Author Topic: Intake manifold heat tube ports  (Read 540 times)

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Offline AlexM

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Intake manifold heat tube ports
« on: November 30, 2018, 12:52:39 pm »
Hey All, For those of you running headers. What do you use to cap off the two ports on the back of the intake manifold? I imagine there should be something covering them?
--Alex
1969 Mach 1
1970 BOSS 302 0F02G120146
1970 BOSS 302 0F02G119233 W code
1969 BOSS 302 9F02G196425
1969 BOSS 429 9F02Z198888 KK 1982

“You can sell a young man’s car to an old man, but you’ll never sell an old man’s car to a young man” - Bunkie Knudsen


Offline JohnKammer

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Re: Intake manifold heat tube ports
« Reply #1 on: December 02, 2018, 05:11:39 am »
Alex,
I think I have some block off plates; Will try to check today.

John
John Kammer
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johnkammer@cinci.rr.com

Offline JohnKammer

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Re: Intake manifold heat tube ports
« Reply #2 on: December 02, 2018, 09:46:57 am »
Alex,
The plates I thought were for the heat tubes are actually too small.
John Kammer
 KK1638 - Wimbledon White
johnkammer@cinci.rr.com

Offline AlexM

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Re: Intake manifold heat tube ports
« Reply #3 on: December 02, 2018, 11:55:37 am »
Hey John, thanks for checking. At this point just knowing what they are called helps. I'm totally new to BOSS 429's so I was surprised to see these missing. Would these have come with the headers back in the day? Or where did you normally get them?
--Alex
1969 Mach 1
1970 BOSS 302 0F02G120146
1970 BOSS 302 0F02G119233 W code
1969 BOSS 302 9F02G196425
1969 BOSS 429 9F02Z198888 KK 1982

“You can sell a young man’s car to an old man, but you’ll never sell an old man’s car to a young man” - Bunkie Knudsen


Offline BOSSHEMI

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Re: Intake manifold heat tube ports
« Reply #4 on: December 02, 2018, 01:28:34 pm »
You just take a piece of flat aluminum and cut to fit one piece covering both holes. Drill the 4 holes to match the existing holes. Use gasket sealer and done. It's all the way in rear of engine bay so it doesnt have to be perfect.
KK1336 Royal Maroon 820S

Offline AlexM

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Re: Intake manifold heat tube ports
« Reply #5 on: December 02, 2018, 04:01:37 pm »
True, making some would not be difficult either. I suppose they would have been made the same thickness as the tube flanges so original hardware could be used to secure them. Unbolt the tube and bolt on the plates.
--Alex
1969 Mach 1
1970 BOSS 302 0F02G120146
1970 BOSS 302 0F02G119233 W code
1969 BOSS 302 9F02G196425
1969 BOSS 429 9F02Z198888 KK 1982

“You can sell a young man’s car to an old man, but you’ll never sell an old man’s car to a young man” - Bunkie Knudsen


Offline AlexM

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Re: Intake manifold heat tube ports
« Reply #6 on: March 13, 2019, 08:33:28 am »
Just to close this loop. I ended up making a couple block off plates for the heat tube ports.

I had found this gasket (on the left) in with the loose parts that came along with the car and used it for a template. I made the plates out of some 3/16" steel and the gaskets I cut from some old spread bore carburetor base plate gaskets I had laying around. Bolts are from a AMK kit for heat tubes.


--Alex
1969 Mach 1
1970 BOSS 302 0F02G120146
1970 BOSS 302 0F02G119233 W code
1969 BOSS 302 9F02G196425
1969 BOSS 429 9F02Z198888 KK 1982

“You can sell a young man’s car to an old man, but you’ll never sell an old man’s car to a young man” - Bunkie Knudsen


Offline flyingfred

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Re: Intake manifold heat tube ports
« Reply #7 on: March 13, 2019, 09:57:43 am »
You have done a nice job and it looks good. Keep in mind that without the tubes to the exhaust manifold and "H" pipe, there is nothing to leak here. Therefore all of this is purely cosmetic and really does not even need gaskets. The plates are not really necessary either but do give the manifold a nice finished appearance.

