Safe to swap pistons?

[BSB67]

........you can get 5cc deshrouding the valves out to the bore.......

This too. If the head has not been ported, and more importantly the combustion chamber opened up to unshroud the valves, do that verses the head gasket if budget allows. CNC like done by Modern Cylinder Head will add 4 cc to the chamber. I'm not a "lose quench and you will die" guy, but if the head is already off, this will add meaningful power too.

 

[1 Wild R/T]

The 88cc Edelbrocks are not giving him quench with a flat top piston so thats not a concern....Like others have said you have lots of options that are easier/cheaper than a piston swap...

 

[wyrmrider]

the 88 cc chamber head is that open chamber \"what were they thinking" head

 

[66Satellite47]

Unshrouding the valves is standard procedure for me. IIRC my EDE RPM's didn't require much unshrouding.

 

[MoparDanMan]

So I built a 500" 400 block based stroker 10 years ago and finally got everything up and running earlier this year. The problem that I am having is the static compression ratio and pinging under heavy throttle.

I have flat top pistons and 88cc heads which gives me a compression of 10.8. My engine builder told me that I should be fine with thicker head gaskets but nope. I have mix or use an octane as is.

My question is, with very low milage(less than 100) and hours am I able to swap out for some dished pistons and use the same rings to bring the CR down without machining the block?

You don't need to machine the block just to replace pistons. You can reuse the rings but I would make sure they go back into the same cylinders.

 

[Xenon]

You can reuse the rings but I would make sure they go back into the same cylinders.

Hence,, why to do a quick hone so not to have to worry about this..

 

[wyrmrider]

yeh but why not?
and don't turn any rings upside down
clean the bores with white old t shirts- no shop rags --lint free and atf- no wd 40

 

[GreatLakesMopar]

This!

If its only has detonation under load you might be able to tune around it.
1) Slow the timing curve
2) bring the total timing back to 32°
3) try a -7 or -8 NGK plug
4) 160 ° thermostat.
5) Jet/transition slightly richer, maybe,
6) back the cam up to 108 like mentioned,
7) tighten the intake lash up 0.005" (cold lash setting of 0.006"-0.007")
8) then try the head gasket.

Check your cylinder pressure.

I run 10.8 in mine. Cranking cylinder pressure is 190 psi. I run 93 octane. I'm at about 1000 ft elevation. I'm not sure I could run on 91 octane. But I would try pretty hard at making what you have work before I'd be thinking pistons.

 

[GreatLakesMopar]

I think he had answered his own ?
10.8 Comp. Ratio on 91 octane ??
And a high end ping. .
Well. .Go to the race shop and buy some OCTANE. OCTANE. IS A WONDER DRUG
FOR DENENATION. I mean. Even try 93. If ypu can buy it. If not 5 gal canns sunoco 100 Octane will,heal,that monsters. Little case of
..GAS A GEN GESTION...

 

[33 IMP]

I think he had answered his own ?
10.8 Comp. Ratio on 91 octane ??
And a high end ping. .
Well. .Go to the race shop and buy some OCTANE. OCTANE. IS A WONDER DRUG
FOR DENENATION. I mean. Even try 93. If ypu can buy it. If not 5 gal canns sunoco 100 Octane will,heal,that monsters. Little case of
..GAS A GEN GESTION...

Op is in sf bay area. There is NO 93 in the whole state. There is NO ethanol-free 91 in the whole state. The cat piss 91 10% is still $3.50, how much is your 93? Racing gasoline is an alternative, but $10-$20/gallon gets steep, if he does any driving.
Op has been offered Multiple solutions, far short of new pistons, by LOTS of smart people here (not including me). All he he has to do is pick one (Or more than one).

 

[GreatLakesMopar]

Our 93 octane here in wisconsin was like 3.10 a gallon .
Knowing now he cant get it.
He could try octane boosters such as Lucus. Octane boost . double dose. Wont hurt.
However some mamanufactures. Say that it does not make a dif. I disagree. . if. Im planning to run hard ,and play i use the booster . and I can tell you. You can not only feel the dif. You can Smell it. .
Possibly. Try a test ..retime the car at only 12 degress at 900 rpm .

 

[66Satellite47]

Changing the timing bit may cure the issue. Octane booster or mixing (110 race, or 100LL aviation fuel , 115/140 purple av gas would be great). These are for limited mileage use of course. I'd use thicker head gaskets before changing pistons.

 

[wyrmrider]

so id we back off on the timing? change the curve s there an advance limit installed so low end advance can be kept, vac advance tuned?
water injection
headgasket
was cranking compression posted
try retarding the cam and recheck comrpession

do a search on water injection
also u tube
we used it on tubo corvairs- works