The Stovebolt Site Forums The Shop Area Engine Shop Exhaust/Intake manifold

I am about to remove my manifold for some minor repairs (I cannot get the heat riser valve to move, tried for a week with the spray then hammer technique with no luck) and I was wondering what I should do to it before reinstalling. I have seen some manifolds that were painted that looked pretty good, so I need to decide if I want to go that way or just clean it well and reinstall. I am not trying to win any show awards with it, just want it to look good and protect it from any rust or corrosion in the future. So the questions are what could I do, and what should I do?
Also, is there anything else that I should do/look at, while the manifold is off? I read one suggestion is to look at and if needed, repair the pivot for the carb linkage. Anything else?

Thanks, Lee.

Hi Lee,
Others may appear with different answers, but I've never had much luck with any of the so-called manifold paints. They look ok for a while, but a rusty bucket if painted will look good for a while, too. You can paint the intake manifold part. As for the heat riser valve, I believe you'll have a much better chance of making it work once the manifold is off and you can see things better. Usually if you're patient you can get them to work again. As for the carb linkage pivot, please keep in mind the screw for it usually goes into the water jacket. At least on every 235 I've ever worked on it does. I can't think of much other than that. You'll have a bit more room to adjust your steering box with the manifold out of the way and if you need to replace the drain cock with a new one (at the rear of the engine) that will be easier. Good luck.

Oh, one other thing. When you get your heat riser valve (flapper) freed up, check to see if it needs to be straightened to fit right. I've seen a few that were bent oddly. About the only thing I could imagine was that somebody stuck something up there with the exhaust pipe removed (pipe, broomstick or something) and beat on it trying to free it.

I just went thru the same process with a frozen heat riser valve. After removing the manifold I sprayed it with pb blaster inside and out ,let it sit then repeat for a couple days. Eventually with a pair of vise grips i got it to move and then reapplied more PB blaster. Bit by bit it freed up. Basically the manifold was all coked up with black exhaust crud and required scraping and careful chiseling to remove the carbon from the passage ways. Good luck. After cleanout I ordered the spring that operates the valve. Does anyone know if the spring requires presetting the tension by winding the spring up or if it is installed straihgt without preloading? thanks all....

I took mine to a machine shop to have it decked. I had an exhaust leak.

Couple of places didn't want to mess with it, to small a job for their time.

Found a guy who charged me 50 bucks..

If you do something like that you might have to dress down your port rings

Thanks Jon for the paint suggestions; I may just see how it looks cleaned up well and leave it at that. I saw a tip in here a few weeks ago (I think) about how to re-bush the pivot under the carb; does anyone remember where that was? If I remember right, you drilled it out enough to fit in a brass sleeve, but I do not remember the details.
My spring is still good, so if you don’t have an answer Swami for your question, I’ll see if I can find out.

Lee.

The spring is in the heat on position .... cold

Dads50, I don’t think I have an exhaust leak, but I would not be surprised if there is something small. I do not have a sandblaster, so I may be taking it to a shop and hopefully they can check it carefully for cracks or other issues. When you say decked, is that to align the ports into the same plane and flatten the faces?

Lee.

Correct

Some the the skilled old-timers can do this by hand or draw file . Even a large belt sander. I chose the machine shop route since I know I had a leak
You can check yours with a long straight edge. If it looks good then you'll be ok. Not much torque used on manifold bolts so having a good surface to start out with helps.

Instead of paint, I’ve been pleased with manifold dressings that are made for cast iron. More can be applied with an old toothbrush at any time to touch up areas. I think it holds up pretty good.

Here’s a picture of my 230 manifolds. Intake has Calyx manifold dressing. It’s pretty expensive for what you get.
I ran out of Calyx so I decided to try Rutland Pot Belly Stove Polish on the exhaust. I like the contrast.

I also used the Rutland stove polish on the LS engine exhaust.

Lee, one "trick" I've used on manifolds, to provide a somewhat more durable coating than paint, is to spray graphite lube on a rag, then wipe to an even dark-gray/black color. The solvent dries, leaving the graphite in a thin coat on the manifold. The manifold should be given a wire brush cleanup to remove loose rust, before applying, of course. The graphite will last pretty well, and is easy to reapply when it wears thin.

The graphite spray works very much like the "stove polish" my Dad got at the local hardware store when I was a kid, which was a liquid mix of carbon black, wax and solvent. My job was to wipe it on our woodstoves to bring back a dull-black shine to the cast iron. As it dried, it left a waxy black finish on the stove, and I had black finger nails for a few days. Stove polish is still available, and although I've never tried it on manifolds, it might work pretty well, too. [Edit: LugNutz beat me to this one, while I was typing...].

Lee & Swami, As for the heat-riser spring pre-tension, yes, the spring gets 1/2 turn from unhooked position to set it correctly (ref, bottom right column p. 6-19 of the '54 Chevy Shop Manual), set cold as Dad said. The Shop Manual also recommends a mix of "kerosene and a small mount of baking soda" to loosen stuck shafts. I had forgotten that one. Might be worth a try.

