243 heads, few questions...
Thread Starter
Melting Slicks
Joined: Feb 2014
Posts: 2,725
Likes: 149
From: chicago area IL.
243 heads, few questions...
I have a pair of 243 heads at the machine shop being checked out i got some info today about them, what bothered me is that stock 243 (non ls6) from what i read has a 64.45cc chamber, The machine shop checked them and they are 65.5cc chambers?
the heads have been ported here is what info I got on my heads
65.5cc chambers
215cc intake
77.5cc exhaust
this is what I read online for stock untouched 243 heads
64.45cc chambers
210cc intake
75cc exhaust
I'm worried compression will be lower since there is 1 point difference? this is a daily driven street car, can or should I bump compression to 11.1? for a daily driver is 11.1 ok? "if" I do bump the compression will i need to change push rod length?
list of mods 03 c5z
224/230 .581 .592 114 lsa cam
ported fast 92 / ls2 tb
kooks long tubes & gutted x pipe
monster stage 2 clutch
rpm lv5 m12
c6 diff upgrade & 3.73
B&B exhaust
of course dyno tune
tick adj master
I guess i'm really just trying to see "if" these heads are going to give me any Hp gain and should I mill them or is it opening up a can of worms?
the heads have been ported here is what info I got on my heads
65.5cc chambers
215cc intake
77.5cc exhaust
this is what I read online for stock untouched 243 heads
64.45cc chambers
210cc intake
75cc exhaust
I'm worried compression will be lower since there is 1 point difference? this is a daily driven street car, can or should I bump compression to 11.1? for a daily driver is 11.1 ok? "if" I do bump the compression will i need to change push rod length?
list of mods 03 c5z
224/230 .581 .592 114 lsa cam
ported fast 92 / ls2 tb
kooks long tubes & gutted x pipe
monster stage 2 clutch
rpm lv5 m12
c6 diff upgrade & 3.73
B&B exhaust
of course dyno tune
tick adj master
I guess i'm really just trying to see "if" these heads are going to give me any Hp gain and should I mill them or is it opening up a can of worms?
AMP Racing
Joined: Aug 2006
Posts: 10,757
Likes: 589
From: Washington TWP NJ
2023 C5 of the Year Finalist - Modified
2017 C5 of Year Finalist
St. Jude Donor '09-'10-'11-'12
I can see no reason not to mill those heads provided you have decent pump gas available.
11:1 is the lowest compression I would run. Why not go to 11.5:1? A good tune and good gas and you'll be fine.
You should measure pushrod length regardless of what you do to the heads.
Have fun with your project.
11:1 is the lowest compression I would run. Why not go to 11.5:1? A good tune and good gas and you'll be fine.
You should measure pushrod length regardless of what you do to the heads.
Have fun with your project.
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
I have had two sets of heads on my car killed to 58 cc. You may need shorted pushrods or you could possibly shim the rockers instead. With a cam the bump in compression is worth a few hp.
