Milling an intake manifold.

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Scampin

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Long story short, have the motor apart installing the new camshaft @PRH spec'd out. Bought a new borescope that can twist the head 180* and decided to see what the port match looked like on the intake to head. Well, it's atrocious. The intake manifold is clearly way to high. When I put the motor together last fall with the new heads and intake, I final port matched to the gaskets but was rushing and obviously missed this (first fire up was 9pm the night before the race with a 8hr drive). Without any gaskets between the head and intake the port match is perfect. The gaskets are felpros that are .060 thick. A machinest buddy of mine is trying to cut the flanges on the intake, I told him take .060 off, he did some math and came up with we need to take .042 off. Thought we could set it up in his horizontal mill by bolting one flange down, and then realized it isn't a 90, but 84.
Is there a fixture anyone sells for milling a Mopar small block intake in a horizontal or vertical mill? I know a Bridgeport would be perfect, but I don't have access to one. Any tips or tricks?
 
If he has a adjustable fixture for cutting heads, that's what I use to cut intakes. You bolt through the intake flange to the fixture, then indicate in the gasket surface in both axis.
 
I would cut the heads, not the intake......otherwise those heads heads are married to THAT intake. What happens with the intake if there is a divorce....
 
I agree but I have a race soon and don't have another set of head gaskets. Also, I have so much time into this intake, when I get done with the next version it will just go on the shelf as wall art. Lol
 
We unfortunately do not have a head fixture.
 
replicaracer43 said:
If he has a adjustable fixture for cutting heads, that's what I use to cut intakes. You bolt through the intake flange to the fixture, then indicate in the gasket surface in both axis.
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You wouldn't be near the upstate NY area?!?
 
What machine shop doesn't have a way to cut precision angles? I have a hobby machine shop & have three different ways to accomplish precise angles without thinking about it to hard...
 
You math is correct. If the manifold lines up with no gasket, you need to machine whatever the thickness of the gasket is off the intake.

And I do not start counting the say .060 that you say your gasket is until I take a light cut or two until the surface just cleans up.

Unless you need to worry about port volumes for some class, I never ever machine the head.

Why? Because of tolerance stacking you can never say the next intake will fit either.

Once you machine that head it’s ONLY going to be correct for a block with that deck height and an intake with that exact width.

You can measure 5 brand new manifolds that are exactly the same part number and such and none of them will be the same.

And the difference can be quite large.

A manifold is far cheaper than heads. I always adjust the manifold and not the heads.
 
We d
1WildRT said:
What machine shop doesn't have a way to cut precision angles? I have a hobby machine shop & have three different ways to accomplish precise angles without thinking about it to hard...
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We only have a couple local machine shops, neither that I have had spectacular results with, and both turned down the job. My buddy is a retired machinest that retired, moved, and hasn't built his garage yet. Most of his tools are scattered and we went into this thinking we could do it on his horizontal mill since I assumed it would 90*. He has the tools to do it, just needs to get them together. Thus I was trying to help him out if anyone had some quick ideas for fixtures. If the intake wasn't a 40lb chunk of cast iron it would probably be easier.
 
Scampin said:
We d

We only have a couple local machine shops, neither that I have had spectacular results with, and both turned down the job. My buddy is a retired machinest that retired, moved, and hasn't built his garage yet. Most of his tools are scattered and we went into this thinking we could do it on his horizontal mill since I assumed it would 90*. He has the tools to do it, just needs to get them together. Thus I was trying to help him out if anyone had some quick ideas for fixtures. If the intake wasn't a 40lb chunk of cast iron it would probably be easier.
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I’ve surfaced lots of intake and exhaust manifolds on a mill.

The exhaust stuff can be a PITA but an intake on a mill is pretty easy.
 
Scampin said:
We d

We only have a couple local machine shops, neither that I have had spectacular results with, and both turned down the job. My buddy is a retired machinest that retired, moved, and hasn't built his garage yet. Most of his tools are scattered and we went into this thinking we could do it on his horizontal mill since I assumed it would 90*. He has the tools to do it, just needs to get them together. Thus I was trying to help him out if anyone had some quick ideas for fixtures. If the intake wasn't a 40lb chunk of cast iron it would probably be easier.
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Are you on Facebook and if so how many local friends do you have on there. I could probably post up that I need an intake cut and 20 friends would say bring it over. A case of beer and a few hours later I’m heading back home.
 
No social media. And Rhett it's not my fault no one likes me because I'm quicker than them.. lol
We will get it done. Thanks everyone.
 
Newbomb Turk said:
I’ve surfaced lots of intake and exhaust manifolds on a mill.

The exhaust stuff can be a PITA but an intake on a mill is pretty easy.
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My guy made a jig

20230927_192221.jpg
 
Just went through this exact scenario. Intake sat way too high because heads and block have been cut multiple times. My intake fit perfectly with no gaskets and my gaskets are .031” so I had .040” cut off the flanges and now it fits perfectly. I believe your thinking of taking .060” off is correct.
 
SSG_Karg said:
Just went through this exact scenario. Intake sat way too high because heads and block have been cut multiple times. My intake fit perfectly with no gaskets and my gaskets are .031” so I had .040” cut off the flanges and now it fits perfectly. I believe your thinking of taking .060” off is correct.
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Maybe not on the cut, I had a stock 78 Power Wagon 318 never touched, bought it off the original owner, stock as a rock, even had 1978 dated plug wires.
The truck had 49,000 miles, engine such a grease ball, when I pressure washed it, the soft plug on the drivers head started seeping, the grease was holding the coolant in.
Anyways, went to bolt a virgin LD4B intake on, it would fit with the metal gaskets, but super tight with the felpro blue gaskets.
I did put it together with the metal gaskets, yeah I knew better, and yes after time it started leaking.
Tore the intake back off and managed after alot of cussing install it with the felpro gaskets.

I think alot of older aluminum intakes were designed off the cast intakes, when it comes to intake fitting.

The last intake I bought was a new Victor 340 and it fit perfect on slightly milled J heads with the Felpro 2113 gasket.
 
You may have said but is this a street car or a drag car. If a drag car how many races are left??? Tu said this is going on a shelf soon right.
 
pittsburghracer said:
You may have said but is this a street car or a drag car. If a drag car how many races are left??? Tu said this is going on a shelf soon right.
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Completely stock 340 that wants to be a racecar. We have 2 Maryland races coming up I am hoping to make. I am slowly working on another intake that I am trying a different direction on.

PXL_20231104_194914398~2.jpg
 
Scampin said:
Completely stock 340 that wants to be a racecar. We have 2 Maryland races coming up I am hoping to make. I am slowly working on another intake that I am trying a different direction on.

View attachment 1716305788
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I was just wondering it you could use a set of .015 steel shim gaskets to get you through the year. That would have to get you pretty close.

IMG_4577.png
 
It runs 10.30’s, so as serious as you can get starting with stock castings.
 
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