The Stovebolt Site Forums The Shop Area Engine Shop Adding Fenton headers

I/m thinking of changing to Fenton headers on my '59 Apache 235 6cyl. With the original intake, do I need to block off the heat riser hole on bottom of intake? Do I leave it open? I'm confused! The Fenton headers have no provision for the square heat riser hole like the original exhaust manifold.
Darren

You don't need to block off the heat riser chamber under the carb. You can add a heat kit to the Fenton's, that's what those plugged holes that are visible on the Fenton's are for. Langdon sells a kit and so do other vendors. The kit will include a plate, tubing and fittings to plumb exhaust gasses into the chamber and seeing you live in Indiana, you're probably going to need the heat kit.

Darren,

From what company are you considering buying the Fentons? That company will most likely have a kit for connecting to (heating) the intake manifold. If you cannot find examples of kits, ask for us to post links.

There are various styles of kits and methods of providing heat to the bottom of the intake manifold - a necessity for smooth acceleration. Some styles use cooling system water and other styles use exhaust air). The method that people use is a little like choosing a religion.

I have used circulating heated water from the cooling system (this requires more complicated plumbing) but have changed to exhaust air delivered through the plugged hole on the outward side of each Fenton header (no worry about water leaks or water line breaks).

Jim Carter

Chevs of the 40s

Langdon's (fittings are for water hoses)

Now that Tim has provided excellent pictures, make your own plate out of 3/8" plate. Use the gasket to outline and locate the holes, tap, fittings from hardware store.

Important to grind down area as shown in the Tom Langdon's Stovebolt Site picture, otherwise the Fenton header touches.

Good advice, Cosmo

Are you running water or hot air to warm the intake manifold? Your experiences are valuable, since, I understand, your truck is a daily driver.

Running on hot air. Many would agree with this observation.

I ran a set of Fenton headers on the engine in my '60 Chevy Biscayne a way back in the day when I was a young buck and was starved for attention. It had a cast heat plate that came with the kit from Fenton at the time. Drove it for several years before selling it to a little old lady complete with the straight thru mufflers and all. I think she felt like all the noise translated to power, it didn’t!!!!
I never had a problem with the way it ran up here in our northern Illinois winters or the year I was in hot Wichita Falls, TX or the year I was warm Sacramento, CA.

But now that I know better, I would question having the intake heated by the exhaust all the time. In the stock design it is only heated directly by the exhaust gases on start up then only a little by gases after it’s warmed up.
Also with that hot air plate there isn’t a complete path for the exhaust gases to circulate, so basically all it’s really doing is providing a conduct for heat to rise up by convection to the intake manifold.

Not a perfect set up by any means. Because of this I would think that hot water circulation would be the best choice of the two after the engines has warmed, but would not be effective at all the first 15 minutes or so. The hot exhaust gases in the original GM design supply heat within a few seconds to the intake but wouldn’t be all that effective with the Fenton hot air plate.

Denny Graham
Sandwich, IL

Denny,

I agree about the heat transfer being conductive in the exhaust gases setup. My exhaust set-up heats up the intake manifold faster than my old cooling system water setup. I have had no problems with the exhaust-gas setup so far. And, I have no worries about coolant leaks or hoses going bad.

The stock intake/exhaust arrangement is also conductive (very little circulation, I would think). The only different is the "flapper" in the stock set-up. Do you think that the Fenton exhaust-gas setup will be too hot after the engine warms up?

Someone (maybe Alvin?) reported that he found substantial carbon buildup in the exhaust tubes set-up (or maybe carbon buildup inside the cavity in the heater-chamber in the bottom of the manifold).

Well then... Many different opinions! I think before I lay out cash for the kit, I'll try it for a while without it. Thanks everybody!

you should run the tubes from the exhaust to one of the holes in the plate and run the other tube to a little tiny muffler that way you will get some flow and more heat. But really though I am about at the same point, and I am anticipating using the water method as it can only get so hot. Cold start up will be ugly, but that is fine with me, as I don't intend on going any where when its cold outside anyway

No, I don't think the Fenton set up will allow to much heat to get to the intake. And that was my point, the Fenton plate doesn't allow any circulation so it's not gonna get as much heat as it would if it was passing gas. They've been using that setup for well over 50 years that I'm aware of and as I said, mine ran fine and I've never heard of any complaints to the contrary. Still, it's not the ideal set up but it's better than nothing.

The stock heat riser setup does indeed flow about 90% (appx. 10% leakage) of the exhaust gases under the intake till the coil tightens up and allows the valve to re-direct about 90% of it directly out the head pipe. The heat riser butterfly valves have a lot of leakage around the edges so there is always a little exhaust gas passing across the floor of the intake even when it ‘s warmed up. As far as any conduction goes, sure it happening all over that intake/exhaust setup when the engine is up to operating temps.
The stock heat risers worked for many decades on millions of Cars and trucks made by almost all of the automobile makers. It's still the best set up. But of course when you customize your ride than there are compromises that you have to live with.
Denny Graham
Sandwich, IL

Thanks, Denny.

It has been a long while since I looked at the manifold heat riser and heat control valve.

Durwoods59,

Let us know how well it accelerates from sitting still - when cold and when warmed up. The heated intake manifold is needed in both situations.

Since no two cylinder are firing at the same time wouldn't there be flow back and forth through the tubes to the intake manifoldd??? There are no check valves on the system are there? Am I thinking about this wrong? Dave

Yes, the way a Stovebolt fires there is exhaust pressure alternating between the front header and the rear in even pulses. Someone mentioned earlier about carbon buildup in the tubes, wouldn't that be an indication of exhaust flow in the heat tubes?

All that being said, I've run Fenton's for years without heat and only see the need for manifold heat on very cold days (temps in the 30's), any other time after a warmup, all is good. After a short drive at outside temps of 50 and above, you really don't want to touch the intake manifold since it sits right above the exhaust headers and is bolted securely to the head - there's a lot of heat in that area guys!

I've got a metal fuel block that sits above the intake manifold and I'm concerned it's getting too hot, possibly bubbling the fuel. I'm going to try to isolate the block someway from all that heat.