383 cam and carb choice

[Tim440RT]

Hey guys, looking for a suggestion to help me out a little bit. I have a 383 with a trw L2293 dome piston in it. 908 heads, ported just about as far as they can go. It's got isky ductile iron rockers which im guessing are stock ratio i don't know much about them. MY question here is this, im looking to run a cam that isn't so radical; its a .631 solid cam now. what's the smallest cam ill be able to run with this kind of compression. I heard this piston makes 13-1 with a 78 cc head, and 11.5-1 with an 88cc head. I have at my  house, a lunati Voodoo hydraulic cam P/n 60303 lift is .494intake .513 exhaust advertised duratio 268*intake 276*exhaust. Could i run this cam? How about if i used a thicker head gasket to lower the compression. If not what cam would you recommend, also what intake and carb would you recommend. I have a torker intake laying around, would get something else though. I am trying to be able to run on pump gas, or pump gas with an octane boost. I hope i didn't lose you there, thanks for all your help, and let me know if you need any more info....Tim

[Chryco Psycho]

do you want to stay with hydraulic cam even when you already have the adjustable rockers ??
 I have used a lot of the UltraDyne solid grinds , they are ground through Lunati < you can have them custom ground with different cl etc to comntrol compression etc
 if you have 906 heads [ there are no 908 castings ]  & .038 thick gaskets you will have approx 11:1 compression which is tough on pump fuel , I can give you a # of different grinds from UltraDyne that would work or contact Steveslavik@holley.com & he can  help you get the cam you need , most of the UltraDynes are high .500 lift but with faster ramp speed & shorter duration than you are likely runnign now
 the 276* VooDoo would build a lot of compression & would not be my foirst choice for a 11:1 engine

[moper]

Beofer you chose a cam, you need to know where teh engine really is in terms of building. I have a set of those domed TRWs on a shelf here. They were installed ina  440 block, and ran 906 heads. You'd think... well, the ctalog says they are 11:1... Except they were just installed. The deck height was never corrected for them. They were .070 down in the bore, and the resulting compression ratio was just shy of 10:1. See what you really have...My guess is you're just guessing any other way. Which does little to make it right.

[Tim440RT]

Ok, checked it out there, and the top of the piston is pretty darned close to being level with the deck, only about .008 in the hole. The only reason I had brought up using the Lunati cam was just because i have it laying around. Now I would like to start making power as close to 2,000 rpms as I can with this set-up so I think a grind up in the high 500's might be a little much. The cam that is in there is an ultra-dyne, I was told it has a 613 lift, don't know anything else about it. Thats a little too radical for what I am using it for. With all that said, is there a cam out there that'll be right for what I need, and also if you could suggest an intake and about how big of a carb im going to need. Thanks again for all your help and suggestions.

[moper]

Well, I'm guessing a little on a couple values. But... The area that within .008"... That's the flat surface on the top of the dome..right?   When you are asked about the piston's "deck hieght", what is being referenced is no tthe top of the dome, or the bottom of any dish. But the flat surface the dome or dish is protruding from/machined from. So really, if the dome is .008" above the block's deck, the flat the dome comes up from should be at least .060 down in the bore. So that means, that "11.5:1 piston" in your block with the average guestimate 78cc 906 open chamber, is really 8.8:1 static. That was the same issue with that 440 I mentionned before. In order for that to be true 11.5:1, the piston's flat surface would nee to come right close to the deck surface, and the dome would pop way out. If that's the case, that Lunati cam isnt a bad choice really. If you can't find the right cam in a catalog, it's because you dont have the right info top base the decision on.

[Tim440RT]

i was referring to the flat part of the piston is .008 below the deck of the block, this is a big dome, notsure how far up it sits from the deck

[Chryco Psycho]

THe Holley Street Dom or the Eddy RPM are both great choices , the low deck SD is no longer available new but can be found used & both will work well in the 2000-6000 range
 I would use 2X the CI  so a 750 -800 Holley or Proform  Double pump carb would be my choice 
What are you doing with the UltraDyne that you are removing , if it is in good shape I could be interested 

[Tim440RT]

I'll let you know how it looks when I pull it out. Thanks for your help

[moper]

i was referring to the flat part of the piston is .008 below the deck of the block, this is a big dome, notsure how far up it sits from the deck

Ok, then you're fine.  SO much for assuming eh?