Q-Jet Block Off Plate

TravisUT said:

Hey all, I have a stock intake on my 454, and currently the Q-jet uses the hot air stove system for the choke (see pic). I purchased an electric choke conversion, but need to block off those hot air holes. I found this from Edelbrock (https://www.summitracing.com/parts/edl-8961/make/chevrolet) that looks like it might work.

My questions are: 1- Is Edelbrock the only ones that make a block-off plate, or am I just not finding them? 2- Are there other ways to block off those holes?

Thanks!

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fast 99 said:

Unless installing a plate for appearance just leave stock one on and proceed with choke conversion. It is a tube preheated by the exhaust. Will not affect drivability in any way unless rotted out.

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DoubleDingo said:

I believe this method would cause an exhaust leak at the plate.

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fast 99 said:

No, exhaust [for preheat] is on the outside of the tubes never inside. Any tube leak would be an unregulated EGR. However it is possible to have an exhaust leak at the gasket where the tube assembly attaches to the manifold. The 2 tubes that run to the carb can be removed. The vacuum port on carb can be plugged or used for other purposes.

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fast 99 said:

That's correct, there is exhaust within a manifold passage, but it never blends with the intake charge unless EGR equipped. Exhaust should never enter those tubes. If present they are broken or rotted out. I have done countless carb conversions and left that plate in the manifold. Like I said if the appearance bothers you get a plate. Otherwise, it isn't needed.

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fast 99 said:

That's correct, there is exhaust within a manifold passage, but it never blends with the intake charge unless EGR equipped. Exhaust should never enter those tubes. If present they are broken or rotted out. I have done countless carb conversions and left that plate in the manifold. Like I said if the appearance bothers you get a plate. Otherwise, it isn't needed.

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TravisUT said:

So I could just remove the tubes, leave the existing plate in, with the 2 small holes in it, and the only "down side" would be a small amount of extra heat coming from the manifold?

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DoubleDingo said:

I wasn't meaning blending with intake charge. I am talking about the exhaust gasses in the manifold that goes from one head to the other via the heat crossover. Oh, wait, as I typed that I see what you mean. I forgot about the tubes being part of that plate, and thus, no exhaust gasses should come out unless the tubes are rotted out, but they shouldn't be rotted out as they are never exposed to the elements. Yes, the tube goes into the head on the passenger side, but only exhaust heat passes through it/them, and the hot air choke setup on the carburetor has ports that circulate that hot air through the choke. Actually the hot air choke works just fine, just seems the electric choke is opted for on these, and I am guilty of doing that, but only because I swapped to vortec heads that have that have no heat crossover because they are technically FI heads.

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fast 99 said:

I do like the electric thermostats better if one can be found that unwinds at the correct speed for the application. They are not dependent on a clean intake passage or working heat riser.

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DoubleDingo said:

On my application it opens too quickly. Late Spring, Summer, and early Fall and it's fine as it's warm enough outside. But during the wintertime, if the engine doesn't have a chance to get up to operating temperature, it doesn't run right, especially from a stop.

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