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cboy 05-11-2005 01:48 PM

Choke heat tubes - how important?
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In the process of cleaning up the engine on the rat project I discovered the metal heat riser tube from the intake manifold to the choke had completely rusted off and there is also a small hole rusted through the plate attaching to tube to the manifold. (This is a 351 M). Here are a couple shots to get you oriented. My questions are 1) will the choke operate at all well without this heat tube, 2) What is below this plate - and do I need to be concerned about debris getting down those holes if I just left it as is (The bolts are rusted in and I'd just as soon leave them alone if at all possible) and 3) if the choke is pretty well toast without the heat tube, am I better off just tossing the whole automatic choke and hooking up a cable to operate it manually - I'll only be driving this car during nice warm weather anyhow - so the choke should only have to operate occasionally.

The first shot is looking across the manifold toward the passenger side with the heat riser plate just above the taped over intake holes. The second shot is a close up of the plate. 05-11-2005 02:19 PM

All that is is a dip in the manifold over the exhaust x-over, totally sealed from the innards of the manifold. That plate that bolts on (4 bolts is a little overkill!!) is a little 'oven' with the tubing coiled net the iron so the air is heated before being sucked into the choke mechanism on the carb. You can see the inlet of the tube on the right side of the plate. Really efficient system and much better than the aftermarket electric chokes which don't have a clue what the engine temperature is - they just open the choke on time. Should be really cheap @ the Ford dealer or even cheaper if your auto parts store carries them. They should. If you are running a stock type carb with the hot air choke, it would be silly to not use this hot air choke, it is so easy and cheap to put together. ( that reminds me of a line from Curly Howard on the Three Stooges. As they were being chased around a haunted mansion by a gorilla Curly said, "It would be silly to be afraid right now - and I am feeling really silly!")

To get those rusted bolts out, heat them to white hot(just shy of melting) until you are sure they are heated glowing hot all the way down. Iron will be insulated well enough by rust that it won't get that hot. Quench them with a wet rag and when totally cool, they will back out like new bolts. Well, maybe not that easily but I needed to exaggerate for effect!

cboy 05-11-2005 06:34 PM


After posting I went back out to the shop and decided to just pull the manifold and run it through the sandblaster - so I got a good look at what's underneath. Also, I got the nuts off with a little more coaxing so all is well with that. Turns out only two of the bolts in the picture secure the plate - not four. The other two are manifold bolts - which I found out the hard way when the manifold wouldn't budge after I removed all the other bolts. There are two just like it on the other side of the manifold. But they are really deceptive. They have a smaller head and are at an odd angle compared with all the other manifold bolts. Anyhow, looks like I''m out of the woods on this one.

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