67Olds442X2

I'll start by saying that my heads were milled on the exhaust side to bring the center divider flush. This has made it difficult to seal the headers at the head because the head and block are not flush anymore, the exhaust side is indented slightly.

I started with the Mr. Gasket #5945 Ultra seal which worked awhile until it started leaking. I just install the Mr. Gasket #7170 Copperseal and it leaks at all ports. I even filed down the bottom part of the gasket to try to fit the lip where the head and block meet. Might not have filed enough.

I'll assuming I need to build out the area to make the head and block flush. Anybody had this problem before? Wonder if I can use two Copperseal gaskets, they seem like good gaskets. Maybe a flat metal gasket then the Copperseal.

Attached pic.

Thanks.

oldcutlass

Have you tried to double up on the Mr Gasket Fiber ones? I've also soaked them in water prior to install and then retorqued after engine warmup.

Rickman48

You might try to find another flange, maybe 3/8 inch thick, from one of the header manufacturers.
It'd bring the headers to more of an intended angle, and using 2 copper gaskets should seal it up forever.
I've used the capscrew bolts that require allen wrenches with the star type lock washers and they seem good after retightening them twice after heat cyces.

380 Racer

Try not using the center bolt.

67Olds442X2

I'll try the center bolt option then if needed I'll double the fiber gaskets or copper. I did try a stock type gasket with the fiber and it worked for a short time. I had one available at the time so figured I try it.

Thanks for the inputs.

67Olds442X2

Well I tried the Mr. Gasket white fiber gasket and applied some copper RTV around the ports. I trimmed the bottom part of the gasket so it wouldn't hit the lip on the block. Also left out the center bolt. Ran the engine for 5 minutes, which I guess was enough time to blow out a piece 1/2" long on the bottom center of #3 and #5.

I think I'll try the two gasket route sealed together with the RTV. I'll use the ultra seal gaskets. Maybe I'll try the copper gasket in between the fiber gasket and head since I already got one. Something has to work.

ah64pilot

I have an idea, but it isn't as cheap as a gasket...but I think it would work.

You could get a header flange blank (head side) without pipes and then put a gasket between the blank and the head and another between the blank and the header flange. This would make up for what was machined off of the exhaust ports, theoretically.

Also, I use Doug Thorley gaskets and have never had one leak. You might invest in 2 sets ($18 each set) and the blank header flange and call this one done...maybe

Shizzy

what headers are you running and what do the flanges look like? do they have a raised weld bead on the gasket side? If so that isn't helping any.

67Olds442X2

I think my problem is the pipes or header ports are not flush with the flange. The ends stick out somewhat and are pinching the gasket maybe. I should have checked this out before installing the engine. I may have to remove the headers and grind down the ports so the whole face of the flange is flat.

Picture shows header doesn't bolt up flush.

67Olds442X2

I got Doug Thorley, 70's era headers and yes I think the weld bead is the problem now that you mention it.

TripDeuces

How about milling the bottom of the header flange so it doesn't hit the block.

ah64pilot

My Doug Thorleys seal really well but require the use of the Thorley gasket.

Just a thought, are your collectors bolted up to the pipes? I think I remember you saying you have an X pipe which wouldn't allow the headers to cozy up where they need to be.

67Olds442X2

The bottom of the header flange doesn't hit the block, so I'm good there.

I do have an X-pipe and 3" pipes which seems to put pressure on the headers, they're kinda heavy. May have to adjust them somewhat to take the pressure off the headers.

TripDeuces

My bad, I thought I read that in the post earlier. I see I was mistaken. With exhaust systems you need to start at the front and move backwards to the rear of the car. Sounds like you've figured out the the exhaust system is splaying out the header collectors and cause the leak and bad seal. You'll have to adjust the pipes in front of the X pipe to fix it it seems. Good Luck

67Olds442X2

No problem. Yeah I got to adjust the pipes again. There's pressure on the headers but not a lot. I got a show to go to this weekend and I'm going to try a stock manifold gasket cause it's available, I'll put RTV on that. Who knows, maybe it'll work.

Lalo442

As long as the flange is flush should seal , I was having a problem with blowing header gaskets first the stock ones that came with my Flowtech headers , then tried copper gaskets couldn't get them to seal either finally tried Percy's carbon gaskets worked like a charm and have only had to retorked a few times ,,,..here is the ones I got

http://www.summitracing.com/parts/PHP-68039/

leadfoot067

http://catalog.remflex.com/

these gaskets work!!!

michael hilsabeck

remflex dose work tryed alot of gaskets but that one realy works it worked on my 350.

67Olds442X2

I'll give the Remflex and/or Percy's a try if what I'm going to do fails. Thanks.

ah64pilot

Mondello has Edelbrock heads, complete, for $1579...you know, in case you were contemplating fixing the REAL problem LOL!

67Olds442X2

Yeah that would be sweet.

