PE-90 o520 conversion

[skatercat68]

i have started my tear down an i was wondering if i went with the lycoming 180 connecting rods and the standard 520 pistons would that be to much compression? would i have to use avgas or would pump gas 93oct of course be enough

[signcoc43]

I got 10:1 and lyco rods. Im just having a hard time finding a starter that will stay together . Only avgas I was in a pinch and ran half n half boat ran like shizz. If I can't get av I don't go ride jmo

[AntiqueFarmEquipment]

I've got standard 520 cylinders with lycoming rods on my 6 cylinder conversion. Avgas only. As for compression my starter has a little trouble initially on a cold start but it gets it done!

[skatercat68]

i was thinking of using the standard 8.5x1 piston and rods and decking the case .080.

does anyone know the standard throw on the pe90 crank? is the throw the same as the io520, i don't wanna lose compression if it is a shorter throw! keep in mind im not building a race boat, just a strong 4cyl

[JT540]

your gonna build too much compression. do one or the other not both! either deck the case 90 thousandth or run Lycoming rods and cut the pistons! if you do both the motor wont live long. and you will have to cut the hell out of the pistons to fit up in the cylinders. try to find round top pistons instead of the flat top so you don't have to machine the top edge as much.

[Outlawaircraftengines]

I have a set of 6 that I removed that are cut. They had the case decked with lycoming rods.

[Bruce]

deck the case .85 thousandths and itll run on pumpgas will run better on av thats how my gpu 520 is built now

[skatercat68]

So leave the continental rods and standart compression pistons for the 520 and Deck the case .080 or .085 is the consensus?

What kind of compression "should" that give me?

[airboatchris]

I have done it both ways. I like decking the case better especially if you are doing a cam grind easier to get the overhead right. decking the case will change your push rod length (longer)

[skatercat68]

I just sent the cam to aircraft specialties to be refinished. The crank looked pretty good. Still wanna have it put on a good micrometer to be sure.

[boobidges]

Angle valve 0520 cylinders, fuel injected pistons, h290 grind on cam, case decked .125. Starts fine, runs awesome. Only avgas. Don Davis told me I was around 9.5-1.had to shave the skirts on the pistons, and cut clearance in cylinder skirts .also had to shorten the pushrods.