123jon321

So I finally got the lt4 intake gasket to match it to the vortecs. This is the new gasket from GM to correct the problem of the original lt4 gasket partially covering the intake ports. Hence there is extra room to assure no port coverage as can be seen on this pic I found of the gasket on an lt4 motor. Notice the room that is also between the lt4 ports and the gasket. The lt4 gasket doesn't cover ANY of the intake ports at any time, the fit is very close if you ask me. Take it for what you will, here are the pics....

lt4 gasket on vortec head:


lt4 gasket against vortec gasket:


lt4 gasket on lt4 engine:


...so there it is, let me know what ya'll think.

QuickGlass

How are you installing this intake to these heads?
Are you drilling the intake for the vortec head bolt pattern?
or
Drilling the heads for the Lt4 intake pattern?
or
Drilling the heads for a standard intake parttern and drilling the lt4 intake for a standard pattern?

thirdgen88

We need a little smiley man with a little WTF flag.. lol

I'm also confused as to what exactly you're trying to do..

Halmari

It looks like the intake ports in the LT4 intake will fit nicely with the vortec heads. I'm in the process of fitting an LT1 intake to the vortecs. I know the LT1 will need material added to the intake runners and the mounting hole locations. I suspect the LT4 will also need material added to the mounting holes.

How were you planning on getting the intake mounting bolt hole locations transferred to the new intake? This is where I would need help. Does anybody have the relative locations for the vortec intake mounting holes and the distributor hole, or a place to get them?

John Millican

iTrader: (1)

If I was to attempt a LTx intake conversion to Vortec heads I would drill the Vortec heads for the LTx bolt pattern. There is way too much material to add to the intake for it even to be close to the weird intake bolt pattern on those Vortecs.

You transfer intake bolt patterns with gaskets.

Chris89GTA

iTrader: (2)

What is the goal here...

The difficulty was never whether the gasket would line up, but actually bolting the intake on...

newbynjess

After searching and searching the net I have finally found
someone else working on this conversion. Your pics
answered my last question! Check this out though... GMPP
is now making a votec/bowtie head part number 25534351

http://www.gmgoodwrench.com/perfpart...373&section=ep

and guess what, its all set up for BOTH bolt patterns! dont
have to worry about drilling/tapping your own holes. plus
being a 'botie' head, the performance should be up. maybe
up with the etecs? wouldnt that be awesome.

Though here is my delima... Do I try and find an lt4 intake
for cheap(anyone got any good sources?), modify it and go
from there; OR do I buy a holley stealth ram VORTEC which
is due out next month? (part number 91704201 for the whole
kit with ecu, fuel rails, etc. I'm waiting for the part number for
the intake only)

I am starting with nothing... Current motor is a carbed 305
from an 85 caprice with an old performer intake and bad valve
guides. pitiful. I think 150 hp would be pushing it for this
motor, though gas mileage is good... 25 mpg on the freeway
(previous ownwer dropped in some 3. somethings in the rear,
75 mph is only 2grand in third) still, very sad. So i'm shopping
for everything.

On paper, I dont like the holley ecu all that much. Using
a GM ecu would be cheaper, but I'm new to the SC area
and dont know anyone doing any tuning that could help
me. This being my first dive into efi I would like this to be
as painless as possible... so i'm thinking an accel gen VII
for ecu. anyone find the gen VII for less then 1500?

here is what i'm thinking if i go lt4 intake:
new vortec bowties, lt4 intake with only the mounting
holes and coolant passages cut, crank trigger, accel gen
VII, 383 quench 9:1 bottem end (balanced ect.) not sure
on cam yet... Hydralic rollers would be convenient but i've
been hearing horror stories about them floating and comming
apart. wonder if anyone has used the new comp cams
behive springs w/hyd. rollers with any luck? ultimately I
would like to go with 1.6 rockers and as much cam as I can
manage without the ecu freaking out. its a daily driver,
but i'm tired of getting beat by damn near EVERYONE!!!
I want this thing to be a BEAST but still get some sort of
fuel mileage out of it (hence the efi and eventually a 6
speed or at least OD).

any thoughts?

newbynjess

as a funny aside, before I found your posted pics I actually emailed a WELL KNOWN GMPP dealer / pro shop and asked if they could lay an lt4 gasket ( I gave them a part number ) over a vortec head for me and see how the ports lined up. The response I got was 'that gasket isnt right for your vortec heads, use this one...'