The stock exhaust gasket seems to be working for now, but have other issues. Two rockers came loose and broke two push rods, had one come loose a few weeks back. Using Comp Cams Die cast aluminum rockers and the polylocks are not working. The tips of the hardened push rods broke and not sure where all the pieces are. Time to put the car away for now.

ah64pilot

That's odd...bad product you think? Are you running a hyd cam? I could only really see that happening if the lash was set incorrectly on a solid cam but you'd have to really wrench down on it to have that problem with a hyd. That sucks man...

Run to Rund

I bent the header flange with Remflex and they tore after one use. I use Summit copper, number xxx440 or something, trim about 1/4" off them so they don't hit the block. Check that the header flange is pretty flat because youj might have bent it with soft gaskets and high torque on the end bolts; bend it back. My heads wwere also milled, about .19" or so on the exhaust side.

Shizzy

here are a couple of pics to illustrate what Im talking about.

This first one shows the center ports and where they leak. Again, this set leaked right out of the box. the area that is the worst is the area on the bottom between the two center ports. with the gasket laid on the flange there is only about a 1/16" area sealing.

IMG_2968.jpg

in this second one is after I ground the welds own and then went over the flange with a 40 grit belt sander. Its not ground all the way down yet, but you can see ill now be using the whole entire flange and not just a 3/8" wide weld bead. IMG_2974.jpg

I did however grind most of the way through the welds so Ill be re-welding the tubes to the flange. In the end it will be a few hours worth of work, but its the only way to get them to seal properly.

67Olds442X2

Thanks for the pics. yeah mine are raised slightly just around the ports and I'll grind them down if I run out of options. The stock gasket I put on with the RTV seems to be holding up for now. Only ran for a hour until the valvetrain gave out.

JamesPDX

Sorry, it took awhile for my account to be activated. I started this dialogue on 01 May. It is long, but has relevant information, with little opinion.


I do not care for the Mr Gasket and similar thin and low end gaskets. The fiber or copper gaskets are good. I like FelPro for most of my gasket needs and use Remflex for my head gaskets because they are thick carbon gaskets that compress 50% under normal torque specs to make a very good seal. I’ve not used Percy's carbon or Doug Thorley gaskets, but I've heard good recommendations on them. The primarily exception is with my Porsche and VW builds, where I use Gasket Cinch rubber cement to hold the cork gaskets to the valve covers, and a few thin paper gasket hear and there because of tight tolerances and things just fit correctly.

I prefer to retain the center bolt, but maybe with a little less torque (5 or 10% less). I use Grade 8 bolts (ARP or equivalent) throughout my assemblies (180,000). Where there may be issues on the Olds, I use a blue RTV sealant except for high temp like exhaust connections. I also, use AN fitting where ever I can for reliability.

You were right on about using a second header flange between the heads and headers with a pair of gaskets on each side of the flange. This has worked well for me You might check also for good clearance where there are brake lines near the headers.


The header flange is typically designed to be parallel with the mating head surface. Poor workmanship on welding the tubes to the flange may leave too much tube extruding through at the top or bottom and cause the headers to rotate into the starter or the brake line. I insulate the header pipes from the oil and transmission sumps, the cooler flow lines, and anything that I want to keep away from those hot pipes.

I was pressed to get it running and installed two gaskets and no center flange on the left side. This worked well until I had a short developed at the starter causing the starter to run non-stop. The short was caused by the metal backing on the insulation material that I used. I immediately disconnected the battery, and the next day, I removed the starter and header because to correct the problem. The headers and starter had to be R&R because there was no room to access anything. Again this was a poor header design.

On Wednesday I installed a solid .063” copper flange (that I fabricated) between 2 RemFlex RP11-003 (350 heads) on my ’79 412 Olds (.040” over). This is to adjust for Headman headers that were not welled correctly. I did not realize that the off angle caused by the misalignment (angle) does matter. It pushes the hot pipes directly against the starter and crushed the upper part of the gasket more than the lower part. This can also cause a gasket to blowout. I’m also adding 3000 degree F shielding to protect the starter, in addition to other insulation (advisable in all situations).

Do not use aluminum for a spacer flange. While it is used for intake manifold and heads, the heat is dissipated easily but as a flange there is no way to dissipate the heat and will break down to cause problems. The melting point of aluminum as ~1220, whereas brass is ~1700 and copper at ~1980 degrees F. The cost of copper is ~10% more than brass but twice that of aluminum. Copper is best. My flange took 1 ½ hours to make, and the header took 3+ hours to file by hand.

Best of all (2 weeks ago), after a 1 hour engine break-in drive along Marine Drive, I took a 3 day trip to Seattle and back from Portland without a problem. Check the following averages: Speed @ 70 mph, Water temp @ 170-180 F, Oil temp @ 160-170 F, Oil pres @ 80 psi (60 psi @ idle), TH-4R Trans temp @ 150-160 F, and 15 mpg . I estimate (and felt) a gain of ~60% increased torque and ~40% increased HP over my stock 307. I’m very pleased with these increases and the reliability that I built into the engine. The only issue that I had was with the exhaust to starter clearance (poor workmanship on the part of Headman).

