I have some 0.040+ 8.5:1 pistons going in a 350 block with the 3.75 crank. The pistons are from Speedpro.

Why the low compresion, cause a Procharger will be utilized!

Or does anyone have Speedpro's number.

 

Bad choice of parts, specifically recommended against by the piston mfr. The correct choice would be forged.

Too little gap is much worse than too much; too much gap and you'll have a small amount of extra blowby, too little and you'll blow the top of the pistons off when the rings heat up and expand, and the ends butt.

I would suggest something in the .030" range.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

rb is correct i'd return them or sell them and buy forged pistons. if you do ude them there should be a piece of paper packed in the box that tell the correct end gap. it should say something like 40% over stock end gap.

------------------
ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

I've heard mixed opinions about hypereutectic. The common factor sounds like that hypers are not very forgiving with detonation.

But that is fairly easy to watch/control. So what is the beef with the hypers???

 

hyper pistons ae stronger than forged, also more brittle and prone to breakage if you have detanation problems and they transfer heat alot more than forged or cast pistons. considering the small cost savings it isn't worth the risk to me, i'd buy a set of forged pistons.

------------------
ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

btt

http://www.kb-silvolite.com/speclear.htm#CHART


BTW this is in a boat, so the water intercooler will work great!!! And I will try to up the boost!!!!

Using the "marine supercharger" factor of 0.0090, the gap comes out to 0.036" for the top ring. This seems way excessive from what I have done.


Also the PISTON TO WALL CLEARANCE of .0030"-.0045" makes me wonder. Right now I'm at 0.002" clearance with the hypereutectics.

I've also found this...

http://www.racingsecrets.com/article_racing-10.html

Quote from it goes


quote:
--------------------------------------------------------------------------------
Marine Applications require an extra .001"-.003" clearance because of the possible combination of high load operation and cold water to the block. A cold block with hot pistons is what dictates the need for extra marine clearance.

--------------------------------------------------------------------------------

I didn't think of this. The engine never gets past ~140°F.

More searching on the web. At least the engine is apart.


[This message has been edited by a73camaro (edited October 12, 2001).]