Compression with 272s?

[1fast97gsx]

What type of compression numbers are you guys getting with hks 272s? I was getting a solid 180 all the way across before the cams ( 9:1 pistons with thicker headgasket ), but once I put the cams in I only got 155 all the way across. I know its normal for static compression to drop, but 25 psi per cylinder??? My vacuum at idle is also only 11. I was expecting more like 13-14?

 

[scottsee]

yeah i've read it pretty common to expernce drop in compression #'s new cams.

 

[boostedinaz]

yeah i've read it pretty common to expernce drop in compression #'s new cams.

Yes, it is very normal to drop reading like that not only with compression numbers but also, vacuum at idle. I think 11 is a little low, but I still have stock cams so I cant say for sure.

 

[Waredtalontsi]

11-12 sounds about right for HKS 272's, thats what i get at idle. As for your compression that doesn't sound right. One my car have 8:5 compression and also a four layer head gasket and it blew 180 across all four.

 

[FourG63 97GST]

and what was the compression be4 the cams

 

[Staytuned]

I had 175-180 before and after cam installation. Thats with stock pistons and a Mitsu HG. I also pull 14 inches of vacuum at 900 rpm's. No boost leaks at all.