67 327 Heat Riser

[Gerard F.]

Does anyone have a picture of a wired open heat riser.

I need to do this. Just wondering about the best way.

[Loren L.]

Re: 67 327 Heat Riser

How about replacing it with the FI spacer?

[Ed S.]

Re: 67 327 Heat Riser

Gerald,
I wired the heat riser on my '64 L76 open. Can't get you a pic as my car is not near me at the moment but I can suggest a wire that works and does not work. I first tried thin wire on a spool, the kind that you would hang a picture with. It was strong enough but too pliable, difficult to keep it taught as I tried to tighten it. I then tried 14 gauge copper wire - a piece of ground wire for a 15 amp household electric circuit. Much better - as you wrap it around something it is stiff enough to hold its shape - the coil spring on the heat riser is not strong enough to overcome the copper wire - but.... the copper wire is soft enough to easily bend around the heat riser counter weight and then around the header pipe - you can do this by hand and then tighten it with a pair of pliers...... and it won't rust.

[Duke W.]

Re: 67 327 Heat Riser

The melting point and work hardening properties of copper, which causes it to become very brittle makes it far less than ideal for this application. The best material to use is stainless steel safety wire, which I think is about 10 - 20 thou diameter. You should be able to wrap it around one the the manifold studs using two to three wraps, then tying it off.

It should last, and is, of course, easily reversible.

Duke

[Gene M.]

Re: 67 327 Heat Riser

Jerry,
Just cut out the plate or remove the entire shaft and weld up the holes. I also open up the hole to match the manifold. It is restrictive. My guess you only drive in warm weather anyway....!

[John D.]

Re: 67 327 Heat Riser

I used generic steel wire 10 years ago. Wrapped it around the exhaust stud and it' still there. Don't overthink it

[Timothy B.]

Re: 67 327 Heat Riser

Hi Jerry,

I can't remember what type of wire I used, it may have been aluminum. I looped it around the weight and opened the heat riser and made a loop on the other end that attaches to the starter brace stud. It slides over the stud and I hand tighten another nut, it's very easy to reverse. I will try to get a picture tomorrow.

I would not cut the inside out, I think this heat is good for the cast manifold, what problem are you having.

[Ralph E.]

Re: 67 327 Heat Riser

Jerry, I agree with Gene, just cut out the plate. Easy to do and nothing looks like bubba was in there.
Amazed after all these years and all the trips you have taken that you haven't cut out the plate or wired it open!

[Brian M.]

Re: 67 327 Heat Riser

I cut the plate out, looks and functions like OE to the eye.

[Stuart F.]

Re: 67 327 Heat Riser

If you use and FI spacer, it is not too difficult to go an extra step and round out the inside. I did on mine, but don't know if it helps more than letting you sleep better at night.

Stu Fox

[Douglas L.]

Re: 67 327 Heat Riser

I could be wrong here but isn't the plate what holds the shaft from sliding out? Either way, I've used safety wire in the past but for the most part I don't wire them open anymore, seem to work just fine as the factory designed them.

[Gerard F.]

Re: 67 327 Heat Riser

Tim,

I have been trying to troubleshoot some flooding problems with my 3810 and the inability to get it to idle down.

I took it on a 2800 mile trip to Denver in July, and then a trip to Lake Tahoe in Sept. A lot of high elevation driving and had to set the idle up to keep it running when hot and stopped.

Just changed the plugs (R45's). The R44's which I took out all had dry black carbon on them, all the same. Have now put on a newly refurbed 3810 and having problems idling down. She runs great on fast idle or high revs but as soon as she goes off the fast idle, she seems to be flooding out. I'm trying to adjust the mixture and idle settings. Also bought a new coil which I haven't put on yet. Ready to also adjust the timing. Will probably be working on it this next weekend.

I'm thinking that I may have a little bigger problem (valves), but I'm trying to do a step by step process to eliminate the easy stuff. The intake manifold and heads have never been off this 327 at 76 k miles.

Thought I'd wire the heat valve open as one of my troubleshooting steps.

I don't want to modify the heat riser, as I or others may take this car through Flight Ops again. The heat riser and idle worked perfect before my Denver trip and I have always had near perfect Ops at Flight judging. Always liked the way the exhaust shifts from side to side on warm up from a cold start.

I have had the heat riser wired open in years past, but was just wondering how everyone else does it.

[Timothy B.]

Re: 67 327 Heat Riser

Jerry,

The higher elevation the richer the carburetor will get because the air is less dense but same amount of gasoline. After shut down and heat soak, the fuel with ethonal can be a problem because it's more volatile until the carburetor cools back down which takes some time. When fuel is vaporized, heat is removed by the process so heat is good except for high performance where you want cool dense air and fuel. Remember those functional hood scoops that opened by a vacuum door.

Did the engine act the same way with each carburetor. I know you have done this but make sure there are no vacuum leaks from rubber hoses, V/A control etc.

A few things to think about. At idle/high vacuum the metering block gasket to main body can leak internally if not a good seal. I use a miti vac and pull vacuum through the bottom power valve chamber hole to make sure it does not blow down fast. It will not hold a perfect vacuum, it will bleed down maybe 10-15 seconds but not blow down right away.

Make sure the P/V gasket is tight, make sure the P/V is good, these are another two leak spots that will allow fuel under the throttle blades causing a rich condition. Another is the throttle plate to main body gasket, I remember your post some time ago about the gasket. Another is the little constant feed holes in the secondary under the transfer slot. If these holes are bigger than .020-.022 they will make the motor rich at idle and deceleration when vacuum is pulling hard on them. Is the snake channel connected on the secondary side or just there but not drilled for curb idle holes under the throttle blades. Mine was drilled but I plugged it with 8-32 brass set screws because the little constant feed holes are enough fuel back there.

Can you kill the motor turning the emulsion screws in toward the stop?

[Gene M.]

Re: 67 327 Heat Riser

Jerry,
Black carbon build up on plugs, "she seems to be flooding out", " runs great on fast idle or high revs", sounds like too rich. Are you concerned the heat riser is not opening? Jerry check out all the things that go rich, fuel level, stuck inlet seat, power valve, loose jet, sticky choke plate, gasket leak, etc. Vacuum leak would lean you out. Do simple leak down and compression check. I'm assuming ignition is up to snuff.....

[Gerard F.]

Re: 67 327 Heat Riser

Tim, Gene,

Thanks for the advice. I'll get back to you when I figure out a solution.

I have driven this car for 47 years. Have had problems in the past, but this time I'll figure them out. Trial and error, as usual.