Cadillac Owners Forum banner

Fast 92 intake rebuild

3174 Views 20 Replies 3 Participants Last post by  Billfrombyron
Hi guys, the Fast install manual isn't particularly helpful, and I cannot seem to locate any videos or other guides/diy on how to replace the inner seal. My problem is that I've figured out that the bolts and nuts which go around the perimeter are missing from mine, there are 6 ea - 3 up front and 3 aft. I am also missing the valley cover bolts, so I ordered the full fast hardware kit, which has these missing pieces.

I have ordered a fast rope gasket, but cannot find any good info on how to install it. Anyone have some pics? All else fails I'll figure it out and take a very nice diy video for my channel and update here so someone can hopefully be aided in the future.

Does anyone know the torque for the fasteners on the front and rear? Not the manifold torque.

The problem with it sealing began with the shop removing the button head screws and replacing them with standard bolts, and just got worse from there. I don't understand why they chose to do this, and I'm still pretty pissed about it, but I also take it as an opportunity for growth and learning as I will be making a diy video of the install process to aid those in this situation going forward.

Now the rear half of the seal is destroyed and the lower to head seals are destroyed.

I've cleaned it all up, and the porting work was done by someone very skilled, it's a thing of beauty and I really want to get it back on the car asap.

There is not much difference between the LS2 and fast 92 stock performance wise, but after heads and cam I have really noticed a difference since switching back to my LS2 stock manifold.
Wire Drawing Branch Plant Sketch
Tire Automotive tire Bumper Auto part Automotive exterior
Auto part
Auto part Engine Vehicle Car Automotive engine part

Also FYI for people swapping back to stock LS2 manifold with LS6 length injectors, you need a 1/2" spacer. I already had the FAST kit, so I had to find long enough hardware. The steam vent bolts are long enough to the mm to secure the taller injectors and rails to the manifold.

Any pointers from people who have done it are appreciated!

See less See more
1 - 14 of 21 Posts
Here are some pics of the damages now that it's all cleaned up.

I caught it just right, and if I had caught it later on, it would have ended horribly for me.

The hex head bolts did some superficial damage, but nothing that's not repairable easily.

I did a white light inspection for cracks and found none. I'm going to scuff the bottom outer shell, do a layer of DP190 to provide a layer of abrasion resistance surface just in case. When I install the button heads, I will fill the cavity with a mold release and then rtv just in case it makes contact.

I'm also considering a layer of DEI heat foil to see if IAT drops any.

Automotive exterior Photography Automotive lighting Metal
Audio equipment Auto part Subwoofer Rim Metal
See less See more
I'm not sure what I'm seeing. I think the circular marks are what I'm supposed to see, but I don't know what those are.
What you are looking at is the damages from the hex head bolts.

It's from chaffing against the hex head bolts on the bottom shell of the fast 92.

This is why I will add a layer of epoxy based filler material, to ward off any further potential chaffing. I'll be installing the FAST button heads as I've ordered a full hardware kit, and doing this as a precaution.

Got everything built up Thursday night and installed Friday morning.

I made sure to take a good video of the build up. The fast gasket wasn't long enough, so I reused some of the better condition pieces and placed the new ones around the perimeter and closest to the edge.

FYI when handling the fast 92 off the car, you use nuts to pull the intake pieces together, via the center 4 intake mount holes, this allows you to smoothly compress the seal and install the 6 perimeter bolts.

I used a lot of permatex black high temp to hold the lower to the mid piece as it's the only way to seal it properly.

All in all it's a 3 out of 10 for ease of doing, but 7 of 10 for attention to detail.



See less See more
Here are the 2 videos I ended up making. I'm a far cry from a Hollywood studio, so please don't be too critical about the super awesome editing.

This is the build up for all 3 parts and how to seal it properly.

This is the install part that covers the injectors and fuel rail, valley cover bolts etc and removal only f the stock intake.

I have some other diy stuff on the channel also, and I'm documenting everything as I go.

See less See more
Whatever you do, don't order that gasket set as it's not for an LS2/6 no matter what felpro says! Same for the TB gasket.

The part numbers for the fast stuff, o rings etc is legit and good to go. You need the larger injector O rings to seal the fast 92 properly, and the fast directions fail to mention that tidbit.

