340 intake leak

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downsr

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What does every one use on 340 intake to seal it in the front and back.Do you use gasket and
sealant or just rtv or some other sealant.I was also told some use a plate in the front and back then set your intake on that.Is there such a plate you can purchase.Finally if you run a
breather on each valve cover should you still use pcv valve .Thanks
 
I always use the cork gaskets at the front and rear. With RTV to fill the gaps at the ends. I usually give the cork strips a light smear of RTV just to keep them in place. Also, RTV around the water ports on both sides of the gaskets.
I always run a PCV.
 
Use a large bead of Permatex blue silicone, plus make sure those dowel pins are removed from the block.

IMHO, if you have a good clean breather in each valve cover, there is no need for PVC.
 
I always toss the cork gaskets in the trash and run a thick bead of Permatex black RTV silicone on both ends of the intake. Then, carefully put the intake on and snug it down. I have had zero leaks with this method...I have had multiple leaks with the cork gaskets before going this route.
 
I use the composite gasket for the ports, the cork gasket for the ends. Gaskacinch on both sides of the gaskets, and clear RTV in the corners.

Don't forget to put sealer on the two center bolts on each side of the intake to prevent oil wicking up through the threads...
 
downsr said:
69-340-gts would it hurt to run pvc with the two breathers
Click to expand...

PCV has to pull the crankcase fumes out. You need the PCV valve on one valve cover, and a breather on the other valve cover. Usually this breather gets filtered air from inside the air cleaner, but if that's not feasible run a good filtered breather like a K&N.
 
Throw the end gaskets in the trash get yourself a tube of the"right stuff" put a nice fat bead on both end surfaces careful put the intake in place..
 
When i took the car out the first time a couple of days ago .It blew oil on top of the timing cover when i cranked it up, maybe from oil stick.I did not have breathers on valve covers .Did have pcv hooked to back of intake.I have a couple of valve cover breathers coming tomorrow.Should i still run the pcv with both breathers or it does it matter.
 
downsr said:
When i took the car out the first time a couple of days ago .It blew oil on top of the timing cover when i cranked it up, maybe from oil stick.I did not have breathers on valve covers .Did have pcv hooked to back of intake.I have a couple of valve cover breathers coming tomorrow.Should i still run the pcv with both breathers or it does it matter.
Click to expand...


There's a good argument in this thread on crank case venting. Read through it, and it can answer some questions....

http://www.forabodiesonly.com/mopar/showthread.php?t=309502
 
I agree with the use of rtv only. I have had to pull my intake or change it a few times and I have never had a leak from those areas.
 
downsr said:
When i took the car out the first time a couple of days ago .It blew oil on top of the timing cover when i cranked it up, maybe from oil stick.I did not have breathers on valve covers .Did have pcv hooked to back of intake.I have a couple of valve cover breathers coming tomorrow.Should i still run the pcv with both breathers or it does it matter.
Click to expand...

As I said earlier, the PCV valve goes in one valve cover, the breather goes in the other one. I suppose 2 breathers in the valve cover opposite the one with the PCV would be okay too, if that's what you want to know.
 
Positive Crankcase Ventilation means just that - getting enough ventilation thru the crankcase - pulling All the bypass gasses - the cylinder bypass gasses - into the intake for cleaner emissions - lowering overall emissions. Older engines used to dump the gasses out the back of the engine compartment via a dump tube. Modified engines are not especially compliant with burning all bypass gasses. More than one breather may or may not comply with the original intent of sucking ALL the bypass gasses from the crankcase.
As for the manifold gasket problem - the gaskets can be nightmares.
The manifold to engine/head distance is considerable at the front and rear and gasket sealer is not sufficient. AND Remember the PINs. Original manifold or aftermarket???

Above ALL - Take your time. It will be worth it. Hearing the thing run properly the first time Beats the Hell out of hours and hours of screwing around because of a vacuum leak.

Gaskets (if used should be cork - thicker and stickier in my opinion.) In either case let the silicone sealant - a good thick coat - cure on the base (engine side - with or without gasket) until firm - it should still be somewhat tacky but no release when touched. Then a layer - a fresh thin layer laid on the manifold side before installation. Install manifold. DO Not get in a hurry to Clean the Excess. Let it sit and cure before cleanup or you may pull Uncured Sealant from Critical Areas. This is a pain - but well worth the time - maybe even wait a few days before cleanup. It can take a long time for silicone to cure but well worth it.
A good startup without problems will allow you to concentrate on true top startup and performance issues rather than dicking around with a problem that will drive you crazy especially when you have fresh engine components needing attention.

Hope this is helpful.
Been There Done That University student, Retired. Just Yakking.

Later,
Bcudamatt
 
If you read the instructions that come with new Edelbrock intakes it specifically says do not use the cork gaskets, and only use RTV. It does work.
 
I am having this problem as well on a fresh motor. The front passenger side bolt has some sort of liquid that seeps through under the bolt head and runs down the block. The color is orange so I can't tell if it's oil or coolant or a mix of both. Would applying some sealant to the threads possibly stop the leak?

Oh and it's a Victor W2 intake if that makes any difference.
 
I was having oil leaking issues on my 460, so I was advised to set put a PCV in the passenger cover to the manifold and a spin on oil filer on the other that has a baffle and a nipple to attach a tube to go to the air cleaner. Did that and all my oil weeping "breather" issues went away. Seems to work well for a street engine.
 
There is no downside to running a PCV. NOT running a PCV has a couple of downsides.
Besides the above reasons for running one; Most carbs are calibrated to run one. The PCV is a calibrated,below-the-throttle-air-leak, and allows for proper synchronization of the transfer port timing. If you dont run one, you will likely have to increase the curb idle opening and very likely lose that sync. and run into tuning issues.
At high rpm theres a good chance the PCV will actually revert to near closed operation. Then the crankcase pressure has to find another way out. The factory solves this problem buy running a connector pipe between the valve cover breather and the air filter housing.
I have seen 2cfm going out the breather on a PCV equipped engine in good condition and not working very hard.Thats 2 cubic feet per minute.I have seen 4cfm when it was Wot. If it cant get out through a breather it will get out another way, usually messy.
If it needs 2 breathers the motor is either worn out, internally damaged,or working very hard indeed.
 
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