Like AH64Pilot said, the push rods should not have broken unless there was an installation mishap, like a torque issue. Check each of the rocker base studs for the correct torque. You may have missed some during the assembly. I installed Mondello roller rockers with .040 orifice push rods (8.500”) and locked things down with PolyLocks, and have no issues.

I found the same narrow sealing area that Shizzy had, when I pulled the headers off, but mine did not leak. Again, I reworked the left side only correct the starter short issue. I used 2 new RemFlex RF11-003 gaskets and the .063” copper spacer. Today it ran fine. My heads do not have a center post between the middle ports. I needed to re-weld the headers after grinding off the flat post to make it more rounded.


I took a lot of photos, but this is too long already, to show them.

67Olds442X2

JamesPDX, thanks for the info and suggestions. I'm still working my valve train issue then I'll do the headers.

roamer

I know this may sound a bit funny, but have you checked to make sure that your exhaust system has enough flex? It sounds like your engine has a bit of torque and will probably rock a bit in the engine mounts. If your exhaust doesn't have enough travel on the rubber mounts it will resist the engine's rocking and the header could actually slide (very slightly) across the gasket until it comes hard up against the header bolts.

67Olds442X2

It could be an issue and I need to check it out. The engine moves quite a bit actually.

JamesPDX

Good call Roamer. It is also possible that there is not enough header clearance to the frame and cause the same wearing on the gaskets. This and even less torque could present an issue with the motor mounts and head(s). You may rethink your intended use of your engine.

My engine is up and running very well. I achieved the intended purpose of reliability with ample thermal control throughout. Excessive heat is a major cause of failure, especially for the Siamese 403 block, compounded with a .040 over-boar. There is ~3/16” separation between the cylinders. The compression ratio must be kept below 9.5 and 9.0 preferably. My displacement is ~410.08 not 412 with a compression just under 9.0.

ah64pilot

Did I miss something? I believe your post just got hijacked...PDX just wants to interject how well his engine is running? What does this have to do with headers not sealing properly?

No matter how hot an engine runs there IS a gasket that will accommodate it. And I don't believe there was a problem with burning through gaskets, only that the header won't seal properly because the exhaust flange on the head has been milled.

JamesPDX

So how different is that from what others have done (not to make it right). The point was not to boast, but to give useful relevant info, suggestions, and examples. I do feel proud of a job well done on my first Olds build without specific training or Olds experience. I also have ample background with Porsche and VW builds from my own professional shop (in the past). Although, I did studying and I learned a great deal from this project. To others, don’t fear the unknown, just prepare for it.

ah64pilot

"This and even less torque could present an issue with the motor mounts and head(s)."

Less torque? What are you talking about? I'm not trying to be mean but this doesn't make sense to me...if he had less torque his engine wouldn't move as much and the exhaust wouldn't bind as much.

"You may rethink your intended use of your engine."

Are you suggesting he rebuild his engine to make less power because he has a header sealing problem? I really don't get it.

"My engine is up and running very well. I achieved the intended purpose of reliability with ample thermal control throughout. Excessive heat is a major cause of failure, especially for the Siamese 403 block, compounded with a .040 over-boar. There is ~3/16” separation between the cylinders. The compression ratio must be kept below 9.5 and 9.0 preferably. My displacement is ~410.08 not 412 with a compression just under 9.0."

I really don't understand how this is pertinent to the conversation. I'm kidding when I say you hijacked the thread but to see you defend yourself makes me want to point out the shortcomings of your post. I am, however, delighted to see that your engine has developed a hog problem...like much of the Southern U.S. •BOARS have become a real problem.

Shizzy

I highly doubt flex or lack of flex is causing any kind of leak. once you tighten down the header bolts they aren't moving anywhere. The closest connection point to the frame on the exhaust system is going to be at the mufflers and that is a few feet back.

I once had a broken rubber engine mount, cheap paper gaskets on a set of headers that had flanges that were ground flat once on my car and I didn't develop any leaks. I witnessed the engine torque over a good couple of inches and the paper gasket held just fine.

JamesPDX

“Are you suggesting he rebuild his engine to make less power because he has a header sealing problem? I really don't get it.”

Not at all. I meant that even with less torque (lower engine torque) and insufficient movement, the same wearing of the gasket is possible.

I agree with Shizzy in that flex or the lack of flex is not the cause of this gasket leak.

I only used my engine example to show that gaskets do hold (very common knowledge).

Has anyone considered the assemble technique used?
Were things properly torqued to spec?

67Olds442X2

The stock type gasket with the RTV is working for now. Thanks for the inputs, I'm done with this thread.

67Olds442X2

I just had to post what seems to be working. Mr. Gasket Ultra seal with copper RTV. Basically didn't trim the gaskets at all. Maybe 1/16 " off of two ports and that's it. Drove the car for 15 minutes and re-torqued bolts after. So far so good. Drove another 45 minutes and still holding. The bolts always are loose after though.