model a manifold

[clay co 27]

How is the best way to true up a manifold to fit the engine block without
going to a machine shop? thanks

[tbirdtbird]

?? u need a machine shop

[colin1928]

Having your manifold surface at a machine shop is always the best way
machine shops here hate doing manifolds hard to set up on the table so can take them weeks to do
that said I have used a flat surface with a light coat of Prussian Blue to find the high spots and then removed them (high spots) with large belt sander attached to a grinder and then hand file until sure it is flat
lapping is another way to finish
good copper gaskets will except 0.010-0.012 thou so try for less

[Ed Saniewski]

I got the granite cut out for a kitchen sink from a job I was working on. Wet it down with water and lay a piece of sandpaper on it. The paper holds in place and you can run the manifold back and fourth to true it up. This will not work if you have to take a lot off, but is great for dressing up a manifold that is off a little. Ed Saniewski

[Mitch//pa]

buy two new ones and you wont have to true them plus it will look better.

[Joe K]

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I have done some "flatting" of cast iron things (like Stanley woodworking plane bottoms) using a surface plate technique similar to Ed's above. Instead of a granite piece I use the top surface of my table saw and a sheet of sandpaper.

Be sure to clean the grooves for the miter gauge out nicely afterwards.

Joe K

[J Franklin]

You may still need to true new manifolds.

[Mitch//pa]

Originally Posted by J Franklin

You may still need to true new manifolds.

nope

[Joe K]

Yes, although you likely will send a non-true back to the source thus saving yourself the re-true.

Builders of precision machine tools frequently would let time, weather, and "seasoning" stabilize their castings before making a machine tool from them. Quality builders would let this process occur for a year or longer. Frequently they would "rough machine" the casting to approximate form - season - and then final machine to finished size.

Today, cast brake disks are usually available from the auto parts stores in "two" grades. The "el-cheapo" which the lucky (or don't care) buy and use - and the "more expensive" which are usually put on the car as they come "pre-seasoned" and subsequent thermal seasoning is minimal.

Joe K

[Terry,NJ]

New manifolds will cost you $85 + $91 + shipping out Snyders catalog.
I have a Machine shop that grinds them for $30.
The last manifolds I bought cost me $15 for the set of an Autolite waffle, heater exhaust and a stock intake.
OR you can get a piece of plate glass, old tombstone, or Granite remnant and put some Prussian (High spot) blue on one side. Move the manifoldS around on it. Make sure they're bolted together and see just how for out they are. Then flip the glass/stone over and put some lapping compound on it and proceed to lapp them flat. If you have the patience, it will take some time! If you find that the intake protrudes beyond the gasket surfaces of the exhaust a few thousandths, but more than you want to lap off, just shim it the correct amount.
Terry

Originally Posted by clay co 27

How is the best way to true up a manifold to fit the engine block without
going to a machine shop? thanks

[Tinker]

Originally Posted by Terry,NJ

OR you can get a piece of plate glass, old tombstone, or Granite remnant and put some Prussian (High spot) blue on one side.

old tombstone? Like one no one is using anymore? ... Sorry just had to ask.

[tbirdtbird]

i know of a guy who trues blocks with a belt sander......maybe....nah, bad idea

[Gunmetal blue2]

When you true the exhaust manifold you have to do the intake manifold to so they are the same thickness.

[SAJ]

Hi Clay Co 27. I recently had to flatten my manifolds after I made the surfaces less even by trying to linish them on a too-short belt sander. I ended up with 12 thou depressions sanded in between the inlets and exhausts and about the same in flame erosion at either end of the exhausts.
I glued 30 grit Alox paper onto a granite surface plate (3m’s spray adhesive) and spent 20 minutes moving both manifolds, still bolted together, over the paper at about 1 stroke per second. This was removing so much material that I had to stop 4 times and sweep it off the grit paper and into a dustpan. I collected about half what I removed and you can see it in the glass dish in the photo attached. The rest of it I either breathed in or it was blown onto my face by the large cooling fan I had going. Wear a mask! I am always in too much of a hurry to practice what I preach, but should have done so here. The collected grit weighed 20 grams and all of it was magnetic, so none was dust or carbon. It was not fun getting it off my welding magnet after I tested it!
I did not imagine I could remove so much cast iron with so little effort. I have a universal mill, but it would have taken far longer to set this up for the job.
You may wish to put on a finer finish with 80 grit after the coarse grind. What do others think about this coarse finish?
Visible is a small silvery piece of what looks like nickel, arced on over a casting fault – maybe from the Ford plant?
Also interesting is one of the central exhaust ports is very egg shaped. Still well covered by the gasket, but I doubt if a gland ring would stay in. There were no rings when I took it off the motor.
SAJ in NZ

[Terry,NJ]

They should bolted together so the gasket surfaces are flush with each other and ground, machined, lapped, whatever, as one unit.
Terry

Originally Posted by Gunmetal blue2

When you true the exhaust manifold you have to do the intake manifold to so they are the same thickness.