intake manifold installation
Safety Car
Joined: May 2003
Posts: 4,797
Likes: 239
From: Ocean Township NJ
Yes. That's what I thought, and said in post #15. If the ports in the head are larger than the ports in the manifold, as they should be, then the slight misalignment won't do any harm. Elongating the holes with a round file or drill bit is cheaper and more forgiving on the manifold than having it shaved.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,871
From: Greenville, Indiana
I'm often in favor of putting a little "Kentucky windage" in things when necessary to get them back together in a reasonable fashion.
In this case, I'd strongly recommend you NOT file the manilfold holes for clearance to the bolts. If you file those holes you've lost your reference to the heads/block in case you wind up with an oil leak at the ports or the end seals because of metal/metal interference. If the manifold needs cut, do it.
In this case, I'd strongly recommend you NOT file the manilfold holes for clearance to the bolts. If you file those holes you've lost your reference to the heads/block in case you wind up with an oil leak at the ports or the end seals because of metal/metal interference. If the manifold needs cut, do it.
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,915
From: Washington Michigan
If you know (or can find out) the previous history of that engine, the chart below shows the amount that should be cut from the sides and front/rear of the intake manifold based on how much the heads were milled (or how much the block was decked) in order to maintain alignment of the ports and bolt holes. 
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 960
Likes: 25
From: Middlesboro KY
If you know (or can find out) the previous history of that engine, the chart below shows the amount that should be cut from the sides and front/rear of the intake manifold based on how much the heads were milled (or how much the block was decked) in order to maintain alignment of the ports and bolt holes.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,871
From: Greenville, Indiana
If you dry fit the manifold (without gaskets) and the manifold sits on the block with a gap to the heads, and the bolt holes in the manifold are still high to the heads, you need to machine the bottom ends of the manifold.
It's still not clear what the problem is.
It's still not clear what the problem is.
Safety Car
Joined: May 2003
Posts: 4,797
Likes: 239
From: Ocean Township NJ
Not always a 1:1 correlation between surfacing block and/or heads, and alignment of manifold.
Case in point: 1965 "861" block was decked 0.030" (average) to provide 8.995" deck height, and "461" iron heads were "milled" .020", for a total dimensional change of 0.050". The LT1 aluminum intake manifold fit up perfectly using standard FelPro gaskets and about 1/16" thickness RTV on the front/rear rails. Bolt holes aligned, as well.
Brumbach: you never mentioned what heads you're using. If they are aftermarket, then everything might "go out the window".
Case in point: 1965 "861" block was decked 0.030" (average) to provide 8.995" deck height, and "461" iron heads were "milled" .020", for a total dimensional change of 0.050". The LT1 aluminum intake manifold fit up perfectly using standard FelPro gaskets and about 1/16" thickness RTV on the front/rear rails. Bolt holes aligned, as well.
Brumbach: you never mentioned what heads you're using. If they are aftermarket, then everything might "go out the window".
Last edited by 65tripleblack; Jun 13, 2012 at 07:47 PM.
Le Mans Master
Joined: Feb 2008
Posts: 6,429
Likes: 1,854
From: Folsom CA
Fel-Pro used to list angle gauges to correct or identify these issues.
The gauge sat in the valley and showed you if the heads had proper angles.
If they were wrong it told you what way they needed to move. They were solid machined aluminum pieces that were quick to set in place and view the results.
Maybe a local machine shop has a set and you could get the to check out your block and heads? Sometimes in the rebuild market engines were in their third or fourth rebuild and no history was available. When a rebuilder found these issues they pulled the angle gauge and quickly knew what needed done. If needed I can look and see if they are still offered.
The gauge sat in the valley and showed you if the heads had proper angles.
If they were wrong it told you what way they needed to move. They were solid machined aluminum pieces that were quick to set in place and view the results.
Maybe a local machine shop has a set and you could get the to check out your block and heads? Sometimes in the rebuild market engines were in their third or fourth rebuild and no history was available. When a rebuilder found these issues they pulled the angle gauge and quickly knew what needed done. If needed I can look and see if they are still offered.
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Tech Contributor
Joined: May 2005
Posts: 15,570
Likes: 116
From: Conroe Texas
http://www.jegs.com/i/Fel+Pro/375/2520/10002/-1
Le Mans Master
Joined: Feb 2008
Posts: 6,429
Likes: 1,854
From: Folsom CA
Is this the item you are describing? This for a 1986 and earlier 23 degree small block Chevy. I also see them for 18 degree small blocks as well as big blocks.
http://www.jegs.com/i/Fel+Pro/375/2520/10002/-1
http://www.jegs.com/i/Fel+Pro/375/2520/10002/-1
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 960
Likes: 25
From: Middlesboro KY
I've been out of town helping one of my kids move. I dry fitted the intake manifold and it bolts right up. Using the Felpro MS9617 they don't. If I line up one side, the other side is off. Here's other info that might help. Is there such a thing as a shim gasket? I've used them to mount heads for another build. They were ultra thin.
