Thread: Intake gaksets blowing out....

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I have a 406 SBC, 13:1, fairly radical cam (697 lift, 290 dur), solid roller, Dart block, heads. Motor runs very strong, and has gone 9.80's in a Vega, with 1 850 carb. I recently bought it, and proceeded to replace the intake with a Pro Dominator Holley tunnel ram w/ 2 660's. Again...this motor runs very strong, but blows out the front and rear intake seals as soon as I do a test burn out in my parking lot. I have breathers to the headers for crank case pressur evac. I have replaced the intake gasket 3 times....same situation. The intake looks good....like new....I picked it up from a fairly reputable seller at a swap meet......there are some of those. The motor is 23 degree. Is it possible that this intake was modified for an 18 degree application? Do you even have to modify the intake for that? Thanks in advance for any input.

i did re work a blower intake for pro heads the ports need to be re work by welding ports .i think what you have going on is that you need to lose the rubber end seals and use only RTV and you engine is not breathing and it going to find a way to vent your headers do not have the egr check valves in or they are junk try running it with your header hook up on start the car un hook it off your breather and if there is EX pressure pumping up your hookup hose then your egr valves can be bad

I have used RTV only.....I always do, but when this happened twice, I used the cork gaskets that come with the 1206 Fel Pro kit w/ RTV over them. Still blows out. I will check the egr valves as you suggested, but everything was fine until I changed intakes. Now, I'm wondering about the oil pan capacity. I bought this motor fully assembled, and was told by the previous owner that it was a 7 qt. pan, excluding the filter. Maybe he was wrong, and I over filled this thing. I need to find the mfg. of the oil pan, and confirm the capacity....I would imagine too much oil + high volume pump might = blown intake seals. Thanks.

the egr is a ez check and have had them go bad .your engine could be way over fill i never done that but could add to what you have going on but this is ez to tell the oil presure go s all over the place i have need told . was thinking the first thing that happens is you push oil out the dip stick if not vented good if you have a dip stick . did you do a comp check on the engine i never use RTV on any end gaskets they have a way to squirt out

use the 3-M (yellow) weatherstripping.

I did a compression check......150 -175lbs. I have used RTV many times before without any problems, but it's worth a try. I guess I will try the cork gaskets that come with the Felpro intake set....I'm not familiar with the 3-m yellow weatherstripping. Is that just a material you pick up at the hardware store, or is it specifically for gaskets? Thanks.

Forget about using ANY type of cork/rubber gasket that comes with the gasket package. Throw them away.... just use straight 3-m weatherstripping you can pick it up at Autozone or pretty much any where. Racers use it a lot

How big is the gap, it could be parts not matching correctly.

The gap appears to be between 1/16" and 1/8". I would think that's pretty normal. Thanks for the tip on the 3-m weatherstripping.

If this started with an intake change it probably is the intake. Or you could have damaged the motor doing the burnouts. Or you have to much crankcase pressure. Either to much blow by or not enough venting.

Originally Posted by BigTruckDriver

use the 3-M (yellow) weatherstripping.

yellow is good for rubber or cork but i never try to build a 1/8to 1/4 bead with yellow death your better with RTV yellow death as not much body to it the omc type M is much better the 3m yellow for rubber and cork if you have a boat yard round you that sells OMC

dont get it

yellow 3m cement is runny has no body to it to use just to fill a gap .rtv is better to fill gaps with out a gasket then yellow death is.3M to glue gaskets it is ok but not as good as it use to be. OMC type M is alot better for cement for rubber and cork gaskets

Originally Posted by BigTruckDriver

dont get it

i guses i did not get it till i look at it better you are talking about a 3m Wether Strip and is yellow .what i was thinking 3m weather strip yellow cement i sorry i will now go to my room

i too thought they are talking about 3M 1300 vinyl adhesive. AKA 'monkey snot' It is a GOOD gasket adhesive, but I have never heard of it being used for gasket replacement as is silicone.

[QUOTE=Mikej;342322]If this started with an intake change it probably is the intake.

I have to keep coming back to this, also. I've changed dozens of intakes, using cork, rubber, rtv, without problems. I guess the thing to do is to remove it, clean it up, and take it to a qualified machine shop to check it out. I am convinced that the crank case evac tubes are working, and if it had a hole in the piston, broken rings, etc. the motor would not be running properly. Thanks.