Doug

I have been using Calyx Manifold Dressing for at least 20 years.

It has to be "re-dressed" every so often, but, the good news is: if a little rust shows through, you just "re-dress" in place.

Also, thanks for the kerosene/baking-soda reminder, Doug

other products - manifold dressing/coatings

If the manifold is taken apart, tighten up theblock bolts while manifold bolts are snug, then tighten everything up.

Ed

The tip about fixing a loose throttle pivot is from a fellow member “Chev 235 Guy” on this forum. Here is a [LINK].

If it isn't clear by now, you really need to free the heat riser valve as a priority. If stuck in the heat-on position you will burn valves pretty soon. IF stuck in the heat off position it will take forever to warm up and run well.

Heat the exhaust manifold with a torch being careful not to overheat it, then tap the shaft of the riser valve left and right rather than trying to twist it. Once overheated by a stuck closed heat riser, the exhaust manifolds tent to warp and cause exhaust leaks. Sometimes they crack. You're on the right track to have it refaced but do the exhaust manifold separately from the intake. Be very careful removing the bolts that connect the two manifolds together. They tend to crystalize and weaken to the point where they will snap off and then an easy-out will become your best friend or worst enemy depending on how it goes.

On old trick for stopping exhaust leaks on warped manifolds was to retard the timing and get it good and hot then snug down the retaining bolts for all you're worth. Doesn't always work though but usually worth a try.

When reassembling, leave the bolts that hold the manifolds together loose till last. Tighten the manifold-to-head bolts first then the manifold-halves bolts at the end.

I had my Exhaust manifold Powder coated. They (my shop) only does this "Silver" on Exhaust.(High Heat) Its two years old and still looks good. The intake was powder coated gloss black. Both still look great two years later, over 1,000 miles on engine.
Todd

I just installed my manifolds and had a similar experience to Schaffer’s1950. When I bolted the intake/exhaust manifolds together I noticed the the intake and exhaust ports were not on the same plane, so I loosened them and checked with a straightedge to see It there was enough slack to get them aligned and there was. When I installed them, I tightened both the manifold port bolts and bolts that attach the two manifolds together at the same time so they would basically self align. Seemed to do the trick but I won’t really know until I start the engine.

PS: Lugnuts, I love the Stove Polish idea and I’m running out to the local Ace to pick some up! [LINK]

One other thought. Evan (Coilover) posted this some months ago. The discussion was about Remflex gaskets (which I will not endorse for a couple of reasons). Evan mentioned he used high temp rtv sealer...you can read/see here: https://tinyurl.com/yxnsycdb

I've been meaning to try Evan's method, but I don't think either of my manifolds is leaking.

Cmon, John,

You opinions respected: why do you not recommend the Remflex 235/261 manifolds gasket?

Thanks, Tim

I got the manifold off with no problems; it even separated easily. Still working on freeing up the heat valve, but I did find that my thermo spring is broken. I also see that the valve has a bend on one side (see attached photo); is this normal?

Thanks, Lee.

Here is a 216 manifold valve to compare

Thanks, yours has that slight bend on one end too. I would guess that it fits better up against the side when closed; once I get mine loose that should be obvious.

Tim, for the same reason I can't recommend Pertronix. Too many failures and the basic product is the same as it was on day one. I have friends who can't even say Pertronix without including a long and often creative string of profanity and from everything I've read, this gasket may possibly have a worse track record. Stepping away from the 235/261, for some vehicles the failure rate appears to almost be guaranteed. Subaru for one. I own a Subaru, by the way. I can't recommend this gasket for any vehicle.

I know there are people who consider these gaskets to be terrific, have had great luck with them, sing their praises and that's fine. I just don't like any product that works sometimes for some people in some cases.

I think people tend to forget when a gasket like this fails on a modern vehicle very unwanted things can happen. The list begins with: all of a sudden your vehicle will not pass the state vehicle inspection. Depending on where you live this can be irritating or worse...you may not be allowed to drive your vehicle away from the inspection station in that condition.

As I said earlier, I think Evan's idea was clever and he says it has worked for him for 15 years. A tube of that stuff is what...$8 or so? I'd say try that first.

One thing to remember is, we are dealing with antique 6 cylinder engines. The Remflex has proven time after time to be effective at sealing up the exhaust/intake manifolds on Stovebolt sixes. I can’t recall any failures being reported. Your bad experience with Remflex on modern engines is certainly worthy of note but should not deter anyone from using them on our inline sixes. JMO

Whew,

Thank you, Martin

My question was about 235/261 REMFLEX gaskets.

I have another (perhaps stupid) question about the REMFLEX gasket on a stove bolt : do you still use alignment rings ?

Martin I said I couldn't recommend these for any engine. So let me offer a little more because it appears I may have been misunderstood or at least I think what goes into my thinking might need clarification. I belong to, participate in or observe several other forums similar to this but aligned with other vehicles, general auto repair, performance, off-road, restoration, etc. And I am friends with and am in contact with people in the auto business who will never participate on this or any other forum. This gasket has been around and has been discussed for about 15 years now and if you search you'll find the complaints are nearly all the same. To say its failure is limited to modern engines is incorrect but the modern-day use example does go to the heart of the problem as I see it and I'll explain that in a moment. This gasket has never been presented as an improvement over OEM gaskets and no vehicle makers use this as an OEM gasket as far as I know. With a failure rate this high I can't imagine even the Vega engineers would consider it. What it is and has been is nothing more than a quick and less expensive "fix" to a more expensive, more sinister and time consuming problem. The other thing I've come to believe is it works best on engines which are not used often and it may have a short life span if used frequently (routinely) or more severely. It may be a convenient answer for a vehicle which needs to be sold quickly without spending much money on it. Pig lipstick. The point of mentioning a modern day vehicle just points out when this gasket is subjected to frequent and routine use (what a modern day vehicle will get) there's plenty of documentation showing it doesn't hold up well in some cases and in some other cases it is almost guaranteed to fail.

But my guess is a lot of trucks like ours don't get used often. Check with some of the Stovebolt devotees of this gasket and let's see how often their engine is used. 15 years of daily use plus long trips? If you hear that, it will be a pleasant surprise to me, because I'm expecting people to say something like "oh, I drive it around town once a month or so and last year I drove 60 miles one day." And let's also find out how many people are using it. 20 or 200? Evan said he had success with an $8 tube of sealant for 15 years, posted an image of it and pointed out he takes long trips in the vehicle. Until I hear something like that from somebody I trust, I won't recommend this gasket any more than I'd recommend taking your family up in an airplane you built yourself from watching a YouTube video.

In the auto industry there have been products which do work and which do solve some problems...but about which full knowledge often must be learned through experience of the user. An example? Drive flat tires. They work and they cost 50 to 100% more than regular tires, but try to have one repaired after you've suffered a puncture and driven on it. Tire shops won't touch it and with good reason. Driving wrecks the structure...the structural integrity to be more precise and the tire is off to the recycle pile now. If it is repaired, belts may start separating, the tire may wear funny, drive unpredictably and some say it may fail catastrophically.

Alignment rings on the gasket? I don't know, but that's a good question. My first inclination might be to say yes, but with this design they're not going to work as originally designed, you know.

Take care with that shaft and resting pin for the spring. They can be brittle and easily damaged/snapped

Heres the test of my spring and valve when I had it apart 216 manifold on a 235.
...link...


...link...


...link...

Truck shop manual is excellent source for reassembly

Thanks for the pics and videos; I am having no luck with freeing up the valve. I have tried the torch trick too with no success. The side with the weight seems to be free (it will move just a little bit up and down), but not the end with the spring. I’ll be taking it to a local machine shop for cleaning, if I cannot get it free, maybe they can. Or maybe with all the gunk off that will help free it up.

Lee.

I took the manifolds to a local machine shop for cleaning and surfacing the ports (maybe they will have more luck freeing the heat valve) and I should have them back this afternoon. My question is what kind of lubricant should I apply to the shaft once it is free?

Lee.

GM p/n 88862628 Heat valve lubricant

I have used the rim flex for quite some time now on my 235 and 261 builds and truth be told, they work great for me. Not a single failure, not with stock cast iron manifolds and not with my pesky Clifford long tube headers that always, always, always gave me fits with leaks. Its also easier to use as its a one piece gasket.

Thanks to all who helped with this project; the test run today was successful. I was able to get the heat valve working, and ‘painted’ both manifolds with graphite spray. The color looks real close to the gray of the rest of the engine and it was easy to do.
Thanks again for everyones help.

Lee.

Always keep the inter manifold bolts loose until the port bolts are tight, then tighten the other bolts.

Ed

I did that and it went very easy. Ended up doing it twice as after the first time I looked at the workbench and saw the alignment rings sitting there. It went just as easy the second time at least. The machine shop surfaced (decked?) both manifolds with the exhaust being the most off. Unfortunately, the work removed what I believe is the date code (C276) on the exhaust manifold. At least I wrote it down before dropping it off.

Lee.

I have used the Remflex gasket on my 1959 261 for the last 3 yrs. No problems at all. I have the petronix ignition in my distributor for the last 12 yrs. never a problem. I put 3,000/4,000 miles a yr. on the truck. Drive it all the time. There are people on this page that say these two products are the worse things you could spend money on. Why? Because they have Experience and know better than every one else.

I've been here a long time and I've heard all of the stories of the imaginary things that they have or will be constructing, because they have Experience. How ever I've never heard of any of these magnificent projects being completed and put in use.
I and many other people here have used these product without any problems, Do I think they are the greatest thing since sliced bread. No, how ever, if you follow the instructions and check everything twice , there doesn't seem to be a problem for the Unexperienced people here that have used these products.
That is the end of my comments.