Correct Timing at Idle for 75 GMC Motorhome

[campingman]

got a 1975 22 ft motorhome small block 350 stock HEI 73k miles. and going to be setting the timing on it. wanting to know what you all think the best timing would be btdc at idle? Im thinking 10 or 12 but need a refresher on this. Ain't worked on a small block in years. need to set it for heavy duty use since its a motorhome and will be going up some steep hills. Thanks for your alls input.

[Corts60]

12 degrees would cause you some pinging going up hills most likely. I would say 6-10 degrees for a stock small block of that era.

[Kinze]

I am all for going by the book but I will advise you to use the book as a baseline and tweak from there as I find these motors to be all over the place in what each likes.

[campingman]

Yea the closes I can find to the book is the specs Autozone lists for a 1975 G3500 Vandura. Which is about the closes I can find make/model that matches it. Its basiclley a G3500 frame with a van nose and a 22 foot camper on the back. Kinda like this one in the photo. autozone says 8 degrees. But I don't know if thats for just a truck or van. also says light duty timing. cant find heavy duty

[Bigstevex4]

Just put new distributer in. although 250 six book says 4 degrees it would barley pull hill got it about 12 now think might try a liitle more. depends on gas compression like some one said try it at 8-10 easy enough to change.