About a month ago I ordered a 390 kit from Flatlander Racing from Phil. I had the engine kit number MK1061 for a 390 and told him I wanted flat top pistons for a 67 Fairlane Ranchero. I received the engine kit and took the parts over to the machine shop, it took him a couple of weeks to get the engine bored cam brg installed ect. I picked up the block noticed that the pistons were hypertectic I thought wow thats great. While I was waiting for more parts I started to compare the pistons to some of my other 390 pistons and noticed a huge difference in compression height. I measured the difference and came up with .100 difference so I got a hold of Sealed Power and found out that these are 360 pistons (flat top hypertectic). So I called Phil back and they have not decided what to do with it yet. He admits that it was there mistake. I have talked to my machinest and he says that as long as we get in the same brand that it should be OK. Also Phil says that I should not have gotten Hypertectic pistons and I would have only gotten flattop piston if the model that I ordered, came that way. I also went over and looked at the box and in very small letters at the bottom it does say ford 360, but did you know that 360 looks like 390 that small. I have heard of how good Flatlander is and have received other parts from them. We will see what they will do for me. thanks guys Does anybody know what Sealed Power piston is equivelent to a Silvolite 1139 or if they make a hypertectic or a keith Black piston of the same compression height to make a 410 engine. Those Hypertectic pistons looke awesome compered to cast pistons.

 

You still should be able to use those pistons unless the have the full skirts. As the crank does not touch the bottom of the piston and the compression isn't too high for ya they might work great.

 

Todd, you have to be very careful dealing with Phil. I really get the impression he has no idea what he is talking about. If you are building a 390, and Phil sent you 360 pistons with a slipper skirt and a 1.76 tall height, you'll be fine. You will have 10 to compression however, which may be too much for the fuel available. If the 390 pistons you measured had a 1.66 pin height, they most likely came from a 73-76 truck engine, which was assembled with leftover Mercury 410 pistons. The 390 car engines have a pin height of 1.76. I don't have a SpeedPro book handy, but if memoroy serves they bought TRW and are using TRW's numbering. TRW dosen't have an equivalent piston to the silvolite 1139. The L2291F is a 4 eyebrow flattop that most closely matches the 1131. If you are building a 410, the normal way is to mill .100 off the top of a set of L2291Fs,....thats what I did. What brand and what part number pistons did Phil send you ? Are you assembling as a 390 or as a 410 ? DF

 

[updated:LAST EDITED ON 01-15-03 AT 07:14 PM (EST)]
>What brand and what part number pistons did Phil send you ?
>Are you assembling as a 390 or as a 410 ? DF

The pistons that I received are H395P (Flat top w-4valve releifs) .040 they are not a full skirt in fact the skirt is shorter than my 1139 by about 1/4" the compression height is .176. What compression sould this be. I wanted to build a 390, but since I ordered these pistons I have found a 410 engine with a broken piston and a good crank. the 410 engine also came with a 105 390 engine with 381P pistons, I am thinking that these are Sealed power pistons because of the numbering. The 105 block is in great shape the cylinder wall still have honing marks and no compression lip. The 381P pistons have a .010 shorter compression height, so I think that I should be able to use these pistons for my 410 crank they look like the 1139 just shorter comp height. This would be a little less compression I am not shure how much. This would be a cheap 410 to build but now I am not shure what to do with the 390 block complete engine.