OK, guys, help me out here.

I'm looking to build/re-build my L98. I plan on 350ci, possibly 355 if the block needs some freshening....(it's old). I also know that I'm going with the SLP long tube set-up, fully ported, hi flow intake etc. Yea, I'm one of those long tube faithful. For financial reasons, I'm gonna go with Iron heads, no Aluminium. I've been reading just about anything I can to learn all the little details, and I've decided that I'm gonna have the shortblock assembled proffesionally. That's about as far as I've gotten so far, and here's the problem that I stuck on:

How do I decide what pistons / heads I need, in respect to my compression. Obviously I don't want my compression to high. Most of the heads I'm looking at have either 76cc or 64cc chambers, (or close). Do I want a larger combustion chamber and a domed piston? Maybe a smaller chamber, but pistons with 4 valve releifs? See, I've learned about all these options, but I don't understand how they all relate. I looked into just buying a replacement shortblock, but figured since I have the option...might as well do it right, while it's still an option. With all these options, i'm a bit overwhelmed, but I don't want to just hand someone my checkbook, and hope they know what they're doing. I want to know why I have a certain type of piston....why I chose a certain size combustion chamber.

Now I realize we could discuss each and every combo till the cows come home, but a specifc combo is not what I'm looking for. I'm simply looking for some basic ideas. I'm not looking for ridiculous HP either, but again, if I can make the right choice now while it's still out of the car, I'd like to do that.

Oh, and my stock L98: flat top pistons/76cc chambers right?



....and by all means, if I'm not asking the right questions, please tell me.

 

Stock L98 has 64cc chambers.

I'd suggest a good set of heads; Dart Iron Eagles, or Pro Toplines, or something like that. Moderate port volume; 200 cc is probably too much. 180 is a better match.

If you upgrade the intake base, you can increase the head size. You want to avoid the situation where you have a trickle of flow (stock base) into a huge lake of head port. Large tube headers, and a cam with about 220° of intake duration and lift appropriate to the heads, would help.

 

I'm by no means an expert, but....
I'd say go with a flat top and a smaller cumbustion chamber. Most engine builders feel that a dome can hurt flame travel, by "cutting it off", or basically getting in the way. a flat top piston with 4 valve reliefs and a 64 cc chamber is around 9.5:1 compression (off the top of my head, the # may be off), which is about where you want it for 93 octane.
A dished piston is usually used where lower compression is warranted, i.e. forced induction, nitrous, 87 octane.

 

Yea, I heard that about domed pistons. I've been looking at the Pro Topline heads....not sure which, but they seem to be affordable AND good performers.

...and the L98 has 64cc.....I should have known that

I'm gonna hog out the intake....probably the Accell.

Thanks

 

for the $$$, i like the sportsman IIs, they have a weak exhaust port, but the intake side flows really well, with pretty good velocity outta the box. You can just port out the exhaust side of the heads while you are doin the intake...
IMO, of course...

 

Your stock L98 heads have some potential.

On my set-up, I had 2.02 1.60 valves installed, pocket porting, screw in studs, enlarged spring pockets, some serious springs installed, milled .004", push rod holes enlarged, and guide plates installed for $400.
I did a mild port/polish job myself and saved a few more $$.

Someday I'll move up to some AFR's, but for now I'm happy.

For an every day driver that will never see power adders, hyperutetic pistons are a good choice. If you go with the hypers, make sure the short-block builder knows to use a larger ring gap for the top ring.