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Intake Residue Question

Road Grabber said:
How do I check the fit of the gaskets to see if the ports line up and determine what thickness gaskets to use? Do I use a new valley pan gasket for a test fit?
How do I know just steel, one gasket, two gasket, one thick , two thin…
I’d like to do this once….
Thank you
Click to expand...

I'm not exactly sure I follow the questions, are your questions pre or post machining? Here goes:
1) How do I check the fit of the gaskets to see if the ports line up and determine what thickness gaskets to use - In short, if the intake bolt holes are relatively centered with the threaded hole in the head, you'll be fine. Probably do this without the pan. If you start with an assembled motor with an intake that fits, just do the math.

2) How do I know just steel, one gasket, two gasket, one thick , two thin… - Use two per side, what ever fits.
 
beanhead said:
And then there's Edelbrock. I have four of them out in the stash from different years of production, and the angles and thickness of the sealing rails are/were all over the place from the factory, top to bottom, side to side, and front to back. Some fit 'okay' and some fit like ****, regardless of the block/head combo. So sometimes you end up needing to mill the manifold as well to get a precise fit.
Just like neat little snowflakes, every one's different...
Click to expand...


I would argue that the intake is usually the problem. I have had really bad aftermarket intakes and the gaskets will seal the bad intake angles. Milling the head intake surface and using paper gaskets is not about fixing the angles, its about make room for the gaskets for sealing the bad angles.
 
BSB67 said:
I would argue that the intake is usually the problem. I have had really bad aftermarket intakes and the gaskets will seal the bad intake angles. Milling the head intake surface and using paper gaskets is not about fixing the angles, its about make room for the gaskets for sealing the bad angles.
Click to expand...
I was talking about intakes, I guess I didn't really clarify. I've had trouble relying on gaskets to seal angle mis-matches so I just have them milled to correct anymore...my guy here is very good and only charges me $40 per side. Leaves no excuse not to make them right, even for a cheap sumbitch like me!
 
beanhead said:
I was talking about intakes, I guess I didn't really clarify. I've had trouble relying on gaskets to seal angle mis-matches so I just have them milled to correct anymore...my guy here is very good and only charges me $40 per side. Leaves no excuse not to make them right, even for a cheap sumbitch like me!
Click to expand...

I fully understood. DP4B and CH4Bs are the worst I experianced. They are terrible. The intake will noticably rock corner to corner when set directly on the heads. The pan gasket can only tollerate a few thousandths of an inch gap, but 0.060" worth of paper can tollerate a lot lot more. The only time I have seen the paper not work is when someone tries to stuff them in there when there was no machining (intake or head) to allow them to fit properly.
 
BSB67 said:
I fully understood. DP4B and CH4Bs are the worst I experianced. They are terrible. The intake will noticably rock corner to corner when set directly on the heads. The pan gasket can only tollerate a few thousandths of an inch gap, but 0.060" worth of paper can tollerate a lot lot more. The only time I have seen the paper not work is when someone tries to stuff them in there when there was no machining (intake or head) to allow them to fit properly.
Click to expand...
That's interesting to know, my issues were with RPM's and Torkers.
FWIW I'm currently using Trick Flow's intake, that one fit very nicely with no rocking around or odd gaps.
 
beanhead said:
That's interesting to know, my issues were with RPM's and Torkers.
FWIW I'm currently using Trick Flow's intake, that one fit very nicely with no rocking around or odd gaps.
Click to expand...

As I thought about it since my last post, the DP6B I had for my 383 was actually the worst. The Indy 2D I'm using now is pretty bad. But unless you measure a bunch of stuff, you really don't know the magnitude of the contributing causes. One dowel pin hole off is all it takes, not to mention the other 10 or so key machining steps.
 
There is excellent information on this in Hughes tech articles. Sorry I can't provide the link
Road Grabber said:
I had used two paper gaskets from the Felpro 6pack set. They are two thin gaskets. They worked great on my 6pack aluminum manifold but they must have been too much for the 383.
How do I check the fit of the gaskets to see if the ports line up and determine what thickness gaskets to use? Sorry if I didn’t pick that up somewhere else.. Do I use a new valley pan gasket for a test fit?
How do I know just steel, one gasket, two gasket, one thick , two thin…
I’d like to do this once….
Thank you
Click to expand...
 
Road Grabber said:
Thank you. Really appreciate that reply. I like the carb plate idea. I have to scout out some material.
Would this require using a fresh gasket after the test? Leaving no stone unturned here…
Click to expand...

You can test it with a used valley pan and use a set in gaskets that come with a new valley pan.
Double check, as some valley pan kits come with and some without a set of 4 gaskets before ordering.
After the fitment check you can use a new valley pan and gaskets if required with a coat of permatex to ensure good sealing.
I made a gasket to seal of the carb flange with the lifting plate and installed a quick disconnect fitting on the brake booster 1/2" connection on the cyl #7 port.
Then i applied a slight pressure from my compressor reservoir to pressurize the intake (with the rocker shafts removed) and used soapy water to check for leaks.
It's just a double check during installation to make sure you have no vacuum leaks that cause trouble later on.
 
Or you could simply start the engine go for a ride and check for a leak. Spraying stuff is a 50/50 deal at actually finding a leak. Just cover the carb.

Going for a ride a is important. Initially, it might present as sealed. You need to go for a ride, run the engine to your max rpm and take your foot off the gas and let it decel, causing max negative intake pressure. Probably about -25 mmHg. I’ve had this happen too

Man, it’s amazing how this stuff come back to you after over 40 years.
 
BSB67 said:
Or you could simply start the engine go for a ride and check for a leak. Spraying stuff is a 50/50 deal at actually finding a leak. Just cover the carb.

Going for a ride a is important. Initially, it might present as sealed. You need to go for a ride, run the engine to your max rpm and take your foot off the gas and let it decel, causing max negative intake pressure. Probably about -25 mmHg. I’ve had this happen too

Man, it’s amazing how this stuff come back to you after over 40 years.
Click to expand...

Great stuff to pick up. My aluminum six pack manifold gave me trouble for awhile. I took it to a shop and he ran it over a large wide belt sander and discovered it was warped. No problems afterwards. I also found that it was better to flatten the valley pan intentionally and permatex both sides using the felpro gasket set specifically for six barrel application with four thin gaskets. It provided more surface area. One thin gasket placed on each side during assembly. I noticed the metal valley pan was sealing fine on one side protruding out but the concave side wasn’t really crushing well with the double thin gaskets. it may not be what others here would do after reading through these posts but it did work well just flattening out the metal and gluing both sides.
 
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