Heat Riser on a Fenton Spit

Hi, I am doing over a 48 GMC and am keeping the '55 235 with vintage Fenton and Offenhauser daul manifold. The problem is there are no ports on the early Fenton to pipe a heat hiser. The Offy has an open rectangular flange for this purpose. I was planning to weld or braze bungs to tap the exhaust myself. I will locate them about where Fenton puts them.
Anyone have any tips on doing this? I have yet to look at firing order to see how the exhaust pulses work their way through the intake manifold and back into the other spit. Is there a trick not to over or under heat the manifold. I live in Massachusetts and will see extreams in ambient temps.
I prefer to keep the vintage parts rather than buy new unless I am setting myself up for failure.

 

Some people use coolant to heat the intake. If I'm not mistaken Langdon's stove bolt has a kit for this.

 

There are a couple guys that advertise heat plates to bolt to the bottom of your intake, but I made the first one I ever used from a piece of 3/8 inch steel plate. After cutting it to shape and using a heat riser gasket as a pattern to drill the four mounting holes in it, I put two heat holes in it with 3/8 pipe thread and ran copper pipes from both Fenton headers to it. Fenton actually sold a cast iron heat riser plate back in the '50s to go along with the headers---I don't know why Pat Dykes never saw fit to reproduce it. Just 'cause he lives in Arizona doesn't mean that everybody does! By the late '50s, Fenton redesigned the rear header to incorporate an integral heat passage.

 

I don't need no stinken heat riser.

 

That's about what I am planning. I have seen the heat riser kits that are out there. My question has to do with locating and attaching the pipe treaded bungs to the old Fentons. Also, how do you insure that the exhaust distributes the length of the intake. Do you have to baffle the two ports in the plate to force the flow to the extremities or is there a baffle in the intake?

 

50's Dreams, I saw the kit for that somewhere. The plate bolts behind the water pump.
Water would be slow to heat the manifold but it is cleaner and easier that using exhaust.

 

I went through the brass fitting cabinet at my local NAPA store and found two fittings with 3/8 pipe thread on the male end and female ends that accepted a 3/8 inch fuel line fitting (it seats like a flared brake line, only larger). I then put 3/8 fuel line nuts on my copper tubing and flared the ends with a flaring tool. Another thing---if you're going to use exhaust to heat an aluminum intake manifold, I'd suggest either making a stainless steel plate to sandwich in between the intake and the heat riser plate, or just buying the plate that's reproduced for '53-'54 Corvettes. I've seen several aftermarket intakes for 216/235 engines that had holes eaten through them from prolonged exposure to raw exhaust.

 

Good point about the corrosion potential. THANKS. The coolant approach sounds better. I wouldn't have to braze/weld to the Fentons and adding a st. steel intermediate plate would slow down the heat transfer probably making it like the coolant approach.

 

You would if you lived in the great frozen North. You'd be looking for a heat riser in your toilet paper dispenser.

 

Why do you think you'll have to weld something to your headers? That's what those two pipe plugs that are currently filling holes in your headers are for.

 

Langdon's has a plate that bolts to the intake. You can plumb exhaust heat from the headers (some have bungs for this, some do not), or plumb coolant. Langdon's also has this plate. It bolts in between the thermostat housing and the block, IIRC

 

This bolts to the bottom of the intake. We used one on my wife's car

 

I lived near Sandpoint, in beautifull northern ID for 20 years. Never used chokes, OR heat risers on hot rods. Hotrods don't do well on frozen roads. That is why I moved to CA where they are driven 12 months every year instead of 3-4 months. And we had indoor plumbing with real wood heated homes.

 

I would look for a heat riser from a v8 tap into the exaust above the valve make a spacer if you have to and plumb it back to the head pipe not the header.

 

There are no fittings on the split headers I have. They must be an eary version or maybe there not Fentons. I would look closer but they went out with the engine for overhaul.

 

That could work too. Thanks. Is it necessary to shut off the exhaust (heat) to the manifold once the engine is hot?

 

Heres where they go for pic reference. Make your own plate, the kit are rather expensive for what they are.

 

This is what I would suggest, if you don't want to buy the part you can fab your won from sheetmetal/plate. Weld a couple of bungs in it run one of your heater lines through it.

 

Langdons does have these. Running one on my Plymouth flathead. Works great.

 

If you use a heat riser valve it will open when it warms up and little or no exhaust will go to the intake.