hey, i just picked up a 383 shortblock for a steal of a price. the fella told me that using stock heads, compression is just about 10:1.

id like a little more out of it, also, ive seen on here that some of you feel compression should definitly be higher on a 383.

im using le2 heads, and a close variation of an le2 cam.

how much can i safely mill the heads and what kinda compression ratio jump can i expect?

i also have a really nice pushrod set and id like to be able to use them so can i take off any decent amount without needed new p.r's? there stock legnth btw

 

Instead of taking his word for it, can you measure the piston indentation or is that info available? Was the deck machined and if so how much? What gasket are you using? What are you going to be using the car for? What power adders are you going to have?

You are talking SCR but you also need to talk DCR. I would have to assume (I know bad to do) but with your cam and that SCR, you are talking under 8:1 DCR. I would have to say you can do much better especially if you can do some tuning. I have noted my SCR/DCR in my sig for instance. My Hawk 383 was similar DCR.

 

How much you can mill the heads, depends on what pistons your using..

 

working back into a PR length is just silly - I know you know that. Measure - if they work, consider yourself fortunate.

 

lolz but there so nice

so what affect would milling the heads have, say like, how much compression would be gained per amount milled off, anyone know that?

 

you don't know b.c the more you mill the mless cc you take out b/c the chamber is getting smaller and smaller.....

Why does it need more? is it down on power?

I would get the static where you want it first, then get a cam to get the dcr where you want it, then get spushrods...thats a drop in the bucket. If it runs and everything like it is I wouldn't mess with it.

also do you KNOW its 10:1 or just what the guy told you?

 

thanks for helping. it dosent NEED more power, i bought it as a long block and basically stripped it down to the rotating assembly and i thought 10:1 was kinda wimpy and would like a little more.

i dont know absolutely its 10:1 but the heads are stock cc and the pistons look similar to stock as far as relief depth.

i think ill just mill them .05 or .1 and whatever it does it does. im not looking to gain much here by just messing with the heads

 

Real men run 12:1on the street.

On a more serious note, if all I wanted to do was bump the compression, I would not tore a long block apart, to much work for small gain in my opinion. If it was me, I would just run a thinner head gasket if I was in your situation. Do what you want though. While you have the engine apart, does everything else checkout that the guy claimed? That might make believing his 10:1 more believable.

 

well if its a flat top and 52cc chamber you are looking at about 12.4:1

 

i wish it was 12:1..

i didnt tear it apart strictly to bump compression, i wanted to check out the pistons/cylinder/valves etc

everything checks out, in fact the rotating assembly looked mint. im gonna probably just gonna keep the stock thickness head gasket ( i have one already) and do a small deck off the heads and have them gone through again since there 4 years old and there was a fair amount of carbon buildup on the valves

so lets say i have like 10.4:1, something in that arena, will that be good with nitrous?

 

Victor Rentz Head Gaskets PN5898- you might want to try this out!

 

I run 12:1 on my build. I wanted to get the most possible out my N/a setup and be able to benefit from race fuel and advanced timing at the track so I went this route. Street tuning is vital though...

 

if its in fact a 383 with a flat top piston (-5cc relief) you have alot more then 10.4:1 on a flat top. its not a 350 anymore, the added stroke raises the CR alot.

 

that is exactly what i have and with the piston .01 in the hole, the victor gasket i mentioned above and a 55cc head its like 12.5:1 and i also run a 245/253 @ .050 to bring down the DCR.

 

Correct and here is a good resource for calc'n the CR.

http://www.csgnetwork.com/compcalc.html

I'm runnin' bout 10.5 (stock ratio) on my 383 with flat top SRP pistons -5cc) and AFR 190cc heads (68cc combustion chamber). Kinda wish I was running 11.5 or 12:1 as there is more power potention with a more stout cam as I am thinking of going with a custom grind later this year.