The felpro gaskets I showed in the video are not right. I am not 100% what they go on, but it's definitely not an LS2.



See less See more
Just realized the reason I didn't find the gasket info is because I was scanning through the 2nd, longer video. If I had watched the first couple minutes of the first video, I would've seen it. Oops.

Anyway, when I had my intake off recently I used the ACDelco 12533587, which I seem to recall looked like the brighter green ones in your pics. I also seem to recall that the gaskets that came out looked like the Felpro ones. Based on your second pic, it looks like the Felpro ones would work, they're just a different style.

Have you talked to FAST to tell them their gasket/rope replacement part is too short? That's pretty crazy that the manufacturer's own part isn't right!
The gasket was a freebie from a friend with an extra on hand, So I doubt fast customer service will aid me on that issue. It's holding quite well, so I am considering it a done deal.

The different style lower seals from felpro are for a ls3 intake, and may seal for a while, but isn't the proper part for the application.

I'm going to take a few minutes and exchange the gaskets later on next month during some down time for the same ac Delco gaskets you mentioned. It's pretty quick to accomplish now that everything is setup properly.

The gaskets which are lighter green towards the end of the build up video are my serviceable spares from the previous intake. I may just purchase the fast seals as they are $20 cheaper. I'll figure it out when I get there.

I located the previous proper button head screws for the fuel rail spacers, and swapped out the hardware.

I also decided to torque check the installed hardware and they snugged up another 1/4 for every installed bolt.

Torque check is a simple process and should be done with the fast hardware as it is well documented that it can loosen up on the various LS forums. Simply set the torque wrench to 89 inlbs and follow the sequence.

As they were all uniformly 1/4 turn loose, I can only assume this is the seal internally settling.

I will check them again tomorrow and if they move again, I will repeat the process and install a bead of torq seal, which will provide visual evidence of the bolt backing loose. You can do the same with a fine tip sharpie marker.

Changed back to stock mounting bolts. The fast hardware will not stay torqued.

I even verified the calibration on my torque wrench. Been tearing my hair out because it won't stay torqued. Even with loctite.

I will recheck the hardware in the morning before work to make sure it stays put.

For a more scientific explanation of why the fast bolts suck, see this link.

But just don't use the fast bolts and everything should be good.

See less See more
It will again be coming off. Sigh.

Intake bolts keep loosing torque. I've got 3 sets of hardware, and all 3 sets won't stay tight.

I've ordered a thread cleaning tap and yet another set of stock bolts. I'll update of I figure it out. I'm assuming junk/oil on the threads of the cylinder head are keeping the thread locker from properly adhering.

Well, that sucks. I'll admit to having never re-checked mine on the couple of occasions I've installed it. Based on what you're seeing, I suppose I should!
Good news is that they have stayed put the last few days.

I took some pipe cleaners and worked then through the mount hole threads, then again applied a dab of everyone's favorite blue goo.

I've torque checked it daily and no changes, so I feel I'm out of the woods almost. (I've learned to never say never with this car).

My new lower intake gaskets arrive next week, so it's coming out again to exchange them, and the current lower gaskets will be again put into my serviceable spares box. I went with the FAST part number 54009-8.

When I pull the entire intake again, I'll really get in there and clean/degrease the threads properly.

The neat thing about all this headache is that it will help the next guy down the road. And I've gotten to the Jedi skill level of pulling an LS2 intake on the car. :)

See less See more
Going to be pulling the intake off again to add a heat shield to the base of it. 1 it will add a layer to the bottom to provide abrasion protection, and 2 hopefully limit heat transfer. There will still be a 1/8" gap between the intake and valley cover.

Should be a fun product, and if it works as advertised, I will add some to the volant box to further reduce engine heat entering the filter, and will add their intake sleeve to further the experiment.
If all goes well, I will have ambient temperature for my IAT and I'll consider anywhere near that to be a success.

See less See more
Someone will need this information one day.

The intake manifold mount bolts are M6x1.0mm thread and 110mm length under the bolt head.

McMaster Carr sells them, part number is in the image, or you can search and find it using those parameters I listed above. The new ones are grade 12.9, which doesn't mean much for only 89 inlbs of torque.



See less See more
  • Like
Reactions: 1
1 - 14 of 21 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.