 0-60 and 15.7 quarter are pretty specific numbers, lol. Whats your reasoning for those? Just curious.

 

[1990Z71Swede]

7.2 0-60 and 15.7 quarter are pretty specific numbers, lol. Whats your reasoning for those? Just curious.

There is a clue in my first post...

 

[PlayingWithTBI]

Whatever it takes to get it from 0 to 60 in 7.2 seconds or less. And if it ever went to a track (it won't. It's my daughters Daily Driver) make it over the line in 15.7 Seconds or less

I was pretty much there with a 46 mm TB @20 PSI, aluminum heads, and a Lunati Flat tappet cam (about the same specs as your LT4), and 4.11 gears (gained 3/10ths second over 3.42s), until I wiped out the cam and subsequently spun a rod bearing . Now, with a Blue Print stroker and an XR282HR cam, I'm way better than that.

The issue is, getting the power to the ground. The 454SS had a 14 bolt G80 rear end. If you have a 10 bolt G80 in your Z71 K1500 you'll probably grenade it trying to get there. If it's an open diff, good luck getting off the line, ask me how I know

 

[L31MaxExpress]

I was pretty much there with a 46 mm TB @20 PSI, aluminum heads, and a Lunati Flat tappet cam (about the same specs as your LT4), and 4.11 gears (gained 3/10ths second over 3.42s), until I wiped out the cam and subsequently spun a rod bearing . Now, with a Blue Print stroker and an XR282HR cam, I'm way better than that.

The issue is, getting the power to the ground. The 454SS had a 14 bolt G80 rear end. If you have a 10 bolt G80 in your Z71 K1500 you'll probably grenade it trying to get there. If it's an open diff, good luck getting off the line, ask me how I know

My buddies 6.0L swapped ECSB has been into the very low 13s and maybe even a few high 12s with a detroit true trac in an 8.5 with stock axles. Swap something other than a G80 into it and the 8.5 or 8.6 is alot better off. He has rear disc brakes on it so that should prevent a wheel from leaving should an axle break near the c-clip where they tend to fail. He is about to find out how it holds up to a big honkin Whipple.