YA DONT SAY!?! hmm, I guess i'm the stupid one...

Why cant you just do what I asked? grr.

In my response I explained I was trying to pull off an lt4 on vortec head combo much like the lt1/standard head combos done by many other people... like lt1intake.com for example.

the reply (and this I quote verbatium and in its entirety)

'interesting...'

you rock mr. performance guru at P*** Performance

Steve91Z28 L98

The LT4 intake can be used with the Vortec style heads. I did this conversion over 2 years ago. I used the Fast Burn heads because they are drilled for both the Vortec and standard bolt patterns. The LT4 intake ports matched up very nicely to the Fast Burns although I did do some very minor porting on the intake to make it perfect. The rest of the conversion was just like the LT1 intake swap. I drilled the intake for the standard bolt pattern and used a Felpro 1255 gasket.

1bad91Z

iTrader: (1)

Steve - Any pics of your car?

Sounds awesome!

I've been preaching the LT-4 intake to vortec/fast-burn heads a along time ago. It's good to see someone who's actually done it.



Mike

Larry

vortec lt4 intake

3.8TransAM

Larry,

Do u have any more pics of the lt4 to vortec conversion.

Looks like you did exactly what I figured out to do on a converted Lt1 intake(for mock up and measuring, its on hand)

Might be tracking down and Lt4 intake soon or an L99 lil Lt1 if it fits.

Any pics measurements would be appreciated

thanks
Jeremy

B4Ctom1

since the pictures are gone, I am curious if this worked out? is there a port mismatch? will the LT1 intake work as well? or was the LT4 used to make sure the ports would match? are these stock L31's? or other vortecs?

My friend wants to build a TPI Vortec 305. I suggested since the vortecs work well on 305's that he consider the LT1 intake with the distributor and water crossover conversion.

1bad91Z

iTrader: (1)

The LT4 intake will work with a vortec head due to port design (taller intake ports). The LT-1 will intake will not work. The LT-4 intake will still have to be modified for an old school small block though (distrib hole etc...)

Hope that helps.

Larry

That is correct. I spent about $250 on welding and machine work on my lt4 manifold. That is not including the distributer hole and water fittings, which I did myself. I have almost 1000 miles on the conversion with no problems. Even in stop and go traffic with 100* temperature and high humidity the coolant temperature stayed under 200* The remote thermostat is located just below and in front of the throttle body allowing me to use the stock top hose, just shortened a few inches. I am happy with it.

B4Ctom1

I noticed they have these new 206cc iron "bowtie" vortecs which come with the old school manifold bolt holes in addition to the regular vortec bolt holes. I also noticed that there are some regular vortecs that have been modified by enthusiasts and by some dealers with these regular intake bolt holes. Would these facilitate the swap of an LT4 intake by being not requiring so much intake bolt hole modification?

With the idea it would be easier to redrill the heads than it is to modify the intake, along with the flow of the 206cc bowtie heads (one high reving 355 made 632 hp with them), and the flow of the LT4 intake I think this might even be awsome on a large cube motor.

Larry Im trying to figure out what kind of cooling thermostat block you have there?

Larry

The remote housing is a Weiand with a Summit straight up thermostat cover.

I thought about drilling and tapping the heads. Look at the vortec heads where the end bolts would have to be drilled and tapped. On my heads the cast iron is only about 1/8 inch thick and it goes into the water passage. I've heard of people doing that, but I was building a street use car that I wanted to be reliable on long road trips.

B4Ctom1

I like that layout of the thermostat housing

1bad91Z

iTrader: (1)

Very tastefully done Larry! Looks alot better than most coolant line re-works on some of the LT-x conversions that I've seen.