Basically killed the 305 a little while ago and decided to build the 355. Live in Cali so 91 octane is the highest pump gas I can find and hopefully I didnt go out too far on compression so that I can still use that level with out using racing gas. Heres the set up.
'87 350 block bored 30 over, sterling hypernumatic (sp) pistons @ 9.97 compression with 58cc heads and a .039 head gasket. I put down the 58cc heads because I am using vortec heads from my previous 305 set up which I had milled down from 64cc to 58cc to keep compression on the 305. So yes um, Summit stage 1 connecting rods, vortec heads like I said before at 58cc combustion chamber. The new head gasket is at .015 so I know that already bumps the compression up some (how much I dont know) but that puts my quench at .040 because of the stock deck height of my block. ZZ4 cam (208/224 duration @.050 and .474/.510 lift with 1.5 ratio rockers. Using crane gold 1.6 roller rockers so should add on a little to duration (again dont know how much) and puts lift at .505/.544. Full exaust TES Headers, to 2.5"-3" Y pipe, 3" all the way back to dual 3" outlets. Performer RPM Air Gap Intake and 750cfm edelbrock vaccume secondary carb.

So just in a nut shell did I go with too high of compression pistons or should I get a little thicker head gasket (quench still a factor) or should I be fine running on 91 octane pump gas. Thats basically it thanks for the help in advance and all comments are welcome. Let me know.

 

Would've liked to see a little more duration/overlap to let some of the pressure escape, but it's a pretty small cam so you got what you got. Bout all you can do now aside from installing thicker head gaskets is keep the timing low-which your lucky running the Vortecs as it should be low 30's anyways, then try to keep the temps down on the engine and run'er a little fat. You should be good to go.

Just keep a tuned ear on these upcoming summer months with the extreme heat for the dreaded ping.

 

Just as IHI said, the CR is pretty high for iron heads and the cam you've got.
I wish I could answer from experience, with absolute certainty. But from what I've been hearing and reading, your motor is likely to ping.
I'm from Cali too, and I wouldn't go that high with the gas we have here.
Some options might be:
Dished pistons, larger cam, water injection.
Widening the quench clearance to reduce the CR could possibly result in increased octane sensitivity. Supposedly, tightening the quench clearance more than offsets the CR increase in terms of octane sensitivity. So it makes sense that the reverse would be true for widening it.
If your engine isn't assembled yet, changing the pistons or cam might be a good call.
Richening the mixture would fail you at the smog station, but then so would the rest of your intake system.
There are some guys on the boards who are experienced with water injection who swear by it.
But if your engine already is assembled, maybe you should just experiment... run it and find out.
Try a thicker gasket, if it pings... maybe it'll work... maybe not.
One more idea, use a 2pc timing cover. That way if you do ping and you decide that a larger cam is in order, you can swap it easily.

Just some random thoughts on the subject.
It would be interesting to find out how your "experiment" works out.

If you decide to swap out your zz4 cam - give me a holler, I have an engine that might be good in.

 

I say just have your combustion chambers opened up a couple of cc's and youll be set. Oh and that sounds like a killer combo you got there I hope you have the rest of the car setup for it. Good Luck.

 

Thanks for the comments guys, guess all I can really do is cross my fingers and hope for the best. Wont be changing the cam until I get some better heads (TFS 23 degree) cuz lift wise this cam with 1.6rockers matchs vortec heads like crazy. I was thinkin about just gettin an LT4 hot cam just for the little extra duration but Id rather not pay for another cam that isnt gonna be a lot wilder than this one. Yes the engine is apart but I just ordered the pistons and recieved them a little while ago so I will be using them. Ill be sure to let you guys know what happens im hoping 12s on motor any bets? (On street tires, I know i can pull it off easy with drag radials or slicks)

Thanks again guys appreciate it.

 

Water/methanol injection.

 

Use a FelPro 1044 gasket... .051" instead of .039".

Every little bit helps.

 

Im using a .015" gasket, if I had the .039" one id be at 9.97/1 which would be just fine, I just donno how much extra compression I get from getting such a smaller gasket.

 

This might help out
http://kb-silvolite.com/calc.php?action=comp

Also, the info I gave you in my earlier post was based on a 350 that I had a few years ago, that used 64cc heads with flattops.
It was a basic 300hp 350 with a 210*@.050 hyd cam. But it was also in a chevelle, with 3.42 gears and a stock converter and a th400.
So being in a lighter car that's geared lower, with a 5 speed, such as yours, would give it an advantage as far as octane sensitivity, I believe.

 

I didn't say a .015" gasket; a .051" gasket.

 

I know that bro im saying I already bought one that was .015, if I went up that high to a .051 my quench gets all kindas messed up.

 

There's a long list of things that affect engine performance. If you arrange them starting at the top, you won't find "quench" there.

It's way, way down toward the bottom. Below cubic inches, comrpession ratio, flow, cam profile, ...... and a whole lot of other things.

Building a motor that will actually run on gasoline you can actually buy ranks a whole lot higher on the list of "things that matter" than "quench". To me, anyway. A motor with perfect "quench" that I have to leave sitting in the garage because I can't afford $5 a gallon race gas isn't my idea of how it should be done.

But that's just me; others may feel differently.

 

Agreed, already exchanged those head gaskets and got myself a pair of .0395 ones which should put me at almost exactly 10:1 which should be fine. Thanks for all the help guys.