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I have a 1990 Bonneville with the LN3 3800. The lower intake manifold gasket is leaking again, so I am planning to redo the gasket and replace the intake manifold bolts as well. However, I cannot find the bolts online. I found some 3/8-16'' bolts on Summit but those are for the RWD 3.8. It seems the FWD 3800 bolts are nowhere to be found.
 

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You can note the thread and length of the bolts (below hex head) and head to ACE/Lowes/Home Depot/etc. and buy fresh ones in Grade 8 for standard, 6 lines on top, or metric 10.9 recommended. I went with stainless ("THE" on cap) for mine when I dressed it up, since it's not a high-stressed connection requiring the stronger material. Be sure to put 2-3 laps of teflon tape on each one, since they may go into water passages like the Series 2/3's.

Edit: My L36 lower intake with stainless bolts and NPT-plugged injector holes (using ported L67 heads with their own injector ports)... random pic during removal earlier this year, now swapping to Holden L36 intake.
11010
 

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I don’t recommend Teflon tape for that. Teflon tape is not actually a sealer, it’s meant for pipe threads as a thread lubricant as that style of thread seals from the tapered wedging effect.

To seal those bolts use Permatex Aviation sealant. I’ve used that on repairs for almost 20 years, 15 of which professionally.
Use it on bolts into liquid passages, and paper style gaskets. There’s also a Loctite product specifically made for bolts into coolant or oil passageways. 614 maybe?? Not sure on the number.

Edit: Loctite 567 is the thread sealant. It’s high temp, better suited for head bolts.
 

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It's sometimes fun to be contrarian, but tape has been used by myself and many successful others for the 20yrs we've been building these engines and others. I've built 3800 engines for 10-11-12 second engines that last for years afterwards on the street, for myself and fellow enthusiasts. This is also the recommended method by vendors who've proven their process at even higher volume and power over the decades.

Unless you're going to spend more money/time getting all new OEM replacement hardware with pre-loaded sealant on threads, this is the proven way that thousands have successfully completed this process. There are certainly alternatives like the sealants you mentioned, but it's been common for people to have much more trouble properly applying them, even with instructions available, because the chance of over-applying, etc. increases significantly.
 

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Use whatever you like, if it works it works. I was merely pointing out that Teflon tape was not meant to be a sealant and that other products are far superior for that purpose.

IMO Teflon tape looks messy, has potential to flake off causing debris contamination to fluids and has a higher risk of application failure. I’ve seen plenty of inexperienced people apply Teflon tape with 10-15 wraps or the wrong direction with the threads etc.

The GM factory bolts come with that reddish pink sealant applied to the threads, not Teflon tape. Just sayin.
 

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If we did things that only fit the original intent, this market and our engine bays wouldn't exist and life would be much more boring.

Application mistakes are the responsibility of the user, and over-wrapping tape is much more intuitive to avoid than globbing on a sealant. Of course, I acknowledged the factory items, and am discussing how it is done in the aftermarket and home version.
 

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If we did things that only fit the original intent, this market and our engine bays wouldn't exist and life would be much more boring.

Application mistakes are the responsibility of the user, and over-wrapping tape is much more intuitive to avoid than globbing on a sealant. Of course, I acknowledged the factory items, and am discussing how it is done in the aftermarket and home version.
And I’m discussing how it should be done. There’s the right product for the application and products that work.

If I needed a hammer and had a rock in my hand but the hammer was available by choice. I think I’d choose the hammer because it’s what’s meant for the job.
 

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PTFE tape and PTFE paste are two form factors of a similar polymer that perform the same function. There are various extents you can go to for building a setup, and can prop some on a pedestal over others, if you want... for fuel lines: -AN lines, hard tubing, nylon tubing, injection hose... Multiple things to use that all can perform the function correctly, be taken care to install properly, and so on. Some will swear by a certain version they've fully bought inti from their personal use, but negating another version of something purpose-made for the same function isn't in good faith. Hence, insinuating that teflon tape is a neanderthal's rock, compared to a modern person's use of a hammer is a false dichotomy that is trying to, demean a valid method for your purposes.
 

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PTFE tape and PTFE paste are two form factors of a similar polymer that perform the same function. There are various extents you can go to for building a setup, and can prop some on a pedestal over others, if you want... for fuel lines: -AN lines, hard tubing, nylon tubing, injection hose... Multiple things to use that all can perform the function correctly, be taken care to install properly, and so on. Some will swear by a certain version they've fully bought inti from their personal use, but negating another version of something purpose-made for the same function isn't in good faith. Hence, insinuating that teflon tape is a neanderthal's rock, compared to a modern person's use of a hammer is a false dichotomy that is trying to, demean a valid method for your purposes.
Thread seal tape (also known as PTFE tape, Teflon tape, or plumber's tape) is a polytetrafluoroethylene (PTFE) film tapecommonly used in plumbing for sealing pipe threads. ... Thread seal tape lubricates allowing for a deeper seating of the threads, and it helps prevent the threads from seizing when being unscrewed.

Permatex Aviation Form-A-Gasket Sealant Liquid is a slow-drying, non-hardening sealant. Ideal for close fitting machined surface. Approved for use in aviation as well as automotive applications. Helps seal cut gaskets. Resists gasoline, oil, anti-freeze and axle fluids.


LOCTITE 567 is an off-white, UL approved, low disassembly strength methacrylate thread sealant, ideal for sealing coarse threads up to M80/R3”.
LOCTITE® 567 is an off-white, low strength, thixotropic methacrylate thread sealant. It cures in the absence of air and by contact with metals when confined within threads up to M80/R3”. It is best suited for use on coarse metal threads and its breakaway torque rating is 1.7Nm. Viscosity is 280,000 - 800,000 mPa·s and service temperature -55 to +150ºC.
-Provides an instant low pressure seal
-Doesn’t creep, shrink or block systems
-Single component - clean and easy to apply
-Thixotropic and high/very high viscosity
-UL approved
  • Solvent-based sealing compounds can shrink during cure as solvents evaporate. Fittings must be re-torqued to minimize voids. They lock the assembly by a combination of friction and deformation.
  • PTFE tape lubricates in off direction, allowing fittings to loosen under dynamic loads and resulting in loss of clamping force and leakage. Dynamic loads may accelerate creep, causing leakage over time. The lubricating effect of PTFE frequently results in over-tightening of fasteners, adding stress or causing breakage of parts. Application requires good professional skills to avoid stressing fittings or castings.
  • Hemp and paste are slow to apply, are messy to assemble, and interfere with the torque needed to obtain the correct pre-stress. These can require re-work to achieve a 100% seal of the assembly.

These are all reasons why Teflon tape is a rock. Permatex for intake bolts, Loctite for head bolts/studs.
 

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I can quote things, too, but that doesn't negate any of my statements that both acknowledge your point while providing reason and evidence that alternatives aren't less viable. Hold up the pamphlet all you want, I'll keep building successful engines.
 

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I can quote things, too, but that doesn't negate any of my statements that both acknowledge your point while providing reason and evidence that alternatives aren't less viable. Hold up the pamphlet all you want, I'll keep building successful engines.
I’d say keep hammering away at those builds but instead I’ll say keep on rockin’ instead 👍
 

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Appreciate the sense of humor. 👍
 
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