Pocket

iTrader: (24)

Bit of weight reduction to begin with

This saves about 10 ounces and gets rid of the coolant bungs that love to snag your knuckles

Stock LT1 TB


On the left is the lower section with the coolant passages and IAC housing
On the right is the bottom of the TB
You can see that the IAC part is completely separate and can be isolated


About 15 mins later with a cutoff wheel the IAC housing is cut free


Put back on the TB compared to a unmodified stock TB


Next is for swappers wanting to use vortec heads

This is a pic from lt1intake.com showing the gap at the top of the intake ports disallowing tallport heads and stock LT1 runners


I later confirmed this when mocking them up on my raised runner topline heads using the modified mounting holes


I later slotted all 12 intake holes to line up with my stock L98 heads so this pic is worthless
I assume another faulty alignment for the bolt holes was to blame for the lt1intake.com pic

Here is a mockup of unmodified vortec heads with an unmodified LT1 intake




You can clearly see there is no gap what so ever at the top of the ports
Please note there is no gasket under the intake so it will be raised slightly higher for final install

Here the intake was slid forward to show the overlap of the ports


What does this mean? Not a whole lot, only vortec heads are not automatically out for swappers looking for a better set of heads

vetteoz

iTrader: (13)

While you are at it you can cut the EGR boss off flush with the rear of the plenum and patch the hole.Allows HEI to fit

Pocket

iTrader: (24)

It was done for the modified intake





Several threads have come up about large and raised ports with conversion intakes
Just trying to clear up a few misconceptions

jamez74

iTrader: (1)

Hey, nice info there. What intake gasket did you use? I have done the same swap but have been having some sealing issues.

Here is a pic of mine intalled and soon to be uninstalled..again lol

Pocket

iTrader: (24)

1205 fits the L98 heads good and covers the intake fine

Will go to 1206 when the toplines go on

Reference:
http://www.fbody.com/3gen/73593

Major thing to think of for gasket selection is if you have EGR heads you must use non EGR gaskets. Next is if the gasket fully encloses intake and head ports

85TransAm406

iTrader: (1)

i portmatched mine to a 1205, i don't think it'll go all the way to a 1206 without welding the flanges. I dunno though, any thoughts?

Orr89RocZ

iTrader: (20)

when i did my intake i used quik steel epoxy putty to add material to the ports and water jacket area to make more material to seal.

it hardens very good and seems to hold well enough. I never ended up using that intake but a guy who bought it has it on a 383 and its working out ok so far.

welding material on is best but the putty should work

junkcltr

iTrader: (1)

That picture shows exactly why the EGR port is a problem and exhaust will leak into the lifter valley. There is NO material on the intake holding the gasket against the head so the exhaust pressure (almost none possibly) will push the gasket and leak into the engine. Also, as pictured without the metal EGR shield..........there is a 1/4" by 1" hole from the head EGR exhaust port directly into the engine. I welded angle alum. to the intake at the EGR to keep this from happening.
It amazes me that no one else sees this as a problem with all stock GM heads with an EGR port.

Orr89RocZ

iTrader: (20)

i forgot to mention i added quick steel putty to that area to so that the intake DID seal that port. I also use rightstuff gasket maket instead of traditional gaskets so it seals great as long as you put that stuff where it needs to be and use as much as you want.

junkcltr

iTrader: (1)

I had to weld on the top of the ports also when I installed it with the GM heads (993 part number). I spent a week welding to make the distributor bung, adding material to the exhaust ports, welding the PCV hole, and adding angle alum. at the EGR ports. Overall, I like the intake and think it was worth it.

The epoxy should work at the EGR ports. It just amazes me that a lot of people don't notice the EGR hole problem and some think just installing the non-EGR gaskets with the tin in the hole will stop the exhaust gas from going into the engine. I would love to see an oil analyst of an engine with the LT1 intake using EGR heads using either the non-EGR or EGR intake gaskets. I don't think most people would notice that there oil is blacker than before they installed the LT1 intake.

The exhaust makes a lot of heat and the only way to seal the EGR port is to have material on the intake for the intake gasket to be forced against. Just flapping a piece of tin and/or gasket will allow the exhaust in the engine.

Pocket

iTrader: (24)

You mean this slot?


It doesnt have anything to do with the EGR, its PCV as seen here



Still skeptical? Here is a LT1 intake with the EGR ducting removed, you can clearly see the slot doesnt contact the EGR at all.
The slot is at the bottom



Hmm?

Dont go bigger unless you need to

TA

iTrader: (1)

Has anyone ever tried the LT4 manifold (Taller ports) to use with the Vortec-pattern heads?

TA

Pocket

iTrader: (24)

The majority of this post is specifically for the larger port of the LT4 and vortecs and why you DONT need the LT4 when using vortec heads from a port matching standpoint

To answer your question thou, yes, people have modified LT4 intakes to work on vortec heads
They simply whacked the corners off and welded aluminum on for the mounting holes

In my opinion, it would be simpler to have the heads redrilled to the LTx pattern than to add material and realign everything from scratch

reference:
https://www.thirdgen.org/forums/alte...ght=vortec+lt4
https://www.thirdgen.org/forums/tpi/...ght=vortec+lt4

main pics if you want to skip the threads

junkcltr

iTrader: (1)

No, not that slot. Re-read what I was talking about with the intake gasket where it meets the cylinder head. That is, the EGR exhaust port interface to the head. See the big hole between the center two intake bolts...........see the big hole where there isn't any intake backing up the gasket? That is the problem.
The thing you described here is a nothing in terms of the EGR. You completely talked about the PCV passages which have nothing to do with the EGR problem.

IROCJoyce

iTrader: (4)

Pocket I sent you a private message about a week ago if your interested. Just didn't know if you saw it. Thanks

TA

iTrader: (1)

[QUOTE=Pocket;3883768]The majority of this post is specifically for the larger port of the LT4 and vortecs and why you DONT need the LT4 when using vortec heads from a port matching standpoint

Uh, taller ports have a flow benefit, and thus greater power potential, especially on a 383. My ports are already significantly taller than stock "truck" Vortec intakes, so an LT4 would be a smarter starting point for me.

Thanks

TA

Pocket

iTrader: (24)

You said vortec heads, which is what the post was about

I also gave several references to LT4's being cut up

Unless I missed something... question answered