Marathoner's Opinion Wanted

Probably not, but anything's possible. This guy just did Philly in 4:16 with a long training run of only 13.1:

 http://www.beginnertriathlete.com/discussion/forums/thread-view.asp?tid=30837&posts=3

More likely, you'll go out after it and be fine for 16, 18, even 20 miles, then hit the wall hard. Sounds like there's even a chance that you'll re-injure, maybe even further injure your back. Why chance it" Last time I looked there were, what, over 300 marathons held in the US, and they hold these races EVERY YEAR! Get better, get trained, try it then.

You have a prayer of finishing a 4 hour marathon, however, I would just go in with a pace bracelet (from Runners World.com) and running at a 9min/mile pace or a little slower. How did you feel at the 8:53 pace?...ok, you don't know how you're going to feel after 18 miles, you might feel great, you might feel horrible. The best advice that I've heard (and given) over and over is start slower, a comfortable pace. You can't "bank" time and running faster than 8:50 miles will only hurt you in the end.

Go in with 3 goals for the race. The first one is your "if everything goes perfect and I feel great" (your real/perfect goal) time. Your second one is "well, it hurt, wasn't that easy" time...say 4-4:15 for you...then your last one is "FINISH" and be happy with that.

Good luck.

I felt pretty good on the 16 mile run.  The 8:53 was my overall pace.  I did start much slower than that(around a 10 min mile and built up to maybe an 8:15-8:30 mile as my fastest).  Now don't get me wrong, I was tired at the end of the 16, but I have felt much worse in some triathlons.  I have no intention of trying to go out hard and bank time.  I know that doesn't work.

Sixteen miles is about one-third of a marathon.

Don't really follow your math there, but I was simply replying to Comet's question as to how I felt when I held a 8:53 pace which was during my longest run of 16 miles.  I was not implying that because I held a 8:53 pace for 16 miles then I can surely hold a 9:15 pace over the remaining 10.2 miles.

Not math just opinion. As far as effort goes, 16 miles is about one-third as difficult as running a marathon. Holding X pace for sixteen miles takes about one-third of the training that holdng an equivalent pace over the length of a marathon would take. Yada yada, void where prohibited, actual mileage may vary.

He's saying that most of the marathon happens after mile 16. heh. You'll see...

I know.  Just poking the bear. 

That is the whole reason I asked the question.  I don't know what to expect after 16 miles.

Bingo. "You'll see..." indeed. Sixteen is just a taste.

If you've trained your muscles and systems properly to efficiently use stored and ingested fuels, and to dispose of waste products, you can expect a high degree of bearable fatigue, bearable through adrenaline and  developed mental effort.

If you haven't, expect bonk.

It really depends on the race. One HIM I did, I ran perfectly, only walked water stops, could have run 13 more miles. Another one I did, I walked 75% of it. Same thing can happen in a marathon. You never know, but I can guarantee you'll be tired and your legs will hurt. Don't want to keep scaring you, but just remember to go comfortable, watch your water intake and be in a good place mentally.

I have often dreamed of being in a good place mentally. 

Never done a HIM so I can't speak from experience. I would tend to think it would be "easier" for the very reason you cite, but let's assume that the HIM swim/bike offers the same prelude as does the 1st half of a marathon. Have you completed the run portion of the HIM comfortably at 8:50 or faster pace needed for the 4-hour marathon? If not, what run-specific training have you done that would result in the necessary improvement?

I've stated on here before, and honestly believe, that over 90% of BTers, being relatively active and in reasonably fair physical condition, could go out and "finish" a marathon tomorrow without an ounce of marathon-specific training. Gary is asking about achieving a time-specific goal.

Thanks for all the info everyone.  What have I learned?  4 hours is most likely out of the question.  I probably should not even attempt that pace.  So I will most likely go out at a slightly slower pace and if for some stupid reason I am fealing fresh as a daisy come mile 16, 18, 20, 22, 24 etc then I can always make up time, right? 

My back has felt a ton better today.  If it continues, would I be ok going 18 or so this weekend(2 weeks before).  Or would that be too much too close considering it has been 3 weeks since I did 16 miles?

I've been told that it's the TIME that's important...like, do a 3 hour run...not an 18 mile run.  Of course, that doesn't work super great for me, because 3 hours doesn't get me nearly as long a run as I'd like to see before a marathon...but it works for a lot of folks.

Two weeks out is pretty close to be doing a super long run...but...if you could get 18 in this weekend (or three hours) you will probably suffer a little less in the marathon without completely destroying yourself for it.  I wouldn't run any longer than that.

I skimmed some of the answers above before posting.  Lots of good advice.  Definitely don't put time pressure on yourself for the amount of training you've done.  Just go out at a nice effort and see what happens.  Every time I have tried to hit a 'pace' in a marathon I end up crashing...and the one time I just ran easy I set my PR.  Go figure.  As for the comparison to a Half Ironman run...I am 10 times more sore from a marathon than I am from a half ironman.  Heck, I really am not all that sore after half ironmans and I can barely walk after my marathons...so, I don't think there is really any comparison at all...but that could just be me.

Since originally posting this, my fate has been sealed.  I have been sick since the day before Thanksgiving and haven't run a lick.  Looks like I will just be looking to finish the dern thing.  I almost don't even want to run it now.

As the saying goes, discretion is the better part of valor. How about trying Austin in February?