Another header gasket question
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Elder User
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Another header gasket question
So my 390 sounds like a lawn mower under the hood lol. Can someone recommend a decent gasket? There 8 bolt headers, not sure of the make as I just got the truck and would like to do this right the first time and have it last. I read other posts about rtv copper and plan on using it for insurance, back pressure isnt a problem and I dont know why they leak now but they definitely are. also how do I figure out what year my FE is? or dose it even mater?
Postmaster
Joined: Jan 2009
Posts: 4,584
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From: Chesapeake, Va.
So my 390 sounds like a lawn mower under the hood lol. Can someone recommend a decent gasket? There 8 bolt headers, not sure of the make as I just got the truck and would like to do this right the first time and have it last. I read other posts about rtv copper and plan on using it for insurance, back pressure isnt a problem and I dont know why they leak now but they definitely are. also how do I figure out what year my FE is? or dose it even mater?
gaskets should last for years if you do it that way, mine have.
Posting Guru
Joined: Jul 2003
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There is a reason for the exhaust leaks..
1. header is warped.
2. head, "exhaust side" is warped.
3. bolts are loose.
If #1 buy new headers.
If #2 surface the head or heads.
If #3 tighten your bolt sequence as per Moto Mel suggests.
You should not have to use two exhaust gaskets if everything is right.
I use Felpro gaskets on most of my engines. Some race application heads use special gaskets.
1. header is warped.
2. head, "exhaust side" is warped.
3. bolts are loose.
If #1 buy new headers.
If #2 surface the head or heads.
If #3 tighten your bolt sequence as per Moto Mel suggests.
You should not have to use two exhaust gaskets if everything is right.
I use Felpro gaskets on most of my engines. Some race application heads use special gaskets.
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Postmaster
Joined: Jan 2009
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From: Chesapeake, Va.
The system I've been using has been with the kind of soft OEM type and Mr. Gasket parts. The biggest cause of blown header gaskets is improper torque and not doing the multiple retorques needed, almost always once the gasket starts to leak it's too late to retorque because the damage has been done.
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I know what causes it max and I dont have a ton of money for new headers or to re-surface the heads. I have had headers leak with brand new heads and headers on a 5.0 efi, i tried everything from extra thick gaskets to copper race gaskets, i wish I knew about copper rtv back then.
Posting Guru
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I know what causes it max and I dont have a ton of money for new headers or to re-surface the heads. I have had headers leak with brand new heads and headers on a 5.0 efi, i tried everything from extra thick gaskets to copper race gaskets, i wish I knew about copper rtv back then.
Sometimes you get a bad set of headers from the factory. They should not leak if the surfaces are flat and the bolts are tight. I use stage 8 locking fasteners on my race engines, because of the many heat cycles and vibration. They work for me.
World's Best Locking Fasteners & Locking Nuts and Bolts STAGE 8
Postmaster
Joined: Jan 2009
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From: Chesapeake, Va.
When you are working on a budget, a man has to do what he has to do.
Sometimes you get a bad set of headers from the factory. They should not leak if the surfaces are flat and the bolts are tight. I use stage 8 locking fasteners on my race engines, because of the many heat cycles and vibration. They work for me.
World's Best Locking Fasteners & Locking Nuts and Bolts STAGE 8
Sometimes you get a bad set of headers from the factory. They should not leak if the surfaces are flat and the bolts are tight. I use stage 8 locking fasteners on my race engines, because of the many heat cycles and vibration. They work for me.
World's Best Locking Fasteners & Locking Nuts and Bolts STAGE 8
If you do it the way I suggested I don't think you will have a problem. I've built a lot of FEs and have never seen warped exhaust side flanges on the heads.
Posting Guru
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Then you have been lucky. I have seen warped exhaust side heads. I have been working on and rebuilding FE engines since 1962. It is not a common occurrence, but it does happen. I have a set of 1970 428scj heads that had to be surfaced on the exhaust side just recently. I have seen 390 and 352 heads that also needed resurfacing.
When I purchased our Edelbrock rpm heads for our 434, they needed surfacing on the combustion side, and they were new in the box.
Things happen, and it is always good to check.
Thick gaskets and lots of rtv can hide problems.
When I purchased our Edelbrock rpm heads for our 434, they needed surfacing on the combustion side, and they were new in the box.
Things happen, and it is always good to check.
Thick gaskets and lots of rtv can hide problems.
Mountain Pass
Joined: Jul 2010
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You could try Percy Soft Seal gaskets. They are pricey (~$40 pair) but are made of aluminum and thick, so when you torque down on them they deform and conform to the surface well. They are even supposed to be reusable.
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From: saxton pa.
Header Leak
I would check the alignment of the headers to the head ports. Some headers only seal by a small amount. It may help to slot the bolt holes in your headers to get a better alignment. Just as a example the 390 in my 57F600 wrecker with a set of headmans would blow gaskets regularly , I discovered that the ports didn't line up with headers , only had about a 1/8th in seal. I slotted the holes and no more problems . I used stock style manifold gaskets and silicone. I hope this helps.
Have a great Day ----- Hotwrench
Have a great Day ----- Hotwrench