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2806178 Intake Manifold Replacement - What Date Code do I need?

Michael, you bought a vacuum gauge recently, right?
Have you hooked it up yet - that should clearly show if your intake isn't sealing.

Yes i did and it currently only reads 15". From what i've been told 17-18" would be normal.
 
I don't think 15" is an issue on an old engine if the needle is steady and the car idles and drives ok.
Have you tried spraying carb cleaner on the sides of the manifold where you believe it is leaking? Do it while the engine is running obviously - if the idle rpm increases then you have a leak.
 
I think we found the problem today.

Just take a look at the fitment of this NOS vs. New "Made in the USA" Fel-Pro Gasket:

image2.jpeg


More (Detailed) Pictures: Album — Postimages

Not only is the fitment of the new fel-pro gasket really POOR, its also noticeably lighter and thinner.

In the next few days we will take a look at the old manifold and decide weather we will reuse that or go with the new one
but looking at those gaskets i think this is probably the issue.

It's really a shame that you cannot even buy a simple metal gasket as a repro part these days.
If things continue to go this way nobody will be driving these cars in the not so distant future due to not being able to get parts that work!

One question:
The guy that helps me with this (retired mechanic) wonders if he should put any RTV at all or just put the NOS gasket in DRY?
I think the factory did NOT use any type of sealer - just the blank gasket - right?
 
So you're saying the retired mechanic didn't notice this the FIRST time you installed the manifold...and then blamed the manifold for being warped? So it isn't warped after all?

Is this a new gasket or are you re-using the gasket from last time (you could if it's only got 20 minutes run time on it)? I'm confused as to how many gaskets you have.

Regardless, that gasket looks like it can be shaped to fit the bolt holes, if not, just open the bolt holes up a bit (on the gasket obviously). Stick some bolts in one side of the manifold while it's upside down, press on the gasket and see how far the holes are off on the other side - you may find that they line up.
If you're referring to the ports - they never match anyway - that's why you port match an intake. Look how rough the openings are from the factory, the gasket always allows for this.

With regards to RTV - just use what you need to get the manifold to seal - don't get hung up on what the factory did and what your "survivor" car might like. If the gasket fits poorly then a light skim of RTV is fine or add the paper gaskets as suggested by others many times previously.

Be thankful it's not a small block with coolant passages to seal up as well - you're head would really be spinning.
 
So you're saying the retired mechanic didn't notice this the FIRST time you installed the manifold...and then blamed the manifold for being warped? So it isn't warped after all?

Well we noticed it but we assumed the poor fit was normal and tried to make the best out of it.
I still don't know if the old manifold is warped or not. But i hopefully will within a couple days...

Is this a new gasket or are you re-using the gasket from last time (you could if it's only got 20 minutes run time on it)? I'm confused as to how many gaskets you have.

I originally ordered 2 gaskets from 2 different companies but ended up getting 2 similar (fel-pro) ones from rockauto.
After the failed attempt to seal the intake manifold i ordered this NOS gasket. I will not be reusing the old valley pan gasket.

Regardless, that gasket looks like it can be shaped to fit the bolt holes

Of course it can be "massaged" for a better fitment, that's what we did on the first attempt. But this gasket is still a JOKE compared to the NOS gasket. As i said also in thickness and weight.
 
I still don't know if the old manifold is warped or not. But i hopefully will within a couple days...
Isn't it upside down on the workbench right now - for you to take all those photos that don't really show anything? Can't you simply put a straightedge on it - or are you waiting for a NOS straightedge to come from the US to be able to check?

There's more drama than Shakespeare here.
 
Bolt the gasket to the block with the end rails and leave it a tad loose and line up the ports and intake bolt holes on each head. This will tell you if it lines up or not. Before the intake goes on.
 
So today we finally re-did the job.
Car is back together, now we let it sit overnight for the RTV to cure and then tomorrow we will see if this time was a success or not.

For all the people that think we are to stupid to change a gasket here are a couple pictures what
the intake manifold looked like when we pulled it back out with the fel-pro gasket still attached.
Correct me if i'm wrong but i think you cannot do this any better: Album — Postimages

But once you detach the gasket from the manifold you see that it instantly goes back into its original form despite it has
been installed for at least a month by now: https://i.postimg.cc/bdXFyQT1/10-F31237-D47-B-4202-86-C4-3-C4-B3-A8-D09-CD.jpg
IMO those fel-pro gaskets are JUNK.

We checked the manifold for warpage with a straight edge + flash light and to be honest it does look good, we cannot find any signs of warpage or other damage.
Despite this we still went with the new manifold because for one the discoloration is somewhat uneven, a lot more in the center (below the carb) which i tend to believe is normal? BUT also we
are not a machine shop and that NOS gasket cost 150$ so i didn't want to risk wasting that money.
See pictures:

Here are even more pictures where you can see the cylinder head mounting surfaces etc.:
Album — Postimages (NOS Valley Pan Gasket install with RTV)
IMO everything looks very nice despite 95k miles on the engine.

If it's not leaking anymore then IMO the issue was that crappy fel-pro gasket.
 
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