Underside of Intake manifold

[Studdley]

What's the bulge under the intake manifold that goes on the across the bottom of it and has a small port on each side, also does a cleveland have to be run with a lifter valley pan?

 

[delawarebill]

if it's what i think your talking about it's for attaching a pan/shield onto the bottom of manifold to provide heat shield to carb. so it don't vaporize fuel before getting into cyl's.

 

[73pony]

The bulge is a heat cross over. It uses exhaust heat to heat up the intake manifold. You do not have to run a valley pan, I do not run one but I have my heat crossover blocked off.

 

[Studdley]

The bulge is a heat cross over. It uses exhaust heat to heat up the intake manifold. You do not have to run a valley pan, I do not run one but I have my heat crossover blocked off.

so need to worry about that port causing a vacuum leak?

 

[73pony]

Correct. It allows exhaust gasses to cross through the intake to heat up the intake manifold. When you set the intake manifold what did you use for the end seals?

 

[Studdley]

Correct. It allows exhaust gasses to cross through the intake to heat up the intake manifold. When you set the intake manifold what did you use for the end seals?

I bought gaskets from summit and it came with cork end gaskets

 

[turtle5353]

Correct. It allows exhaust gasses to cross through the intake to heat up the intake manifold. When you set the intake manifold what did you use for the end seals?

I bought gaskets from summit and it came with cork end gaskets

I always ditch the end gaskets and run a fat bead of RTV black silicone across the ends.

 

[73pony]

Correct. It allows exhaust gasses to cross through the intake to heat up the intake manifold. When you set the intake manifold what did you use for the end seals?

I bought gaskets from summit and it came with cork end gaskets

I always ditch the end gaskets and run a fat bead of RTV black silicone across the ends.

+1. that's why I asked. I have never had any luck getting the cork end seals to seal properly.

 

[Stanglover]

This is what I did, not saying you have to, but I carefully "hand milled" a step about .080" deep and cut some 1/16" SS, then using a center punch, stitched the plate in place using some high heat exhaust paste to seal it. I also had previously inserted 5/16 set screws into the holes in the carb mating surface, see pic.

By doing this I practically eliminated any heat getting to the underside of the Holley 670 carb. This heat riser was intended for the Autolite 4300 carb only. My car was experiencing a huge amount of fuel vaporization causing hard hot starting until I "fixed it"

Also, when I install a valley pan, I do NOT use RTV. It's expensive, but well worth it to use Permatex "The Right Stuff" on the manifold ends. Do NOT use any silicone based product around the intake ports. Here I use Permatex 2 non-hardening gasket maker/sealer. Just a small bead around valley pan port grooves. There are other products that can be used here, but I have had no issues with P 2. There was another precaution I took, but then I'm a bit anal that way, was to cut and insert a .020" SS plate into the paper gasket to act as a double block-off for the heat cross-overs. The paper is slightly thinner than .020", but on the VP, I flattened that groove to allow for it. Tighten according to pattern and spec. There is a "trick" you can use and that is cut the heads of a couple of long 5/16" bolts, screw them into the head holes at center. These will act as a guide when lowering the manifold, just make sure they are long enough to remove!! Another tip is to get a couple of eye bolts that can be screwed diagonally into the carb mounting holes, then use a rod of some sort as a handle. Help from a buddy is a GOOD idea here!!

Hope that helps.

Geoff.

 

[Studdley]

This is what I did, not saying you have to, but I carefully "hand milled" a step about .080" deep and cut some 1/16" SS, then using a center punch, stitched the plate in place using some high heat exhaust paste to seal it. I also had previously inserted 5/16 set screws into the holes in the carb mating surface, see pic.

