Advise from engine builders, I keep blowing intake seals?

[fastzcars]

As the heading saids, I keep blowing the rear intake seal? I've got a sbc 383, I've got the PVC hooked up to the carb from the passenger side valve cover and a small K&N breather on the driver side? This is the third time it does it. The first time when I went down the track. The second when I decided to try to run without the PVC valve, It blew right away! Now the third time when I was reving it, after an adjustment to my carb. I know it has to be crankcase pressure buildup. Maybe I need a bigger K&N breather? Any input would be great! Now I have to take that intake off one more time.:cuss:Thanks for listening!

Luis.

[grumpyvette]

naturally the main problem is cylinder pressure getting past the rings, but adding a couple breathers , and a working PVC should help,

Id suggest all valve covers with dual breathers on one side and hooking the PVC to the other valve cover

http://www.midwestmotorsportsinc.com/order_part.php?item=CP146&line=MWM

 

 

step 1

throw the rubber front and rear intake seal bars in the dumpster

 

step 2

clean the block rails and the matching intake surfaces with acetone,or toluene soaked shop rag. clean all previous gasket material and sealant off the heads and block surfaces with a gasket scrapper or razor

 

step 3

place a 1/4" wide bead of black silicone sealant along the center of BOTH the block rails and lower intake mateing surfaces,place the port gaskets and align the bolt holes with the holes in the cylinder heads and put a small bead of sealant around 360 degrees of the water transfer ports,on both sides of the gasket, on both gaskets then place the intake straight down into place so the wet sealant beads mesh, blend and squeeze out a bit.

step 4

tighten slowly in stages working from the center bolts outward, use a #2 phillips screw driver to make minor adjustments to the intake thru the bolt holes if it moved a bit durring the install, then drop into place and thread all bolts finger tight before tightening any of them,.

 

step 5

 

allow to dry for a couple hours minimum over night,will be better, before use

 

OPTIONAL but RECOMMENDED

 

use a sharp object to DIMPLE both upper and lower surfaces to give the silicone sealant a firmer grip, by lightly dimpling the surfaces over a large surface

[pparaska]

Grumpyvette - thanks for the tips! As usual!

 

I'm having this issue with my latest build also. I have a breather in one valve cover (going to the air cleaner, and it is not pushing oil into that area) and a PCV valve on the other cover.

 

Sustained 6000rpm on the straights at VIR last week had oil coming out of the back of the intake/block interface on the passenger side. I do know that when I had to pop the intake at the 11th hour before leaving last week (Professional Products Crosswind, like the Edelbrock RPM Air Gap), that it completely separated from the Ultra Black RTV I used around all of the ports and water passages and the front and rear block rails (I was reusing Fel-Pro gaskets with blue sealing rings, so I used RTV everywhere oil could get to air, etc.)

 

NOTHING stuck to the manifold. I had cleaned all surfaces with Berryman's carb cleaner. I will use Acetone next time. The manifold has a machined surface that catches the fingernail, so it's not smooth. I will use the dimple mark method on the block and remove all RTV and new gaskets this time.

 

This problem stole one 30 minute track session from me as I tried to determine and fix the leak. As it turned out not much was actually leaking so I put it back on the track. I couldn't even measure the leaking amount on successive dipstick checks. But I want this FIXED!!!

[Guest 350zgto]

Dimpling...I use a punch, make a bunch of random dimples on the intake manifold mounting surfaces, can also be done on the block and head surfaces. If the RTV beads are blowing out, might try using the gaskets for the ends of the manifold and Gaskasinch. Eldebrock sells Gaskasinch, but it is also available at auto supply stores.

 

If there has been block or head milling, it will cause some misalignment for the intake manifold, but if your bolt holes are lining up well, then this is not an issue.

[Guest 350zgto]

Left out this thought in my previous post....while racing, on the track as you are..remove the PCV valve, it has a little snap ring holding it inside the breather, or get a breather cap with a hose nipple and no PCV, a common aftermarket part. Drag cars vent from the valve cover right into the headers, no PCV. You will be making a bigger exit for crankcase pressure and eliminate any chance of the PCV valve fluttering.

[fastzcars]

Thanks for the input guys!!!! I'll be dimpling my intake!

[Turbo Meister]

Luis,

My twin turbo engine requires large ring end gaps for heat expansion. This creates much blowby. I vent the valve covers to an overflow bottle.

In order to remove my intake manifold I have to use a crowbar, it is on so tight. Say goodbye to your blown intake seals if you use "The Right Stuff" by Permatex as I do. I have blown pistons, in the past, and had the seals stay intact.

See you at Irwindale.....when it cools down!

Hanns

[fastzcars]

Hey Hanns, It's nice to hear from you Hanns! So you say " The right stuff " . Is it a silicone? or a varnish? I don't recall seeing it at the auto parts stores? Then again my memory isn't so good any more! I used the dark grey permitex silicone. So you have both valve cover breathers connected to a bottle? Do you have a PVC valve connected any where? Do you leave out the rubber/cork end gaskets? Whats your install technique?

Hopefully we'll see you at Irwindale!

Luis

[Turbo Meister]

So you have both valve cover breathers connected to a bottle? Do you have a PVC valve connected any where? Do you leave out the rubber/cork end gaskets? Whats your install technique?

Hopefully we'll see you at Irwindale!

Luis

 

No cork end gaskets

No PCV

The stuff can be obtained in any local Auto Parts Store and it is black silicone.

Clean front and rear engine rails with lacquer thinner.

Apply a thick bead of the stuff and allow to sit 5 minutes before carefully placing manifold onto engine.

I also glue the intake gaskets to the head with the stuff. However, it will only come off in little pieces when you need to take the intake manifold off.

Both breather hoses enter a overflow bottle. But I never see any oil because the valve covers have baffles glued on just below the valve cover openings. You know what I used to attach the baffles that have been there the last 6 years.

Hanns