PsychoGTA

I was wondering if this is possible. I got a 92 GTA w/ a 350 tpi L98 engine. Summit has this kit to convert your lt1 to lt4, it comes with the heads, cam, and intake. I was wondering if this can hook up on to my block or is there no chance in hell this will happen? Thanx for your replys.
Peace Out,
PsychoGTA

John Millican

iTrader: (1)

Yes you can. To do this you would need to modify the heads quite a bit including welding. Here's a couple links on the LT1/4 head conversion to SBC.

http://www.lt1intake.com/LT1_retrofit.htm

https://www.thirdgen.org/techbb2/sho...hreadid=178262

Then the intake would require a distributor hole to be located and machined. No coolant fittings or bolt pattern mods would be required since it will bolt up to the orginal heads.

zerotosixtyV8

LT4s are for use with Vortec heads, an LT1 intake is what you'd want for a standard SBC head

John Millican

iTrader: (1)

That's an incorrect statement. LT4's are only for LT4 heads or Fastburn heads (intake modifications required).

LT1 intakes can be used of course on LT1 heads or standard (early or late) SBC heads (intake modifications required).

The only intake that will fit Vortec heads is an intake specificly designed for it.

zerotosixtyV8

fast burns use vortec bolt patterns though

91GTABird

I dont know why but i always had the impression that lt4 heads and lt4 vettes were DOHC. But reading around for the last year i have understood that isnt right. What motor and heads were
32v DOHC? Whats the engine code? The ZR1 was a DOHC right? What about the 96' Grand Sport?

85TransAm406

iTrader: (1)

LT5=overhead cams

John Millican

iTrader: (1)

Correct, Fastburns use standard SBC and Vortec bolt patterns.

But.........Fastburns have standard SBC intake ports...........Vortecs do not.

zerotosixtyV8

ahhh. I wonder why they did that??? why have a bolt pattern for vortec manifolds if the ports differ?

z_power

So, I can't fit LT4 intake to Vortecs, with reasonable amount of work? Water outlets, bolt pattern and distributor hole aren't a problem, how about intake ports; do they mismatch a lot? Both types of heads are raised port design, and I've read that there's a lot of material around openings in LT4 intake.
I'm asking because this combination of parts looks like low $$$ powerful combo for us, FI guys, only comparable to LT1 heads/int. (and you don't have to modify deck surface...)

What is the final answer, then? to go or not to go with Vortecs?

1bad91Z

iTrader: (1)

Actually, the fast-burn heads do have the taller ports (just like the vortecs AND LT-4's).

Why do you think the mini-ram III, ram-jet, AND SDPC TPI base will work with vortec and fast-burn heads?

Answer, because the ports and bolt-patterns are the same.


In theory, the LT-4 intake can be modified to work with vortec/fastburn heads and an old-school SBC (modify intake for distrib. hole and water passages, etc....) which is alot easier than modifying the LT-4 heads to work with an old-school SBC, but even that can be done.

MrDude_1

when it comes down to it, unless you're doing the machine work yourself, it isnt cost effective. get heads that fit the SBC.

the vortech and fast burns have the same ports and bolt pattern. ive been told the LT4s also match em, but ive never seen it in person, so i cant confirm that.

LT1 intakes have the same pattern and ports as a SBC, so with a lil machining for a distrib hole, and the addition of a remote thermostat, it fits.