By doing this I practically eliminated any heat getting to the underside of the Holley 670 carb. This heat riser was intended for the Autolite 4300 carb only. My car was experiencing a huge amount of fuel vaporization causing hard hot starting until I "fixed it"

Also, when I install a valley pan, I do NOT use RTV. It's expensive, but well worth it to use Permatex "The Right Stuff" on the manifold ends. Do NOT use any silicone based product around the intake ports. Here I use Permatex 2 non-hardening gasket maker/sealer. Just a small bead around valley pan port grooves. There are other products that can be used here, but I have had no issues with P 2. There was another precaution I took, but then I'm a bit anal that way, was to cut and insert a .020" SS plate into the paper gasket to act as a double block-off for the heat cross-overs. The paper is slightly thinner than .020", but on the VP, I flattened that groove to allow for it. Tighten according to pattern and spec. There is a "trick" you can use and that is cut the heads of a couple of long 5/16" bolts, screw them into the head holes at center. These will act as a guide when lowering the manifold, just make sure they are long enough to remove!! Another tip is to get a couple of eye bolts that can be screwed diagonally into the carb mounting holes, then use a rod of some sort as a handle. Help from a buddy is a GOOD idea here!!

Hope that helps.

Geoff.

Very helpful

 

[Stanglover]

This is what I did, not saying you have to, but I carefully "hand milled" a step about .080" deep and cut some 1/16" SS, then using a center punch, stitched the plate in place using some high heat exhaust paste to seal it. I also had previously inserted 5/16 set screws into the holes in the carb mating surface, see pic.

By doing this I practically eliminated any heat getting to the underside of the Holley 670 carb. This heat riser was intended for the Autolite 4300 carb only. My car was experiencing a huge amount of fuel vaporization causing hard hot starting until I "fixed it"

Also, when I install a valley pan, I do NOT use RTV. It's expensive, but well worth it to use Permatex "The Right Stuff" on the manifold ends. Do NOT use any silicone based product around the intake ports. Here I use Permatex 2 non-hardening gasket maker/sealer. Just a small bead around valley pan port grooves. There are other products that can be used here, but I have had no issues with P 2. There was another precaution I took, but then I'm a bit anal that way, was to cut and insert a .020" SS plate into the paper gasket to act as a double block-off for the heat cross-overs. The paper is slightly thinner than .020", but on the VP, I flattened that groove to allow for it. Tighten according to pattern and spec. There is a "trick" you can use and that is cut the heads of a couple of long 5/16" bolts, screw them into the head holes at center. These will act as a guide when lowering the manifold, just make sure they are long enough to remove!! Another tip is to get a couple of eye bolts that can be screwed diagonally into the carb mounting holes, then use a rod of some sort as a handle. Help from a buddy is a GOOD idea here!!

Hope that helps.

Geoff.

Very helpful

 The more I think about it, the more I remember. If you have question or don't understand, I'll elaborate later.

 

[Ron Tanzi]

I personally like to keep the carb heat crossover open due to living in New England. On cool days I can start it and just drive without hesitation issues. I have run my engine (351C) with the heat crossover blocked and with it open. Open works better for my application. The fuel needs to atomize and when cold it will condense in the intake and cause issues. Just my opinion based on experience. I do not use the turkey pan gasket and have never had an issue oil burning on the bottom of the intake (EDL 2750), This I have checked after extened operation.

Ron

 

[Don C]

A Cleveland does not need to have the "turkey pan", it can just use regular gaskets. The pan helps keep the intake manifold and air and fuel cooler by keeping hot oil off it.

If you want to keep the hot oil off it and use regular gaskets you can trim off the pan and drill a couple of holes in it for drainage.

You can also paint the bottom of the manifold with engine paint to provide some insight into.

 

[Stanglover]

I personally like to keep the carb heat crossover open due to living in New England. On cool days I can start it and just drive without hesitation issues. I have run my engine (351C) with the heat crossover blocked and with it open.  Open works better for my application.  The fuel needs to atomize and when cold it will condense in the intake and cause issues. Just my opinion based on experience. I do not use the turkey pan gasket and have never had an issue oil burning on the bottom of the intake (EDL 2750), This I have checked after extened operation.

