[Found!] 273 4 bbl sheet metal plate underside of intake manifold

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Bob Jasinski

Bob Jasinski

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The sheet metal plate attached to the underside on my 273 4 bbl intake manifold for my '65 FS has gone missing. I'm pretty sure my machinist lost the part, as I have looked everywhere for it. The plate is normally riveted to the underside, and I know some folks feel they're not needed, but I want to keep it original. Picture of the plate installed on backside of manifold:

IMG_5355.JPG
 
Could make it before you'll find one. Only you would know........Those 'rivets' were coursly threaded so you could 'screw' them out. It just prevented coking of the oil hitting that exhaust crossover. If you blocked that at the intake gasket, it would not be an issue unless you need the heat.
 
Pishta, The reason I brought the plate to the machinist was to repair one hole and thread both for reattachment with bolts. I do not plan on blocking off the exhaust ports on the intake, I've got it really clean and want it to work as designed. If you block off the ports, the choke won't pull off properly.
 
It looks just like a flat metal plate in the picture, but even if it has turned-up edges it wouldn't be that difficult to fabricate. The exact material isn't crucial since it's just a splash barrier. Pretty sure the machinist could make it.
 
Is the 2bbl plate different? I have to admit, I never compared them. If so, a used 2bbl intake shouldn't be too hard to find or cost much.
 
I have some 20 gauge steel here. Glad I took the photo, it doesn't look that hard to do. But still, if you have one you'd sell let me know.
 
Chrysler....and everyone else stopped using those later in time. There was a reason.
 
Yup, probably because the oil quality got a lot better and wouldn't coke up as easily. That and different designs on the intake with no further need for a choke as we know it.
 
cudamark said:
Yup, probably because the oil quality got a lot better and wouldn't coke up as easily. That and different designs on the intake with no further need for a choke as we know it.
Click to expand...

Yes they did it so oil would have fewer places to coke up. Why anyone would want that is beyond me.
 
Rusty, As far as I have been able to determine, this part serves a purpose, that is to shield the hot underside of the intake manifold exhaust port from oil directly splashing onto it by the lifters, burning the oil and turning it into coke to then fall off onto the lifters. Please enlighten me as to why I would not want to replace this factory part.
 
Bob Jasinski said:
Rusty, As far as I have been able to determine, this part serves a purpose, that is to shield the hot underside of the intake manifold exhaust port from oil directly splashing onto it by the lifters, burning the oil and turning it into coke to then fall off onto the lifters. Please enlighten me as to why I would not want to replace this factory part.
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Oh I know exactly what its purpose is. So did Chrysler. But they, along with everybody else, eliminated them because they were catching and cooking oil, more than they were insulating the bottom of the intake.

There are plenty of heat paints on the market that would do just as good if not better job of that piece of metal. Red Glyptal comes to mind. It also has fantastic oil drain properties that aids in oil runoff.

As for "enlightening" you on why you wouldn't want to replace that shield, I cannot do that. That's not my job. You seem dead set on it anyway, so have at it. I know I wouldn't want anything at all that could catch and hold oil until it turns to cooked sludge and possibly fall into my engine later. There are tons of modern carburetor insulator gaskets that will do a far better job of keeping the carburetor cool, than that shield ever did.

Just because car makers did something, doesn't mean it was always a good idea. They evolved just like the rest of us. Good luck with whatever you decide.
 
Rusty et al,

As I mentioned when I started the part wanted ad, I recognize that not all agree on the need for the shield (plate), and I don't want to turn this into a debate, but I will respond to your suggestions as follows:

<There are plenty of heat paints on the market that would do just as good if not better job of that piece of metal. Red Glyptal comes to mind. It also has fantastic oil drain properties that aids in oil runoff>

Glyptal is good stuff, proven to facilitate oil runoff from rough engine castings, I agree. In this application however, I fail to see how Glyptal or any other "paint" would have the heat insulating ability created by the air gap between the plate and the underside of the manifold exhaust passage. Exhaust gas temps get into the 500 degree range, and conventional oil will flash burn at those temps, turning into coke on the underside of the manifold.

