I am about to recurve the distributor in my 454 motorhome. I notice a lot of controversy over ported vs. manifold vacuum advance. I plan on starting out with 36 degrees @ 3500 and 9 degrees @ whatever manifold vacuum @ cruise. I will check it before I start. Any thoughts I don’t want an extra hole in one of my pistons

I'm definately no motor home expert, but I think you may want to take a different approach setting your timing than what you would with a Camaro.

I'm thinking that since your 454 will be lugging a very heavy chassis up hills, etc. you want a much less agressive timing curve. I'm thinking like setting it to 6 or 8 degress initial and about 28 - 30* total. With the advance curve starting about 2,000 RPM and fully in at about 3000. But that is just a SWAG.

Gene,
You did not mention what year the motorhome is, but most of them after about 1980 or so are right on the ragged edge as far as timing etc go. The distributor has got to work in conjunction with all the emmission control parts. I personally would not mess with it. If you feel the distributor is worn out and needs rebuilding, so be it, but dont fool with the curve, or the vacuum hookups etc.
If you really feel that recurving the distributor will help in some way, before you touch it, go to Amazon.com and by the book that Jacobs Ignition sells called "The doctors guide to optimizing your ignition" It is a must read for anyone wanting to modify ignition curves in modern vehicles. The ISBN # is 0-9650856-0-0

Hope this helps,

Thanks, guys for all the good words. I've been debating this issue for some time. GM has the total 32 degrees @ 4200; I don't remember what the can is and that is what I was most concerned about. I had thought beings it was an emission motor (egr and pumps) it would be somewhat lazy on timing.