New install with new headers and new gaskets on newly rebuilt heads. And it still leaks. Everything is torqued to specs. Using about a $30 Fel Pro gasket set. Only one side leaks. Doubled up on gaskets on the one side that leaks and all it did was push the leak around. Anyone ever had this problem and has anyone ever used RTV to help seal leaks? 350 rebuilt rocket in my 69 Cutlass. Didn't leak before it was pulled and rebuilt.

 

I have heard of guys using RTV to help seal header leaks, Have you given any thought about the Remflex gaskets or similar? I use them on my 76 with hedman headers and have had very good luck with them myself. I'm not familiar with the $30. Fel pro's.
I hope this helps
Eric

 

The factory didn't use a gasket. Is your cross over been filled and center divider welded flush? I use nothing but a thin coat of RTV. So far no leaks.I posted this with pictures on a thread some where. Glw your choice.

 

I used many different type of gasket to try to get my headers to seal. Theses are the only ones I've used that work well:

https://www.summitracing.com/parts/p...ake/oldsmobile

I also run a high quality set of Hedmann headers. If you have cheap Chinese ones that could be a contributing factor. I also use locking bolts:

https://www.summitracing.com/parts/p...ake/oldsmobile

Don't bother with the Stage 8 bolts, they're junk. I tried them before going to the Percy's bolts.

 

I ran the gamut on header leaks on my non-Olds.

I cut the flanges of the headers so each tube bolted up individually of the one next to it. That made a world of difference. But it wouldn't solve burnt gaskets.

What DOES eliminate burnt gaskets is going to the Copper gaskets. Mine have never leaked and they're even reusable should you ever need to take the joint apart.

 

You did not mention which side? Make sure the headers have no interference with anything that will keep them from mounting flush. I always go back and tighten all the header bolts after a couple of heat cycles. I never followed a torque spec, just tightened to a point I thought would work.

 

What brand headers do you have?

I have Heddman as well and never had any issues with leaks. I currently have regular Fel Pro exhaust manifold gaskets and they seal up fine.

 

I didn't have any luck with the Fel Pro gaskets.

 

I use a high temperature Permatex RTV on both side of the header gasket. Never leaked.

 

I have used these on our '68 Toronado with good success. The Felpros kept blowing out. I know that these did not come with gaskets, but once they get out of shape, something has to be done. In our case, they had been decked one too many times, leaving barely enough clearance for the dip stick tube.
No, RTV did not work for us. I even tried muffler cement, but the Toro big blocks just get too hot.

 

Back in the day I used to use two pair of Mr. Gaskets gaskets. They sucked individually but I would glue two together really tight with RTV. Once dry I'd soak them in a bucket then bolt them up and re-snug after use. They still sucked imo.
Soft copper or aluminum are the way to go these days although Remflex and Cometic make very nice gaskets also.

 

Did you soak them in water so the fiber gasket would swell?

Just trying to understand.

 

Try using the RTV to help the gasket seal. Also carefully inspect the header for a void in the weld, happened to me and once I fixed the void I was good. I still used RTV because I was working with old headers on an old engine.
Just the nature of headers to leak.

 

Yes exactly Olds64. They would swell and then tightening them and then starting the engine would bake them in place giving a better seal. I think the problem overall was they would become brittle and still tend to blow out.
The soft metal gaskets of today or the wire reinforced type are just so much better. Of course thick header flanges and not being a gorilla on the bolts helps.

 

I was considering installing new header gaskets when I tune up the engine before the spring. I liked the Percy's aluminum gaskets. I was wondering if these were any good:

https://www.summitracing.com/parts/p...ake/oldsmobile

 

Just a tip here, on these Olds heads, whenever you have them in for rebuilding/reconditioning I would recommend having the shop take a nice flat pass on the milling machine on the exhaust flanges.

I have never seen any of these heads after years of service with decent flanges, can't recall a single one. We mill EVERY Olds head in this area!

Thanks, Gary in N.Y.

P.S. Here's a shot of the flange on one head during a recent build. Difficult to see from the photo but if you look closely you can see where the cutter passed over much of the surface without touching it. Took close to .050" to make a good clean surface! Customer has absolutely no leaks whatsoever. Same goes for the thermostat flange area on the OEM intakes, these often need as much attention/milling also.

 

One thing I will caution people about when milling the exhaust port flange on the head is the header flange on the headers hangs below the exhaust flange on the head many times. Typically you will have the header flange hitting the block at that point and cocking the whole header and not allowing it to sit flat at that point which obviously leads to a huge leak.
You might scratch your head for awhile looking for that.

 

Don't bother tightening the top center exhaust bolt. I had good luck with the Green Felpro gaskets. I had to double up the gaskets on my Flowtech headers. Coat the gaskets in high temp RTV, let them dry, it makes a difference. I just did that with the stainless collector gaskets that leaked a wee bit cold, worked like a charm.

 

I'm happy I spent a few more bucks and got the Remflex Gaskets that Performance Improvements suggested. They do exactly what they claim to do when evenly torqued/tightened up.

 

I am happy to skip all the stuff the most of you are doing and just use the RTV.I moved the header thread in sbo forum to the top.I did that to refresh memory's that i did post a picture of my headers using blue rtv and no gasket. You can lead them to water but i will be damn if you can make them drink.

 

If you are going to use RTV make sure you use the right compound: