Intake/Exhaust manifold questions

[Praxiss454]

Rebuilding my 230, and I have the manifolds off. They are still connected together, as I was advised by the machine shop as well as an experienced buddy not to separate them. I have a few questions I was hoping someone here could help shed some light onto.

1. Why shouldn't I separate them? I'd like to blast them, paint them, and replace the old gasket between them. I could paint them together as-is I suppose. Would just like to understand the reasoning for not disconnecting them.

2. The heat riser spring is long gone. The valve rotates, perhaps not as smoothly as it once did but rotates none-the-less. It gets cool here (SF Bay area) but not ice cold. Thinking of leaving it without a spring. Dumb idea? I guess I could get the spring.



3. On the intake manifold, there is a pin held in place with a cotter pin on the end. It rotates freely. I've cleaned mine up a bit. But I don't know what it's for. There was a small piece of metal on one end, like the end of a spring that might be connected to the carb or throttle, but whatever it was, it broke. What's it for? What's the replacement spring called?



4. These studs snapped off. They were pretty corroded anyway. I have them drilled out and re-tapped (3/8-16, hope that was right). Didn't have the forethought to measure them first, what is the right length? Anything special about them or just any threaded rod will do?



5. Same picture as #4 - my understanding is the only mating surface is the small chamfered ring. Do I need to do anything special to clean this up or get it to seal well on reassembly?

Thanks guys, feel like I'm in the final stretch here.

[shp4man]

When I got my truck, the exhaust manifold was cracked/leaking. It was a safety hazard, so had to replace it. I ordered a new one from Rockauto, a cheap $130 Chinese knockoff. I read some other guys experiences with that manifold saying when you put it together, use high temp silicone on all the gasket surfaces snug everything up a little, then tighten all the manifold to head bolts/nuts first, then tighten the intake to exhaust manifold flange bolts evenly. I did that, and ended up also having to grind on the exhaust manifold a little to get a good seat for those retainer stampings.
After all that, it works OK, got about 8000 miles on it with no issues or leaks- and a working heat riser.
I would use the recommended studs on there, those fasteners take a crapload of heat.

[Praxiss454]

Originally Posted by shp4man;

I would use the recommended studs on there, those fasteners take a crapload of heat.

Do you happen to know where I find info on the recommended studs?

[shp4man]

I couldn't see the pics at work and thought you were talking about the studs on the head. Haha. I would make an estimate of the length an go into a NAPA and ask the counterman. 3/8 16 is the thread size.

[Short 3/4]

The main reason not to separate is you usually wind up breaking studs. I personally like to replace all the 50 year old corroded studs and bolts ( PB Blaster, anti-seize and patience are your best friends here). Any real auto parts store can sell you the correct studs and brass barrel nuts ( very important).
As mentioned you need to assemble everything loose, and then gradually snug manifolds together while snugging up to head. When all is tight I like to then take the manifold assembly back off and then have a machine shop skim the head mating surface of the manifolds-cheap insurance.
I have lived in both Sacramento and San Luis Obispo Counties and never had a heat riser, so shoudn't be a problem in Marin Co. Even the occasional Tahoe trip was not an issue (now if you move east to where they have real weather, all bets are off)
Good luck
Tom

[Praxiss454]

Originally Posted by Short 3/4

The main reason not to separate is you usually wind up breaking studs. I personally like to replace all the 50 year old corroded studs and bolts ( PB Blaster, anti-seize and patience are your best friends here). Any real auto parts store can sell you the correct studs and brass barrel nuts ( very important).
As mentioned you need to assemble everything loose, and then gradually snug manifolds together while snugging up to head. When all is tight I like to then take the manifold assembly back off and then have a machine shop skim the head mating surface of the manifolds-cheap insurance.
I have lived in both Sacramento and San Luis Obispo Counties and never had a heat riser, so shoudn't be a problem in Marin Co. Even the occasional Tahoe trip was not an issue (now if you move east to where they have real weather, all bets are off)
Good luck
Tom

If I go this route and take apart the manifold to clean things up, when I assemble it loose do I do that w/o a gasket, just to get everything lined up as well as possible?

Is there any sense in painting the exhaust manifold? Will any paint even last? The intake still has some red paint on it that I assume is original, but not much.

[Cris]

On your original question #3. The pin is part of the throttle linkage. Here's a shot of the linkage on my 1963 with a 230 inline 6

.

[Praxiss454]

Originally Posted by Cris

On your original question #3. The pin is part of the throttle linkage. Here's a shot of the linkage on my 1963 with a 230 inline 6

.

Thank you. I guess that would have become obvious at some point during reassembly. I tried to take pictures of things during tear down but was confused by what appeared to be a broken piece of spring on that pin.

[paulspickupparts]

Originally Posted by Short 3/4

The main reason not to separate is you usually wind up breaking studs. I personally like to replace all the 50 year old corroded studs and bolts ( PB Blaster, anti-seize and patience are your best friends here). Any real auto parts store can sell you the correct studs and brass barrel nuts ( very important).
As mentioned you need to assemble everything loose, and then gradually snug manifolds together while snugging up to head. When all is tight I like to then take the manifold assembly back off and then have a machine shop skim the head mating surface of the manifolds-cheap insurance.
I have lived in both Sacramento and San Luis Obispo Counties and never had a heat riser, so shoudn't be a problem in Marin Co. Even the occasional Tahoe trip was not an issue (now if you move east to where they have real weather, all bets are off)
Good luck
Tom

X2 ^

Very good advice . If it is not leaking I would not mess with it . Sometimes you open a can of worms. All of the advice by Tom is great . Especially on the
the re assembley . I am taking a 250 intake manifold for a Nova guy that tried to seperate the intake from the exhaust. Because the bolt was so froze into the intake , the intake cracked. Now he needs a new manifold.

When I take them apart I do everything Tom said but take it one step farther . I heat the bolt area with a torch until really hot . And then gently try to remove the bolt that holds them together . Reheat , repeat until all four bolts out. Carefully. In this case a bigger hammer or bigger wrench does not apply . Sometimes when you do get them apart there will be extreme pitting which means having that area machined by a machine shop. On assembly you do need to install the gasket loosely and then attach intake exhaust to engine . After attached to the engine tighten up the intake exhaust adjoining bolts. Torque down to correct specs . Then you can make the decision if you are going to have the faces that attach to the block . Also check them for pitting . If so machine .

In the end it is all about how good you want it to be . Daily driver , nuts off restoration, etc. That will determine what you want to do. Good luck

[Praxiss454]

About 95% of the advice I've gotten is to leave it be, so that's what I plan to do for now. I can always take it off later. I am still going to blast it and hit it with some Eastwood manifold paint.

From my original set I think the only thing I could use some info on is what length and type of studs do I need for the exhaust pipe mounting studs that snapped off. 3/8-16, but a single thread the entire way, or two threaded sections w/ a built-in stop? And what length? Google just returns generic Dorman stud kits.

When I install the studs, am I supposed to hit em w/ red loctite?

[paulspickupparts]

The length of stud you need is going to be determined by you . Depends on how thick your donut is , what type of flange on your exhaust pipe and the length of the threaded area of the attaching nut. I would not use locktite on the studs . it will do it itself after numerous heat cyles. Use the one with the stops . I would use brass nuts .

[Praxiss454]

Originally Posted by paulspickupparts

The length of stud you need is going to be determined by you . Depends on how thick your donut is , what type of flange on your exhaust pipe and the length of the threaded area of the attaching nut. I would not use locktite on the studs . it will do it itself after numerous heat cyles. Use the one with the stops . I would use brass nuts .

Thanks paulspickupparts, these probably seem like dumb questions to most of y'all. In my defense, I was never around this kind of thing as a kid and I'm trying to figure things out as I go. Since the exhaust is probably one of the last things I'll hook up I can postpone making any decisions about it.

[Praxiss454]

Well, dang. Blasted my manifolds, they look pretty good. Go get some 2000F primer, spray em down. Now I notice what appears to be a crack in the exhaust.

[shp4man]

That's fairly common, I think. Spray some WD-40 inside the manifold and see if any comes out that crack.

[Praxiss454]

Originally Posted by shp4man

That's fairly common, I think. Spray some WD-40 inside the manifold and see if any comes out that crack.

Sprayed some PB Blaster quite liberally from the inside, let sit several minutes and no seepage. Hit the manifold with a propane torch for a few seconds from the inside, still no seepage. The metal is pretty thick right there, so I don't think it's through.

Would you suggest just leaving it as-is? Or file into it a bit?

[shp4man]

Originally Posted by Praxiss454

Sprayed some PB Blaster quite liberally from the inside, let sit several minutes and no seepage. Hit the manifold with a propane torch for a few seconds from the inside, still no seepage. The metal is pretty thick right there, so I don't think it's through.

Would you suggest just leaving it as-is? Or file into it a bit?

I've heard you can braze manifolds. Not sure about that, though. If that's the only suspect crack I might run it. Just keep an eye on it, and at least now you know how replace the manifold if needed.
Then again the heat might expand it. Was it making noise before?

[Praxiss454]

Originally Posted by shp4man

Then again the heat might expand it. Was it making noise before?

Not that I noticed, no high pitch whistle or anything. When I had the muffler replaced, the muffler guy said the exhaust sounds good too.

[Praxiss454]

Can anyone confirm that the manifold is held on by 4x 3/8-16 3/4" bolts, plus two 3/8-24 nuts? My engine has studs that are 3/8-16 going into head but 3/8-24 on the mounting side.

[shp4man]

My truck's engine is, from the casting numbers, a 69 or 70 250. It's head mounted studs are the same thread size on both sides, but I'm not sure you have anything to worry about there.

[The Rocknrod]

The cast iron exhaust manifold on my yellow panel was modified to a dual exhaust. Drove it for years and years and never had a problem.

[Praxiss454]

Originally Posted by shp4man

My truck's engine is, from the casting numbers, a 69 or 70 250. It's head mounted studs are the same thread size on both sides, but I'm not sure you have anything to worry about there.

It seems pretty weird to me that one side would be 3/8-16and the other would be 3/8-24. Like those aren't the original studs and someone replaced them with USS/SAE studs. But, fine threads should be fine for this application, so I think I'm just going to run with them.

Regarding one of my earlier questions about exhaust pipe studs, from my picture above I counted the threads, and it looks like there are about 24 threads at 16 threads per inch, so those studs are 1.5" on the pipe side. Looks like they have about half an inch to thread into the manifold, so 2" overall should just about do it.

[Praxiss454]

And closing out the question on exhaust pipe studs, the counterman at the local NAPA found these for me, which look to be a perfect fit. Part #: NOE 6001816 Exhaust Stud Kit 3/8-16, 2.5" long.