Block 3914668
Heads 3917291
Intake 3890490
Block 3914668
Heads 3917291
Intake 3890490
Last edited by Brumbach; Jun 18, 2012 at 01:43 PM.
Le Mans Master
Joined: Feb 2008
Posts: 6,429
Likes: 1,854
From: Folsom CA
There are copper shims available for the heads,Fel-Pro 7733SP, If memory serves correctly these are .010 thick, usually used to correct blocks that have been decked once too many or to lower compression in certain applications. Victor gaskets or Corteco gaskets most likely offers these also.
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 960
Likes: 25
From: Middlesboro KY
There are copper shims available for the heads,Fel-Pro 7733SP, If memory serves correctly these are .010 thick, usually used to correct blocks that have been decked once too many or to lower compression in certain applications. Victor gaskets or Corteco gaskets most likely offers these also.
Thanks
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,871
From: Greenville, Indiana
If you have the steel shim head gaskets on that engine, you might be able to get what you need by using the Fel-pro composition head gasket (.038 thick?).
I don't like the idea of cutting the manifold and I don't think shim type manifold gaskets would seal, even if you could find them. I sure don't like just filing the holes out as I think you are asking for trouble/leaks.
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
Somebody else may have a better idea but it sounds like you need to have the manifold cut across the port side and the block ends and then use the standard gaskets.
If you have the steel shim head gaskets on that engine, you might be able to get what you need by using the Fel-pro composition head gasket (.038 thick?).
I don't like the idea of cutting the manifold and I don't think shim type manifold gaskets would seal, even if you could find them. I sure don't like just filing the holes out as I think you are asking for trouble/leaks.
If you have the steel shim head gaskets on that engine, you might be able to get what you need by using the Fel-pro composition head gasket (.038 thick?).
I don't like the idea of cutting the manifold and I don't think shim type manifold gaskets would seal, even if you could find them. I sure don't like just filing the holes out as I think you are asking for trouble/leaks.
.....however in these situations, you really need a thicker side gasket for rail clearance for the silicone bead. too tight and it will squeeze the sealant right out of the end rails or the stock rubber ones too....you are at a crossroad, you either need to elongate the manifold holes with a rat tail file and live with some small port alignment issues that are no big deal or have the manifold milled on the sides and ends
been there done that many times over the last 40 odd years.....the bubba-rat tail works!......thinner side gaskets are not the answer......
Le Mans Master
Joined: Feb 2008
Posts: 6,429
Likes: 1,854
From: Folsom CA
Somebody else may have a better idea but it sounds like you need to have the manifold cut across the port side and the block ends and then use the standard gaskets.
If you have the steel shim head gaskets on that engine, you might be able to get what you need by using the Fel-pro composition head gasket (.038 thick?).
I don't like the idea of cutting the manifold and I don't think shim type manifold gaskets would seal, even if you could find them. I sure don't like just filing the holes out as I think you are asking for trouble/leaks.
If you have the steel shim head gaskets on that engine, you might be able to get what you need by using the Fel-pro composition head gasket (.038 thick?).
I don't like the idea of cutting the manifold and I don't think shim type manifold gaskets would seal, even if you could find them. I sure don't like just filing the holes out as I think you are asking for trouble/leaks.
Mike was thinking.
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 960
Likes: 25
From: Middlesboro KY
I think the Felpro MS 9617 has a thickness of .045. Am I correct? The Felpro Q1277 or Q12371 has a thickness of .030. It might be worth the money to purchase one of these two and see if the bolts will line up. If not, I'll have the intake milled as suggested.
Since the bolts line up with a dry fit, if I go for the milling, I assume it should be milled equal to the thickness of the gasket I'll use. Correct?
Since the bolts line up with a dry fit, if I go for the milling, I assume it should be milled equal to the thickness of the gasket I'll use. Correct?
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
I think the Felpro MS 9617 has a thickness of .045. Am I correct? The Felpro Q1277 or Q12371 has a thickness of .030. It might be worth the money to purchase one of these two and see if the bolts will line up. If not, I'll have the intake milled as suggested.
Since the bolts line up with a dry fit, if I go for the milling, I assume it should be milled equal to the thickness of the gasket I'll use. Correct?
Since the bolts line up with a dry fit, if I go for the milling, I assume it should be milled equal to the thickness of the gasket I'll use. Correct?
some machinists prefer to see the whole engine ......
Le Mans Master
Joined: Feb 2008
Posts: 6,429
Likes: 1,854
From: Folsom CA
When you bolt aluminum manifolds to cast iron blocks the gasket needs to allow the aluminum to slide a little when torqued. If it does not allow the sliding it will cause the gasket to leak. Aluminum expands differently than cast iron when exposed to heat so you have constant movement between the aluminum manifold and cast iron block in normal operation. Be sure the gasket you choose is designed for aluminum on cast iron and make sure the correct side of the gasket faces up to avoid issues.
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 960
Likes: 25
From: Middlesboro KY