Ultra Timeline Question

There's a 50M race I'm thinking of doing on August 16. This would be my first 50M. Now I'm running Boston and plan on running as hard as I can. This race would be 17 weeks after Boston. For a first 50M, is that enough time to recover and train properly?  I know it can be common once you've done one, but for a first is that enough time to at least have a respectable race and not death walk the last 20?

Thanks.

I did Chicago last Oct and followed with the JFK 50 for my first (only 50M?) before Thankgiving.  I think it was 5 or 6 weeks in between.  I walked some at the end, but that was more a matter of inexperience than being ready.  My one lack in training was back to back long runs and I didn't have time to do anything more than a 20 after recovering from Chi and ramping back up.  So training will suffer a bit, but 17 weeks sounds like eons compared to what I did.  I say go for it and you won't have any problems.

I would say way more than enough time. I'm running a 50 mile trail race 2 1/2 weeks after Boston.  Which to be honest works out pretty well since normally I like to run 80% of my ultra race distance 3 weeks out. So in the case of a 50 miler that would be 40 miles. Since I plan on running Boston hard the shorter distance of not running 40 miles I believe is made up by the intensity.

plenty of time. you'll be fine

Not only is it plenty of time, but you may want to consider running at least one if not a couple more marathons during that period of time as training runs.  When I ran my 50 miler, I ran marathons in February, March and April for the target race in early June.  It was great preparation.

What Jeff said is good advice. My best 50 mile race to date was after I ran 9 miles to the Chicago Marathon and then ran the marathon 3 weeks before my 50 mile race.