Packard Forum Index » V-8 (1955-56)

Has anyone with a 1956 Senior had an issue with the bronze enamel discoloring or peeling on the intake manifold exhaust crossover? I am going to repaint a 374 and the paint now on it is pretty sad looking on the hot side of the intake.... wondering if the current engine enamels from the usual vendors have that same problem. I'm thinking that maybe a jet-hot type coating prior to topcoat might prevent that.

Thanks

I had burnt my intake once, but when I redid the heads(hardened exhaust seats) I blocked off the heads so that the hot exhaust could not travel thru the intake. That being said I disconnected the manifold heat control valve spring.
I also run with the choke wide open all the time.
Since the hot exhaust cannot go up thru the intake manifold, the paint still looks great.
If you don't block it off, there is no paint that will withstand exhaust heat.

A common problem with any engine other than a display engine; it just gets too hot for the engine enamel to resist. Friend Randy Berger has blocked off the heat passage in his intake to prevent this. It is a solution, though at some trade-offs.

On my 374, I just wire brush it every couple of years and 10 minutes with the paint brush and I'm good again for a while.

Good info guys, thanks. Randy, did you use freeze plugs?...if so, I'm guessing steel not brass? The choke oven is not an issue as it is running an Edelbrock USCG approved Marine carb with electric choke and I don't anticipate arctic operating conditions, so the heated intake is likely not a must.

The motor really needs the heat control valve.

It goes a long way toward reducing sludging (a significant problem in the V-8).

It also gives more horsepower and gas mileage. Not having it inhibits proper caburetion significantly.

On cars where the valve is stuck open or missing, stuffing a rag in one tailpipe during warm up will help.

Of course if it is stuck closed it should be repaired or removed.

I respectfully disagree:

The motor really needs the heat control valve.
Why? if it opens up quickly in the summer, why not just leave it open. I've been running this way over 20 years, but of course I'm not running in the winter. I don't need the temporary heat to help the carb.


It goes a long way toward reducing sludging (a significant problem in the V-8).
I don't have any sludging problem and change oil once a year.

It also gives more horsepower and gas mileage. Not having it inhibits proper caburetion significantly.
If it opens up quickly in the summer, what's the difference?
I have no mileage problem and the car runs fine with quick pickup and a lot of power.

On cars where the valve is stuck open or missing, stuffing a rag in one tailpipe during warm up will help.
I would never plug up a tailpipe - the car warms up within a couple of miles and runs fine.

IF I were driving it year-round as I did in the early sixties, I wouldn't have the car set up this way, BUT...

Thanks for your input Tim. The engine I am painting is a marine conversion with water cooled exhaust manifolds and does not have the usual heat riser valve on the left exh manifold. I am assuming that even with a more or less open exhaust some hot gas will be directed through the intake manifold?

My experience with marine engines is that they are usually in an tightly enclosed space and cooling is more of an issue than heating. My gut feeling is that after a few minutes of operation the intake will draw and retain enough heat from the heads to aid fuel vaporization.

John