I'm finally making a thread on this site after lurking for so long. On my 87 Vette with a TPI I'm installing a converted LT1 intake and patriot heads. I know the heads take a 1206 gasket and the intake takes a 1205. When I set the intake in place it covers the ports but I know there is not much coverage. I have read on this forum that the stealth ram has the same problem and you need to add aluminum to the intake and have it milled. Has anyone done this with an LT1 intake and did it seal without welding? I would love to install this intake manifold this weekend but if welding and milling is needed .....i guess I'll be pushed back a week or so. Off topic, if John Millican is still a member of this forum, I want to say thanks. All the information on that LT1 intake site and posts I have read on this site have helped me a lot.

The new version of the stealth ram can be ported to the 1206 size...the old castings do require new material.

The LT1 intake i DO believe can be opened up to a 1206 port


i think thats a 1206 on a LT1. its VERY close but it may seal enough. you have to widen the port .03" which isnt much, and raise it .12" to match a 1206. It should match but its hard to say how much material will be left to seal. take a 1206 gasket for the head and place it on the intake to see how much room you have


Here's another thread discussing it
http://www.thirdgen.org/techboard/al...e-got-lt1.html (Has anyone got a LT1 intake to seal on 1206 ports?)

That looks alot like the 1205 gasket I have (I have the 1206 gaskets too)
I'm not worried about porting it to match the gasket. I just want to know if it will seal or not.
There is not a lot of overlap above the ports on the heads.

I actually knew that about the stealth ram. Won't fit under my hood though.

To be on the safe side, i'd port it all out first, and get material welded to it if you havent already. IF your heads have EGR ports you'll need to cover up the LT1 intake EGR port as well with extra material as seen above. that gap is huge

Also around the water jackets, that area reallly needs material to seal well.
When i was doing the swap, i just used epoxy putty called QuikSteel. I'm not sure how well it would hold up to the heat of a motor, but it was pretty strong when attached to the manifold in the right way, wouldnt pop off. Kinda brittle tho, it would crack when hit hard or dropped alittle so i decided not to do the swap and got a HSR instead. i didnt want to weld material, too much money invested, might as well get a HSR

I have TFS heads ported to a 1206 and tried a converted LT1 intake that was port matched to a 1206 and it would not seal at all. Had internal vacuum leaks and the coolant ports were leaking into the lifter valley and out to the exterior. I had them siliconed and let it sit for 24 hours and still no luck.

I installed a HSR a month or so ago on the same heads. I did not port the heads to the 1206 (left them 1205 for now) and it sealed perfectly. No problems at all, and plenty of vacuum at idle... and there is plenty of meat on my newer casting of the HSR to actually port to a 1206... I checked.

Thanks Chris',

I think I'm going to go for it.
I am not going to port the intake so I'll have as much material as it will offer even though most of it is not in the right spot.
I'm not ready to by a new hood for my car so the HSR isn't an option.
you mentioned silicone, what did you use exactly. I have heard good things about "the right stuff" and my plan is to circle the ports with it.
Lots to do after the intake is on so it will be weeks before I turn the car over even if I do the intake this weekend.

Orr', I didn't see the link in your first post until a few minutes ago. Good reading, thanks.

you can shave the plenum and top of the base down alittle to get it to fit. some guys have done it


And i have used Right Stuff for my build and it works GREAT.

The pic has stock L98 gaskets

Im using 1206 gaskets in my LT1 intake right now with no issues

You dont port out coolant passages
Install the intake correctly before you say it cant be done

RTV sealant is your friend
A light bead circling the ports never hurts
Be sure to get a good seal around the water jackets and china walls

Thanks Pocket,

What heads are you running with your LT1 intake?
Are the heads made for the 1206 gaskets, is this why you are using them.

I appreciate all the good advice, there are many people who have done similar builds. I was hoping to hear from at least one person who has insalled both the Patriot heads and an LT1 intake.(on the same engine)

The intake is going to get 3 coats of red and 2 coats of clear today. Hopefully I can install it Saturday or Sunday.

Wow... no ****? I never would have guessed that!

I didn't port out the coolant passages you moron. Thanks for the guess though.

The intake ports the heads, and the intake ports on the LT1 intake were matched to a 1206. Not the coolant ports!

I didn't say it can't be done, but I discussed my luck w/ the intake. The main issue I mentioned in regards to the 1206 ports and gaskets is in regards to the INTERNAL VACUUM LEAK that created a situation where there was little to no vacuum at idle. Small problem when you are cruising around and using power breaks!

