Cometic Intake Manifold Gasket - Heat Passage Blocked

[Mongoose930]

I am planning on starting the disassembly and testing of my engine tomorrow to address the white smoke coming out of one of my side pipes. Hoping it is just an intake manifold gasket. Whatever the problem is, I will still need to install a new intake manifold gasket at some point and I just noticed that the Cometic C5137-060 gasket set I ordered does not have the heat passage cutout. Should I cut this out or leave the passage blocked? I also have a set of of Felpro 90145 gaskets that I bought when I was planning on using the cork for the front and real rail - Cometic does not include these two gaskets. Any opinion on which gasket is better of these two? I have Edelbrock aluminum heads and and a Blue Thunder aluminum intake manifold.

[undy]

Heat passage open = a bit better cold drivability, a slight quicker warm up.

Heat passage blocked = better performance due to colder/denser air charge, a bit more HP. A bit crankier cold engine.

In a Cobra my vote's for leaving it blocked. Performance is PARAMOUNT!

[lovehamr]

I wouldn't use the cork end gaskets either. I use The Right Stuff.

[DonC]

Use about a 1/4 inch bead of RTV silicon or, as recommended, the Right Stuff for the end gaskets. The cork tends to want to drift around when you're installing the manifold and when you're tightening the bolts. As I recall Edlebrock recommends the RTV over cork or other material.
If you don't feel you need every erg of performance out of the engine open up the heat passage. It makes for a more civilized cold motor.
DonC

[ERA Chas]

I don't think E'brock's even have a heat passage-do they?? No high-perf aluminum heads do that I know of.

[Mongoose930]

That's a great point. I was looking at the Felpro 90145's next to the Cometic C5137-060's this morning and noted that difference but when I looked up the Felpro 1247's which have been the bane of my existence, they do not have a provision for the heat passage. I guess I will know for sure tomorrow morning when I take the manifold off. All of that worrying for nothing...

[fordracing65]

Originally Posted by lovehamr

I wouldn't use the cork end gaskets either. I use The Right Stuff.

Is this a must, (the right stuff) I've heard of it, do all engine builders use it.

[Rick Parker]

It is far superior to RTV.

Mongoose930: Go to Edelbrocks site and see if the heads you have utilize a heat passage, then use your own good judgement on which gaskets to use.

[Mongoose930]

Hi Rick,

I just checked out the Edelbrock site and the heads do NOT have a heat passage so I was getting a bit ahead of myself. For the front and rear rails, I will be using either the "Right Stuff" or what KC uses as I have a few cans of that also:

https://kimballmidwest.com/Catalog/C...6#lnkgrdItems0

[ERA Chas]

Get FelPro 1247 S-3 intake gaskets. Barry has them.

[bobcowan]

Originally Posted by fordracing65

Is this a must, (the right stuff) I've heard of it, do all engine builders use it.

Originally Posted by Rick Parker

It is far superior to RTV.

I use it occasionally, but not often. The up side is that it seals really well, and will cure to usability in less than an hour. I had to do an overnight gasket change on a race week end, and that worked really well.

Of course, just like anything else in life, there are a couple of down sides. It's very expensive, 2-3 times the cost of a tube of good RTV. It sets fast, so you gotta move. No messing around. Get that manifold on straight and torqued down pretty quick. Because it forms such a strong seal, it can be a bear to take apart and clean up later.

I generally use standard RTV with good results.

One trick for installing the manifold. Because of the rapid cure time, you want to get the manifold set in place correctly the first time. If you have to shift it around much, you displace the gasket and disrupt the sealant. Then you have to buy a new gasket and start over.

There are a couple of tricks that make this job really easy.

- Put a light smear of whatever sealant your using on the gasket around the water ports, front and rear. Just a light smear, and only on the head side. Set the gasket in place exactly where you want it, and press down for minute or so. That will "glue" the gasket in place so it doesn't shift while you install the manifold.

--- I also put a small smear on the other side of the gasket around the water ports. I'm not sure that's really necessary. But it seems to work, and I'v never had a failure.

- Get a couple of bolts (or a piece of All-Thread) the same size as the manifold bolts. Cut the head off the bolts, and cut a screwdriver slot in one end. Screw those into the head holes as guide studs. Then you can drop the manifold over the guide studs and into place correctly the first time. You'll probably have to adjust the manifold a little bit, but usually not more than about 1/16" or so.

[blykins]

Originally Posted by bobcowan

- Get a couple of bolts (or a piece of All-Thread) the same size as the manifold bolts. Cut the head off the bolts, and cut a screwdriver slot in one end. Screw those into the head holes as guide studs. Then you can drop the manifold over the guide studs and into place correctly the first time. You'll probably have to adjust the manifold a little bit, but usually not more than about 1/16" or so.

Works great for a small block, but won't work on an FE...

[undy]

Originally Posted by bobcowan

- Get a couple of bolts (or a piece of All-Thread) the same size as the manifold bolts. Cut the head off the bolts, and cut a screwdriver slot in one end. Screw those into the head holes as guide studs. Then you can drop the manifold over the guide studs and into place correctly the first time. You'll probably have to adjust the manifold a little bit, but usually not more than about 1/16" or so.

