Changing over 395558 block from Delta 9.0 CR to 10.25 for Cutlass. What kind of piston would be good for this swap. I know the 10.25's had a different dome/dish to them. Doing a complete overhaul on unit. Any other advice would be appreciated.

 

Unless you're a real good tuner and have a 3.90 gear or better I wouldn't do a true 10.25:1 on pump gas with iron heads. You're asking for trouble imo.

 

go flat tops measure everything up deck hieght, cylinder head volume,. do the math the 10.25 to 1 had a small 6 cc dish if i remember correctly and the 10.5 to 1 had flat tops but if you add a thicker head gasket it drops compression im runnnig cast flat tops off a high compression 350 with the heads milled .024 and the pistions .025 in the block im at 9.89 to 1 everyone says the heads where 64 cc's thats just not true some where closer to 68 cc's some more you will be fine with flat tops. i would also not advise that much compression specially on the street 10 to 1 is about as far as i would go imo

 

You've done almost exactly what I'm getting ready to do. What head gaskets (thickness) did you use with your combo and what did you end up with for squish or squash depending on how you talk to??

 

.038 felpro blues worked good., squish ???? i beleive compressed thickess is .038 is usually what they say. keep in mind if you add bigger valves the take up some cc's also if you get your heads milled that much you will need to mill the intake otherwise it will not fit

 

Squish that's the measurement between the bottom of the head and the top of the piston, the tighter the squish the better the mix is in the combustion chamber, I know an Oldsmobile doesn't have much squish area in there heads but every little bit helps.

 

gotcha didnt measure that now im curious to figure it out lol .,anyway when i got the heads machined they said i would have a much better quench area i took their word for it i was looking to build compression i was originally gonna use the 14 cc dish pistons with a shim gasket but the shim gaskets i got where not correct had to find a set of flat tops and used the thicker gasket

 

Bad info there. Machining the heads will have 0 effect on squish.

Sorry but your posts are still very hard to read and understand.

 

Its ok I'm a horrible typer. But the squish area is that how far the piston is in the cylinder in relation to face of the cylinder head ?????? I know machining the heads will not affect squish but machining the block will or at least I think

 

Squish/quench is the combination of the compressed height of the head gasket plus the deck height.

 

Oh ok I got confused its .068 for my combo I was overthinking and thinking it was something more complex

 

As mentioned, if you are not building a perfomance engine, then, the 10.25 pistons would not be appropiate in a daily driver. However, if you are building an engine for perfomance, then, that would be a different story.

On another note, you can get nice performance from a low compression engine with the right combination. With a low compression engine, cam selection is key. I think Cutlassfi sells custom cams and off the shelf cams.

Good luck

 

Thanks, everybody for the info. Will be closer to a daily driver, not racing engine. Just trying to get a little performance out of her. Keep it coming. Love the back and forth.

 

you would be amazed at the potential of a 9 to 1 olds 350., my last motor was a 9 to 1 350 with a towing cam got a 13.71 out of it in the quarter mile

 

Copper, could you define "towing cam"?

 

very mild lift low duration to build up tourqe. i had the comp cams 260h cam which if i remember correctly was 447 lift on intake and exhaust and 212 duration at .050 lift

 

http://www.realoldspower.com/phpBB2/...ic.php?t=28012

13.9 in a wagon, 9 to 1 355, shifted at 4600.

 

thats awesome in a wagon. im running 13.4's with my current set up almost the same as yours only i got alittle more compression and sligtly bigger cam my converter is killing my 60 ft. times

 

Great cam used it in my 71 supreme!

 

OK guys, here's another possibilty...What about stock 6 heads on a fairly stock (maybe putting in the aformentioned cam), 72 block (395558) that I'm guessing is probably 9/9.5:1 compression with the stock pistons? What would you think the comp would be on this combination? Still pretty much just looking for some better performance. Not racing anything here!

 

Use a compression calculator. But imo those 72 pistons have massive 23cc dishes even with the 6a head milled you would have to deck the block and use a shim gasket to get near 9 to 1 I would suggest checkin egge machine out and using the cast 6cc piston they will yeild better compression and you shouldn't have to balance the bottom end since they are cast .

 

You will be right around 8 to 1 +/- with aftermarket head gaskets.

A better bet would be to find a 73-76 block (solid webs, 14cc pistons) with relatively low miles. Then, mill some older 350 heads. But, if you are rebuilding the engine and replacing the pistons, just end up at 9.5 to 1 with a cam in the 210 @ .050 neighborhood and have a fun driver.

 

i have 6 14cc pistons you can have for 20 bucks and im sure somone on here has 2 . The machine shop broke 2 taking them off but yes the 14cc pistons will also work . i agree with captinjim the 73 short blocks have 14cc pistons they will work great with a nice cam with 210 duration you will have a very stout street engine my last combo was a 73 short block and 7A heads with shim gaskets after some machining it put me at 9 to 1 i had the comp cams 260h cam that motor would just roast the tires