I've personally seen 4 different guys put an LT1 intake on their L98 w/ no luck. Two of us w/ aftermarket heads (my TFS and 89gta383's AFRs both with 1206 ports) and 2 stock headed L98s that all had the exact same problems I did... internal vacuum leaks and coolant ports not sealing EVEN WITH RTV SILICONE. I even installed w/ RTV around the intake ports along with the coolant ports and still could not get rid of the vacuum issue. It was sucking air from the lifter valley along w oil...

But again... thanks for assuming I was a complete retard.
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I use Copper RTV silicone that you pick up from the local parts store. Has always worked great for me.

that was great

Thanks Chris, I have the copper and the right stuff here.
I've heard more success stories with the right stuff so I think I'm going to use it.
When you say internal vacuum leaks do you mean from the seal or somewhere within the intake itself?
If it's a sealing issue I may be able to get lucky and make it work. If its a design issue with the intake itself maybe I need some JB weld or something but I need to know where to spread it.

I have spoken to many who have made this swap work and are very happy with it.
It's not helping my confidence any knowing that 4 people you know couldn't get it to seal.

Im using Topline heads, they need the 1206 gasket

Prove that you're not a complete retard and Ill take your word for it
Its a conversion intake, if you cant do it properly, buy a miniram

Im one of the many successful LT1 swappers

Correct he has a poor seal somewhere
Whether he forgot to seal up the plugs on the underside, poor port seal, loose vacuum line or bung, bad seal around the TB, missing injector O rings or some other blatant screw up where air is going in where its not supposed to

when i was doing my swap i had to add material around the intake ports as well as coolant ports just to get enough material to seal against the stock L98 heads!

i dont believe you can do it without adding the material to help seal. I had the coolant ports drilled inthe back of the manifold and used quick steel epoxy to make more gasket sealing surface..i just never ran it to see if it worked but i think it would have. I rather have seen metal on it tho since i am not sure how strong epoxy is under constant heat cycling that a motor goes thru.

you can kinda see the buildup of material around the coolant nipples at the back of the manifold

Pocket, Tell me more about these plugs on the underside that could be a potential leak.

Thanks Orr',
I can see where you added material around the cooling ports.
Looks like it should have worked but who knows how the epoxy would hold up.

I just finished painting my intake. Too late to add material now.
2 coats of primer, 3 coats or red and 2 more coats of clear.
At least it looks good, even if it never works.

i'm sure you could touch it up if you need to add material via epoxy. i just didnt trust it. If you weld material, then yeah i bet the intake paint would burn off

Look at the pic near the top of the thread

Those ports

Okay,
This is the first I have seen where someone filled those holes with JB Weld or whatever that is.
Mine are all like the center one. Should I remove the threaded inserts and fill the holes?

Who would know if an epoxy like JB Weld would hold up if I use it to extend the material around the intake ports?

best way to know for sure is take a spare piece of metal and put that stuff on it. then run it thru a fire or oven or something to heat cycle it.

And plus 1 on those holes... mine were all threaded and not open

Well congratulations. I bet retards everywhere are rejoicing your accomplishments!

I know people have gotten it to work, and I know that there are great success stories. I'm just passing along the information that I personally, along w/ another member here had issues w/ getting a John Millican converted LT1 intake to seal when using a 1206 intake and head port. Anyone that is interested needs to know that there are POTENTIAL issues with it. A lot of guys go into it thinking it is a simple bolt on, which both you and I know is not the case.

My situation did not end in a successful swap. I gave it a good effort with the help of 89gta383 and we BOTH had the same issues with our setups. Those issues also showed up with different intakes, on different cars, with different installers and stock L98 heads...



Man you are really on a roll. You gonna be here all week w/ the veal?

There were none of those issues that you are suggesting my "weak" intellect or "non-mechanical" skills would have produced. The intake simply did not work. Plain and simple. Glad you and the other guys got their's to work, but my experience is different. Due to that I ended up w/ a HSR and love the product. To each their own...

My guess is that the bottom of the intake ports would not seal causing air to be pulled from the lifter valley along w/ the oil I found in the ports on the heads.

So Chris, what do you think the problem was (with your itake)?
Is it a sealing issue? intake doesn't sit properly?
Something else?

That's a great question. I found oil in 6 of 8 of the head ports and oil on the actual gasket. The RTV I put around the ports also was sucked in as if the air had pulled it through into the head ports.

The intake were torqued per spec, and I tried it with both a 1206 and 1266 (twice as thick gaskets) and it did not work properly. The heads were only milled to ensure flatness (.002) and the block was zero decked so I could get the best quench possible on the 355. It is possible that the block being decked played a part in this, but I don't think so.

Again, I am not trying to dissuade you from trying the swap. I'm simply trying to ensure that you know there COULD be issues that come up.

