Alright fellas I have got a set of 243's off of an 01 vette I bought for my 5.3 what is going to be my compression ratio with a 45ths gasket? Also how much am I going to need to have shaved off to get to 10 to 1 compression with a 40ths gasket??

 

which 5.3L do you have ? pro code ? or VIN ?or model ,, 5.3L is really near 10:1

if you use ls1 heads i think it would be around 11:1

 

I have an 01 5.3 it is 9.5 to one now with 57cc heads and I am going to 64cc heads I just wanted to know if anyone else here has done this swap and knows ???

 

5.3 Heads are 61cc and yes 243 heads are 64cc. And a 5.3 stock has about 9.5-9.6 compression. 706 and 862 (or 863 i forget) both have 61cc chambers. 0.030 mill will get you to about 57cc on a 5.3 head. Which will gain you about half a point in compression. So going to a 243 head will lose you almost half a point. Mill the 243 about .030 and you should be close to a stock 5.3 head. Hope this helps.

 

Thanks man you are a big help

 

that should get you close...

 

That swap has been done and it will lose a little power Unless you restore the comp ratio, with stock 862 heads the lm7 5.3 is 9.49:1 and 9.17:1 with 64cc LS6 or 243 heads, if you can mil them .035 and use .045 thick head gaskets you'll get 10.06:1 compression which would really help!

 

ok I am going to shave mine 30 and run a 40 gasket will I have to buy shorter push rods ??? I am asumming so

 

the 5.3 in question is mine. i have the 243 heads and .040 gaskets and im going to have them cut .030. do i have to worry about any clearance issues with a 224/228 cam? or what about my fast intake hitting my valley cover? or having to grind on my dowel pins because the hole is smaller? i need to know asap on what to cut them for a fact. id like more than 10.0 but if thats all i can get thats fine.

 

so?? I'm not exactly sure what I should do... what is the max compression you could have with a healthy cam on pump gas, from a daily driver?