That's sorta hard with a FE...

[lovehamr]

Originally Posted by undy

That's sorta hard with a FE...

A note with that; remember that the distributer determines the final resting place of the intake, so it needs to be ready to stab as well. Only after the dizzy is in and NOT bound up should you start snugging down bolts. Lots of weird requirements for FEs.

Steve

[RICK LAKE]

Rick Parker Rick A good RTV sealer from GM, Ford or Honda will last as long if not longer than the right stuff. Right stuff drys and cures too fast. Over time it hardens. 10 & 15 years on a motor build without a leak with gray RTV. Have never seen Right stuff last that long. Other down side is cleaning of removal. If job is a couple of years or less in age, a good sharp razor blade will remove from surface. Longer time needs chisle and hammer or grinder. Only down side to RTV grey is curing time of 24 hours. You can still move gaskets around within the first 2-3 minutes. You don't have this with Right stuff.


Mongoose 930 The grey RTV will work better than the cork gaskets on the front and back of the intake. Need 2 guys to install manifold and install the distributor quick to center and others have said. Just make sure that the ports on the manifold and heads match the ports on the gaskets. Also check the coolant passages for gaskets not blocking flow. This happens on the Fel Pro 1247 ones and need to trim openings and then RTV both side of gaskets. Good luck. Rick L.

[Mongoose930]

Hey everyone - thanks for all of the great advice. I just pulled the plugs on 5,6,7 & 8 and turned her over. Lots of antifreeze coming out of 8 and it looks like some in 7. I kept turning it over with the fuel pump fuel pulled and the coil wire connected to the spark tester until no more oil / antifreeze spray. Cleaned and gapped all the plugs. Did a compression test. 190 on 5,6 & 7 and 210 on 8. Took me about an hour to get the anti-freeze residue out of my compression tester. This would lead me to believe that it is an intake gasket failure that caused the white smoke. I will be pulling the valve covers shortly and will let you know what I find.

[bobcowan]

Originally Posted by undy

That's sorta hard with a FE...

Oh yeah, I keep forgetting about those wierd Fe motors; I havn't worked on one in a long time.

Now, a small block..........

[lovehamr]

One of the few times that I would ever disagree with Rick but I've gotta raise the BS flag on his Right Stuff (TRS) bemoaning. TRS is an OEM approved sealer and gasket maker for a lot of manufacturers for a reason. Going beyond that, I as well as many others here and other boards have used this stuff for a few years without having to use a "chisle and hammer or grinder" on disassembly. Then there's the "haven't seen it last that long" comment. If that is the case then you haven't looked very far. You only have to google the test results to know that TRS easily outlasts RTV. If you don't want to google just take a look outside. See any stock cars or trucks out there that are less than say 15 years old? Then you're most likely seeing the same compound in use and lasting 100s of 1000s of miles.
Here's a list of manufacturers that say it works:

Automotive OEM Interchange
The Right Stuff
GM 998 5990 998 5675
12378479 10953472
998-5990 998 5675
12346286 12345997
Ford WSE-M4G323-A6 TA30
Chrysler GF-44-A GF-44-B
MSGF-44B 04883971
Daewoo PS 9120016
Land Rover LRNA-25223
Mercedes Benz A0029897320
Mitsubishi 3M8663 3M8672
3M8678 3M8679
3M8661
Saturn 21019581
Toyota 00001-01001 00295-00102
00001-01002 00295-01208
00295-01282 00295-01281
004403007 TB1215
TB1207 TB1217B
3MT3#08670
Right Stuff GREY
GM 998 5943
Ford WSE-M4G323-A3 TA29
WSE-M4G323-A4
Chrysler GF-44-D 82300234
Honda 296380 08718-0001
296380 08718-0003
Heavy Equipment OEM Interchange
The Right Stuff
Caterpillar 4C9612
Detroit Deisel 23509603
Mack 5166-58730
International 1653885C1
Volvo GM V1111015

To take it even farther, some well-known engine builders here use it as well and have tested the living crap out of it with their own pocket-books. Does it set up fast? Yes, you need to have your fecal matter fully congealed before you go smearing it around. But, as soon as you bolt the thing together you have a full seal. There is no waiting around on curing time. Is it expensive? Yes, but you don't need a lot unless you ignore that other rule.

Bottom line; TRS is superior to normal RTV in all performance aspects and is only beaten in cost and lazy cure time.

Well, that's my rant for the year, Steve

[blykins]

I use it on every intake manifold that I bolt on.

It doesn't set up that fast though, you have plenty of time to get everything positioned, bolted, and tightened.

[ERA Chas]

Originally Posted by lovehamr

Well, that's my rant for the year, Steve

Agree 100% with your rant and you back it up with impressive facts.
I've used it extensively from it's inception and it's the real deal. The only material a smidge superior is Motorcraft TA-31 Gray, used extensively by Barry and the whole diesel trade.
And anything that works as well as these do should not be easy to undo. My secret is my trusty 1", ultra thin blade spackle knife.