@curly I spoke with my tuner and we think we found the reason for the discrepancies in the spark map. I moved over to MS3 from MS2 a month or so ago and I did not account for the switch from 12x12 to 16x16 table. So the spark map will need to be adjusted accordingly. The WUE enrichment thing is my fault from quick tuning the whole table at once the other day and then not turning that last cell back down.

 

P2W is way too much. ST pistons do not expand as much as others. Pistons are Will Smith and your cyl walls are Chris Rock.

 

Whats unfortunate is that I specifically requested .003 for P2W to the shop, but they used the .004 clearance that Jesse Prather (my builder friend/consultant) uses for ST alloy as they have built over 30 BPs for him. I thought that kind of wasn’t cool. None of the other pistons are slapping at all though. So I don’t necessarily think that is solely the issue.

 

Nick,

I'm in about the same place-- 9.5:1 Supertechs in bores with 0.0035-0.0040" clearance. 140 miles on the rebuild. It makes a very similar noise, which decreases when warm, but doesn't go away. I wonder if I can get away with just driving it, or if it is eventually going to blow up.

Nic

 

Thread update/conclusion:

I swapped the pistons for the second set of Supertech’s I had sitting on the shelf and the noise is finally gone. So I am going to have to assume the verdict is a manufacturing defect in one of the pistons. Be weary ordering ST stuff. This kind of incident plus their documented bad round of valve failures gives me some quality control fright. This cost me 2 months and 2 teardowns.

to be transparent, I am not speaking out against ST, I know lots of people have ran their products for years with no issues, this just happens to be the unfortunate experience I had. **** happens. Thanks everyone for the feedback.

 

Did you measure any of these pistons before slapping them in? There are always going to be variances no matter whos making the pistons. I would be interested to see the measurements on them, and the spread across the full set.

 

This is relevant to my interest. I am in Topeka, KS, Jesse Prather headquarters. I assume you had Siebert Performance do the work? I have my BP4W head at Prathers getting assembled after a refresh, and will be dropping off my engine at Siebert to get machine work done, similar to what you had.

The only main difference between your build and what I am in the process of building is your 9.5 vs my 8.6 ST pistons, also 84mm. Did you find what the "manufacturing defect" actually was? Im curious how/what may have been overlooked by the shop.

 

i had this noise with a 97 head, it was driving me nuts, it felt like i had pinging on free revs but under load, nothing

i had the volve stiffer springs, swapped out to a vvt head with oem springs and the noise went away....now i'm weary of upgrading to supertech dual springs, i don't want the noise to come back :(