<There are tons of modern carburetor insulator gaskets that will do a far better job of keeping the carburetor cool, than that shield ever did>

This is not about insulating the carburetor, the plate has nothing to do with that. The exhaust gasses will be there either way, with or without the plate.
It's important to note that when I removed the original plate, there was NO carbon buildup on the underside of the manifold, NONE. This alone proves (to me at least) that the plate served its intended purpose. Yes, there was sludge on top of the plate, this was a high mileage engine, and the engine was full of sludge, but no coke buildup under the manifold that was protected by the plate. I have thoroughly cleaned the exhaust passage in the intake manifold, and I have a fully functioning heat riser and choke pull off, so it is all to stock specs.

For those that have an interest, here's a picture of the plate I just fabbed up.

DSC_3723[1].JPG
 
Bob Jasinski said:
Rusty et al,

As I mentioned when I started the part wanted ad, I recognize that not all agree on the need for the shield (plate), and I don't want to turn this into a debate, but I will respond to your suggestions as follows:

<There are plenty of heat paints on the market that would do just as good if not better job of that piece of metal. Red Glyptal comes to mind. It also has fantastic oil drain properties that aids in oil runoff>

Glyptal is good stuff, proven to facilitate oil runoff from rough engine castings, I agree. In this application however, I fail to see how Glyptal or any other "paint" would have the heat insulating ability created by the air gap between the plate and the underside of the manifold exhaust passage. Exhaust gas temps get into the 500 degree range, and conventional oil will flash burn at those temps, turning into coke on the underside of the manifold.

<There are tons of modern carburetor insulator gaskets that will do a far better job of keeping the carburetor cool, than that shield ever did>

This is not about insulating the carburetor, the plate has nothing to do with that. The exhaust gasses will be there either way, with or without the plate.
It's important to note that when I removed the original plate, there was NO carbon buildup on the underside of the manifold, NONE. This alone proves (to me at least) that the plate served its intended purpose. Yes, there was sludge on top of the plate, this was a high mileage engine, and the engine was full of sludge, but no coke buildup under the manifold that was protected by the plate. I have thoroughly cleaned the exhaust passage in the intake manifold, and I have a fully functioning heat riser and choke pull off, so it is all to stock specs.

For those that have an interest, here's a picture of the plate I just fabbed up.

View attachment 1715770655
Click to expand...
That’s a nice plate that will certainly do its job. Kim
 
Bob Jasinski said:
Rusty et al,

As I mentioned when I started the part wanted ad, I recognize that not all agree on the need for the shield (plate), and I don't want to turn this into a debate, but I will respond to your suggestions as follows:

<There are plenty of heat paints on the market that would do just as good if not better job of that piece of metal. Red Glyptal comes to mind. It also has fantastic oil drain properties that aids in oil runoff>

Glyptal is good stuff, proven to facilitate oil runoff from rough engine castings, I agree. In this application however, I fail to see how Glyptal or any other "paint" would have the heat insulating ability created by the air gap between the plate and the underside of the manifold exhaust passage. Exhaust gas temps get into the 500 degree range, and conventional oil will flash burn at those temps, turning into coke on the underside of the manifold.

<There are tons of modern carburetor insulator gaskets that will do a far better job of keeping the carburetor cool, than that shield ever did>

This is not about insulating the carburetor, the plate has nothing to do with that. The exhaust gasses will be there either way, with or without the plate.
It's important to note that when I removed the original plate, there was NO carbon buildup on the underside of the manifold, NONE. This alone proves (to me at least) that the plate served its intended purpose. Yes, there was sludge on top of the plate, this was a high mileage engine, and the engine was full of sludge, but no coke buildup under the manifold that was protected by the plate. I have thoroughly cleaned the exhaust passage in the intake manifold, and I have a fully functioning heat riser and choke pull off, so it is all to stock specs.

For those that have an interest, here's a picture of the plate I just fabbed up.

View attachment 1715770655
Click to expand...
Nicely done!
 
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