-Fred-

Offline AlexM

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Re: Intake manifold heat tube ports
« Reply #8 on: March 14, 2019, 08:02:42 am »
Thanks Fred. Not ever having one of these engines apart I don't understand how those holes are plumbed. It was weird to have them up plugged and I guess they've been open for many years since the PO installed the headers in the early 70's. There was definitely some crap down in the ports that I had to suck it out with a shop vac.

If it was all hooked up what's the air flow? Should I be concerned about any junk that may have gotten in there or water etc?
--Alex
1969 Mach 1
1970 BOSS 302 0F02G120146
1970 BOSS 302 0F02G119233 W code
1969 BOSS 302 9F02G196425
1969 BOSS 429 9F02Z198888 KK 1982

“You can sell a young man’s car to an old man, but you’ll never sell an old man’s car to a young man” - Bunkie Knudsen


Offline flyingfred

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Re: Intake manifold heat tube ports
« Reply #9 on: March 14, 2019, 09:02:00 am »
Thanks Fred. Not ever having one of these engines apart I don't understand how those holes are plumbed. It was weird to have them up plugged and I guess they've been open for many years since the PO installed the headers in the early 70's. There was definitely some crap down in the ports that I had to suck it out with a shop vac.

If it was all hooked up what's the air flow? Should I be concerned about any junk that may have gotten in there or water etc?

The exhaust gasses are directed to flow through the intake manifold to heat it when the exhaust heat riser valve is closed when the engine is cold. The exhaust heat riser valve has a bimetallic spring that opens the valve as the exhaust passes through and heats up the valve. Any junk inside the passage ways are harmless to the engine as they are in a separate circuit from all other engine processes. Blowing air through the passages is far more effective in removing debris from them but as dirty as it may be inside of the passages, it does not affect the engine. It is just nice to know that they are clean. Just think of these passages as a small exhaust pipe and part of the exhaust system when hooked up. In most all other engines this passage is built into the heads and enters the intake manifold at the intake gasket.

-Fred-

Offline AlexM

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Re: Intake manifold heat tube ports
« Reply #10 on: March 14, 2019, 02:06:20 pm »
Ah ok makes sense now. Up one tube through the manifold and down and out through the other tube. Closed path the whole way like you mentioned. I'm looking at the photo on the inside of the back cover of Strange's BOSS 429 book (the newer one) and that helps too. The heat riser valve off the passenger side exhaust manifold would put back pressure on the system to push exhaust up through the tube, around the intake manifold and then down and out to the h-pipe.

Thanks Fred!
--Alex
1969 Mach 1
1970 BOSS 302 0F02G120146
1970 BOSS 302 0F02G119233 W code
1969 BOSS 302 9F02G196425
1969 BOSS 429 9F02Z198888 KK 1982

“You can sell a young man’s car to an old man, but you’ll never sell an old man’s car to a young man” - Bunkie Knudsen


Offline ed meyer

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Re: Intake manifold heat tube ports
« Reply #11 on: March 15, 2019, 07:55:59 am »
426 hemi has same heat tube & flapper design that routes into far rear of intake because of the 2x4  carb setup

Offline crossboss

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Re: Intake manifold heat tube ports
« Reply #12 on: March 15, 2019, 08:05:33 am »
Boys,
I did a similar 'block off plate' to the rear breather when I ran the 427 'Sidewinder' intake on my 428 CJs.
Current lifelong projects:
1969 Mustang Fastback/FOX chassis, 6 speed, 4 wheel discs, with a modern Can-Am 494 (Boss 429), Kaase headed, intake mounted with a 1425 cfm 'B' Autolite Inline carb, ala Trans-Am style…Whew!
 
Volvo 1800, being converted to Boss 302 power…coming soon!

Offline 429bossman

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Re: Intake manifold heat tube ports
« Reply #13 on: March 15, 2019, 12:20:07 pm »
I once used small freeze plugs .
69 BOSS 429 bought in 1971
69 Boss 302
69 428 Torino cobra
69 428 Mach 1 SCJ
70 429 Torino cobra bought new
70 429 SCJ  Torino cobra  4.30 four speed
66 HI PO 289 mustang
70 SS 454 Chevelle LS6
70 GTX 440 6 pac
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