Building a 383 (was already built, might change a few things). Currently as it sits it has some what the guy said flat tops made by speed pro. Im going to put some older dart II heads on it (sportsman II now). The current cam is this...(http://www.summitracing.com/parts/CCA-12-223-4/), or i can put the 306s solid in it (also have it). I also have some of these pistons (http://www.summitracing.com/parts/UEM-KB111-030/) that are spec'd and good to go in the block. It has a summit forged 383 crank in it and i'm guessing stock rods. I plan on running an edelbrock "street" tunnel ram with 2 holley 4776 450cfm carbs. I also already have all of this. I want to keep it on pump gas, will this be possible with the bigger cam and the KB pistons? The block has not been milled down to my knoweldge and the heads are 64cc combustion chanmbers and haven't been shaved either. Just looking for some advice. Just an fyi, this is goin in my 89 rs camaro.

 

going to those dome pistons is going to put your compression way up and using cast iron heads would make it a big problem even with the larger 306 cam. Rule of thumb if using iron head's try to stay around 9.5CR to avoid detonation when the engine is new you can get away with higher CR's untill carbon starts to build up.

 

Rough guessing deck height and gasket thickness, I come up with 10.7:1 CR, using the KB hyps. With cast iron heads, that's pushing it on pump gas. The current cam with the flat tops(about 9.5:1 CR) is probably more what you want for the street.

 

Kind of what I was thinkin. Anyone ever mess with e85? How much hp would be lost with the flat tops and smaller cam?

 

E85 is more detonation resistant. If you run this motor on Ethanol, you may be able to run the dome pistons. As far as the bigger cam goes, the problem is loss of low RPM drivability. The ZZX cam I run is 290 degrees and .560 lift single pattern. I run it with 10.2:1 CR. But its also a roller cam. The difference between roller and flat tappet is low rpm compression loss. I still get the same high rpm power. If you were to ask me about a 300 degree roller cam, I might say go for it.

 

for the bigger cam, are you talking my bigger cam or a bigger one than my bigger one? Sorry for all the biggers and questions....haha. I have plans of putting a different rear end in it in the near future so a gearing change is something i can do to help with the low end loss.....i know the 306s cam makes some serious power up top from what i hear. My goal is 450hp at the lowest, would like more and with the KB pistons and the big cam i can see higher 400s maybe? I would love to run the tunnel ram but if i end up going with a fuel that requires me to modify the carbs, i'll just put it on my chevelle instead.

 

By bigger cam, i mean the 306s. That cam is massive for the street. I dont see you making that work in a streetable combo. And I like big cams. Again, if it were a roller cam, I might feel differently. It's huge even as a roller but would be much more forgiving. The 282degree cam will put you easily at 450 with proper tuning.

 

So 282 with the flat tops? What about the 282 with the kb pistons and 72cc combustion chambers? Just lookin at it from all different angles

 

Tomato/tomato, either combo gets you about the same CR. All other things being the same, cant say it makes much difference. you will probably like the hypo pistons better on the street. No cold start piston knock. And the KB Silvolites are plenty strong for serious duty.

 

well, the flat tops and the 282 cam is currently in the motor with some stock heads, so i'll probably just leave it as is and put my Dart IIs on it and call it good. I would be happy with 450 hp for now.

 

What's the intake runner size on the Dart IIs?

 

Pretty sure its 200cc

 

Stock were all 200cc. Ported - well.....

 

they are stock, never been touched other than some guides and seals at one time.

 

200cc is too small for the 306 cam. That cam would want more like 230cc. However, with the 282 cam, those ports should work fine. 450hp shouldn't be a problem with tuning. I would suggest something like an Edelbrock Performer RPM with 750cfm carb. The 282 cam and 200cc ports are almost big enough for a single plane intake like the Victor Jr. The Victor Jr will produce max top end horsepower, the dual plane Performer RPM will produce a more streetable torque curve.