Hopefully the SUCCESS stories can help and weigh in w/ any issues they had and HOW THEY FIXED them!

Thanks Chris, I have heard about the intakes sitting too high on the heads because there is too much material at the front and back china walls.
It isn't able to drop enough that the sides fit tight.
Maybe if you had the intake milled at the front and back, the sides would have dropped and it would have fit better.
Your thicker gasket shold have has a similar result but i don't thing any gasket will fully overcome something that just doesn't fit.

I'm going to measure how mine fits tomorrow, before I actually install it.
I'll use a feeler guage or something.

It's possible. I definately recommend test fitting WITH the intake gaskets to see how it sits. I tested mine before and I had plenty of room on both china walls for the intake to crush the gaskets. Something just did not line up correctly. I can't remember how much room there was, but I use RTV instead of the cork gaskets, always have, and it sealed fine in both the front and back.

I threw my corks away earlier today.

I can vouche for the strength of epoxy under heat cycleing. My brother put epoxy on my mothers old cracked water furnace like 8 years ago and it lasted for about 3 years. The crack was directly above where the flame hit the water furnace so it was under direct heat and cooling. It eventually failed but 3 years of direct heat is pretty good. I doubt an intake will ever get this hot.

thats good to know... i think LT1intake used to use JB weld for alot of stuff too so it must be strong enough. the intake never gets that hot anyway

I would only worry about the expanding and contracting with heating and cooling. I would assume the JB Weld would expand and contract at a different rate than the aluminum.
The seam is the only place I figure it would fail.

Here are some pictures of my intake as it is now.







I think it's a 6 to 10 footer.
Looks great from 6 to 10 feet away.

looks better than mine did

not bad you really cut out that back egr boss

That is so that I can use my huge stock vette distributor.

Looks great! I was thinking of taking the EGR boss down as far as you did. I have a lot of time to work with my LT1 intake before I actually get the chance to put it on my 1980 Vette. I'll probably reduce the boss further and fill it with JB weld for aesthetics.

It's on my car now.
I hope it seals.

Paint isn't quite as nice now. LOL.
just touch it with a wrench and the paint comes off.
I'm sure I can touch it up once I'm done with the fuel rail, lines, cooling,etc.

Still lots of work to do on it to be finished but there is still about 2 feet of snow on the ground here so I have lots of time.

You can cut alot of the EGR part off

This is how far mine got trimmed

It got powedercoated black afterwards


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Also, I didnt see any buildup on the waterjackets

Have you test fitted to make sure they will fully cover?

I did test fit it and it looked like it covered. I'm not sure by how much or if it will work long term but I went for it.
My concern was more with the other ports than with the cooling, they were closer to not covering.
We will see how good 'the right stuff' is.

if used right, it will work i bet. I had good success with it as well as my local LSx shop. they swear by the right stuff

I have my fingers crossed.
I did the best I could with following instructions from this and other forums, the permatex website and what ever other information I could find.
The only thing that might throw a wrench into the mix is that my garage only has a small portable heater and it was damn cold in there.
It was likely 10*F in the morning when I went in and turned on the heater.
The warmest it likely got was 32*F but the engine would have still been colder.
I won't be starting the engine for a couple of weeks or longer so if it just takes longer to set I shouldn't have a problem.

yeah it should setup ok. i kinda let mine somewhat setup for a few minutes before i started snugging the bolts down. that way not much material squeezed out

I think it took me more than a few minutes just to get the bolts in and finger tight.

thats the issue i had too me awhile to get the bolts in and ready to be tightened. So it had a chance to start setting up before i snugged it down. you should be fine if you covered everything.

Yeah the RTV packages tell you to let it setup w/o being crushed for a few minutes. I let mine setup by itself for about 5 minutes, then slowly started to apply pressure. For as much as I had put down, it worked well b/c not much squeezed out.

It was just a little tacky to the touch... which is what I wanted.

Is this with your HSR, LT1 or both?


So, last night I walked into the dining room and sitting on the table is the metal sheild that is supposed to attach to the bottom of the intake.
GM must have put that on there for a reason.
Anyone know if i'm going to run into any problems without this thing?

I'm guessing it is to keep the hot oil off the bottom of the intake and out of the one little hole that goes to the large port on the drivers side. PCV valve I think.

It keeps hot oil from splashing onto the bottom of your intake

Minor heat shield

I couldnt use a stock LT1 shield with the distributor so no-go for me

I didn't even think of the dizzy, If you had fitting issues, I likely would have as well.
Thanks.

Both

Thanks Chris, I was just asking because without reading the thread over again, I think I remember you didn't have much luck with your LT1 intake.

Good to know it wasn't the procedure that was the problem.