Mystery intake port question

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fiatfam
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Mystery intake port question

Post by fiatfam » Sat Feb 09, 2019 2:49 pm

I am replacing the intake manifold on my 79 spider with a waffle manifold for 40 IDF's. The old manifold covered the front ports on the head, which look to be a water port. Is it ok to plug it, if so what is the best way?
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It looks like it was used to heat the manifold, there is another on the rear of the manifold.
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friedman
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Re: Mystery intake port question

Post by friedman » Sat Feb 09, 2019 6:01 pm

The 79 head had an exhaust recirculation port extending across the front of the head. A pipe went from the exhaust manifold to the exhaust side of this port at the front of the head and the 79 intake manifold had a port that matched with it on the driver side. If you still have the pipe going from the exhaust manifold to that port on the head then you will need to block it on the intake side to keep exhaust blowing out, not coolant. I always removed the pipe on the exhaust side and just left it open at both sides of the head.

By the way, if you are using a 79 exhaust manifold with the 4-1 configuration you are losing horsepower. If you have replaced it with a 4-2-1 exhaust manifold from an earlier model then you have no problem as there is nothing feeding into that cross head opening.
Carl in Virginia
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Re: Mystery intake port question

Post by bartigue » Sat Feb 09, 2019 6:48 pm

Personally I’d throw that 79 head in the trash and get a 1800 or 2000 FI head. But if you can’t do that then I’d be concerned not about the circular port (it’s egr, disconnect it on both sides and plug the exhaust) but that second port looks like a water port your manifold isn’t covering.
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Re: Mystery intake port question

Post by friedman » Sun Feb 10, 2019 8:38 am

I think we are getting confused about which ports we are talking about but in any event there should be no water ports at the front of the head pointing out to the side.
Carl in Virginia
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Re: Mystery intake port question

Post by fiatfam » Sun Feb 10, 2019 8:52 am

Carl and Bradley Thank you for the information. I am ok with the large hole ,if I understand that can be left open with a 4-2 header. What should I do with the second port, the one Bradley said looks like a water port? Can I stretch the intake manifold :D
Thanks
Nick
Ps
I was just thinking if I left the exhaust/intake hole open wouldn't that cause a loss of vacuum on the intake?
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Re: Mystery intake port question

Post by friedman » Sun Feb 10, 2019 1:20 pm

If you are talking about that funny foot shaped depression above the EGR port then I think that is just a cast depression that is not open to anything, you will need to verify.

I have run several 79 heads with the EGR cast in opening open at both ends...it literally just goes from the exhaust to intake side, earlier heads had a metal pipe extending above the head. I have no idea why Fiat thought that going to the expense of casting a new head configuration to delete the pipe made fiscal sense.
Carl in Virginia
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Re: Mystery intake port question

Post by fiatfam » Sun Feb 10, 2019 4:21 pm

Thanks, I was thinking of the "foot"hole. I'll just ignore it.
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Re: Mystery intake port question

Post by friedman » Sun Feb 10, 2019 4:51 pm

Although you have the photos mis-oriented, you do realize the hole in the IDF manifold that you have a bolt stuck in is for a vacuum port for the brake booster, right?
Carl in Virginia
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Re: Mystery intake port question

Post by fiatfam » Sun Feb 10, 2019 10:46 pm

Well thats news ,the more I learn the less I know. Thanks, but why would they put in the front of the manifold and not the rear?
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Re: Mystery intake port question

Post by friedman » Mon Feb 11, 2019 8:51 am

Don't know why it's at the front but I have had many IDF manifolds over the decades and they are all at the front. Not a big deal but you do have to source a longer vacuum hose.
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