Exhaust/intake manifold machining

N

Nodakwalleyer

Member
Hello, Purchased a new exhaust manifold from snyder's last year and installed it, the intake manifold and exhaust manifold was not perfectly straight across intake was back about .020-.025. I double gasketed the intake and had no problems or leaks. Well the exhaust manifold rusted during winter storage (was painted when installed new), so, while taking it off to sandblast, re-paint, I thought I would have it machined flat. Took it to 3 machine shops and nobody says it is possible to do, I know other people have had it done, what are those machine shops using to do this, thanks!
 
Same here no machine shops will do it... They say they can't. [USELESS N.Y.] I went and bought a lg flat,wide ******* file and put the 2 manifolds together , used a very good level and filed straight across all the ports.Worked out very well...just take your time.
 
Both Charlie and Peters180a have the right idea.

The local shop that does heads does them by laying them down on a wide belt sander that does the entire head at one pass. Quick and dirty and not that accurate - but accurate enough for most heads. And it will work for the exhaust/intake manifolds (do them together for best effect) BUT there is a tendency for the proper angle of the exhaust to be lost due to the off-center weighting of the exhaust manifold.

Your first flattening by this method will probably work fine. After that not so much.

The flat ******* file is similar but may cause you to lose the proper angle faster. Still, your first flattening may be fine - and that might be all you need in the life of your vehicle.

My solution is somewhat the combination of both. I used my table saw table along with a length of 80 grit belting from the 4" stationary belt sander. Opened up and stretched out I laid it on the table saw and clamped it on the ends to hold it in place. Then I "rubbed" the exhaust manifold on the grit/belt and kept at it until all the ports showed equal "touch."

Yup. I might lose some of that correct angle - but it did work - and is still working.

Joe K
 
A lot of modern shops know how to do that job but don't want to take the time for a setup like that.
For most modern heads or manifolds they have dedicated fixtures to minimize setup time.
Then again, there are many that just plain don't have a clue.
 
Thanks guys for all suggestions, since the exhaust manifold ports are perfectly flat across, I think I will try the filing method, but I will file the exhaust manifold on the opposite side of the ports, and hopefully the intake will move closer to being flat with the exhaust ports and the exhaust ones stay flat, thanks again!
 
i know you already bought the exhaust manifold new, but the ceramic coated new ones hold up better than any hi temp paint....
 
I have a guy, in NJ, who does them on a Blanchard grinder. He's an old "Gear Head" and I guess years ago, built his fixture. $30 bucks get you a very nice finish and flatness. Be careful that the guy who does it doesn't tilt it. It must be square to the carb flange.
Terry
 
Thanks Terry, shipping both ways would probably not make it worth it, I have been working on it and it is very close to being close enough that a single gasket will fill the gap, thanks!
 
There is a very good chance if you found another intake manifold that they would not need to be machined, I had no problem, it would be a pity to resurface a new exhaust manifold, if you can find someone to surface it, $40-$50 if I remember, do a search on Castblast to stop the rusting.
Regards, Brian.
 
Hi guys,
Just had my manifolds done on a belt sander at my local engineering shop. Works great.
Regards
Chris
Cape Town
 
Nodakwalleyer said:
Hello, Purchased a new exhaust manifold from snyder's last year and installed it, the intake manifold and exhaust manifold was not perfectly straight across intake was back about .020-.025. I double gasketed the intake and had no problems or leaks. Well the exhaust manifold rusted during winter storage (was painted when installed new), so, while taking it off to sandblast, re-paint, I thought I would have it machined flat. Took it to 3 machine shops and nobody says it is possible to do, I know other people have had it done, what are those machine shops using to do this, thanks!
Click to expand...

Was it a stock style manifold, or a header? And what kind of intake was it? Since I machine certain parts for Snyder I am curious to know if something got out of my shop with a flaw. That would make me VERY upset.

Tod
 
Tod , it was a factory type exhaust manifold with an original intake. I don't think the exhaust manifold had a flaw, it is perfectly flat (square) across. The original intake when bolted to it sits back about .020-.025. So it leaves a gap when the entire piece is bolted to block. I just double gasketed the intake, no issue, I just thought I would have it trued up while painting it. Thanks for your concern , glad you were concerned about the products, take care!
 
You can also add metal shims or mill the area between where the two manifolds bolt together to even up the ports.

Tom Endy
 
Nodakwalleyer said:
Tod , it was a factory type exhaust manifold with an original intake. I don't think the exhaust manifold had a flaw, it is perfectly flat (square) across. The original intake when bolted to it sits back about .020-.025. So it leaves a gap when the entire piece is bolted to block. I just double gasketed the intake, no issue, I just thought I would have it trued up while painting it. Thanks for your concern , glad you were concerned about the products, take care!
Click to expand...

OK. Good. I do not machine the factory type exhaust manifolds (yet). It makes me wonder if the original intake has been cut at one time. .02-.025 is pretty wide of the mark in machining. Good luck.

Tod
 
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