Another 4.9 head question
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Another 4.9 head question
I have a 1990 F150 4.9 auto 2wd. I just got and installed a machined head but it was one with the air tubes in the head. The oringinal was not, so the machine shop plugged the holes. My problem is the exhaust manifolds do not line up exactly and I can't get all the bolts in. It seems like its about 1/8 in off on both manifolds. Also, does this year truck use an exhaust manifold gasket? As I recall when taking it apart there wasn't one. Any help/suggestions on these issues? thanks.....
Fleet Mechanic
Joined: Nov 2011
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From: New York
Hmmm, odd set of circumstances as I thought the Air pump first appeared in 1987, same year as fuel injection. Perhaps your engine/head had previously been replaced? I also would have thought that the exhaust manifold was the same '87 - '95, so that too seems to suggest something wasn't stock in the first place.
I'm thinking there is no gasket from the factory. Usually with iron-to-iron fitments they skipped a gasket. Regardless, it's not required even if they did have one from the factory.
I'm thinking there is no gasket from the factory. Usually with iron-to-iron fitments they skipped a gasket. Regardless, it's not required even if they did have one from the factory.
Elder User - What???
Joined: Dec 2011
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From: Moore, OK
Exhaust manifolds have a habit of shrinking when you take them off. This used to be a real problem with Chevy V8 manifolds to the degree that special spreaders were devised to allow the reinstallation of the exhaust manifolds. I recently ran into what you are experiencing and ended up using a Dremel tool and a little sanding drum to gain the clearance I needed. I simply removed a little from both outside bolt holes until I could get them to bolt up.
Regarding a gasket, from the factory they did not come with one. However, most intake gasket sets will have the exhaust portion of the gasket built in. How it is built in depends on the manufacturer. Some are stapled to each other because the gasket materials are different between intake and exhaust, others are simply one piece made of the same material, such as the gasket I just put on my truck (this one came from Fel-Pro in my head gasket set).
<O
I hope this helps.
Regarding a gasket, from the factory they did not come with one. However, most intake gasket sets will have the exhaust portion of the gasket built in. How it is built in depends on the manufacturer. Some are stapled to each other because the gasket materials are different between intake and exhaust, others are simply one piece made of the same material, such as the gasket I just put on my truck (this one came from Fel-Pro in my head gasket set).
<O
I hope this helps.
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Thanks for the replys, I was thinking that widening the holes a little would work I can handle that. Yaga, are you saying use the intake gasket (intake to head) and not the exaust? I too have the felpro kit....
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Use the gasket for both intake and exhaust. From the factory there was no exhaust manifold gasket, but that was when the parts were new and straight. Countless heat cycles have caused the manifolds to no longer be straight and true, the gasket helps take care of this issue.
Some of the 4.9's in our year range had the air pump running into the exhaust manifold instead of the head from what I can tell. I have never seen one of these, but when checking out 4.9 heads one of the questions I always have to answer is air-in-head, or air-in-manifold, so they must be some out there with air in manifold.
Does your truck have air tubes in the manifolds?
Some of the 4.9's in our year range had the air pump running into the exhaust manifold instead of the head from what I can tell. I have never seen one of these, but when checking out 4.9 heads one of the questions I always have to answer is air-in-head, or air-in-manifold, so they must be some out there with air in manifold.
Does your truck have air tubes in the manifolds?
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Ok, drilled the holes out and got everything lined up and installed with the gasket in place. My truck is "air-in-manifold" which is just the egr tube runing from exaust manifold to intake. The head I got was the one with "air-in-head" so the machine shop pluged the holes so no more "air-in-head".. If that makes sence?
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