Can anyone post a good timing table . I have a 383 twin turbo Windsor with a Holley efi. Just melted 4 pistons 21# boost 16* timing 93 octane. I plan on running race fuel when I get it back together.

 

16° is probably a bit much but I dont have any experience with that much boost. Could it have leaned out? Are you measuring a/f somehow? Are all 4 cyl the same bank? Melted pistons sounds like lean. Broken chunks and pitted surfaces usually timing

 

I'm thinking too much timing for 21psi and pump. IC? For comparison the 351 in my truck is intercooled,12.5psi, pump gas, 18* timing.

 

The data log of the afr looked good. Pistons melted on both banks. I believe the 93 was the problem. Like I Saud race fuel when I get it back together this time

 

Anyone else have an opinion on the total timing I should be at?

 

21 psi is alot of boost and 16*/93 oct probably did it in. Could of been a shitty batch of fuel that pushed it over the edge. Not sure about Fords, but us LS guys w/o a dyno test keep total timing to 12*, maybe even lower on 93 at that boost. With meth and an intercooler maybe a bit more. In fact, 21* psi is not a good idea at all on pump. Race fuel you probably would run the 16*.

Sounds like a nice setup, so you REALLY need to spend a couple of hundred bucks and hit the dyno to find out what she likes.

 

With pump gas, keep the timing alone and drop the boost to 10 or less.

 

I think it was possibly bad gas also. I had a dozen passes on it with a best of [email protected]

 

I have a 383 and single 76 in my truck. I run only Sunoco 93 and have it tuned for such. Even at that I still throw about 20-25% 110 into each tankful for re assurance. Above 7 psi my timing is 15* through the rest of the map under boost.

 

18*/25psi, Alkycontrol, 93 pump, here....But, it's only a v-sicks.

 

Too many variables to just put a number on it... Heads, cr, cam, turbo, iat's and hot side all play a role. Take it to the track, start low, advance a degree or two at a time, watch plugs and mph, and stop when mph levels off, you see signs of detonation, or when additional timing nets very little mph gain. Start all over again if you change fuel, or boost level.

 

My biggest problem at the track is I'm not consistent enough. But I don't want to take it to a tuner. Wish I could afford my own dyno.