tomlesli

How much total advance can a 350 mag rollor with no knock sensors take, or need for max power ? Just installed new ignitions in my boat, set the total advance at 31 degrees. Ran it for a day and nuked the starboard motor. dont think it was related to my ignitions, but kinda worried about it after buying a new motor. any advise ?

Uncle Dave

I usually setup aluminum head marine small blocks for 34 degrees total, they will run better at 36, but if you get a marginal tank of gas at a lake, the 34 will keep you alive.

when you say nuked- what happened?

Uncle Dave

tomlesli

looks like detination in cyl 5 only. on a carb motor found that kinda strange. Head gasket was blown between 3 and 5 . I think the gasket was the prob letting spark from 3 prelight 5 . Prob been that way for awhile, Looks like a plasma cutter shot between the 3 and 5 cyl . Took out the head and block . so new motor time . kinda stressing about the timing ! dont want to see that again. took the fun right out of that day !

Uncle Dave

Bummer-

Iron heads right?

Aluminum will quell detonation better. although the blown gasket wont help anything- at least you can repair aluminum heads.

http://www.offshoreonly.com/forums/d...ent-years.html

Here my setup on the dyno- we started at 32, went to 34, then 36 (comment from the old timers was thats <36>where we would end up anyway) no detonation, but that was on 93- kind of hard to get.

I think with an aluminum head setup youll be fine at 34 as long as you are running premium, if you only think you can get junk gas then go down to 33/32. Im staying at 34.

Please document your build so we can all live and learn from it as well as others.

Uncle Dave

tomlesli

yeah the heads are iron. ever heard of that ? the head and block both had about 1/8 in deep grove cut into them. looked like ya hit it with a plasma cutter. never seen that execpt for cars running a lot of nitrous . the top of # 5 piston came off to the second ring at wot. not a good thing ! looked detinated to death . ya thinking timing and poor gas issue. or head gasket ?