The Stovebolt Site Forums The Shop Area Engine Shop Heating Intake Manifold

has anyone had problems with their stovebolts missing out alot with headers on? i still have the original intake manifold with a Roch. 1 barrel. i've been told that i need to warm the intake manifold (it makes sense to me as the original exhaust manifold diverted heat to the intake manifold) or it will always run badly. There is a heating plate available at Langdon's Stovebolt Engine Company. but is it made to work on the original intake manifold or the dual/triple carb manifolds?

You didn't say what type of headers you have. If you have Fentons you can make yourself a plate by tracing the lower intake onto half in steel,and then tapping holes. Bolt it up and run lines to the Fenton header fittings. Or run hot water from the thermostat area and back to the water pump on a loop which includes your intake.

Call Tom @ Stovebolt, he'll fix you up, great guy, wealth of knowledge. He has all the parts you need to heat your manifold properly for best fuel atomization.

Cosmo's right. But unless you has his cell #, calling Tom at home before the end of the month is a waste of time. His wife has a message on their voice mail which says that Stovebolt is shut down until later in the month. You can try the swap meet or Ebay in the meantime to see if you can find what you need there.

But if you have any doubts it may be worth waiting on Tom. He is is priceless source of inline info.

-ftyler

thanks for the info i'm hoping that it will do the job. I'm not sure what type of headers they are, though i'm pretty sure they aren't Fenton. i've seen plenty of literature on fenton cast iron headers for the I6's and mine just aren't even near the same. i inherited these when i bought the truck and kept them when i had a newer 235 put in. dual pipes looked good

Borla headers for the 300 frud 6-cylinder engines us an extruded finned aluminum block that bolts onto the bottom of the intake just under the carb.Seems to work pretty well in fleet vehicles

I have (had) an aluminum Offy manifold designed to fit the stock exhaust, but I also had Fentons. I made a plate to fit the Offy, then drilled and tapped for 1/8" NPT and fitted
lines to bring hot water through it.

Disclaimer: I haven't run the motor, but the fab and fitup was easy.

Cheers!
George

It probably takes about as long for the cast iron manifold to heat up as it does for the water temp to rise. Your question about shutting it off I don't know the answer to. I guess the water temp is low enough even when the engine is warmed up.

I'am running a steel intake with three carbs and tube headers on my 250. You are right about the cold water and cold castiron. Start up is when you need the heat and the exhaust does a pretty quick job of heating right under the carb. Mine runs pretty rough for a minute or two till the heat starts radiating up to the intake. A few miles of driving and its good to go. We haven't had real cold weather yet but I suspect it will act about the same. The intake gets plent of heat with out adding more. My fuel milage has increased along with throttle responce. You may just need to rejet a little as adding headers will change the calibration of any engine. Check your plugs for real light or real black color (lean, rich). You can also fine tune by rasing or lowering the float a little. Joe

The heat-up with radiator water is almost as fast as the heat-up from exhaust gases. The water is taken from the warm side of the thermostat. After the engine is fully warmed up, the maximum temperature of the heated water will be less than 190 degrees.

The heated water (or air) is needed to keep the intake manifold warm on systems where the intake is not attached to a stock exhaust manifold. When the gas vaporizes there is a significant drop in temperature that would chill the intake manifold and cause the vaporized gas to condense. This is especially important on multiple carb manifolds that do not bolt to the stock exhaust manifold (that is why Offenhauser intakes have internal water journals that allow water to folow from one end of the manifold to the other).

Since there is heat transfer after warm-up on manifolds that are bolted together, there is always enough heat to keep the gas vaporized (even after the stock exhaust "butterfly" closes).

Tim

TCL is correct (except on the Offy intakes - Cliffords have the water jackets).

The water heat won't help much on cold starting. That's the job of your choke or carb enrichment circuit. It's main value is constant gentle heat to prevent fuel "puddling" in a cold intake, which causes a lot of flat-spot symptoms and poor response. Tom Langdon's tech tip at Inliners explains this much more eloquently than I can.

The early Datsun 240Z is one of the sweetest-running inlines ever produced - and uses a water-heated intake.

Since most multiple carb intakes and headers were derived from racing applications, intake heat was not provided. If you're running WOT all the time, you don't need it.

The Offenhauser intake has a full length water jacket/hournal . With the correct cover plate (from Tom Langdon and a few others), water flows into a fitting on one side of the plate, to the end of the intake manifold, and then to the other side of the manifold, and finally flows out the second hole (hose fitting) in the manifold. The Offy manifold has a "divider" where the water plate mounts - this allows the water to flow from one side to the other.

Clifford's water-heated intake manifolds (they used to also sell non-water-heated manifolds) do not need a water-hose mounting/cover plate; the hose fittings attach directly to the manifold, into the journal/jacket cast into the manifold.

One feature of the Offenhuaser manifold is if you are using the stock exhaust or a dual exhaust manifold that still has the damper/butterfly on one of the manifolds (this might be true for conversions from Kansas Kustoms), you can obtain heat to the multicarb intake from the header that is attached to the intake (no need for water hoses or the water plate).

Tim

Thanks Tim,

I haven't seen an Offy with the water jacket you describe. Sounds like it would work fine. BTW Clifford changed to the water heated intake in response to years of customer and dealer requests.