ok i am lost Help on compression ratio goal PLEASE

[My427stang]

I think I'd call Barry and see what he knows

[fe66comet]

He does not recall? I think I am going to have to swap them out in the end. Originally my target was 10:1 but it seems like I didn't reach that for some reason. I could always save them for a supercharger project.

[Cyclone03]

will a -.005" deck with a .041" head gasket clear the head with a 4.25" stroke ? .036" deck, Quench  is going to be very lively.

Can you cam it up a bit to build more dynamic compression ?
Is the 50hp loss really going to kill the driveability ? 

You have pistons above the deck correct? = -.005 ? with a .041 head gasket you are at .036" quench clearence IIRC the rule of thumb is .010" X 4.25 (stroke) = .0425 min clearence.

What I'm saying is I don't think you can  get away with less than a .041-.045 compressed head gasket. Without the piston hitting the head at RPM.

[fe66comet]

Well everything I have, throttle body, custom machined 90mm EGR plate, camshaft, heads, T&D race rockers and the proposed intake to make it all work would be a lost cause at 9:1 compression. I would be back to the 300- 400 hp range at that compression, along with being sluggish and a complete dog. At this point I have way more invested than a 600 dollar set of pistons and three hundred dollar set of rings in everything else so it comes down to the pistons or everything else. If they were 10:1 pistons I would mill the heads and use a copper gasket. But I have a -26 volume, good for boost but that is about it. I also would have to ditch my 1000 dollar 2" primary headers as those would not work either.

[ScotiaFE]

Here is the classic picture = 1000 words.
Show us a picture of the top and underside if you can.
I can post any picture you send me.

[fe66comet]

Well I took the pan off and looked at the bottom of the piston, it is exactly what the box says on it . I have a nice set of 9:1 ashtrays too bad I do not smoke.

[sumfoo1]

http://www.jegs.com/i/Paxton/769/1001864SL/10002/-1?CAWELAID=1710769436&CAGPSPN=pla&catargetid=230006180000848976&cadevice=c&gclid=CKnw_eSbn8ACFcZQ7Aod5CwAEQ

lemonade?

[fe66comet]

I pulled the rotating assembly apart last night, I am going to get some pistons and rebalance. It would seem the best way to handle the problem at hand and maybe I can use the pistons in another project later.

[Barry_R]

Geez - step away from the internet for a little while and....

John
I cannot remember how we ended up with that set of pistons - it's been a long time since you got the stroker kit.  I know that a year or so ago we could not get anything out of Probe & we may have gone another route expecting to mill the heads.

I have another customer who wants less compression.
Send me those pistons and I'll send you some with a smaller dish
It will not hurt the balance at all.

[machoneman]

Yeah! Barry to the rescue! Nice move Barry!

[BH107]

Well that solves that issue. Good work Barry!

[fe66comet]

Ok I could do that , I need to just have them pressed off.

[My427stang]

FEs aren't pressed on.  Although removing  the spirolocks will drive you crazy, once you get them off, the pins just slide out.  All you need is a small screwdriver and some paitience

I will say this though, I think it's time to slow down to go faster.  Seriously

- Measure your chambers
- Measure your deck height on all 4 corners if not off all mains to see if you are straight
- Then work with Barry to end up with as tight of a quench as you can and the compression you want
- Be sure to know the cam and the cam timing you will run.  Barry doesn't like DCR calculations, but knows cams, some of us other guys also know cams and like DCR, so if you want to calculate it and get our opinion put the info up here.  However, no-one can calculate anything until you have exact numbers
- You should not pick one without the other. 

[machoneman]

2X to M427Stang's advice. Getting the pin locks out, once you've done a lot, is easy with two small screwdrivers and /or a driver and a steel dental pick. Have seen guys though mess up the soft piston material doing so. There is a tool that makes it a snap. Not cheap at IIRC $75-$95 per pop. Still, it makes it a snap.

http://www.lockintool.com/

Just be sure to get the right head diameter, if you buy the tool, for the pin o.d. (FE's will be all the same) and note if they are flat SpiroLocs. as round wire retainers (almost all aftermarket piston uses Spirolocs btw) would require a different head.  'Course, you only need to remove one lock per piston to pull the pin and send all back to Barry.

Try YouTube as well for vids on how to remove same without the tool. Practice, practice, practice and your fingers will hurt for a week!   

[Barry_R]

Or he can just send the (carefully packaged!) pistons and rods here and let me remove them.
He's gonna pay for some shipping either way - an extra few pounds won't matter much.