intake castings

jamie2370 · 08-15-2020, 03:38 PM

Hypothetical question. I know with sbc intake castings(iron) the castings vary a good bit. So, 2 intakes, same casting number, obvious diff production dates. One has around .070 avg wider ports at gasket surface on all ports. is this much variance normal?

Adger Smith · 08-16-2020, 01:06 AM

Let me make a guess... the wider/bigger one has an earlier date code..

SSDiv6 · 08-16-2020, 03:00 PM

Core shift due to an acid trip???

jamie2370 · 08-16-2020, 05:26 PM

Quote:

Originally Posted by SSDiv6

Core shift due to an acid trip???

By the amount of views and lack of response....I have my answer

Adger Smith · 08-16-2020, 08:21 PM

OK, here is what my friend JV Brotherton (Owner of Brodix) told me when I was complaining about port size/Vol matching specs.
As the molds are used the ports shrink due to the wear on the mold.
I'm not a mold maker so I took him at his word. He said the early part of the production run will be on size and the tail end will be smaller.
I was hoping someone that knew the mold process at GM would take the bait and tell us. I hope that helps. BTW I always flow the manifolds to be sure.

SSDiv6 · 08-17-2020, 01:14 AM

Quote:

Originally Posted by Adger Smith

OK, here is what my friend JV Brotherton (Owner of Brodix) told me when I was complaining about port size/Vol matching specs.
As the molds are used the ports shrink due to the wear on the mold.
I'm not a mold maker so I took him at his word. He said the early part of the production run will be on size and the tail end will be smaller.
I was hoping someone that knew the mold process at GM would take the bait and tell us. I hope that helps. BTW I always flow the manifolds to be sure.

He is correct. This happened with the old days casting processes.

SDT1DYI · 08-17-2020, 12:49 PM

Best to test intake manifolds on a dyno. They can be different. In one case 15 "stock' CI manifolds same casting #, were tested on one engine , same day. HP varied 15 .

Steve Teeter STK/SS 620.

Glenn Briglio · 08-17-2020, 03:46 PM

Quote:

Originally Posted by Adger Smith

OK, here is what my friend JV Brotherton (Owner of Brodix) told me when I was complaining about port size/Vol matching specs.
As the molds are used the ports shrink due to the wear on the mold.
I'm not a mold maker so I took him at his word. He said the early part of the production run will be on size and the tail end will be smaller.
I was hoping someone that knew the mold process at GM would take the bait and tell us. I hope that helps. BTW I always flow the manifolds to be sure.

Wouldn't the ports be bigger if molds wear and get smaller?

SSDiv6 · 08-17-2020, 03:55 PM

Quote:

Originally Posted by Glenn Briglio

Wouldn't the ports be bigger if molds wear and get smaller?

No. As the intake runner pattern wears with use, the runners get smaller and more material surrounds the pattern.

Ralph A Powell · 08-18-2020, 07:55 AM

With wear the sand core gets larger therefore a smaller port

08-15-2020, 03:38 PM	#1
jamie2370 Member Join Date: Dec 2014 Location: Perry, GA Posts: 331 Likes: 11 Liked 239 Times in 90 Posts	intake castings Hypothetical question. I know with sbc intake castings(iron) the castings vary a good bit. So, 2 intakes, same casting number, obvious diff production dates. One has around .070 avg wider ports at gasket surface on all ports. is this much variance normal?

08-16-2020, 01:06 AM	#2
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: intake castings Let me make a guess... the wider/bigger one has an earlier date code.. __________________ Adger Smith (Former SS) Last edited by Adger Smith; 08-16-2020 at 01:26 AM. Reason: sp

08-16-2020, 03:00 PM	#3
SSDiv6 VIP Member Join Date: Feb 2003 Location: Glendale, Arizona Posts: 3,043 Likes: 712 Liked 1,577 Times in 581 Posts	Re: intake castings Core shift due to an acid trip???

08-16-2020, 08:21 PM	#5
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: intake castings OK, here is what my friend JV Brotherton (Owner of Brodix) told me when I was complaining about port size/Vol matching specs. As the molds are used the ports shrink due to the wear on the mold. I'm not a mold maker so I took him at his word. He said the early part of the production run will be on size and the tail end will be smaller. I was hoping someone that knew the mold process at GM would take the bait and tell us. I hope that helps. BTW I always flow the manifolds to be sure. __________________ Adger Smith (Former SS)

08-17-2020, 12:49 PM	#7
SDT1DYI Member Join Date: Nov 2016 Location: Indianola Washington Posts: 401 Likes: 0 Liked 453 Times in 146 Posts	Re: intake castings Best to test intake manifolds on a dyno. They can be different. In one case 15 "stock' CI manifolds same casting #, were tested on one engine , same day. HP varied 15 . Steve Teeter STK/SS 620.

08-18-2020, 07:55 AM	#10
Ralph A Powell Member Join Date: Oct 2017 Location: Bay City Texas Posts: 388 Likes: 2 Liked 225 Times in 136 Posts	Re: intake castings With wear the sand core gets larger therefore a smaller port