Ron

 Ron, it is really a matter of opinion, some like it hot, some not so much. Not only do I have the cross-over blocked off, I also use a 1" thick fiber spacer. It's in the hot summer that I find the benefit of less heat under the carb, but I do see why you lean in the opposite direction. Cool days can be a bit of an issue until it warms up and the choke come off.

 

[Stanglover]

A Cleveland does not need to have the "turkey pan", it can just use regular gaskets. The pan helps keep the intake manifold and air and fuel cooler by keeping hot oil  off it.

If you want to keep the hot oil off it and use regular gaskets you can trim off the pan and drill a couple of holes in it for drainage.

You can also paint the bottom of the manifold with engine paint to provide some insight into.

 So Don, it begs the question, Why did  Ford build the 351C with a valley pan and not just gaskets? It would have been cheaper and quicker not to install the valley pan or whatever it's called. But then again, engineers aren't always the smartest bunnies in the bunch.

 

[Ron Tanzi]

I personally like to keep the carb heat crossover open due to living in New England. On cool days I can start it and just drive without hesitation issues. I have run my engine (351C) with the heat crossover blocked and with it open.  Open works better for my application.  The fuel needs to atomize and when cold it will condense in the intake and cause issues. Just my opinion based on experience. I do not use the turkey pan gasket and have never had an issue oil burning on the bottom of the intake (EDL 2750), This I have checked after extened operation.

Ron

 Ron, it is really a matter of opinion, some like it hot, some not so much. Not only do I have the cross-over blocked off, I also use a 1" thick fiber spacer. It's in the hot summer that I find the benefit of less heat under the carb, but I do see why you lean in the opposite direction. Cool days can be a bit of an issue until it warms up and the choke come off.

Stanglover, I know a lot of guys have said they have had issues with the crossover being open. I have found that the heat crossover really helps my drivability . This has been the case with the original replacement stock 2 barrel cam (first stock rebuild) and the Comp cam (CJ copy) I am running now. As well as 2 different 4 bbl carbs. Some like it hot and some sweat when the heat is on. Name that tune LOL. 

Ron

 

[Don C]

I believe the primary reason Ford used the turkey pan was for cooling the intake manifold, cooler air is denser and denser means more power. The second reason was to keep oil off the exhaust crossover.

For them, it was probably faster to install the turkey pan with end gaskets already attached, rather than dealing with gluing on the two side gaskets and then the two end pieces.

 

[Ron Tanzi]

I believe the primary reason Ford used the turkey pan was for cooling the intake manifold, cooler air is denser and denser means more power. The second reason was to keep oil off the exhaust crossover.

For them, it was probably faster to install the turkey pan with end gaskets already attached, rather than dealing with gluing on the two side gaskets and then the two end pieces.

I agree Don. We also have to factor in that the stock cast iron intake manifold retains a lot of heat. An aluminum intake will hold less heat and dissipate it more efficiently making the turkey pan less important. 

Ron

 

[Stanglover]

I believe the primary reason Ford used the turkey pan was for cooling the intake manifold, cooler air is denser and denser means more power. The second reason was to keep oil off the exhaust crossover.

For them, it was probably faster to install the turkey pan with end gaskets already attached, rather than dealing with gluing on the two side gaskets and then the two end pieces.

 Don, that's a logical explanation. Thank you.

 We are getting off track a bit now, but an interesting discussion non the less. There are always pros and cons.

 For my engine, it definitely works better without the crossover open. When the weather is cool, yes it takes a bit longer to run well, but I'll take that over hard starting because the gas has vented off the primary bowl. I do not get this problem anymore.

As a side note, I have the original Autolite 4300 that was changed by a PO for a Holley 670 SA. The bottom of the throttle plate is quite burned and actually useless  as it is. I assume this is because either the steel and paper primary gasket burned through, or someone did not bother to put one on at a later date. I still retain that gasket regardless as an added precaution should the "fix" leak hot gasses.