when to install exhaust?

prkaye · #1 01-18-2009, 01:33 PM

I'm unsure when I should install my exhaust system. The plans say "before attempting to install the cowl, the engine (without the exhaust system installed) must be mounted."
So I fit the cowl, and then install the exhaust? I would have thought you'd want the exhaust on so you can be sure it's not interfering with the cowl...

flion · #2 01-18-2009, 04:31 PM

Actually, I fit the cowl with the exhaust on, then removed the exhaust to fit the FAB; it's easier to reach down there and make adjustments from the top. You definitely want the exhaust on before you fit all the wire/sensor runs, but you only have to lock it down before the engine start. You may find that you install and then remove some systems more than once.

noelf · #3 01-18-2009, 04:37 PM

...can be quite the chore. If the exhaust pipes are in place, it is that much more difficult. You will probably fit the upper cowling, then fit the lower cowling. There is quite a bit of trimming and nudging in this task. Eventually, the two cowl halves will fit, and then you can add the exhaust pipes and get them to exit the lower cowling air exit duct.

N941WR · #4 01-18-2009, 04:41 PM

Go ahead and put the exhaust on now, just don't tighten it up and crush the gaskets now as you will probably pull it off at least once.

rv6rick · #5 01-18-2009, 05:03 PM

Right after I mount the engine the first thing I do is install the exhaust. I have yet to remove an exhaust system once installed......but that's just me

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Quote:

Originally Posted by prkaye

I'm unsure when I should install my exhaust system. The plans say "before attempting to install the cowl, the engine (without the exhaust system installed) must be mounted."
So I fit the cowl, and then install the exhaust? I would have thought you'd want the exhaust on so you can be sure it's not interfering with the cowl...

Captain Avgas · #6 01-18-2009, 07:55 PM

Quote:

Originally Posted by prkaye

I'm unsure when I should install my exhaust system. The plans say "before attempting to install the cowl, the engine (without the exhaust system installed) must be mounted."
So I fit the cowl, and then install the exhaust? I would have thought you'd want the exhaust on so you can be sure it's not interfering with the cowl...

Phil, your lovely overhauled O320 will have come from Aerosport with seals on the exhaust ports (and dessicant plugs). I'd leave them in place as long as possible to prevent rusting inside the cylinders. I wouldn't bother about the exhausts until the cowling and the baffling is all finished. That can take a long time (longer than you think). Why expose the cylinder bores to moisture unnecessarily in the mean time. Instal the exhausts just before you start all the FWF plumbing (which is after cowls and baffles).

n8zg · #7 01-18-2009, 08:40 PM

Phil -
My exhaust has been on and off at least a dozen times. No lock-washers yet. Probably the week before the DAR shows up.

prkaye · #8 01-19-2009, 08:13 AM

Thanks guys... I'll put the exhaust on the shelf and get to work on the cowl.

Quote:

then removed the exhaust to fit the FAB;

What's the "FAB"?

ddurakovich · #9 01-19-2009, 08:23 AM

Quote:

Originally Posted by prkaye

Thanks guys... I'll put the exhaust on the shelf and get to work on the cowl.

What's the "FAB"?

"Filtered Air Box"

flion · #10 01-19-2009, 08:27 AM

FAB = Filtered Air Box. Personally, it was my preference to have the exhaust on the engine when I mounted the cowl because you can't adjust the exhaust position (except the final run). But it's probably safe to do the cowl without; it's not even close to interfering unless something is terribly wrong. The FAB, as you can find on other threads, can be adjusted for better fit in the cowl. Basically, I followed the advice from Firewall Forward that said to start fitting the major, hard-to-relocate stuff first and then fit other stuff around it. So, exhaust, alternator, starter, cowl, baffles, FAB, ignition, oil and fuel lines, sensors, etc. in generally that order. Prop and spinner very last. Some things are easier to fit if you remove other things; I had to remove the exhaust to fit the FAB and I had to remove parts of the exhaust while running the starter cables and CHT probes. The oil cooler and lines had to come out while routing wires behind the engine but was kept handy to make sure nothing interfered while I did those routings. But it sounds worse than it really is; the engine stuff was much easier to work on, if more complicated than a lot of the riveting I had to do for the structure.